Add more lints

.cargo/config

@@ -15,4 +15,7 @@ rustflags = [
     "-Dclippy::todo",
     "-Dclippy::unnecessary_wraps",
     "-Dclippy::useless_transmute",
+    "-Delided_lifetimes_in_paths",
+    "-Dunused_lifetimes",
+    "-Drust_2021_prelude_collisions"
 ]

README.md

@@ -86,7 +86,7 @@ fn sum_as_string(a: usize, b: usize) -> PyResult<String> {
 /// the `lib.name` setting in the `Cargo.toml`, else Python will not be able to
 /// import the module.
 #[pymodule]
-fn string_sum(_py: Python, m: &PyModule) -> PyResult<()> {
+fn string_sum(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(sum_as_string, m)?)?;
     Ok(())
 }

benches/bench_call.rs

@@ -8,7 +8,7 @@ macro_rules! test_module {
     };
 }
 
-fn bench_call_0(b: &mut Bencher) {
+fn bench_call_0(b: &mut Bencher<'_>) {
     Python::with_gil(|py| {
         let module = test_module!(py, "def foo(): pass");
 
@@ -22,7 +22,7 @@ fn bench_call_0(b: &mut Bencher) {
     })
 }
 
-fn bench_call_method_0(b: &mut Bencher) {
+fn bench_call_method_0(b: &mut Bencher<'_>) {
     Python::with_gil(|py| {
         let module = test_module!(
             py,

benches/bench_dict.rs

@@ -4,7 +4,7 @@ use pyo3::prelude::*;
 use pyo3::types::IntoPyDict;
 use std::collections::{BTreeMap, HashMap};
 
-fn iter_dict(b: &mut Bencher) {
+fn iter_dict(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 100_000;
@@ -18,14 +18,14 @@ fn iter_dict(b: &mut Bencher) {
     });
 }
 
-fn dict_new(b: &mut Bencher) {
+fn dict_new(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 50_000;
     b.iter(|| (0..LEN as u64).map(|i| (i, i * 2)).into_py_dict(py));
 }
 
-fn dict_get_item(b: &mut Bencher) {
+fn dict_get_item(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 50_000;
@@ -38,7 +38,7 @@ fn dict_get_item(b: &mut Bencher) {
     });
 }
 
-fn extract_hashmap(b: &mut Bencher) {
+fn extract_hashmap(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 100_000;
@@ -46,7 +46,7 @@ fn extract_hashmap(b: &mut Bencher) {
     b.iter(|| HashMap::<u64, u64>::extract(dict));
 }
 
-fn extract_btreemap(b: &mut Bencher) {
+fn extract_btreemap(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 100_000;
@@ -55,7 +55,7 @@ fn extract_btreemap(b: &mut Bencher) {
 }
 
 #[cfg(feature = "hashbrown")]
-fn extract_hashbrown_map(b: &mut Bencher) {
+fn extract_hashbrown_map(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 100_000;

benches/bench_err.rs

@@ -2,7 +2,7 @@ use criterion::{criterion_group, criterion_main, Bencher, Criterion};
 
 use pyo3::{exceptions::PyValueError, prelude::*};
 
-fn err_new_restore_and_fetch(b: &mut Bencher) {
+fn err_new_restore_and_fetch(b: &mut Bencher<'_>) {
     Python::with_gil(|py| {
         b.iter(|| {
             PyValueError::new_err("some exception message").restore(py);
@@ -11,7 +11,7 @@ fn err_new_restore_and_fetch(b: &mut Bencher) {
     })
 }
 
-fn err_new_without_gil(b: &mut Bencher) {
+fn err_new_without_gil(b: &mut Bencher<'_>) {
     b.iter(|| PyValueError::new_err("some exception message"))
 }
 

benches/bench_frompyobject.rs

@@ -9,7 +9,7 @@ enum ManyTypes {
     String(String),
 }
 
-fn enum_from_pyobject(b: &mut Bencher) {
+fn enum_from_pyobject(b: &mut Bencher<'_>) {
     Python::with_gil(|py| {
         let obj = PyString::new(py, "hello world");
         b.iter(|| {

benches/bench_gil.rs

@@ -2,7 +2,7 @@ use criterion::{criterion_group, criterion_main, BatchSize, Bencher, Criterion};
 
 use pyo3::{prelude::*, GILPool};
 
-fn bench_clean_gilpool_new(b: &mut Bencher) {
+fn bench_clean_gilpool_new(b: &mut Bencher<'_>) {
     Python::with_gil(|_py| {
         b.iter(|| {
             let _ = unsafe { GILPool::new() };
@@ -10,14 +10,14 @@ fn bench_clean_gilpool_new(b: &mut Bencher) {
     });
 }
 
-fn bench_clean_acquire_gil(b: &mut Bencher) {
+fn bench_clean_acquire_gil(b: &mut Bencher<'_>) {
     // Acquiring first GIL will also create a "clean" GILPool, so this measures the Python overhead.
     b.iter(|| {
         let _ = Python::acquire_gil();
     });
 }
 
-fn bench_dirty_acquire_gil(b: &mut Bencher) {
+fn bench_dirty_acquire_gil(b: &mut Bencher<'_>) {
     let obj = Python::with_gil(|py| py.None());
     b.iter_batched(
         || {

benches/bench_list.rs

@@ -3,7 +3,7 @@ use criterion::{criterion_group, criterion_main, Bencher, Criterion};
 use pyo3::prelude::*;
 use pyo3::types::PyList;
 
-fn iter_list(b: &mut Bencher) {
+fn iter_list(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 100_000;
@@ -17,14 +17,14 @@ fn iter_list(b: &mut Bencher) {
     });
 }
 
-fn list_new(b: &mut Bencher) {
+fn list_new(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 50_000;
     b.iter(|| PyList::new(py, 0..LEN));
 }
 
-fn list_get_item(b: &mut Bencher) {
+fn list_get_item(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 50_000;
@@ -38,7 +38,7 @@ fn list_get_item(b: &mut Bencher) {
 }
 
 #[cfg(not(Py_LIMITED_API))]
-fn list_get_item_unchecked(b: &mut Bencher) {
+fn list_get_item_unchecked(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 50_000;

benches/bench_pyclass.rs

@@ -26,7 +26,7 @@ impl MyClass {
     }
 }
 
-pub fn first_time_init(b: &mut criterion::Bencher) {
+pub fn first_time_init(b: &mut criterion::Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     b.iter(|| {

benches/bench_pyobject.rs

@@ -2,7 +2,7 @@ use criterion::{criterion_group, criterion_main, Bencher, Criterion};
 
 use pyo3::prelude::*;
 
-fn drop_many_objects(b: &mut Bencher) {
+fn drop_many_objects(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     b.iter(|| {

benches/bench_set.rs

@@ -4,7 +4,7 @@ use pyo3::prelude::*;
 use pyo3::types::PySet;
 use std::collections::{BTreeSet, HashSet};
 
-fn iter_set(b: &mut Bencher) {
+fn iter_set(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 100_000;
@@ -18,7 +18,7 @@ fn iter_set(b: &mut Bencher) {
     });
 }
 
-fn extract_hashset(b: &mut Bencher) {
+fn extract_hashset(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 100_000;
@@ -26,7 +26,7 @@ fn extract_hashset(b: &mut Bencher) {
     b.iter(|| HashSet::<u64>::extract(set));
 }
 
-fn extract_btreeset(b: &mut Bencher) {
+fn extract_btreeset(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 100_000;
@@ -35,7 +35,7 @@ fn extract_btreeset(b: &mut Bencher) {
 }
 
 #[cfg(feature = "hashbrown")]
-fn extract_hashbrown_set(b: &mut Bencher) {
+fn extract_hashbrown_set(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 100_000;

benches/bench_tuple.rs

@@ -3,7 +3,7 @@ use criterion::{criterion_group, criterion_main, Bencher, Criterion};
 use pyo3::prelude::*;
 use pyo3::types::PyTuple;
 
-fn iter_tuple(b: &mut Bencher) {
+fn iter_tuple(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 100_000;
@@ -17,14 +17,14 @@ fn iter_tuple(b: &mut Bencher) {
     });
 }
 
-fn tuple_new(b: &mut Bencher) {
+fn tuple_new(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 50_000;
     b.iter(|| PyTuple::new(py, 0..LEN));
 }
 
-fn tuple_get_item(b: &mut Bencher) {
+fn tuple_get_item(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 50_000;
@@ -38,7 +38,7 @@ fn tuple_get_item(b: &mut Bencher) {
 }
 
 #[cfg(not(Py_LIMITED_API))]
-fn tuple_get_item_unchecked(b: &mut Bencher) {
+fn tuple_get_item_unchecked(b: &mut Bencher<'_>) {
     let gil = Python::acquire_gil();
     let py = gil.python();
     const LEN: usize = 50_000;

examples/decorator/src/lib.rs

@@ -29,7 +29,7 @@ impl PyCounter {
     #[args(args = "*", kwargs = "**")]
     fn __call__(
         &mut self,
-        py: Python,
+        py: Python<'_>,
         args: &PyTuple,
         kwargs: Option<&PyDict>,
     ) -> PyResult<Py<PyAny>> {
@@ -48,7 +48,7 @@ impl PyCounter {
 }
 
 #[pymodule]
-pub fn decorator(_py: Python, module: &PyModule) -> PyResult<()> {
+pub fn decorator(_py: Python<'_>, module: &PyModule) -> PyResult<()> {
     module.add_class::<PyCounter>()?;
     Ok(())
 }

examples/maturin-starter/src/lib.rs

@@ -21,7 +21,7 @@ impl ExampleClass {
 
 /// An example module implemented in Rust using PyO3.
 #[pymodule]
-fn maturin_starter(py: Python, m: &PyModule) -> PyResult<()> {
+fn maturin_starter(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<ExampleClass>()?;
     m.add_wrapped(wrap_pymodule!(submodule))?;
 

examples/maturin-starter/src/submodule.rs

@@ -16,7 +16,7 @@ impl SubmoduleClass {
 }
 
 #[pymodule]
-pub fn submodule(_py: Python, m: &PyModule) -> PyResult<()> {
+pub fn submodule(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<SubmoduleClass>()?;
     Ok(())
 }

examples/setuptools-rust-starter/src/lib.rs

@@ -21,7 +21,7 @@ impl ExampleClass {
 
 /// An example module implemented in Rust using PyO3.
 #[pymodule]
-fn _setuptools_rust_starter(py: Python, m: &PyModule) -> PyResult<()> {
+fn _setuptools_rust_starter(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<ExampleClass>()?;
     m.add_wrapped(wrap_pymodule!(submodule))?;
 

examples/setuptools-rust-starter/src/submodule.rs

@@ -16,7 +16,7 @@ impl SubmoduleClass {
 }
 
 #[pymodule]
-pub fn submodule(_py: Python, m: &PyModule) -> PyResult<()> {
+pub fn submodule(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<SubmoduleClass>()?;
     Ok(())
 }

examples/word-count/src/lib.rs

@@ -17,7 +17,7 @@ fn search_sequential(contents: &str, needle: &str) -> usize {
 }
 
 #[pyfunction]
-fn search_sequential_allow_threads(py: Python, contents: &str, needle: &str) -> usize {
+fn search_sequential_allow_threads(py: Python<'_>, contents: &str, needle: &str) -> usize {
     py.allow_threads(|| search_sequential(contents, needle))
 }
 

guide/src/class.md

@@ -113,7 +113,7 @@ The next step is to create the module initializer and add our class to it
 # struct Number(i32);
 #
 #[pymodule]
-fn my_module(_py: Python, m: &PyModule) -> PyResult<()> {
+fn my_module(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<Number>()?;
     Ok(())
 }
@@ -273,7 +273,7 @@ impl SubClass {
         (SubClass { val2: 15 }, BaseClass::new())
     }
 
-    fn method2(self_: PyRef<Self>) -> PyResult<usize> {
+    fn method2(self_: PyRef<'_, Self>) -> PyResult<usize> {
         let super_ = self_.as_ref();  // Get &BaseClass
         super_.method().map(|x| x * self_.val2)
     }
@@ -292,9 +292,9 @@ impl SubSubClass {
             .add_subclass(SubSubClass{val3: 20})
     }
 
-    fn method3(self_: PyRef<Self>) -> PyResult<usize> {
+    fn method3(self_: PyRef<'_, Self>) -> PyResult<usize> {
         let v = self_.val3;
-        let super_ = self_.into_super();  // Get PyRef<SubClass>
+        let super_ = self_.into_super();  // Get PyRef<'_, SubClass>
         SubClass::method2(super_).map(|x| x * v)
     }
 }
@@ -329,7 +329,7 @@ impl DictWithCounter {
     fn new() -> Self {
         Self::default()
     }
-    fn set(mut self_: PyRefMut<Self>, key: String, value: &PyAny) -> PyResult<()> {
+    fn set(mut self_: PyRefMut<'_, Self>, key: String, value: &PyAny) -> PyResult<()> {
         self_.counter.entry(key.clone()).or_insert(0);
         let py = self_.py();
         let dict: &PyDict = unsafe { py.from_borrowed_ptr_or_err(self_.as_ptr())? };
@@ -524,7 +524,7 @@ gets injected by the method wrapper, e.g.
 # }
 #[pymethods]
 impl MyClass {
-    fn method2(&self, py: Python) -> PyResult<i32> {
+    fn method2(&self, py: Python<'_>) -> PyResult<i32> {
         Ok(10)
     }
 }
@@ -960,7 +960,7 @@ unsafe impl pyo3::PyTypeInfo for MyClass {
     const MODULE: Option<&'static str> = None;
 
     #[inline]
-    fn type_object_raw(py: pyo3::Python) -> *mut pyo3::ffi::PyTypeObject {
+    fn type_object_raw(py: pyo3::Python<'_>) -> *mut pyo3::ffi::PyTypeObject {
         use pyo3::type_object::LazyStaticType;
         static TYPE_OBJECT: LazyStaticType = LazyStaticType::new();
         TYPE_OBJECT.get_or_init::<Self>(py)
@@ -974,7 +974,7 @@ impl pyo3::pyclass::PyClass for MyClass {
 }
 
 impl pyo3::IntoPy<PyObject> for MyClass {
-    fn into_py(self, py: pyo3::Python) -> pyo3::PyObject {
+    fn into_py(self, py: pyo3::Python<'_>) -> pyo3::PyObject {
         pyo3::IntoPy::into_py(pyo3::Py::new(py, self).unwrap(), py)
     }
 }

guide/src/class/numeric.md

@@ -134,7 +134,7 @@ impl Number {
 #
 #[pymethods]
 impl Number {
-    fn __pos__(slf: PyRef<Self>) -> PyRef<Self> {
+    fn __pos__(slf: PyRef<'_, Self>) -> PyRef<'_, Self> {
         slf
     }
 
@@ -328,7 +328,7 @@ impl Number {
 }
 
 #[pymodule]
-fn my_module(_py: Python, m: &PyModule) -> PyResult<()> {
+fn my_module(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<Number>()?;
     Ok(())
 }
@@ -426,7 +426,7 @@ use pyo3::ffi;
 use pyo3::conversion::AsPyPointer;
 
 fn wrap(obj: &PyAny) -> Result<i32, PyErr> {
-    let py: Python = obj.py();
+    let py: Python<'_> = obj.py();
 
     unsafe {
         let ptr = obj.as_ptr();

guide/src/class/object.md

@@ -17,7 +17,7 @@ impl Number {
 }
 
 #[pymodule]
-fn my_module(_py: Python, m: &PyModule) -> PyResult<()> {
+fn my_module(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<Number>()?;
     Ok(())
 }
@@ -220,7 +220,7 @@ impl Number {
 }
 
 #[pymodule]
-fn my_module(_py: Python, m: &PyModule) -> PyResult<()> {
+fn my_module(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<Number>()?;
     Ok(())
 }

guide/src/class/protocols.md

@@ -22,8 +22,8 @@ When PyO3 handles a magic method, a couple of changes apply compared to other `#
 The following sections list of all magic methods PyO3 currently handles.  The
 given signatures should be interpreted as follows:
  - All methods take a receiver as first argument, shown as `<self>`. It can be
-   `&self`, `&mut self` or a `PyCell` reference like `self_: PyRef<Self>` and
-   `self_: PyRefMut<Self>`, as described [here](../class.md#inheritance).
+   `&self`, `&mut self` or a `PyCell` reference like `self_: PyRef<'_, Self>` and
+   `self_: PyRefMut<'_, Self>`, as described [here](../class.md#inheritance).
  - An optional `Python<'py>` argument is always allowed as the first argument.
  - Return values can be optionally wrapped in `PyResult`.
  - `object` means that any type is allowed that can be extracted from a Python
@@ -118,10 +118,10 @@ struct MyIterator {
 
 #[pymethods]
 impl MyIterator {
-    fn __iter__(slf: PyRef<Self>) -> PyRef<Self> {
+    fn __iter__(slf: PyRef<'_, Self>) -> PyRef<'_, Self> {
         slf
     }
-    fn __next__(mut slf: PyRefMut<Self>) -> Option<PyObject> {
+    fn __next__(mut slf: PyRefMut<'_, Self>) -> Option<PyObject> {
         slf.iter.next()
     }
 }
@@ -142,11 +142,11 @@ struct Iter {
 
 #[pymethods]
 impl Iter {
-    fn __iter__(slf: PyRef<Self>) -> PyRef<Self> {
+    fn __iter__(slf: PyRef<'_, Self>) -> PyRef<'_, Self> {
         slf
     }
 
-    fn __next__(mut slf: PyRefMut<Self>) -> Option<usize> {
+    fn __next__(mut slf: PyRefMut<'_, Self>) -> Option<usize> {
         slf.inner.next()
     }
 }
@@ -158,7 +158,7 @@ struct Container {
 
 #[pymethods]
 impl Container {
-    fn __iter__(slf: PyRef<Self>) -> PyResult<Py<Iter>> {
+    fn __iter__(slf: PyRef<'_, Self>) -> PyResult<Py<Iter>> {
         let iter = Iter {
             inner: slf.iter.clone().into_iter(),
         };
@@ -355,7 +355,7 @@ object.  `__clear__` must clear out any mutable references to other Python
 objects (thus breaking reference cycles). Immutable references do not have to be
 cleared, as every cycle must contain at least one mutable reference.
 
-  - `__traverse__(<self>, pyo3::class::gc::PyVisit) -> Result<(), pyo3::class::gc::PyTraverseError>`
+  - `__traverse__(<self>, pyo3::class::gc::PyVisit<'_>) -> Result<(), pyo3::class::gc::PyTraverseError>`
   - `__clear__(<self>) -> ()`
 
 Example:
@@ -372,7 +372,7 @@ struct ClassWithGCSupport {
 
 #[pymethods]
 impl ClassWithGCSupport {
-    fn __traverse__(&self, visit: PyVisit) -> Result<(), PyTraverseError> {
+    fn __traverse__(&self, visit: PyVisit<'_>) -> Result<(), PyTraverseError> {
         if let Some(obj) = &self.obj {
             visit.call(obj)?
         }
@@ -580,10 +580,10 @@ For a mapping, the keys may be Python objects of arbitrary type.
 
 Iterators can be defined using the [`PyIterProtocol`] trait.
 It includes two methods `__iter__` and `__next__`:
-  * `fn __iter__(slf: PyRefMut<Self>) -> PyResult<impl IntoPy<PyObject>>`
-  * `fn __next__(slf: PyRefMut<Self>) -> PyResult<Option<impl IntoPy<PyObject>>>`
+  * `fn __iter__(slf: PyRefMut<'_, Self>) -> PyResult<impl IntoPy<PyObject>>`
+  * `fn __next__(slf: PyRefMut<'_, Self>) -> PyResult<Option<impl IntoPy<PyObject>>>`
 
-These two methods can be take either `PyRef<Self>` or `PyRefMut<Self>` as their
+These two methods can be take either `PyRef<'_, Self>` or `PyRefMut<'_, Self>` as their
 first argument, so that mutable borrow can be avoided if needed.
 
 For details, look at the `#[pymethods]` regarding iterator methods.

guide/src/conversions/traits.md

@@ -253,7 +253,7 @@ enum RustyEnum<'a> {
 #     Python::with_gil(|py| -> PyResult<()> {
 #         {
 #             let thing = 42_u8.to_object(py);
-#             let rust_thing: RustyEnum = thing.extract(py)?;
+#             let rust_thing: RustyEnum<'_> = thing.extract(py)?;
 # 
 #             assert_eq!(
 #                 42,
@@ -265,7 +265,7 @@ enum RustyEnum<'a> {
 #         }
 #         {
 #             let thing = PyString::new(py, "text");
-#             let rust_thing: RustyEnum = thing.extract()?;
+#             let rust_thing: RustyEnum<'_> = thing.extract()?;
 # 
 #             assert_eq!(
 #                 "text",
@@ -277,7 +277,7 @@ enum RustyEnum<'a> {
 #         }
 #         {
 #             let thing = (32_u8, 73_u8).to_object(py);
-#             let rust_thing: RustyEnum = thing.extract(py)?;
+#             let rust_thing: RustyEnum<'_> = thing.extract(py)?;
 # 
 #             assert_eq!(
 #                 (32, 73),
@@ -289,7 +289,7 @@ enum RustyEnum<'a> {
 #         }
 #         {
 #             let thing = ("foo", 73_u8).to_object(py);
-#             let rust_thing: RustyEnum = thing.extract(py)?;
+#             let rust_thing: RustyEnum<'_> = thing.extract(py)?;
 # 
 #             assert_eq!(
 #                 (String::from("foo"), 73),
@@ -313,7 +313,7 @@ enum RustyEnum<'a> {
 # 
 #             let class = module.getattr("Foo")?;
 #             let instance = class.call0()?;
-#             let rust_thing: RustyEnum = instance.extract()?;
+#             let rust_thing: RustyEnum<'_> = instance.extract()?;
 # 
 #             assert_eq!(
 #                 (0, 1, 2),
@@ -337,7 +337,7 @@ enum RustyEnum<'a> {
 # 
 #             let class = module.getattr("Foo")?;
 #             let instance = class.call0()?;
-#             let rust_thing: RustyEnum = instance.extract()?;
+#             let rust_thing: RustyEnum<'_> = instance.extract()?;
 # 
 #             assert_eq!(
 #                 (3, 4),
@@ -350,7 +350,7 @@ enum RustyEnum<'a> {
 # 
 #         {
 #             let thing = PyBytes::new(py, b"text");
-#             let rust_thing: RustyEnum = thing.extract()?;
+#             let rust_thing: RustyEnum<'_> = thing.extract()?;
 # 
 #             assert_eq!(
 #                 b"text",
@@ -464,7 +464,7 @@ use pyo3::prelude::*;
 struct MyPyObjectWrapper(PyObject);
 
 impl IntoPy<PyObject> for MyPyObjectWrapper {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.0
     }
 }

guide/src/ecosystem/async-await.md

@@ -118,7 +118,7 @@ Export an async function that makes use of `async-std`:
 use pyo3::{prelude::*, wrap_pyfunction};
 
 #[pyfunction]
-fn rust_sleep(py: Python) -> PyResult<&PyAny> {
+fn rust_sleep(py: Python<'_>) -> PyResult<&PyAny> {
     pyo3_asyncio::async_std::future_into_py(py, async {
         async_std::task::sleep(std::time::Duration::from_secs(1)).await;
         Ok(Python::with_gil(|py| py.None()))
@@ -126,7 +126,7 @@ fn rust_sleep(py: Python) -> PyResult<&PyAny> {
 }
 
 #[pymodule]
-fn my_async_module(py: Python, m: &PyModule) -> PyResult<()> {
+fn my_async_module(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(rust_sleep, m)?)?;
 
     Ok(())
@@ -142,7 +142,7 @@ If you want to use `tokio` instead, here's what your module should look like:
 use pyo3::{prelude::*, wrap_pyfunction};
 
 #[pyfunction]
-fn rust_sleep(py: Python) -> PyResult<&PyAny> {
+fn rust_sleep(py: Python<'_>) -> PyResult<&PyAny> {
     pyo3_asyncio::tokio::future_into_py(py, async {
         tokio::time::sleep(std::time::Duration::from_secs(1)).await;
         Ok(Python::with_gil(|py| py.None()))
@@ -150,7 +150,7 @@ fn rust_sleep(py: Python) -> PyResult<&PyAny> {
 }
 
 #[pymodule]
-fn my_async_module(py: Python, m: &PyModule) -> PyResult<()> {
+fn my_async_module(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(rust_sleep, m)?)?;
     Ok(())
 }
@@ -316,7 +316,7 @@ async fn rust_sleep() {
 }
 
 #[pyfunction]
-fn call_rust_sleep(py: Python) -> PyResult<&PyAny> {
+fn call_rust_sleep(py: Python<'_>) -> PyResult<&PyAny> {
     pyo3_asyncio::async_std::future_into_py(py, async move {
         rust_sleep().await;
         Ok(Python::with_gil(|py| py.None()))
@@ -466,7 +466,7 @@ tokio = "1.4"
 use pyo3::{prelude::*, wrap_pyfunction};
 
 #[pyfunction]
-fn rust_sleep(py: Python) -> PyResult<&PyAny> {
+fn rust_sleep(py: Python<'_>) -> PyResult<&PyAny> {
     pyo3_asyncio::tokio::future_into_py(py, async {
         tokio::time::sleep(std::time::Duration::from_secs(1)).await;
         Ok(Python::with_gil(|py| py.None()))
@@ -474,7 +474,7 @@ fn rust_sleep(py: Python) -> PyResult<&PyAny> {
 }
 
 #[pymodule]
-fn my_async_module(_py: Python, m: &PyModule) -> PyResult<()> {
+fn my_async_module(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(rust_sleep, m)?)?;
 
     Ok(())

guide/src/exception.md

@@ -38,7 +38,7 @@ the module like this, so that it is importable from Python:
 create_exception!(mymodule, CustomError, PyException);
 
 #[pymodule]
-fn mymodule(py: Python, m: &PyModule) -> PyResult<()> {
+fn mymodule(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     // ... other elements added to module ...
     m.add("CustomError", py.get_type::<CustomError>())?;
 
@@ -151,7 +151,7 @@ struct CustomIOError;
 impl std::error::Error for CustomIOError {}
 
 impl fmt::Display for CustomIOError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "Oh no!")
     }
 }

guide/src/faq.md

@@ -116,7 +116,7 @@ struct Outer {
 #[pymethods]
 impl Outer {
     #[new]
-    fn __new__(py: Python) -> PyResult<Self> {
+    fn __new__(py: Python<'_>) -> PyResult<Self> {
         Ok(Self {
             inner: Py::new(py, Inner {})?,
         })

guide/src/function.md

@@ -13,7 +13,7 @@ fn double(x: usize) -> usize {
 }
 
 #[pymodule]
-fn my_extension(py: Python, m: &PyModule) -> PyResult<()> {
+fn my_extension(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(double, m)?)?;
     Ok(())
 }
@@ -49,7 +49,7 @@ The `#[pyo3]` attribute can be used to modify properties of the generated Python
     fn no_args_py() -> usize { 42 }
 
     #[pymodule]
-    fn module_with_functions(py: Python, m: &PyModule) -> PyResult<()> {
+    fn module_with_functions(py: Python<'_>, m: &PyModule) -> PyResult<()> {
         m.add_function(wrap_pyfunction!(no_args_py, m)?)?;
         Ok(())
     }
@@ -113,7 +113,7 @@ The `#[pyo3]` attribute can be used to modify properties of the generated Python
     }
 
     #[pymodule]
-    fn module_with_fn(py: Python, m: &PyModule) -> PyResult<()> {
+    fn module_with_fn(py: Python<'_>, m: &PyModule) -> PyResult<()> {
         m.add_function(wrap_pyfunction!(pyfunction_with_module, m)?)
     }
     ```
@@ -132,7 +132,7 @@ fn num_kwds(kwds: Option<&PyDict>) -> usize {
 }
 
 #[pymodule]
-fn module_with_functions(py: Python, m: &PyModule) -> PyResult<()> {
+fn module_with_functions(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(num_kwds, m)?).unwrap();
     Ok(())
 }
@@ -273,7 +273,7 @@ An example of `#[pyfn]` is below:
 use pyo3::prelude::*;
 
 #[pymodule]
-fn my_extension(py: Python, m: &PyModule) -> PyResult<()> {
+fn my_extension(py: Python<'_>, m: &PyModule) -> PyResult<()> {
 
     #[pyfn(m)]
     fn double(x: usize) -> usize {
@@ -291,7 +291,7 @@ documented in the rest of this chapter. The code above is expanded to the follow
 use pyo3::prelude::*;
 
 #[pymodule]
-fn my_extension(py: Python, m: &PyModule) -> PyResult<()> {
+fn my_extension(py: Python<'_>, m: &PyModule) -> PyResult<()> {
 
     #[pyfunction]
     fn double(x: usize) -> usize {

guide/src/migration.md

@@ -117,7 +117,7 @@ mod foo {
     use pyo3::prelude::*;
 
     #[pymodule]
-    fn private_submodule(_py: Python, m: &PyModule) -> PyResult<()> {
+    fn private_submodule(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
         Ok(())
     }
 }
@@ -126,7 +126,7 @@ use pyo3::prelude::*;
 use foo::*;
 
 #[pymodule]
-fn my_module(_py: Python, m: &PyModule) -> PyResult<()> {
+fn my_module(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_wrapped(wrap_pymodule!(private_submodule))?;
     Ok(())
 }
@@ -139,7 +139,7 @@ mod foo {
     use pyo3::prelude::*;
 
     #[pymodule]
-    pub(crate) fn private_submodule(_py: Python, m: &PyModule) -> PyResult<()> {
+    pub(crate) fn private_submodule(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
         Ok(())
     }
 }
@@ -149,7 +149,7 @@ use pyo3::wrap_pymodule;
 use foo::*;
 
 #[pymodule]
-fn my_module(_py: Python, m: &PyModule) -> PyResult<()> {
+fn my_module(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_wrapped(wrap_pymodule!(private_submodule))?;
     Ok(())
 }
@@ -346,7 +346,7 @@ Before:
 struct MyPyObjectWrapper(PyObject);
 
 impl FromPy<MyPyObjectWrapper> for PyObject {
-    fn from_py(other: MyPyObjectWrapper, _py: Python) -> Self {
+    fn from_py(other: MyPyObjectWrapper, _py: Python<'_>) -> Self {
         other.0
     }
 }
@@ -358,7 +358,7 @@ After
 struct MyPyObjectWrapper(PyObject);
 
 impl IntoPy<PyObject> for MyPyObjectWrapper {
-    fn into_py(self, _py: Python) -> PyObject {
+    fn into_py(self, _py: Python<'_>) -> PyObject {
         self.0
     }
 }
@@ -676,10 +676,10 @@ let obj: &PyAny = create_obj();
 let obj_cell: &PyCell<MyClass> = obj.extract().unwrap();
 let obj_cloned: MyClass = obj.extract().unwrap(); // extracted by cloning the object
 {
-    let obj_ref: PyRef<MyClass> = obj.extract().unwrap();
+    let obj_ref: PyRef<'_, MyClass> = obj.extract().unwrap();
     // we need to drop obj_ref before we can extract a PyRefMut due to Rust's rules of references
 }
-let obj_ref_mut: PyRefMut<MyClass> = obj.extract().unwrap();
+let obj_ref_mut: PyRefMut<'_, MyClass> = obj.extract().unwrap();
 # })
 ```
 

guide/src/module.md

@@ -12,7 +12,7 @@ fn double(x: usize) -> usize {
 
 /// This module is implemented in Rust.
 #[pymodule]
-fn my_extension(py: Python, m: &PyModule) -> PyResult<()> {
+fn my_extension(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(double, m)?)?;
     Ok(())
 }
@@ -34,7 +34,7 @@ fn double(x: usize) -> usize {
 
 #[pymodule]
 #[pyo3(name = "custom_name")]
-fn my_extension(py: Python, m: &PyModule) -> PyResult<()> {
+fn my_extension(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(double, m)?)?;
     Ok(())
 }
@@ -76,7 +76,7 @@ references to the `PyModule` so that each module registers its own FFI code. For
 use pyo3::prelude::*;
 
 #[pymodule]
-fn my_extension(py: Python, m: &PyModule) -> PyResult<()> {
+fn my_extension(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     dirutil::register(py, m)?;
     osutil::register(py, m)?;
     Ok(())
@@ -86,7 +86,7 @@ fn my_extension(py: Python, m: &PyModule) -> PyResult<()> {
 # mod dirutil {
 use pyo3::prelude::*;
 
-pub(crate) fn register(py: Python, m: &PyModule) -> PyResult<()> {
+pub(crate) fn register(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<SomeClass>()?;
     Ok(())
 }
@@ -99,7 +99,7 @@ struct SomeClass {/* ... */}
 # mod osutil {
 use pyo3::prelude::*;
 
-pub(crate) fn register(py: Python, m: &PyModule) -> PyResult<()> {
+pub(crate) fn register(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(determine_current_os, m)?)?;
     Ok(())
 }
@@ -120,7 +120,7 @@ use pyo3::prelude::*;
 use osutil::*;
 
 #[pymodule]
-fn my_extension(py: Python, m: &PyModule) -> PyResult<()> {
+fn my_extension(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(determine_current_os, m)?)?;
     Ok(())
 }
@@ -146,12 +146,12 @@ For example, you could define the modules `parent_module` and `parent_module.chi
 use pyo3::prelude::*;
 
 #[pymodule]
-fn parent_module(py: Python, m: &PyModule) -> PyResult<()> {
+fn parent_module(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     register_child_module(py, m)?;
     Ok(())
 }
 
-fn register_child_module(py: Python, parent_module: &PyModule) -> PyResult<()> {
+fn register_child_module(py: Python<'_>, parent_module: &PyModule) -> PyResult<()> {
     let child_module = PyModule::new(py, "child_module")?;
     child_module.add_function(wrap_pyfunction!(func, child_module)?)?;
     parent_module.add_submodule(child_module)?;

guide/src/parallelism.md

@@ -23,7 +23,7 @@ fn search_sequential(contents: &str, needle: &str) -> usize {
 To enable parallel execution of this function, the [`Python::allow_threads`] method can be used to temporarily release the GIL, thus allowing other Python threads to run. We then have a function exposed to the Python runtime which calls `search_sequential` inside a closure passed to [`Python::allow_threads`] to enable true parallelism:
 ```rust, ignore
 #[pyfunction]
-fn search_sequential_allow_threads(py: Python, contents: &str, needle: &str) -> usize {
+fn search_sequential_allow_threads(py: Python<'_>, contents: &str, needle: &str) -> usize {
     py.allow_threads(|| search_sequential(contents, needle))
 }
 ```

guide/src/rust_cpython.md

@@ -55,9 +55,9 @@ Here is an example of the PyList API:
 ```rust,ignore
 impl PyList {
 
-   fn new(py: Python) -> PyList {...}
+   fn new(py: Python<'_>) -> PyList {...}
 
-   fn get_item(&self, py: Python, index: isize) -> PyObject {...}
+   fn get_item(&self, py: Python<'_>, index: isize) -> PyObject {...}
 }
 ```
 
@@ -66,7 +66,7 @@ impl PyList {
 ```rust,ignore
 impl PyList {
 
-   fn new(py: Python) -> &PyList {...}
+   fn new(py: Python<'_>) -> &PyList {...}
 
    fn get_item(&self, index: isize) -> &PyAny {...}
 }

guide/src/trait_bounds.md

@@ -133,7 +133,7 @@ struct UserModel {
 }
 
 #[pymodule]
-fn trait_exposure(_py: Python, m: &PyModule) -> PyResult<()> {
+fn trait_exposure(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<UserModel>()?;
     Ok(())
 }
@@ -487,7 +487,7 @@ pub struct UserModel {
 }
 
 #[pymodule]
-fn trait_exposure(_py: Python, m: &PyModule) -> PyResult<()> {
+fn trait_exposure(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<UserModel>()?;
     m.add_function(wrap_pyfunction!(solve_wrapper, m)?)?;
     Ok(())

guide/src/types.md

@@ -103,9 +103,9 @@ let _: Py<MyClass> = obj.extract()?;
 // To MyClass with PyAny::extract, if MyClass: Clone
 let _: MyClass = obj.extract()?;
 
-// To PyRef<MyClass> or PyRefMut<MyClass> with PyAny::extract
-let _: PyRef<MyClass> = obj.extract()?;
-let _: PyRefMut<MyClass> = obj.extract()?;
+// To PyRef<'_, MyClass> or PyRefMut<'_, MyClass> with PyAny::extract
+let _: PyRef<'_, MyClass> = obj.extract()?;
+let _: PyRefMut<'_, MyClass> = obj.extract()?;
 # Ok(())
 # }).unwrap();
 ```
@@ -207,11 +207,11 @@ let _: &PyCell<MyClass> = my_class.into_ref(py);
 let _: Py<PyAny> = my_class.into_py(py);
 
 # let my_class = my_class_clone;
-// To PyRef<MyClass> with Py::borrow or Py::try_borrow
-let _: PyRef<MyClass> = my_class.try_borrow(py)?;
+// To PyRef<'_, MyClass> with Py::borrow or Py::try_borrow
+let _: PyRef<'_, MyClass> = my_class.try_borrow(py)?;
 
-// To PyRefMut<MyClass> with Py::borrow_mut or Py::try_borrow_mut
-let _: PyRefMut<MyClass> = my_class.try_borrow_mut(py)?;
+// To PyRefMut<'_, MyClass> with Py::borrow_mut or Py::try_borrow_mut
+let _: PyRefMut<'_, MyClass> = my_class.try_borrow_mut(py)?;
 # Ok(())
 # }).unwrap();
 # });
@@ -241,12 +241,12 @@ so it also exposes all of the methods on `PyAny`.
 let cell: &PyCell<MyClass> = PyCell::new(py, MyClass { })?;
 
 // To PyRef<T> with .borrow() or .try_borrow()
-let py_ref: PyRef<MyClass> = cell.try_borrow()?;
+let py_ref: PyRef<'_, MyClass> = cell.try_borrow()?;
 let _: &MyClass = &*py_ref;
 # drop(py_ref);
 
 // To PyRefMut<T> with .borrow_mut() or .try_borrow_mut()
-let mut py_ref_mut: PyRefMut<MyClass> = cell.try_borrow_mut()?;
+let mut py_ref_mut: PyRefMut<'_, MyClass> = cell.try_borrow_mut()?;
 let _: &mut MyClass = &mut *py_ref_mut;
 # Ok(())
 # }).unwrap();

pyo3-macros-backend/src/attributes.rs

@@ -23,7 +23,7 @@ pub mod kw {
 pub struct FromPyWithAttribute(pub ExprPath);
 
 impl Parse for FromPyWithAttribute {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let _: kw::from_py_with = input.parse()?;
         let _: Token![=] = input.parse()?;
         let string_literal: LitStr = input.parse()?;
@@ -35,7 +35,7 @@ impl Parse for FromPyWithAttribute {
 pub struct NameAttribute(pub Ident);
 
 impl Parse for NameAttribute {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let _: kw::name = input.parse()?;
         let _: Token![=] = input.parse()?;
         let string_literal: LitStr = input.parse()?;
@@ -48,7 +48,7 @@ impl Parse for NameAttribute {
 pub struct CrateAttribute(pub Path);
 
 impl Parse for CrateAttribute {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let _: Token![crate] = input.parse()?;
         let _: Token![=] = input.parse()?;
         let string_literal: LitStr = input.parse()?;
@@ -64,7 +64,7 @@ pub struct TextSignatureAttribute {
 }
 
 impl Parse for TextSignatureAttribute {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         Ok(TextSignatureAttribute {
             kw: input.parse()?,
             eq_token: input.parse()?,

pyo3-macros-backend/src/frompyobject.rs

@@ -346,7 +346,7 @@ enum ContainerPyO3Attribute {
 }
 
 impl Parse for ContainerPyO3Attribute {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let lookahead = input.lookahead1();
         if lookahead.peek(attributes::kw::transparent) {
             let kw: attributes::kw::transparent = input.parse()?;
@@ -419,7 +419,7 @@ enum FieldPyO3Attribute {
 }
 
 impl Parse for FieldPyO3Attribute {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let lookahead = input.lookahead1();
         if lookahead.peek(attributes::kw::attribute) {
             let _: attributes::kw::attribute = input.parse()?;

pyo3-macros-backend/src/konst.rs

@@ -19,7 +19,7 @@ pub struct ConstSpec {
 }
 
 impl ConstSpec {
-    pub fn python_name(&self) -> Cow<Ident> {
+    pub fn python_name(&self) -> Cow<'_, Ident> {
         if let Some(name) = &self.attributes.name {
             Cow::Borrowed(&name.0)
         } else {
@@ -45,7 +45,7 @@ pub enum PyO3ConstAttribute {
 }
 
 impl Parse for PyO3ConstAttribute {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let lookahead = input.lookahead1();
         if lookahead.peek(attributes::kw::name) {
             input.parse().map(PyO3ConstAttribute::Name)

pyo3-macros-backend/src/module.rs

@@ -120,7 +120,7 @@ pub struct PyFnArgs {
 }
 
 impl Parse for PyFnArgs {
-    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
+    fn parse(input: syn::parse::ParseStream<'_>) -> syn::Result<Self> {
         let modname = input.parse().map_err(
             |e| err_spanned!(e.span() => "expected module as first argument to #[pyfn()]"),
         )?;
@@ -173,7 +173,7 @@ enum PyModulePyO3Option {
 }
 
 impl Parse for PyModulePyO3Option {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let lookahead = input.lookahead1();
         if lookahead.peek(attributes::kw::name) {
             input.parse().map(PyModulePyO3Option::Name)

pyo3-macros-backend/src/pyclass.rs

@@ -38,7 +38,7 @@ pub struct PyClassArgs {
 }
 
 impl PyClassArgs {
-    fn parse(input: ParseStream, kind: PyClassKind) -> Result<Self> {
+    fn parse(input: ParseStream<'_>, kind: PyClassKind) -> Result<Self> {
         let mut slf = PyClassArgs::new(kind);
         let vars = Punctuated::<Expr, Token![,]>::parse_terminated(input)?;
         for expr in vars {
@@ -47,11 +47,11 @@ impl PyClassArgs {
         Ok(slf)
     }
 
-    pub fn parse_stuct_args(input: ParseStream) -> syn::Result<Self> {
+    pub fn parse_stuct_args(input: ParseStream<'_>) -> syn::Result<Self> {
         Self::parse(input, PyClassKind::Struct)
     }
 
-    pub fn parse_enum_args(input: ParseStream) -> syn::Result<Self> {
+    pub fn parse_enum_args(input: ParseStream<'_>) -> syn::Result<Self> {
         Self::parse(input, PyClassKind::Enum)
     }
 
@@ -197,7 +197,7 @@ enum PyClassPyO3Option {
 }
 
 impl Parse for PyClassPyO3Option {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let lookahead = input.lookahead1();
         if lookahead.peek(attributes::kw::text_signature) {
             input.parse().map(PyClassPyO3Option::TextSignature)
@@ -315,7 +315,7 @@ enum FieldPyO3Option {
 }
 
 impl Parse for FieldPyO3Option {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let lookahead = input.lookahead1();
         if lookahead.peek(attributes::kw::get) {
             input.parse().map(FieldPyO3Option::Get)
@@ -478,7 +478,7 @@ pub fn build_py_enum(
 }
 
 fn impl_enum(
-    enum_: PyClassEnum,
+    enum_: PyClassEnum<'_>,
     args: &PyClassArgs,
     doc: PythonDoc,
     methods_type: PyClassMethodsType,
@@ -489,7 +489,7 @@ fn impl_enum(
 }
 
 fn impl_enum_class(
-    enum_: PyClassEnum,
+    enum_: PyClassEnum<'_>,
     args: &PyClassArgs,
     doc: PythonDoc,
     methods_type: PyClassMethodsType,
@@ -630,7 +630,7 @@ fn enum_default_slots(
     gen_default_items(cls, default_items).collect()
 }
 
-fn extract_variant_data(variant: &syn::Variant) -> syn::Result<PyClassEnumVariant> {
+fn extract_variant_data(variant: &syn::Variant) -> syn::Result<PyClassEnumVariant<'_>> {
     use syn::Fields;
     let ident = match variant.fields {
         Fields::Unit => &variant.ident,

pyo3-macros-backend/src/pyfunction.rs

@@ -50,7 +50,7 @@ enum PyFunctionArgPyO3Attribute {
 }
 
 impl Parse for PyFunctionArgPyO3Attribute {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let lookahead = input.lookahead1();
         if lookahead.peek(attributes::kw::from_py_with) {
             input.parse().map(PyFunctionArgPyO3Attribute::FromPyWith)
@@ -87,7 +87,7 @@ impl PyFunctionArgPyO3Attributes {
 }
 
 impl syn::parse::Parse for PyFunctionSignature {
-    fn parse(input: &ParseBuffer) -> syn::Result<Self> {
+    fn parse(input: &ParseBuffer<'_>) -> syn::Result<Self> {
         let attr = Punctuated::<NestedMeta, syn::Token![,]>::parse_terminated(input)?;
         Self::from_meta(&attr)
     }
@@ -243,7 +243,7 @@ pub struct PyFunctionOptions {
 }
 
 impl Parse for PyFunctionOptions {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let mut options = PyFunctionOptions::default();
 
         while !input.is_empty() {
@@ -282,7 +282,7 @@ pub enum PyFunctionOption {
 }
 
 impl Parse for PyFunctionOption {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let lookahead = input.lookahead1();
         if lookahead.peek(attributes::kw::name) {
             input.parse().map(PyFunctionOption::Name)

pyo3-macros-backend/src/pyimpl.rs

@@ -30,7 +30,7 @@ enum PyImplPyO3Option {
 }
 
 impl Parse for PyImplPyO3Option {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
         let lookahead = input.lookahead1();
         if lookahead.peek(syn::Token![crate]) {
             input.parse().map(PyImplPyO3Option::Crate)

pyo3-macros-backend/src/pymethod.rs

@@ -249,7 +249,10 @@ fn ensure_function_options_valid(options: &PyFunctionOptions) -> syn::Result<()>
     Ok(())
 }
 
-fn ensure_no_forbidden_protocol_attributes(spec: &FnSpec, method_name: &str) -> syn::Result<()> {
+fn ensure_no_forbidden_protocol_attributes(
+    spec: &FnSpec<'_>,
+    method_name: &str,
+) -> syn::Result<()> {
     if let Some(text_signature) = &spec.text_signature {
         bail_spanned!(text_signature.kw.span() => format!("`text_signature` cannot be used with `{}`", method_name));
     }
@@ -259,7 +262,7 @@ fn ensure_no_forbidden_protocol_attributes(spec: &FnSpec, method_name: &str) ->
 /// Also used by pyfunction.
 pub fn impl_py_method_def(
     cls: &syn::Type,
-    spec: &FnSpec,
+    spec: &FnSpec<'_>,
     flags: Option<TokenStream>,
 ) -> Result<TokenStream> {
     let wrapper_ident = syn::Ident::new("__wrap", Span::call_site());
@@ -276,7 +279,7 @@ pub fn impl_py_method_def(
     })
 }
 
-fn impl_py_method_def_new(cls: &syn::Type, spec: &FnSpec) -> Result<TokenStream> {
+fn impl_py_method_def_new(cls: &syn::Type, spec: &FnSpec<'_>) -> Result<TokenStream> {
     let wrapper_ident = syn::Ident::new("__pymethod__new__", Span::call_site());
     let wrapper = spec.get_wrapper_function(&wrapper_ident, Some(cls))?;
     Ok(quote! {{
@@ -291,7 +294,7 @@ fn impl_py_method_def_new(cls: &syn::Type, spec: &FnSpec) -> Result<TokenStream>
     }})
 }
 
-fn impl_call_slot(cls: &syn::Type, mut spec: FnSpec) -> Result<TokenStream> {
+fn impl_call_slot(cls: &syn::Type, mut spec: FnSpec<'_>) -> Result<TokenStream> {
     // HACK: __call__ proto slot must always use varargs calling convention, so change the spec.
     // Probably indicates there's a refactoring opportunity somewhere.
     spec.convention = CallingConvention::Varargs;
@@ -307,7 +310,7 @@ fn impl_call_slot(cls: &syn::Type, mut spec: FnSpec) -> Result<TokenStream> {
     }})
 }
 
-fn impl_traverse_slot(cls: &syn::Type, spec: FnSpec) -> TokenStream {
+fn impl_traverse_slot(cls: &syn::Type, spec: FnSpec<'_>) -> TokenStream {
     let ident = spec.name;
     quote! {{
         pub unsafe extern "C" fn __wrap_(
@@ -337,7 +340,7 @@ fn impl_traverse_slot(cls: &syn::Type, spec: FnSpec) -> TokenStream {
     }}
 }
 
-fn impl_py_class_attribute(cls: &syn::Type, spec: &FnSpec) -> TokenStream {
+fn impl_py_class_attribute(cls: &syn::Type, spec: &FnSpec<'_>) -> TokenStream {
     let name = &spec.name;
     let deprecations = &spec.deprecations;
     let python_name = spec.null_terminated_python_name();
@@ -357,7 +360,7 @@ fn impl_py_class_attribute(cls: &syn::Type, spec: &FnSpec) -> TokenStream {
     }
 }
 
-fn impl_call_setter(cls: &syn::Type, spec: &FnSpec) -> syn::Result<TokenStream> {
+fn impl_call_setter(cls: &syn::Type, spec: &FnSpec<'_>) -> syn::Result<TokenStream> {
     let (py_arg, args) = split_off_python_arg(&spec.args);
 
     if args.is_empty() {
@@ -380,7 +383,7 @@ fn impl_call_setter(cls: &syn::Type, spec: &FnSpec) -> syn::Result<TokenStream>
 }
 
 // Used here for PropertyType::Function, used in pyclass for descriptors.
-pub fn impl_py_setter_def(cls: &syn::Type, property_type: PropertyType) -> Result<TokenStream> {
+pub fn impl_py_setter_def(cls: &syn::Type, property_type: PropertyType<'_>) -> Result<TokenStream> {
     let python_name = property_type.null_terminated_python_name()?;
     let deprecations = property_type.deprecations();
     let doc = property_type.doc();
@@ -443,7 +446,7 @@ pub fn impl_py_setter_def(cls: &syn::Type, property_type: PropertyType) -> Resul
     })
 }
 
-fn impl_call_getter(cls: &syn::Type, spec: &FnSpec) -> syn::Result<TokenStream> {
+fn impl_call_getter(cls: &syn::Type, spec: &FnSpec<'_>) -> syn::Result<TokenStream> {
     let (py_arg, args) = split_off_python_arg(&spec.args);
     ensure_spanned!(
         args.is_empty(),
@@ -461,7 +464,7 @@ fn impl_call_getter(cls: &syn::Type, spec: &FnSpec) -> syn::Result<TokenStream>
 }
 
 // Used here for PropertyType::Function, used in pyclass for descriptors.
-pub fn impl_py_getter_def(cls: &syn::Type, property_type: PropertyType) -> Result<TokenStream> {
+pub fn impl_py_getter_def(cls: &syn::Type, property_type: PropertyType<'_>) -> Result<TokenStream> {
     let python_name = property_type.null_terminated_python_name()?;
     let deprecations = property_type.deprecations();
     let doc = property_type.doc();
@@ -518,7 +521,7 @@ pub fn impl_py_getter_def(cls: &syn::Type, property_type: PropertyType) -> Resul
 }
 
 /// Split an argument of pyo3::Python from the front of the arg list, if present
-fn split_off_python_arg<'a>(args: &'a [FnArg<'a>]) -> (Option<&FnArg>, &[FnArg]) {
+fn split_off_python_arg<'a>(args: &'a [FnArg<'a>]) -> (Option<&FnArg<'_>>, &[FnArg<'_>]) {
     match args {
         [py, args @ ..] if utils::is_python(py.ty) => (Some(py), args),
         args => (None, args),
@@ -563,7 +566,7 @@ impl PropertyType<'_> {
         }
     }
 
-    fn doc(&self) -> Cow<PythonDoc> {
+    fn doc(&self) -> Cow<'_, PythonDoc> {
         match self {
             PropertyType::Descriptor { field, .. } => {
                 Cow::Owned(utils::get_doc(&field.attrs, None))
@@ -712,7 +715,7 @@ impl Ty {
         cls: &syn::Type,
         py: &syn::Ident,
         ident: &syn::Ident,
-        arg: &FnArg,
+        arg: &FnArg<'_>,
         extract_error_mode: ExtractErrorMode,
     ) -> TokenStream {
         match self {
@@ -911,7 +914,7 @@ impl SlotDef {
     fn generate_type_slot(
         &self,
         cls: &syn::Type,
-        spec: &FnSpec,
+        spec: &FnSpec<'_>,
         method_name: &str,
     ) -> Result<TokenStream> {
         let SlotDef {
@@ -969,7 +972,7 @@ fn generate_method_arguments(arguments: &[Ty]) -> impl Iterator<Item = TokenStre
 
 fn generate_method_body(
     cls: &syn::Type,
-    spec: &FnSpec,
+    spec: &FnSpec<'_>,
     py: &syn::Ident,
     arguments: &[Ty],
     extract_error_mode: ExtractErrorMode,
@@ -1022,7 +1025,7 @@ impl SlotFragmentDef {
         self
     }
 
-    fn generate_pyproto_fragment(&self, cls: &syn::Type, spec: &FnSpec) -> Result<TokenStream> {
+    fn generate_pyproto_fragment(&self, cls: &syn::Type, spec: &FnSpec<'_>) -> Result<TokenStream> {
         let SlotFragmentDef {
             fragment,
             arguments,
@@ -1111,7 +1114,7 @@ const __RPOW__: SlotFragmentDef = SlotFragmentDef::new("__rpow__", &[Ty::Object,
 fn extract_proto_arguments(
     cls: &syn::Type,
     py: &syn::Ident,
-    method_args: &[FnArg],
+    method_args: &[FnArg<'_>],
     proto_args: &[Ty],
     extract_error_mode: ExtractErrorMode,
 ) -> Result<(Vec<Ident>, usize, TokenStream)> {

pyo3-macros-backend/src/utils.rs

@@ -133,7 +133,7 @@ struct DocArgs {
 }
 
 impl syn::parse::Parse for DocArgs {
-    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
+    fn parse(input: syn::parse::ParseStream<'_>) -> syn::Result<Self> {
         let this = Self {
             _eq_token: input.parse()?,
             token_stream: input.parse()?,

pyo3-macros-backend/src/wrap.rs

@@ -8,7 +8,7 @@ pub struct WrapPyFunctionArgs {
 }
 
 impl Parse for WrapPyFunctionArgs {
-    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
+    fn parse(input: syn::parse::ParseStream<'_>) -> syn::Result<Self> {
         let function = input.parse()?;
         let comma_and_arg = if !input.is_empty() {
             Some((input.parse()?, input.parse()?))

pytests/src/buf_and_str.rs

@@ -38,7 +38,7 @@ impl BytesExtractor {
 }
 
 #[pymodule]
-pub fn buf_and_str(_py: Python, m: &PyModule) -> PyResult<()> {
+pub fn buf_and_str(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<BytesExtractor>()?;
     Ok(())
 }

pytests/src/datetime.rs

@@ -7,7 +7,7 @@ use pyo3::types::{
 };
 
 #[pyfunction]
-fn make_date(py: Python, year: i32, month: u8, day: u8) -> PyResult<&PyDate> {
+fn make_date(py: Python<'_>, year: i32, month: u8, day: u8) -> PyResult<&PyDate> {
     PyDate::new(py, year, month, day)
 }
 
@@ -20,7 +20,7 @@ fn get_date_tuple<'p>(py: Python<'p>, d: &PyDate) -> &'p PyTuple {
 }
 
 #[pyfunction]
-fn date_from_timestamp(py: Python, timestamp: i64) -> PyResult<&PyDate> {
+fn date_from_timestamp(py: Python<'_>, timestamp: i64) -> PyResult<&PyDate> {
     PyDate::from_timestamp(py, timestamp)
 }
 
@@ -94,7 +94,7 @@ fn get_time_tuple_fold<'p>(py: Python<'p>, dt: &PyTime) -> &'p PyTuple {
 }
 
 #[pyfunction]
-fn make_delta(py: Python, days: i32, seconds: i32, microseconds: i32) -> PyResult<&PyDelta> {
+fn make_delta(py: Python<'_>, days: i32, seconds: i32, microseconds: i32) -> PyResult<&PyDelta> {
     PyDelta::new(py, days, seconds, microseconds, true)
 }
 

pytests/src/lib.rs

@@ -14,7 +14,7 @@ pub mod pyfunctions;
 pub mod subclassing;
 
 #[pymodule]
-fn pyo3_pytests(py: Python, m: &PyModule) -> PyResult<()> {
+fn pyo3_pytests(py: Python<'_>, m: &PyModule) -> PyResult<()> {
     #[cfg(not(Py_LIMITED_API))]
     m.add_wrapped(wrap_pymodule!(buf_and_str::buf_and_str))?;
     #[cfg(not(Py_LIMITED_API))]

pytests/src/objstore.rs

@@ -13,7 +13,7 @@ impl ObjStore {
         ObjStore::default()
     }
 
-    fn push(&mut self, py: Python, obj: &PyAny) {
+    fn push(&mut self, py: Python<'_>, obj: &PyAny) {
         self.obj.push(obj.to_object(py));
     }
 }

src/buffer.rs

@@ -38,7 +38,7 @@ unsafe impl<T> Send for PyBuffer<T> {}
 unsafe impl<T> Sync for PyBuffer<T> {}
 
 impl<T> Debug for PyBuffer<T> {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.debug_struct("PyBuffer")
             .field("buf", &self.0.buf)
             .field("obj", &self.0.obj)
@@ -459,7 +459,7 @@ impl<T: Element> PyBuffer<T> {
     /// To check whether the buffer format is compatible before calling this method,
     /// you can use `<T as buffer::Element>::is_compatible_format(buf.format())`.
     /// Alternatively, `match buffer::ElementType::from_format(buf.format())`.
-    pub fn copy_to_slice(&self, py: Python, target: &mut [T]) -> PyResult<()> {
+    pub fn copy_to_slice(&self, py: Python<'_>, target: &mut [T]) -> PyResult<()> {
         self.copy_to_slice_impl(py, target, b'C')
     }
 
@@ -472,11 +472,11 @@ impl<T: Element> PyBuffer<T> {
     /// To check whether the buffer format is compatible before calling this method,
     /// you can use `<T as buffer::Element>::is_compatible_format(buf.format())`.
     /// Alternatively, `match buffer::ElementType::from_format(buf.format())`.
-    pub fn copy_to_fortran_slice(&self, py: Python, target: &mut [T]) -> PyResult<()> {
+    pub fn copy_to_fortran_slice(&self, py: Python<'_>, target: &mut [T]) -> PyResult<()> {
         self.copy_to_slice_impl(py, target, b'F')
     }
 
-    fn copy_to_slice_impl(&self, py: Python, target: &mut [T], fort: u8) -> PyResult<()> {
+    fn copy_to_slice_impl(&self, py: Python<'_>, target: &mut [T], fort: u8) -> PyResult<()> {
         if mem::size_of_val(target) != self.len_bytes() {
             return Err(PyBufferError::new_err(format!(
                 "slice to copy to (of length {}) does not match buffer length of {}",
@@ -506,7 +506,7 @@ impl<T: Element> PyBuffer<T> {
     /// If the buffer is multi-dimensional, the elements are written in C-style order.
     ///
     /// Fails if the buffer format is not compatible with type `T`.
-    pub fn to_vec(&self, py: Python) -> PyResult<Vec<T>> {
+    pub fn to_vec(&self, py: Python<'_>) -> PyResult<Vec<T>> {
         self.to_vec_impl(py, b'C')
     }
 
@@ -514,11 +514,11 @@ impl<T: Element> PyBuffer<T> {
     /// If the buffer is multi-dimensional, the elements are written in Fortran-style order.
     ///
     /// Fails if the buffer format is not compatible with type `T`.
-    pub fn to_fortran_vec(&self, py: Python) -> PyResult<Vec<T>> {
+    pub fn to_fortran_vec(&self, py: Python<'_>) -> PyResult<Vec<T>> {
         self.to_vec_impl(py, b'F')
     }
 
-    fn to_vec_impl(&self, py: Python, fort: u8) -> PyResult<Vec<T>> {
+    fn to_vec_impl(&self, py: Python<'_>, fort: u8) -> PyResult<Vec<T>> {
         let item_count = self.item_count();
         let mut vec: Vec<T> = Vec::with_capacity(item_count);
         unsafe {
@@ -554,7 +554,7 @@ impl<T: Element> PyBuffer<T> {
     /// To check whether the buffer format is compatible before calling this method,
     /// use `<T as buffer::Element>::is_compatible_format(buf.format())`.
     /// Alternatively, `match buffer::ElementType::from_format(buf.format())`.
-    pub fn copy_from_slice(&self, py: Python, source: &[T]) -> PyResult<()> {
+    pub fn copy_from_slice(&self, py: Python<'_>, source: &[T]) -> PyResult<()> {
         self.copy_from_slice_impl(py, source, b'C')
     }
 
@@ -568,11 +568,11 @@ impl<T: Element> PyBuffer<T> {
     /// To check whether the buffer format is compatible before calling this method,
     /// use `<T as buffer::Element>::is_compatible_format(buf.format())`.
     /// Alternatively, `match buffer::ElementType::from_format(buf.format())`.
-    pub fn copy_from_fortran_slice(&self, py: Python, source: &[T]) -> PyResult<()> {
+    pub fn copy_from_fortran_slice(&self, py: Python<'_>, source: &[T]) -> PyResult<()> {
         self.copy_from_slice_impl(py, source, b'F')
     }
 
-    fn copy_from_slice_impl(&self, py: Python, source: &[T], fort: u8) -> PyResult<()> {
+    fn copy_from_slice_impl(&self, py: Python<'_>, source: &[T], fort: u8) -> PyResult<()> {
         if self.readonly() {
             return Err(PyBufferError::new_err("cannot write to read-only buffer"));
         } else if mem::size_of_val(source) != self.len_bytes() {
@@ -607,7 +607,7 @@ impl<T: Element> PyBuffer<T> {
         }
     }
 
-    pub fn release(self, _py: Python) {
+    pub fn release(self, _py: Python<'_>) {
         // First move self into a ManuallyDrop, so that PyBuffer::drop will
         // never be called. (It would acquire the GIL and call PyBuffer_Release
         // again.)

src/callback.rs

@@ -37,7 +37,7 @@ impl PyCallbackOutput for () {
 
 /// Convert the result of callback function into the appropriate return value.
 pub trait IntoPyCallbackOutput<Target> {
-    fn convert(self, py: Python) -> PyResult<Target>;
+    fn convert(self, py: Python<'_>) -> PyResult<Target>;
 }
 
 impl<T, E, U> IntoPyCallbackOutput<U> for Result<T, E>
@@ -46,7 +46,7 @@ where
     E: Into<PyErr>,
 {
     #[inline]
-    fn convert(self, py: Python) -> PyResult<U> {
+    fn convert(self, py: Python<'_>) -> PyResult<U> {
         self.map_err(Into::into).and_then(|t| t.convert(py))
     }
 }
@@ -56,42 +56,42 @@ where
     T: IntoPy<PyObject>,
 {
     #[inline]
-    fn convert(self, py: Python) -> PyResult<*mut ffi::PyObject> {
+    fn convert(self, py: Python<'_>) -> PyResult<*mut ffi::PyObject> {
         Ok(self.into_py(py).into_ptr())
     }
 }
 
 impl IntoPyCallbackOutput<Self> for *mut ffi::PyObject {
     #[inline]
-    fn convert(self, _: Python) -> PyResult<Self> {
+    fn convert(self, _: Python<'_>) -> PyResult<Self> {
         Ok(self)
     }
 }
 
 impl IntoPyCallbackOutput<std::os::raw::c_int> for () {
     #[inline]
-    fn convert(self, _: Python) -> PyResult<std::os::raw::c_int> {
+    fn convert(self, _: Python<'_>) -> PyResult<std::os::raw::c_int> {
         Ok(0)
     }
 }
 
 impl IntoPyCallbackOutput<std::os::raw::c_int> for bool {
     #[inline]
-    fn convert(self, _: Python) -> PyResult<std::os::raw::c_int> {
+    fn convert(self, _: Python<'_>) -> PyResult<std::os::raw::c_int> {
         Ok(self as c_int)
     }
 }
 
 impl IntoPyCallbackOutput<()> for () {
     #[inline]
-    fn convert(self, _: Python) -> PyResult<()> {
+    fn convert(self, _: Python<'_>) -> PyResult<()> {
         Ok(())
     }
 }
 
 impl IntoPyCallbackOutput<ffi::Py_ssize_t> for usize {
     #[inline]
-    fn convert(self, _py: Python) -> PyResult<ffi::Py_ssize_t> {
+    fn convert(self, _py: Python<'_>) -> PyResult<ffi::Py_ssize_t> {
         if self <= (isize::MAX as usize) {
             Ok(self as isize)
         } else {
@@ -104,14 +104,14 @@ impl IntoPyCallbackOutput<ffi::Py_ssize_t> for usize {
 
 impl IntoPyCallbackOutput<bool> for bool {
     #[inline]
-    fn convert(self, _: Python) -> PyResult<bool> {
+    fn convert(self, _: Python<'_>) -> PyResult<bool> {
         Ok(self)
     }
 }
 
 impl IntoPyCallbackOutput<usize> for usize {
     #[inline]
-    fn convert(self, _: Python) -> PyResult<usize> {
+    fn convert(self, _: Python<'_>) -> PyResult<usize> {
         Ok(self)
     }
 }
@@ -121,7 +121,7 @@ where
     T: IntoPy<PyObject>,
 {
     #[inline]
-    fn convert(self, py: Python) -> PyResult<PyObject> {
+    fn convert(self, py: Python<'_>) -> PyResult<PyObject> {
         Ok(self.into_py(py))
     }
 }
@@ -155,7 +155,7 @@ pub struct HashCallbackOutput(Py_hash_t);
 
 impl IntoPyCallbackOutput<Py_hash_t> for HashCallbackOutput {
     #[inline]
-    fn convert(self, _py: Python) -> PyResult<Py_hash_t> {
+    fn convert(self, _py: Python<'_>) -> PyResult<Py_hash_t> {
         let hash = self.0;
         if hash == -1 {
             Ok(-2)
@@ -170,14 +170,14 @@ where
     T: WrappingCastTo<Py_hash_t>,
 {
     #[inline]
-    fn convert(self, _py: Python) -> PyResult<HashCallbackOutput> {
+    fn convert(self, _py: Python<'_>) -> PyResult<HashCallbackOutput> {
         Ok(HashCallbackOutput(self.wrapping_cast()))
     }
 }
 
 #[doc(hidden)]
 #[inline]
-pub fn convert<T, U>(py: Python, value: T) -> PyResult<U>
+pub fn convert<T, U>(py: Python<'_>, value: T) -> PyResult<U>
 where
     T: IntoPyCallbackOutput<U>,
 {
@@ -237,7 +237,7 @@ macro_rules! callback_body {
 #[inline]
 pub unsafe fn handle_panic<F, R>(body: F) -> R
 where
-    F: FnOnce(Python) -> PyResult<R> + UnwindSafe,
+    F: for<'py> FnOnce(Python<'py>) -> PyResult<R> + UnwindSafe,
     R: PyCallbackOutput,
 {
     let pool = GILPool::new();
@@ -250,7 +250,7 @@ where
 #[doc(hidden)]
 #[inline]
 pub fn panic_result_into_callback_output<R>(
-    py: Python,
+    py: Python<'_>,
     panic_result: Result<PyResult<R>, Box<dyn Any + Send + 'static>>,
 ) -> R
 where

src/class/buffer.rs

@@ -18,11 +18,15 @@ use std::os::raw::c_int;
 pub trait PyBufferProtocol<'p>: PyClass {
     // No default implementations so that implementors of this trait provide both methods.
 
-    fn bf_getbuffer(slf: PyRefMut<Self>, view: *mut ffi::Py_buffer, flags: c_int) -> Self::Result
+    fn bf_getbuffer(
+        slf: PyRefMut<'_, Self>,
+        view: *mut ffi::Py_buffer,
+        flags: c_int,
+    ) -> Self::Result
     where
         Self: PyBufferGetBufferProtocol<'p>;
 
-    fn bf_releasebuffer(slf: PyRefMut<Self>, view: *mut ffi::Py_buffer) -> Self::Result
+    fn bf_releasebuffer(slf: PyRefMut<'_, Self>, view: *mut ffi::Py_buffer) -> Self::Result
     where
         Self: PyBufferReleaseBufferProtocol<'p>;
 }

src/class/gc.rs

@@ -11,7 +11,7 @@ pub use crate::impl_::pymethods::{PyTraverseError, PyVisit};
 /// GC support
 #[deprecated(since = "0.16.0", note = "prefer `#[pymethods]` to `#[pyproto]`")]
 pub trait PyGCProtocol<'p>: PyClass {
-    fn __traverse__(&'p self, visit: PyVisit) -> Result<(), PyTraverseError>;
+    fn __traverse__(&'p self, visit: PyVisit<'_>) -> Result<(), PyTraverseError>;
     fn __clear__(&'p mut self);
 }
 

src/class/iter.rs

@@ -17,7 +17,7 @@ use crate::{PyClass, PyObject};
 /// the integers 1 to 5, before raising `StopIteration("Ended")`.
 ///
 /// ```rust
-/// # #![allow(deprecated)]
+/// # #![allow(deprecated, elided_lifetimes_in_paths)]
 /// use pyo3::class::iter::IterNextOutput;
 /// use pyo3::prelude::*;
 /// use pyo3::PyIterProtocol;

src/conversion.rs

@@ -71,7 +71,7 @@ where
 /// Conversion trait that allows various objects to be converted into `PyObject`.
 pub trait ToPyObject {
     /// Converts self into a Python object.
-    fn to_object(&self, py: Python) -> PyObject;
+    fn to_object(&self, py: Python<'_>) -> PyObject;
 }
 
 /// This trait has two implementations: The slow one is implemented for
@@ -84,7 +84,7 @@ pub trait ToBorrowedObject: ToPyObject {
     ///
     /// May be more efficient than `to_object` because it does not need
     /// to touch any reference counts when the input object already is a Python object.
-    fn with_borrowed_ptr<F, R>(&self, py: Python, f: F) -> R
+    fn with_borrowed_ptr<F, R>(&self, py: Python<'_>, f: F) -> R
     where
         F: FnOnce(*mut ffi::PyObject) -> R,
     {
@@ -134,7 +134,7 @@ impl<T> ToBorrowedObject for T where T: ToPyObject {}
 /// }
 ///
 /// impl IntoPy<PyObject> for Number {
-///     fn into_py(self, py: Python) -> PyObject {
+///     fn into_py(self, py: Python<'_>) -> PyObject {
 ///         // delegates to i32's IntoPy implementation.
 ///         self.value.into_py(py)
 ///     }
@@ -156,7 +156,7 @@ impl<T> ToBorrowedObject for T where T: ToPyObject {}
 /// }
 ///
 /// impl IntoPy<PyObject> for Value {
-///     fn into_py(self, py: Python) -> PyObject {
+///     fn into_py(self, py: Python<'_>) -> PyObject {
 ///         match self {
 ///             Self::Integer(val) => val.into_py(py),
 ///             Self::String(val) => val.into_py(py),
@@ -181,7 +181,7 @@ impl<T> ToBorrowedObject for T where T: ToPyObject {}
 #[cfg_attr(docsrs, doc(alias = "IntoPyCallbackOutput"))]
 pub trait IntoPy<T>: Sized {
     /// Performs the conversion.
-    fn into_py(self, py: Python) -> T;
+    fn into_py(self, py: Python<'_>) -> T;
 }
 
 /// `FromPyObject` is implemented by various types that can be extracted from
@@ -218,7 +218,7 @@ pub trait FromPyObject<'source>: Sized {
 /// `T: ToPyObject` is expected.
 impl<T: ?Sized + ToPyObject> ToPyObject for &'_ T {
     #[inline]
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         <T as ToPyObject>::to_object(*self, py)
     }
 }
@@ -229,7 +229,7 @@ impl<T> ToPyObject for Option<T>
 where
     T: ToPyObject,
 {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         self.as_ref()
             .map_or_else(|| py.None(), |val| val.to_object(py))
     }
@@ -239,20 +239,20 @@ impl<T> IntoPy<PyObject> for Option<T>
 where
     T: IntoPy<PyObject>,
 {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.map_or_else(|| py.None(), |val| val.into_py(py))
     }
 }
 
 /// `()` is converted to Python `None`.
 impl ToPyObject for () {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         py.None()
     }
 }
 
 impl IntoPy<PyObject> for () {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         py.None()
     }
 }
@@ -262,7 +262,7 @@ where
     T: AsPyPointer,
 {
     #[inline]
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         unsafe { PyObject::from_borrowed_ptr(py, self.as_ptr()) }
     }
 }
@@ -343,10 +343,10 @@ pub trait PyTryFrom<'v>: Sized + PyNativeType {
 /// This trait is similar to `std::convert::TryInto`
 pub trait PyTryInto<T>: Sized {
     /// Cast from PyObject to a concrete Python object type.
-    fn try_into(&self) -> Result<&T, PyDowncastError>;
+    fn try_into(&self) -> Result<&T, PyDowncastError<'_>>;
 
     /// Cast from PyObject to a concrete Python object type. With exact type check.
-    fn try_into_exact(&self) -> Result<&T, PyDowncastError>;
+    fn try_into_exact(&self) -> Result<&T, PyDowncastError<'_>>;
 }
 
 // TryFrom implies TryInto
@@ -354,10 +354,10 @@ impl<U> PyTryInto<U> for PyAny
 where
     U: for<'v> PyTryFrom<'v>,
 {
-    fn try_into(&self) -> Result<&U, PyDowncastError> {
-        U::try_from(self)
+    fn try_into(&self) -> Result<&U, PyDowncastError<'_>> {
+        <U as PyTryFrom<'_>>::try_from(self)
     }
-    fn try_into_exact(&self) -> Result<&U, PyDowncastError> {
+    fn try_into_exact(&self) -> Result<&U, PyDowncastError<'_>> {
         U::try_from_exact(self)
     }
 }
@@ -426,7 +426,7 @@ where
 
 /// Converts `()` to an empty Python tuple.
 impl IntoPy<Py<PyTuple>> for () {
-    fn into_py(self, py: Python) -> Py<PyTuple> {
+    fn into_py(self, py: Python<'_>) -> Py<PyTuple> {
         PyTuple::empty(py).into()
     }
 }
@@ -534,11 +534,11 @@ mod tests {
             let list: &PyAny = vec![3, 6, 5, 4, 7].to_object(py).into_ref(py);
             let dict: &PyAny = vec![("reverse", true)].into_py_dict(py).as_ref();
 
-            assert!(PyList::try_from(list).is_ok());
-            assert!(PyDict::try_from(dict).is_ok());
+            assert!(<PyList as PyTryFrom<'_>>::try_from(list).is_ok());
+            assert!(<PyDict as PyTryFrom<'_>>::try_from(dict).is_ok());
 
-            assert!(PyAny::try_from(list).is_ok());
-            assert!(PyAny::try_from(dict).is_ok());
+            assert!(<PyAny as PyTryFrom<'_>>::try_from(list).is_ok());
+            assert!(<PyAny as PyTryFrom<'_>>::try_from(dict).is_ok());
         });
     }
 

src/conversions/array.rs

@@ -9,7 +9,7 @@ mod min_const_generics {
     where
         T: ToPyObject,
     {
-        fn into_py(self, py: Python) -> PyObject {
+        fn into_py(self, py: Python<'_>) -> PyObject {
             self.as_ref().to_object(py)
         }
     }
@@ -149,7 +149,7 @@ mod array_impls {
                 where
                     T: ToPyObject
                 {
-                    fn into_py(self, py: Python) -> PyObject {
+                    fn into_py(self, py: Python<'_>) -> PyObject {
                         self.as_ref().to_object(py)
                     }
                 }

src/conversions/hashbrown.rs

@@ -33,7 +33,7 @@ where
     V: ToPyObject,
     H: hash::BuildHasher,
 {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         IntoPyDict::into_py_dict(self, py).into()
     }
 }
@@ -44,7 +44,7 @@ where
     V: IntoPy<PyObject>,
     H: hash::BuildHasher,
 {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         let iter = self
             .into_iter()
             .map(|(k, v)| (k.into_py(py), v.into_py(py)));
@@ -72,7 +72,7 @@ impl<T> ToPyObject for hashbrown::HashSet<T>
 where
     T: hash::Hash + Eq + ToPyObject,
 {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         let set = PySet::new::<T>(py, &[]).expect("Failed to construct empty set");
         {
             for val in self {
@@ -88,7 +88,7 @@ where
     K: IntoPy<PyObject> + Eq + hash::Hash,
     S: hash::BuildHasher + Default,
 {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         let set = PySet::empty(py).expect("Failed to construct empty set");
         {
             for val in self {

src/conversions/indexmap.rs

@@ -76,7 +76,7 @@
 //! }
 //!
 //! #[pymodule]
-//! fn my_module(_py: Python, m: &PyModule) -> PyResult<()> {
+//! fn my_module(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
 //!     m.add_function(wrap_pyfunction!(calculate_statistics, m)?)?;
 //!     Ok(())
 //! }
@@ -102,7 +102,7 @@ where
     V: ToPyObject,
     H: hash::BuildHasher,
 {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         IntoPyDict::into_py_dict(self, py).into()
     }
 }
@@ -113,7 +113,7 @@ where
     V: IntoPy<PyObject>,
     H: hash::BuildHasher,
 {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         let iter = self
             .into_iter()
             .map(|(k, v)| (k.into_py(py), v.into_py(py)));

src/conversions/num_bigint.rs

@@ -40,7 +40,7 @@
 //! }
 //!
 //! #[pymodule]
-//! fn my_module(_py: Python, m: &PyModule) -> PyResult<()> {
+//! fn my_module(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
 //!     m.add_function(wrap_pyfunction!(add_one, m)?)?;
 //!     Ok(())
 //! }
@@ -82,7 +82,7 @@ macro_rules! bigint_conversion {
     ($rust_ty: ty, $is_signed: expr, $to_bytes: path, $from_bytes: path) => {
         #[cfg_attr(docsrs, doc(cfg(feature = "num-bigint")))]
         impl ToPyObject for $rust_ty {
-            fn to_object(&self, py: Python) -> PyObject {
+            fn to_object(&self, py: Python<'_>) -> PyObject {
                 unsafe {
                     let bytes = $to_bytes(self);
                     let obj = ffi::_PyLong_FromByteArray(
@@ -98,7 +98,7 @@ macro_rules! bigint_conversion {
 
         #[cfg_attr(docsrs, doc(cfg(feature = "num-bigint")))]
         impl IntoPy<PyObject> for $rust_ty {
-            fn into_py(self, py: Python) -> PyObject {
+            fn into_py(self, py: Python<'_>) -> PyObject {
                 self.to_object(py)
             }
         }
@@ -146,7 +146,7 @@ mod tests {
     use crate::types::{PyDict, PyModule};
     use indoc::indoc;
 
-    fn python_fib(py: Python) -> &PyModule {
+    fn python_fib(py: Python<'_>) -> &PyModule {
         let fib_code = indoc!(
             r#"
                 def fib(n):
@@ -224,7 +224,7 @@ mod tests {
         })
     }
 
-    fn python_index_class(py: Python) -> &PyModule {
+    fn python_index_class(py: Python<'_>) -> &PyModule {
         let index_code = indoc!(
             r#"
                 class C:

src/conversions/num_complex.rs

@@ -49,7 +49,7 @@
 //! }
 //!
 //! #[pymodule]
-//! fn my_module(_py: Python, m: &PyModule) -> PyResult<()> {
+//! fn my_module(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
 //!     m.add_function(wrap_pyfunction!(get_eigenvalues, m)?)?;
 //!     Ok(())
 //! }
@@ -107,7 +107,7 @@ use std::os::raw::c_double;
 
 impl PyComplex {
     /// Creates a new Python `PyComplex` object from `num_complex`'s [`Complex`].
-    pub fn from_complex<F: Into<c_double>>(py: Python, complex: Complex<F>) -> &PyComplex {
+    pub fn from_complex<F: Into<c_double>>(py: Python<'_>, complex: Complex<F>) -> &PyComplex {
         unsafe {
             let ptr = ffi::PyComplex_FromDoubles(complex.re.into(), complex.im.into());
             py.from_owned_ptr(ptr)
@@ -120,14 +120,14 @@ macro_rules! complex_conversion {
         #[cfg_attr(docsrs, doc(cfg(feature = "num-complex")))]
         impl ToPyObject for Complex<$float> {
             #[inline]
-            fn to_object(&self, py: Python) -> PyObject {
+            fn to_object(&self, py: Python<'_>) -> PyObject {
                 crate::IntoPy::<PyObject>::into_py(self.to_owned(), py)
             }
         }
 
         #[cfg_attr(docsrs, doc(cfg(feature = "num-complex")))]
         impl crate::IntoPy<PyObject> for Complex<$float> {
-            fn into_py(self, py: Python) -> PyObject {
+            fn into_py(self, py: Python<'_>) -> PyObject {
                 unsafe {
                     let raw_obj =
                         ffi::PyComplex_FromDoubles(self.re as c_double, self.im as c_double);

src/conversions/osstr.rs

@@ -11,7 +11,7 @@ use std::ffi::{OsStr, OsString};
 use std::os::raw::c_char;
 
 impl ToPyObject for OsStr {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         // If the string is UTF-8, take the quick and easy shortcut
         if let Some(valid_utf8_path) = self.to_str() {
             return valid_utf8_path.to_object(py);
@@ -112,40 +112,40 @@ impl FromPyObject<'_> for OsString {
 
 impl IntoPy<PyObject> for &'_ OsStr {
     #[inline]
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.to_object(py)
     }
 }
 
 impl ToPyObject for Cow<'_, OsStr> {
     #[inline]
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         (self as &OsStr).to_object(py)
     }
 }
 
 impl IntoPy<PyObject> for Cow<'_, OsStr> {
     #[inline]
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.to_object(py)
     }
 }
 
 impl ToPyObject for OsString {
     #[inline]
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         (self as &OsStr).to_object(py)
     }
 }
 
 impl IntoPy<PyObject> for OsString {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.to_object(py)
     }
 }
 
 impl<'a> IntoPy<PyObject> for &'a OsString {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.to_object(py)
     }
 }
@@ -182,7 +182,7 @@ mod tests {
     #[test]
     fn test_topyobject_roundtrip() {
         Python::with_gil(|py| {
-            fn test_roundtrip<T: ToPyObject + AsRef<OsStr> + Debug>(py: Python, obj: T) {
+            fn test_roundtrip<T: ToPyObject + AsRef<OsStr> + Debug>(py: Python<'_>, obj: T) {
                 let pyobject = obj.to_object(py);
                 let pystring: &PyString = pyobject.extract(py).unwrap();
                 assert_eq!(pystring.to_string_lossy(), obj.as_ref().to_string_lossy());
@@ -201,7 +201,7 @@ mod tests {
     fn test_intopy_roundtrip() {
         Python::with_gil(|py| {
             fn test_roundtrip<T: IntoPy<PyObject> + AsRef<OsStr> + Debug + Clone>(
-                py: Python,
+                py: Python<'_>,
                 obj: T,
             ) {
                 let pyobject = obj.clone().into_py(py);

src/conversions/path.rs

@@ -5,7 +5,7 @@ use std::ffi::OsString;
 use std::path::{Path, PathBuf};
 
 impl ToPyObject for Path {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         self.as_os_str().to_object(py)
     }
 }
@@ -34,40 +34,40 @@ impl FromPyObject<'_> for PathBuf {
 
 impl<'a> IntoPy<PyObject> for &'a Path {
     #[inline]
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.as_os_str().to_object(py)
     }
 }
 
 impl<'a> ToPyObject for Cow<'a, Path> {
     #[inline]
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         self.as_os_str().to_object(py)
     }
 }
 
 impl<'a> IntoPy<PyObject> for Cow<'a, Path> {
     #[inline]
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.to_object(py)
     }
 }
 
 impl ToPyObject for PathBuf {
     #[inline]
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         self.as_os_str().to_object(py)
     }
 }
 
 impl IntoPy<PyObject> for PathBuf {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.into_os_string().to_object(py)
     }
 }
 
 impl<'a> IntoPy<PyObject> for &'a PathBuf {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.as_os_str().to_object(py)
     }
 }
@@ -103,7 +103,7 @@ mod tests {
     #[test]
     fn test_topyobject_roundtrip() {
         Python::with_gil(|py| {
-            fn test_roundtrip<T: ToPyObject + AsRef<Path> + Debug>(py: Python, obj: T) {
+            fn test_roundtrip<T: ToPyObject + AsRef<Path> + Debug>(py: Python<'_>, obj: T) {
                 let pyobject = obj.to_object(py);
                 let pystring: &PyString = pyobject.extract(py).unwrap();
                 assert_eq!(pystring.to_string_lossy(), obj.as_ref().to_string_lossy());
@@ -122,7 +122,7 @@ mod tests {
     fn test_intopy_roundtrip() {
         Python::with_gil(|py| {
             fn test_roundtrip<T: IntoPy<PyObject> + AsRef<Path> + Debug + Clone>(
-                py: Python,
+                py: Python<'_>,
                 obj: T,
             ) {
                 let pyobject = obj.clone().into_py(py);

src/err/err_state.rs

@@ -15,12 +15,12 @@ pub(crate) struct PyErrStateNormalized {
 
 pub(crate) enum PyErrState {
     LazyTypeAndValue {
-        ptype: fn(Python) -> &PyType,
-        pvalue: Box<dyn FnOnce(Python) -> PyObject + Send + Sync>,
+        ptype: for<'py> fn(Python<'py>) -> &PyType,
+        pvalue: Box<dyn for<'py> FnOnce(Python<'py>) -> PyObject + Send + Sync>,
     },
     LazyValue {
         ptype: Py<PyType>,
-        pvalue: Box<dyn FnOnce(Python) -> PyObject + Send + Sync>,
+        pvalue: Box<dyn for<'py> FnOnce(Python<'py>) -> PyObject + Send + Sync>,
     },
     FfiTuple {
         ptype: PyObject,
@@ -33,28 +33,28 @@ pub(crate) enum PyErrState {
 /// Helper conversion trait that allows to use custom arguments for lazy exception construction.
 pub trait PyErrArguments: Send + Sync {
     /// Arguments for exception
-    fn arguments(self, py: Python) -> PyObject;
+    fn arguments(self, py: Python<'_>) -> PyObject;
 }
 
 impl<T> PyErrArguments for T
 where
     T: IntoPy<PyObject> + Send + Sync,
 {
-    fn arguments(self, py: Python) -> PyObject {
+    fn arguments(self, py: Python<'_>) -> PyObject {
         self.into_py(py)
     }
 }
 
 pub(crate) fn boxed_args(
     args: impl PyErrArguments + 'static,
-) -> Box<dyn FnOnce(Python) -> PyObject + Send + Sync> {
+) -> Box<dyn for<'py> FnOnce(Python<'py>) -> PyObject + Send + Sync> {
     Box::new(|py| args.arguments(py))
 }
 
 impl PyErrState {
     pub(crate) fn into_ffi_tuple(
         self,
-        py: Python,
+        py: Python<'_>,
     ) -> (*mut ffi::PyObject, *mut ffi::PyObject, *mut ffi::PyObject) {
         match self {
             PyErrState::LazyTypeAndValue { ptype, pvalue } => {
@@ -88,7 +88,7 @@ impl PyErrState {
     }
 
     #[inline]
-    pub(crate) fn exceptions_must_derive_from_base_exception(py: Python) -> Self {
+    pub(crate) fn exceptions_must_derive_from_base_exception(py: Python<'_>) -> Self {
         PyErrState::LazyValue {
             ptype: PyTypeError::type_object(py).into(),
             pvalue: boxed_args("exceptions must derive from BaseException"),

src/err/impls.rs

@@ -28,7 +28,7 @@ impl std::convert::From<io::Error> for PyErr {
 }
 
 impl PyErrArguments for io::Error {
-    fn arguments(self, py: Python) -> PyObject {
+    fn arguments(self, py: Python<'_>) -> PyObject {
         self.to_string().into_py(py)
     }
 }
@@ -42,7 +42,7 @@ impl<W: 'static + Send + Sync + std::fmt::Debug> std::convert::From<std::io::Int
 }
 
 impl<W: Send + Sync + std::fmt::Debug> PyErrArguments for std::io::IntoInnerError<W> {
-    fn arguments(self, py: Python) -> PyObject {
+    fn arguments(self, py: Python<'_>) -> PyObject {
         self.to_string().into_py(py)
     }
 }
@@ -56,7 +56,7 @@ impl std::convert::From<std::convert::Infallible> for PyErr {
 macro_rules! impl_to_pyerr {
     ($err: ty, $pyexc: ty) => {
         impl PyErrArguments for $err {
-            fn arguments(self, py: Python) -> PyObject {
+            fn arguments(self, py: Python<'_>) -> PyObject {
                 self.to_string().into_py(py)
             }
         }

src/err/mod.rs

@@ -214,7 +214,7 @@ impl PyErr {
     }
 
     /// Consumes self to take ownership of the exception value contained in this error.
-    pub fn into_value(self, py: Python) -> Py<PyBaseException> {
+    pub fn into_value(self, py: Python<'_>) -> Py<PyBaseException> {
         // NB technically this causes one reference count increase and decrease in quick succession
         // on pvalue, but it's probably not worth optimizing this right now for the additional code
         // complexity.
@@ -243,7 +243,7 @@ impl PyErr {
 
     /// Gets whether an error is present in the Python interpreter's global state.
     #[inline]
-    pub fn occurred(_: Python) -> bool {
+    pub fn occurred(_: Python<'_>) -> bool {
         unsafe { !ffi::PyErr_Occurred().is_null() }
     }
 
@@ -256,7 +256,7 @@ impl PyErr {
     /// Use this function when it is not known if an error should be present. If the error is
     /// expected to have been set, for example from [`PyErr::occurred`] or by an error return value
     /// from a C FFI function, use [`PyErr::fetch`].
-    pub fn take(py: Python) -> Option<PyErr> {
+    pub fn take(py: Python<'_>) -> Option<PyErr> {
         let (ptype, pvalue, ptraceback) = unsafe {
             let mut ptype: *mut ffi::PyObject = std::ptr::null_mut();
             let mut pvalue: *mut ffi::PyObject = std::ptr::null_mut();
@@ -327,7 +327,7 @@ impl PyErr {
     /// [PyErr::occurred] or by an error return value from a C FFI function.
     #[cfg_attr(all(debug_assertions, track_caller), track_caller)]
     #[inline]
-    pub fn fetch(py: Python) -> PyErr {
+    pub fn fetch(py: Python<'_>) -> PyErr {
         const FAILED_TO_FETCH: &str = "attempted to fetch exception but none was set";
         match PyErr::take(py) {
             Some(err) => err,
@@ -353,7 +353,7 @@ impl PyErr {
     ///
     /// This function will panic if  `name` or `doc` cannot be converted to [`CString`]s.
     pub fn new_type(
-        py: Python,
+        py: Python<'_>,
         name: &str,
         doc: Option<&str>,
         base: Option<&PyType>,
@@ -393,14 +393,14 @@ impl PyErr {
     }
 
     /// Prints a standard traceback to `sys.stderr`.
-    pub fn print(&self, py: Python) {
+    pub fn print(&self, py: Python<'_>) {
         self.clone_ref(py).restore(py);
         unsafe { ffi::PyErr_PrintEx(0) }
     }
 
     /// Prints a standard traceback to `sys.stderr`, and sets
     /// `sys.last_{type,value,traceback}` attributes to this exception's data.
-    pub fn print_and_set_sys_last_vars(&self, py: Python) {
+    pub fn print_and_set_sys_last_vars(&self, py: Python<'_>) {
         self.clone_ref(py).restore(py);
         unsafe { ffi::PyErr_PrintEx(1) }
     }
@@ -409,7 +409,7 @@ impl PyErr {
     ///
     /// If `exc` is a class object, this also returns `true` when `self` is an instance of a subclass.
     /// If `exc` is a tuple, all exceptions in the tuple (and recursively in subtuples) are searched for a match.
-    pub fn matches<T>(&self, py: Python, exc: T) -> bool
+    pub fn matches<T>(&self, py: Python<'_>, exc: T) -> bool
     where
         T: ToBorrowedObject,
     {
@@ -420,13 +420,13 @@ impl PyErr {
 
     /// Returns true if the current exception is instance of `T`.
     #[inline]
-    pub fn is_instance(&self, py: Python, typ: &PyType) -> bool {
+    pub fn is_instance(&self, py: Python<'_>, typ: &PyType) -> bool {
         unsafe { ffi::PyErr_GivenExceptionMatches(self.type_ptr(py), typ.as_ptr()) != 0 }
     }
 
     /// Returns true if the current exception is instance of `T`.
     #[inline]
-    pub fn is_instance_of<T>(&self, py: Python) -> bool
+    pub fn is_instance_of<T>(&self, py: Python<'_>) -> bool
     where
         T: PyTypeObject,
     {
@@ -436,7 +436,7 @@ impl PyErr {
     /// Writes the error back to the Python interpreter's global state.
     /// This is the opposite of `PyErr::fetch()`.
     #[inline]
-    pub fn restore(self, py: Python) {
+    pub fn restore(self, py: Python<'_>) {
         let (ptype, pvalue, ptraceback) = self
             .state
             .into_inner()
@@ -447,7 +447,7 @@ impl PyErr {
 
     /// Issues a warning message.
     /// May return a `PyErr` if warnings-as-errors is enabled.
-    pub fn warn(py: Python, category: &PyAny, message: &str, stacklevel: i32) -> PyResult<()> {
+    pub fn warn(py: Python<'_>, category: &PyAny, message: &str, stacklevel: i32) -> PyResult<()> {
         let message = CString::new(message)?;
         unsafe {
             error_on_minusone(
@@ -478,20 +478,20 @@ impl PyErr {
     /// });
     /// ```
     #[inline]
-    pub fn clone_ref(&self, py: Python) -> PyErr {
+    pub fn clone_ref(&self, py: Python<'_>) -> PyErr {
         PyErr::from_state(PyErrState::Normalized(self.normalized(py).clone()))
     }
 
     /// Return the cause (either an exception instance, or None, set by `raise ... from ...`)
     /// associated with the exception, as accessible from Python through `__cause__`.
-    pub fn cause(&self, py: Python) -> Option<PyErr> {
+    pub fn cause(&self, py: Python<'_>) -> Option<PyErr> {
         let ptr = unsafe { ffi::PyException_GetCause(self.value(py).as_ptr()) };
         let obj = unsafe { py.from_owned_ptr_or_opt::<PyAny>(ptr) };
         obj.map(Self::from_value)
     }
 
     /// Set the cause associated with the exception, pass `None` to clear it.
-    pub fn set_cause(&self, py: Python, cause: Option<Self>) {
+    pub fn set_cause(&self, py: Python<'_>, cause: Option<Self>) {
         unsafe {
             // PyException_SetCause _steals_ a reference to cause, so must use .into_ptr()
             ffi::PyException_SetCause(
@@ -509,7 +509,7 @@ impl PyErr {
     }
 
     /// Returns borrowed reference to this Err's type
-    fn type_ptr(&self, py: Python) -> *mut ffi::PyObject {
+    fn type_ptr(&self, py: Python<'_>) -> *mut ffi::PyObject {
         match unsafe { &*self.state.get() } {
             // In lazy type case, normalize before returning ptype in case the type is not a valid
             // exception type.
@@ -522,7 +522,7 @@ impl PyErr {
     }
 
     #[inline]
-    fn normalized(&self, py: Python) -> &PyErrStateNormalized {
+    fn normalized(&self, py: Python<'_>) -> &PyErrStateNormalized {
         if let Some(PyErrState::Normalized(n)) = unsafe {
             // Safety: self.state will never be written again once normalized.
             &*self.state.get()
@@ -534,7 +534,7 @@ impl PyErr {
     }
 
     #[cold]
-    fn make_normalized(&self, py: Python) -> &PyErrStateNormalized {
+    fn make_normalized(&self, py: Python<'_>) -> &PyErrStateNormalized {
         // This process is safe because:
         // - Access is guaranteed not to be concurrent thanks to `Python` GIL token
         // - Write happens only once, and then never will change again.
@@ -611,13 +611,13 @@ impl PyErr {
         since = "0.16.0",
         note = "Use err.into_value(py) instead of err.into_instance(py)"
     )]
-    pub fn into_instance(self, py: Python) -> Py<PyBaseException> {
+    pub fn into_instance(self, py: Python<'_>) -> Py<PyBaseException> {
         self.into_value(py)
     }
 }
 
 impl std::fmt::Debug for PyErr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
         Python::with_gil(|py| {
             f.debug_struct("PyErr")
                 .field("type", self.get_type(py))
@@ -629,7 +629,7 @@ impl std::fmt::Debug for PyErr {
 }
 
 impl std::fmt::Display for PyErr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         Python::with_gil(|py| {
             let value = self.value(py);
             let type_name = value.get_type().name().map_err(|_| std::fmt::Error)?;
@@ -646,26 +646,26 @@ impl std::fmt::Display for PyErr {
 impl std::error::Error for PyErr {}
 
 impl IntoPy<PyObject> for PyErr {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.into_value(py).into()
     }
 }
 
 impl ToPyObject for PyErr {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         self.clone_ref(py).into_py(py)
     }
 }
 
 impl<'a> IntoPy<PyObject> for &'a PyErr {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         self.clone_ref(py).into_py(py)
     }
 }
 
 /// Convert `PyDowncastError` to Python `TypeError`.
 impl<'a> std::convert::From<PyDowncastError<'a>> for PyErr {
-    fn from(err: PyDowncastError) -> PyErr {
+    fn from(err: PyDowncastError<'_>) -> PyErr {
         exceptions::PyTypeError::new_err(err.to_string())
     }
 }
@@ -673,7 +673,7 @@ impl<'a> std::convert::From<PyDowncastError<'a>> for PyErr {
 impl<'a> std::error::Error for PyDowncastError<'a> {}
 
 impl<'a> std::fmt::Display for PyDowncastError<'a> {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
         write!(
             f,
             "'{}' object cannot be converted to '{}'",
@@ -683,7 +683,7 @@ impl<'a> std::fmt::Display for PyDowncastError<'a> {
     }
 }
 
-pub fn panic_after_error(_py: Python) -> ! {
+pub fn panic_after_error(_py: Python<'_>) -> ! {
     unsafe {
         ffi::PyErr_Print();
     }
@@ -692,7 +692,7 @@ pub fn panic_after_error(_py: Python) -> ! {
 
 /// Returns Ok if the error code is not -1.
 #[inline]
-pub fn error_on_minusone(py: Python, result: c_int) -> PyResult<()> {
+pub fn error_on_minusone(py: Python<'_>, result: c_int) -> PyResult<()> {
     if result != -1 {
         Ok(())
     } else {
@@ -701,7 +701,7 @@ pub fn error_on_minusone(py: Python, result: c_int) -> PyResult<()> {
 }
 
 #[inline]
-fn exceptions_must_derive_from_base_exception(py: Python) -> PyErr {
+fn exceptions_must_derive_from_base_exception(py: Python<'_>) -> PyErr {
     PyErr::from_state(PyErrState::exceptions_must_derive_from_base_exception(py))
 }
 

src/exceptions.rs

@@ -98,7 +98,7 @@ macro_rules! import_exception {
         );
 
         impl $name {
-            fn type_object_raw(py: $crate::Python) -> *mut $crate::ffi::PyTypeObject {
+            fn type_object_raw(py: $crate::Python<'_>) -> *mut $crate::ffi::PyTypeObject {
                 use $crate::once_cell::GILOnceCell;
                 use $crate::AsPyPointer;
                 static TYPE_OBJECT: GILOnceCell<$crate::Py<$crate::types::PyType>> =
@@ -151,7 +151,7 @@ macro_rules! import_exception {
 /// }
 ///
 /// #[pymodule]
-/// fn my_module(py: Python, m: &PyModule) -> PyResult<()> {
+/// fn my_module(py: Python<'_>, m: &PyModule) -> PyResult<()> {
 ///     m.add("MyError", py.get_type::<MyError>())?;
 ///     m.add_function(wrap_pyfunction!(raise_myerror, py)?)?;
 ///     Ok(())
@@ -231,7 +231,7 @@ macro_rules! create_exception_type_object {
         );
 
         impl $name {
-            fn type_object_raw(py: $crate::Python) -> *mut $crate::ffi::PyTypeObject {
+            fn type_object_raw(py: $crate::Python<'_>) -> *mut $crate::ffi::PyTypeObject {
                 use $crate::once_cell::GILOnceCell;
                 use $crate::AsPyPointer;
                 static TYPE_OBJECT: GILOnceCell<$crate::Py<$crate::types::PyType>> =

src/gil.rs

@@ -164,7 +164,7 @@ pub struct GILGuard {
 impl GILGuard {
     /// Retrieves the marker type that proves that the GIL was acquired.
     #[inline]
-    pub fn python(&self) -> Python {
+    pub fn python(&self) -> Python<'_> {
         unsafe { Python::assume_gil_acquired() }
     }
 
@@ -298,7 +298,7 @@ impl ReferencePool {
         self.dirty.store(true, atomic::Ordering::Release);
     }
 
-    fn update_counts(&self, _py: Python) {
+    fn update_counts(&self, _py: Python<'_>) {
         let prev = self.dirty.swap(false, atomic::Ordering::Acquire);
         if !prev {
             return;
@@ -360,7 +360,7 @@ impl GILPool {
 
     /// Gets the Python token associated with this [`GILPool`].
     #[inline]
-    pub fn python(&self) -> Python {
+    pub fn python(&self) -> Python<'_> {
         unsafe { Python::assume_gil_acquired() }
     }
 }
@@ -424,7 +424,7 @@ pub unsafe fn register_decref(obj: NonNull<ffi::PyObject>) {
 ///
 /// # Safety
 /// The object must be an owned Python reference.
-pub unsafe fn register_owned(_py: Python, obj: NonNull<ffi::PyObject>) {
+pub unsafe fn register_owned(_py: Python<'_>, obj: NonNull<ffi::PyObject>) {
     debug_assert!(gil_is_acquired());
     // Ignores the error in case this function called from `atexit`.
     let _ = OWNED_OBJECTS.try_with(|holder| holder.borrow_mut().push(obj));
@@ -483,7 +483,7 @@ impl EnsureGIL {
     /// Thus this method could be used to get access to a GIL token while the GIL is not held.
     /// Care should be taken to only use the returned Python in contexts where it is certain the
     /// GIL continues to be held.
-    pub unsafe fn python(&self) -> Python {
+    pub unsafe fn python(&self) -> Python<'_> {
         match &self.0 {
             Some(gil) => gil.python(),
             None => Python::assume_gil_acquired(),
@@ -497,7 +497,7 @@ mod tests {
     use crate::{ffi, gil, AsPyPointer, IntoPyPointer, PyObject, Python, ToPyObject};
     use std::ptr::NonNull;
 
-    fn get_object(py: Python) -> PyObject {
+    fn get_object(py: Python<'_>) -> PyObject {
         // Convenience function for getting a single unique object, using `new_pool` so as to leave
         // the original pool state unchanged.
         let pool = unsafe { py.new_pool() };

src/impl_/extract_argument.rs

@@ -101,7 +101,7 @@ pub fn from_py_with_with_default<'py, T>(
 /// single string.)
 #[doc(hidden)]
 #[cold]
-pub fn argument_extraction_error(py: Python, arg_name: &str, error: PyErr) -> PyErr {
+pub fn argument_extraction_error(py: Python<'_>, arg_name: &str, error: PyErr) -> PyErr {
     if error.get_type(py).is(PyTypeError::type_object(py)) {
         let remapped_error =
             PyTypeError::new_err(format!("argument '{}': {}", arg_name, error.value(py)));

src/impl_/frompyobject.rs

@@ -2,7 +2,7 @@ use crate::{exceptions::PyTypeError, PyErr, Python};
 
 #[cold]
 pub fn failed_to_extract_enum(
-    py: Python,
+    py: Python<'_>,
     type_name: &str,
     variant_names: &[&str],
     error_names: &[&str],

src/impl_/pyclass.rs

@@ -32,7 +32,7 @@ pub trait PyClassDict {
     fn new() -> Self;
     /// Empties the dictionary of its key-value pairs.
     #[inline]
-    fn clear_dict(&mut self, _py: Python) {}
+    fn clear_dict(&mut self, _py: Python<'_>) {}
     private_decl! {}
 }
 
@@ -46,7 +46,7 @@ pub trait PyClassWeakRef {
     /// - `_obj` must be a pointer to the pyclass instance which contains `self`.
     /// - The GIL must be held.
     #[inline]
-    unsafe fn clear_weakrefs(&mut self, _obj: *mut ffi::PyObject, _py: Python) {}
+    unsafe fn clear_weakrefs(&mut self, _obj: *mut ffi::PyObject, _py: Python<'_>) {}
     private_decl! {}
 }
 
@@ -82,7 +82,7 @@ impl PyClassDict for PyClassDictSlot {
         Self(std::ptr::null_mut())
     }
     #[inline]
-    fn clear_dict(&mut self, _py: Python) {
+    fn clear_dict(&mut self, _py: Python<'_>) {
         if !self.0.is_null() {
             unsafe { ffi::PyDict_Clear(self.0) }
         }
@@ -102,7 +102,7 @@ impl PyClassWeakRef for PyClassWeakRefSlot {
         Self(std::ptr::null_mut())
     }
     #[inline]
-    unsafe fn clear_weakrefs(&mut self, obj: *mut ffi::PyObject, _py: Python) {
+    unsafe fn clear_weakrefs(&mut self, obj: *mut ffi::PyObject, _py: Python<'_>) {
         if !self.0.is_null() {
             ffi::PyObject_ClearWeakRefs(obj)
         }
@@ -205,7 +205,7 @@ slot_fragment_trait! {
     #[inline]
     unsafe fn __getattribute__(
         self,
-        py: Python,
+        py: Python<'_>,
         slf: *mut ffi::PyObject,
         attr: *mut ffi::PyObject,
     ) -> PyResult<*mut ffi::PyObject> {
@@ -225,7 +225,7 @@ slot_fragment_trait! {
     #[inline]
     unsafe fn __getattr__(
         self,
-        py: Python,
+        py: Python<'_>,
         _slf: *mut ffi::PyObject,
         attr: *mut ffi::PyObject,
     ) -> PyResult<*mut ffi::PyObject> {
@@ -299,7 +299,7 @@ macro_rules! define_pyclass_setattr_slot {
             #[inline]
             unsafe fn $set(
                 self,
-                _py: Python,
+                _py: Python<'_>,
                 _slf: *mut ffi::PyObject,
                 _attr: *mut ffi::PyObject,
                 _value: NonNull<ffi::PyObject>,
@@ -315,7 +315,7 @@ macro_rules! define_pyclass_setattr_slot {
             #[inline]
             unsafe fn $del(
                 self,
-                _py: Python,
+                _py: Python<'_>,
                 _slf: *mut ffi::PyObject,
                 _attr: *mut ffi::PyObject,
             ) -> PyResult<()> {
@@ -416,7 +416,7 @@ macro_rules! define_pyclass_binary_operator_slot {
             #[inline]
             unsafe fn $lhs(
                 self,
-                _py: Python,
+                _py: Python<'_>,
                 _slf: *mut ffi::PyObject,
                 _other: *mut ffi::PyObject,
             ) -> PyResult<*mut ffi::PyObject> {
@@ -431,7 +431,7 @@ macro_rules! define_pyclass_binary_operator_slot {
             #[inline]
             unsafe fn $rhs(
                 self,
-                _py: Python,
+                _py: Python<'_>,
                 _slf: *mut ffi::PyObject,
                 _other: *mut ffi::PyObject,
             ) -> PyResult<*mut ffi::PyObject> {
@@ -611,7 +611,7 @@ slot_fragment_trait! {
     #[inline]
     unsafe fn __pow__(
         self,
-        _py: Python,
+        _py: Python<'_>,
         _slf: *mut ffi::PyObject,
         _other: *mut ffi::PyObject,
         _mod: *mut ffi::PyObject,
@@ -627,7 +627,7 @@ slot_fragment_trait! {
     #[inline]
     unsafe fn __rpow__(
         self,
-        _py: Python,
+        _py: Python<'_>,
         _slf: *mut ffi::PyObject,
         _other: *mut ffi::PyObject,
         _mod: *mut ffi::PyObject,
@@ -675,7 +675,7 @@ pub use generate_pyclass_pow_slot;
 /// Do not implement this trait manually. Instead, use `#[pyclass(freelist = N)]`
 /// on a Rust struct to implement it.
 pub trait PyClassWithFreeList: PyClass {
-    fn get_free_list(py: Python) -> &mut FreeList<*mut ffi::PyObject>;
+    fn get_free_list(py: Python<'_>) -> &mut FreeList<*mut ffi::PyObject>;
 }
 
 /// Implementation of tp_alloc for `freelist` classes.
@@ -737,7 +737,7 @@ pub unsafe extern "C" fn free_with_freelist<T: PyClassWithFreeList>(obj: *mut c_
 /// Workaround for Python issue 35810; no longer necessary in Python 3.8
 #[inline]
 #[cfg(not(Py_3_8))]
-unsafe fn bpo_35810_workaround(_py: Python, ty: *mut ffi::PyTypeObject) {
+unsafe fn bpo_35810_workaround(_py: Python<'_>, ty: *mut ffi::PyTypeObject) {
     #[cfg(Py_LIMITED_API)]
     {
         // Must check version at runtime for abi3 wheels - they could run against a higher version

src/impl_/pymodule.rs

@@ -15,7 +15,7 @@ pub struct ModuleDef {
 }
 
 /// Wrapper to enable initializer to be used in const fns.
-pub struct ModuleInitializer(pub fn(Python, &PyModule) -> PyResult<()>);
+pub struct ModuleInitializer(pub for<'py> fn(Python<'py>, &PyModule) -> PyResult<()>);
 
 unsafe impl Sync for ModuleDef {}
 
@@ -53,7 +53,7 @@ impl ModuleDef {
         }
     }
     /// Builds a module using user given initializer. Used for [`#[pymodule]`][crate::pymodule].
-    pub fn make_module(&'static self, py: Python) -> PyResult<PyObject> {
+    pub fn make_module(&'static self, py: Python<'_>) -> PyResult<PyObject> {
         let module = unsafe {
             Py::<PyModule>::from_owned_ptr_or_err(py, ffi::PyModule_Create(self.ffi_def.get()))?
         };
@@ -154,7 +154,7 @@ mod tests {
         static INIT_CALLED: AtomicBool = AtomicBool::new(false);
 
         #[allow(clippy::unnecessary_wraps)]
-        fn init(_: Python, _: &PyModule) -> PyResult<()> {
+        fn init(_: Python<'_>, _: &PyModule) -> PyResult<()> {
             INIT_CALLED.store(true, Ordering::SeqCst);
             Ok(())
         }

src/instance.rs

@@ -24,7 +24,7 @@ use std::ptr::NonNull;
 pub unsafe trait PyNativeType: Sized {
     /// Returns a GIL marker constrained to the lifetime of this type.
     #[inline]
-    fn py(&self) -> Python {
+    fn py(&self) -> Python<'_> {
         unsafe { Python::assume_gil_acquired() }
     }
     /// Cast `&PyAny` to `&Self` without no type checking.
@@ -251,7 +251,7 @@ where
     /// # Ok(())
     /// # }
     /// ```
-    pub fn new(py: Python, value: impl Into<PyClassInitializer<T>>) -> PyResult<Py<T>> {
+    pub fn new(py: Python<'_>, value: impl Into<PyClassInitializer<T>>) -> PyResult<Py<T>> {
         let initializer = value.into();
         let obj = initializer.create_cell(py)?;
         let ob = unsafe { Py::from_owned_ptr(py, obj as _) };
@@ -351,7 +351,7 @@ where
     ///     obj.into_ref(py)
     /// }
     /// ```
-    pub fn into_ref(self, py: Python) -> &T::AsRefTarget {
+    pub fn into_ref(self, py: Python<'_>) -> &T::AsRefTarget {
         unsafe { py.from_owned_ptr(self.into_ptr()) }
     }
 }
@@ -474,7 +474,7 @@ impl<T> Py<T> {
 
     /// Gets the reference count of the `ffi::PyObject` pointer.
     #[inline]
-    pub fn get_refcnt(&self, _py: Python) -> isize {
+    pub fn get_refcnt(&self, _py: Python<'_>) -> isize {
         unsafe { ffi::Py_REFCNT(self.0.as_ptr()) }
     }
 
@@ -502,21 +502,21 @@ impl<T> Py<T> {
     /// # }
     /// ```
     #[inline]
-    pub fn clone_ref(&self, py: Python) -> Py<T> {
+    pub fn clone_ref(&self, py: Python<'_>) -> Py<T> {
         unsafe { Py::from_borrowed_ptr(py, self.0.as_ptr()) }
     }
 
     /// Returns whether the object is considered to be None.
     ///
     /// This is equivalent to the Python expression `self is None`.
-    pub fn is_none(&self, _py: Python) -> bool {
+    pub fn is_none(&self, _py: Python<'_>) -> bool {
         unsafe { ffi::Py_None() == self.as_ptr() }
     }
 
     /// Returns whether the object is considered to be true.
     ///
     /// This is equivalent to the Python expression `bool(self)`.
-    pub fn is_true(&self, py: Python) -> PyResult<bool> {
+    pub fn is_true(&self, py: Python<'_>) -> PyResult<bool> {
         let v = unsafe { ffi::PyObject_IsTrue(self.as_ptr()) };
         err::error_on_minusone(py, v)?;
         Ok(v != 0)
@@ -535,7 +535,7 @@ impl<T> Py<T> {
     /// Retrieves an attribute value.
     ///
     /// This is equivalent to the Python expression `self.attr_name`.
-    pub fn getattr<N>(&self, py: Python, attr_name: N) -> PyResult<PyObject>
+    pub fn getattr<N>(&self, py: Python<'_>, attr_name: N) -> PyResult<PyObject>
     where
         N: ToPyObject,
     {
@@ -547,7 +547,7 @@ impl<T> Py<T> {
     /// Sets an attribute value.
     ///
     /// This is equivalent to the Python expression `self.attr_name = value`.
-    pub fn setattr<N, V>(&self, py: Python, attr_name: N, value: V) -> PyResult<()>
+    pub fn setattr<N, V>(&self, py: Python<'_>, attr_name: N, value: V) -> PyResult<()>
     where
         N: ToPyObject,
         V: ToPyObject,
@@ -564,7 +564,7 @@ impl<T> Py<T> {
     /// This is equivalent to the Python expression `self(*args, **kwargs)`.
     pub fn call(
         &self,
-        py: Python,
+        py: Python<'_>,
         args: impl IntoPy<Py<PyTuple>>,
         kwargs: Option<&PyDict>,
     ) -> PyResult<PyObject> {
@@ -583,14 +583,14 @@ impl<T> Py<T> {
     /// Calls the object with only positional arguments.
     ///
     /// This is equivalent to the Python expression `self(*args)`.
-    pub fn call1(&self, py: Python, args: impl IntoPy<Py<PyTuple>>) -> PyResult<PyObject> {
+    pub fn call1(&self, py: Python<'_>, args: impl IntoPy<Py<PyTuple>>) -> PyResult<PyObject> {
         self.call(py, args, None)
     }
 
     /// Calls the object without arguments.
     ///
     /// This is equivalent to the Python expression `self()`.
-    pub fn call0(&self, py: Python) -> PyResult<PyObject> {
+    pub fn call0(&self, py: Python<'_>) -> PyResult<PyObject> {
         cfg_if::cfg_if! {
             if #[cfg(all(Py_3_9, not(PyPy)))] {
                 // Optimized path on python 3.9+
@@ -608,7 +608,7 @@ impl<T> Py<T> {
     /// This is equivalent to the Python expression `self.name(*args, **kwargs)`.
     pub fn call_method(
         &self,
-        py: Python,
+        py: Python<'_>,
         name: &str,
         args: impl IntoPy<Py<PyTuple>>,
         kwargs: Option<&PyDict>,
@@ -633,7 +633,7 @@ impl<T> Py<T> {
     /// This is equivalent to the Python expression `self.name(*args)`.
     pub fn call_method1(
         &self,
-        py: Python,
+        py: Python<'_>,
         name: &str,
         args: impl IntoPy<Py<PyTuple>>,
     ) -> PyResult<PyObject> {
@@ -643,7 +643,7 @@ impl<T> Py<T> {
     /// Calls a method on the object with no arguments.
     ///
     /// This is equivalent to the Python expression `self.name()`.
-    pub fn call_method0(&self, py: Python, name: &str) -> PyResult<PyObject> {
+    pub fn call_method0(&self, py: Python<'_>, name: &str) -> PyResult<PyObject> {
         cfg_if::cfg_if! {
             if #[cfg(all(Py_3_9, not(any(Py_LIMITED_API, PyPy))))] {
                 // Optimized path on python 3.9+
@@ -668,7 +668,7 @@ impl<T> Py<T> {
     /// # Panics
     /// Panics if `ptr` is null.
     #[inline]
-    pub unsafe fn from_owned_ptr(py: Python, ptr: *mut ffi::PyObject) -> Py<T> {
+    pub unsafe fn from_owned_ptr(py: Python<'_>, ptr: *mut ffi::PyObject) -> Py<T> {
         match NonNull::new(ptr) {
             Some(nonnull_ptr) => Py(nonnull_ptr, PhantomData),
             None => crate::err::panic_after_error(py),
@@ -682,7 +682,10 @@ impl<T> Py<T> {
     /// # Safety
     /// If non-null, `ptr` must be a pointer to a Python object of type T.
     #[inline]
-    pub unsafe fn from_owned_ptr_or_err(py: Python, ptr: *mut ffi::PyObject) -> PyResult<Py<T>> {
+    pub unsafe fn from_owned_ptr_or_err(
+        py: Python<'_>,
+        ptr: *mut ffi::PyObject,
+    ) -> PyResult<Py<T>> {
         match NonNull::new(ptr) {
             Some(nonnull_ptr) => Ok(Py(nonnull_ptr, PhantomData)),
             None => Err(PyErr::fetch(py)),
@@ -696,7 +699,7 @@ impl<T> Py<T> {
     /// # Safety
     /// If non-null, `ptr` must be a pointer to a Python object of type T.
     #[inline]
-    pub unsafe fn from_owned_ptr_or_opt(_py: Python, ptr: *mut ffi::PyObject) -> Option<Self> {
+    pub unsafe fn from_owned_ptr_or_opt(_py: Python<'_>, ptr: *mut ffi::PyObject) -> Option<Self> {
         NonNull::new(ptr).map(|nonnull_ptr| Py(nonnull_ptr, PhantomData))
     }
 
@@ -708,7 +711,7 @@ impl<T> Py<T> {
     /// # Panics
     /// Panics if `ptr` is null.
     #[inline]
-    pub unsafe fn from_borrowed_ptr(py: Python, ptr: *mut ffi::PyObject) -> Py<T> {
+    pub unsafe fn from_borrowed_ptr(py: Python<'_>, ptr: *mut ffi::PyObject) -> Py<T> {
         match Self::from_borrowed_ptr_or_opt(py, ptr) {
             Some(slf) => slf,
             None => crate::err::panic_after_error(py),
@@ -722,7 +725,10 @@ impl<T> Py<T> {
     /// # Safety
     /// `ptr` must be a pointer to a Python object of type T.
     #[inline]
-    pub unsafe fn from_borrowed_ptr_or_err(py: Python, ptr: *mut ffi::PyObject) -> PyResult<Self> {
+    pub unsafe fn from_borrowed_ptr_or_err(
+        py: Python<'_>,
+        ptr: *mut ffi::PyObject,
+    ) -> PyResult<Self> {
         Self::from_borrowed_ptr_or_opt(py, ptr).ok_or_else(|| PyErr::fetch(py))
     }
 
@@ -733,7 +739,10 @@ impl<T> Py<T> {
     /// # Safety
     /// `ptr` must be a pointer to a Python object of type T.
     #[inline]
-    pub unsafe fn from_borrowed_ptr_or_opt(_py: Python, ptr: *mut ffi::PyObject) -> Option<Self> {
+    pub unsafe fn from_borrowed_ptr_or_opt(
+        _py: Python<'_>,
+        ptr: *mut ffi::PyObject,
+    ) -> Option<Self> {
         NonNull::new(ptr).map(|nonnull_ptr| {
             ffi::Py_INCREF(ptr);
             Py(nonnull_ptr, PhantomData)
@@ -760,7 +769,7 @@ impl<T> Py<T> {
 
 impl<T> ToPyObject for Py<T> {
     /// Converts `Py` instance -> PyObject.
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         unsafe { PyObject::from_borrowed_ptr(py, self.as_ptr()) }
     }
 }
@@ -769,7 +778,7 @@ impl<T> IntoPy<PyObject> for Py<T> {
     /// Converts a `Py` instance to `PyObject`.
     /// Consumes `self` without calling `Py_DECREF()`.
     #[inline]
-    fn into_py(self, _py: Python) -> PyObject {
+    fn into_py(self, _py: Python<'_>) -> PyObject {
         unsafe { PyObject::from_non_null(self.into_non_null()) }
     }
 }
@@ -811,7 +820,7 @@ where
 }
 
 // `&PyCell<T>` can be converted to `Py<T>`
-impl<'a, T> std::convert::From<&PyCell<T>> for Py<T>
+impl<T> std::convert::From<&PyCell<T>> for Py<T>
 where
     T: PyClass,
 {
@@ -890,13 +899,13 @@ where
     T: PyTypeInfo,
     T::AsRefTarget: std::fmt::Display,
 {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         Python::with_gil(|py| std::fmt::Display::fmt(self.as_ref(py), f))
     }
 }
 
 impl<T> std::fmt::Debug for Py<T> {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.debug_tuple("Py").field(&self.0.as_ptr()).finish()
     }
 }
@@ -914,11 +923,11 @@ impl PyObject {
     ///
     /// This can cast only to native Python types, not types implemented in Rust. For a more
     /// flexible alternative, see [`Py::extract`](struct.Py.html#method.extract).
-    pub fn cast_as<'p, D>(&'p self, py: Python<'p>) -> Result<&'p D, PyDowncastError>
+    pub fn cast_as<'p, D>(&'p self, py: Python<'p>) -> Result<&'p D, PyDowncastError<'_>>
     where
         D: PyTryFrom<'p>,
     {
-        D::try_from(unsafe { py.from_borrowed_ptr::<PyAny>(self.as_ptr()) })
+        <D as PyTryFrom<'_>>::try_from(unsafe { py.from_borrowed_ptr::<PyAny>(self.as_ptr()) })
     }
 }
 

src/lib.rs

@@ -10,7 +10,15 @@
 )]
 // Deny some lints in doctests.
 // Use `#[allow(...)]` locally to override.
-#![doc(test(attr(deny(warnings), allow(unused_variables, unused_assignments))))]
+#![doc(test(attr(
+    deny(
+        elided_lifetimes_in_paths,
+        unused_lifetimes,
+        rust_2021_prelude_collisions,
+        warnings
+    ),
+    allow(unused_variables, unused_assignments)
+)))]
 #![cfg_attr(coverage, feature(no_coverage))] // used in src/test_hygiene.rs
 
 //! Rust bindings to the Python interpreter.
@@ -160,7 +168,7 @@
 //!
 //! /// A Python module implemented in Rust.
 //! #[pymodule]
-//! fn string_sum(py: Python, m: &PyModule) -> PyResult<()> {
+//! fn string_sum(py: Python<'_>, m: &PyModule) -> PyResult<()> {
 //!     m.add_function(wrap_pyfunction!(sum_as_string, m)?)?;
 //!
 //!     Ok(())
@@ -226,7 +234,7 @@
 //!         let code = "os.getenv('USER') or os.getenv('USERNAME') or 'Unknown'";
 //!         let user: String = py.eval(code, None, Some(&locals))?.extract()?;
 //!
-//!         println!("Hello {}, I'm Python {}", user, version);
+//!         println!("Hello {}, I'm Python<'_> {}", user, version);
 //!         Ok(())
 //!     })
 //! }

src/marker.rs

@@ -779,7 +779,7 @@ impl<'py> Python<'py> {
     ///
     /// # fn main(){
     /// #[pyfunction]
-    /// fn loop_forever(py: Python) -> PyResult<()> {
+    /// fn loop_forever(py: Python<'_>) -> PyResult<()> {
     ///     loop {
     ///         // As this loop is infinite it should check for signals every once in a while.
     ///         // Using `?` causes any `PyErr` (potentially containing `KeyboardInterrupt`)

src/marshal.rs

@@ -72,7 +72,7 @@ mod tests {
         });
     }
 
-    fn equal(_py: Python, a: &impl AsPyPointer, b: &impl AsPyPointer) -> bool {
+    fn equal(_py: Python<'_>, a: &impl AsPyPointer, b: &impl AsPyPointer) -> bool {
         unsafe { ffi::PyObject_RichCompareBool(a.as_ptr(), b.as_ptr(), ffi::Py_EQ) != 0 }
     }
 }

src/once_cell.rs

@@ -21,7 +21,7 @@ use std::cell::UnsafeCell;
 ///
 /// static LIST_CELL: GILOnceCell<Py<PyList>> = GILOnceCell::new();
 ///
-/// pub fn get_shared_list(py: Python) -> &PyList {
+/// pub fn get_shared_list(py: Python<'_>) -> &PyList {
 ///     LIST_CELL
 ///         .get_or_init(py, || PyList::empty(py).into())
 ///         .as_ref(py)
@@ -42,7 +42,7 @@ impl<T> GILOnceCell<T> {
     }
 
     /// Get a reference to the contained value, or `None` if the cell has not yet been written.
-    pub fn get(&self, _py: Python) -> Option<&T> {
+    pub fn get(&self, _py: Python<'_>) -> Option<&T> {
         // Safe because if the cell has not yet been written, None is returned.
         unsafe { &*self.0.get() }.as_ref()
     }
@@ -61,7 +61,7 @@ impl<T> GILOnceCell<T> {
     ///     exactly once, even if multiple threads attempt to call `get_or_init`
     ///  4) if f() can panic but still does not release the GIL, it may be called multiple times,
     ///     but it is guaranteed that f() will never be called concurrently
-    pub fn get_or_init<F>(&self, py: Python, f: F) -> &T
+    pub fn get_or_init<F>(&self, py: Python<'_>, f: F) -> &T
     where
         F: FnOnce() -> T,
     {
@@ -90,7 +90,7 @@ impl<T> GILOnceCell<T> {
     ///
     /// If the cell has already been written, `Err(value)` will be returned containing the new
     /// value which was not written.
-    pub fn set(&self, _py: Python, value: T) -> Result<(), T> {
+    pub fn set(&self, _py: Python<'_>, value: T) -> Result<(), T> {
         // Safe because GIL is held, so no other thread can be writing to this cell concurrently.
         let inner = unsafe { &mut *self.0.get() };
         if inner.is_some() {

src/pycell.rs

@@ -259,7 +259,7 @@ impl<T: PyClass> PyCell<T> {
     ///
     /// In cases where the value in the cell does not need to be accessed immediately after
     /// creation, consider [`Py::new`](crate::Py::new) as a more efficient alternative.
-    pub fn new(py: Python, value: impl Into<PyClassInitializer<T>>) -> PyResult<&Self> {
+    pub fn new(py: Python<'_>, value: impl Into<PyClassInitializer<T>>) -> PyResult<&Self> {
         unsafe {
             let initializer = value.into();
             let self_ = initializer.create_cell(py)?;
@@ -567,7 +567,7 @@ impl<T: PyClass + fmt::Debug> fmt::Debug for PyCell<T> {
 ///         (Child { name: "Caterpillar" }, Parent { basename: "Butterfly" })
 ///     }
 ///
-///     fn format(slf: PyRef<Self>) -> String {
+///     fn format(slf: PyRef<'_, Self>) -> String {
 ///         // We can get *mut ffi::PyObject from PyRef
 ///         use pyo3::AsPyPointer;
 ///         let refcnt = unsafe { pyo3::ffi::Py_REFCNT(slf.as_ptr()) };
@@ -589,7 +589,7 @@ pub struct PyRef<'p, T: PyClass> {
 
 impl<'p, T: PyClass> PyRef<'p, T> {
     /// Returns a `Python` token that is bound to the lifetime of the `PyRef`.
-    pub fn py(&self) -> Python {
+    pub fn py(&self) -> Python<'_> {
         unsafe { Python::assume_gil_acquired() }
     }
 }
@@ -643,7 +643,7 @@ where
     ///             .add_subclass(Base2 { name2: "base2" })
     ///             .add_subclass(Self { name3: "sub" })
     ///     }
-    ///     fn name(slf: PyRef<Self>) -> String {
+    ///     fn name(slf: PyRef<'_, Self>) -> String {
     ///         let subname = slf.name3;
     ///         let super_ = slf.into_super();
     ///         format!("{} {} {}", super_.as_ref().name1, super_.name2, subname)
@@ -713,7 +713,7 @@ pub struct PyRefMut<'p, T: PyClass> {
 
 impl<'p, T: PyClass> PyRefMut<'p, T> {
     /// Returns a `Python` token that is bound to the lifetime of the `PyRefMut`.
-    pub fn py(&self) -> Python {
+    pub fn py(&self) -> Python<'_> {
         unsafe { Python::assume_gil_acquired() }
     }
 }
@@ -778,7 +778,7 @@ impl<'p, T: PyClass> Drop for PyRefMut<'p, T> {
 }
 
 impl<T: PyClass> IntoPy<PyObject> for PyRefMut<'_, T> {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         unsafe { PyObject::from_borrowed_ptr(py, self.inner.as_ptr()) }
     }
 }
@@ -875,7 +875,7 @@ pub trait PyCellLayout<T>: PyLayout<T> {
     /// # Safety
     /// - slf must be a valid pointer to an instance of a T or a subclass.
     /// - slf must not be used after this call (as it will be freed).
-    unsafe fn tp_dealloc(slf: *mut ffi::PyObject, py: Python);
+    unsafe fn tp_dealloc(slf: *mut ffi::PyObject, py: Python<'_>);
 }
 
 impl<T, U> PyCellLayout<T> for PyCellBase<U>
@@ -889,7 +889,7 @@ where
     fn set_borrow_flag(&self, flag: BorrowFlag) {
         self.borrow_flag.set(flag)
     }
-    unsafe fn tp_dealloc(slf: *mut ffi::PyObject, py: Python) {
+    unsafe fn tp_dealloc(slf: *mut ffi::PyObject, py: Python<'_>) {
         // For `#[pyclass]` types which inherit from PyAny, we can just call tp_free
         if T::type_object_raw(py) == &mut PyBaseObject_Type {
             return get_tp_free(ffi::Py_TYPE(slf))(slf as _);
@@ -921,7 +921,7 @@ where
     fn set_borrow_flag(&self, flag: BorrowFlag) {
         self.ob_base.set_borrow_flag(flag)
     }
-    unsafe fn tp_dealloc(slf: *mut ffi::PyObject, py: Python) {
+    unsafe fn tp_dealloc(slf: *mut ffi::PyObject, py: Python<'_>) {
         // Safety: Python only calls tp_dealloc when no references to the object remain.
         let cell = &mut *(slf as *mut PyCell<T>);
         ManuallyDrop::drop(&mut cell.contents.value);

src/pyclass.rs

@@ -38,7 +38,7 @@ fn into_raw<T>(vec: Vec<T>) -> *mut c_void {
     Box::into_raw(vec.into_boxed_slice()) as _
 }
 
-pub(crate) fn create_type_object<T>(py: Python) -> *mut ffi::PyTypeObject
+pub(crate) fn create_type_object<T>(py: Python<'_>) -> *mut ffi::PyTypeObject
 where
     T: PyClass,
 {
@@ -64,7 +64,7 @@ where
 
 #[allow(clippy::too_many_arguments)]
 unsafe fn create_type_object_impl(
-    py: Python,
+    py: Python<'_>,
     tp_doc: &str,
     module_name: Option<&str>,
     name: &str,
@@ -210,7 +210,7 @@ unsafe fn create_type_object_impl(
 }
 
 #[cold]
-fn type_object_creation_failed(py: Python, e: PyErr, name: &'static str) -> ! {
+fn type_object_creation_failed(py: Python<'_>, e: PyErr, name: &'static str) -> ! {
     e.print(py);
     panic!("An error occurred while initializing class {}", name)
 }
@@ -479,7 +479,7 @@ pub enum IterNextOutput<T, U> {
 pub type PyIterNextOutput = IterNextOutput<PyObject, PyObject>;
 
 impl IntoPyCallbackOutput<*mut ffi::PyObject> for PyIterNextOutput {
-    fn convert(self, _py: Python) -> PyResult<*mut ffi::PyObject> {
+    fn convert(self, _py: Python<'_>) -> PyResult<*mut ffi::PyObject> {
         match self {
             IterNextOutput::Yield(o) => Ok(o.into_ptr()),
             IterNextOutput::Return(opt) => Err(crate::exceptions::PyStopIteration::new_err((opt,))),
@@ -492,7 +492,7 @@ where
     T: IntoPy<PyObject>,
     U: IntoPy<PyObject>,
 {
-    fn convert(self, py: Python) -> PyResult<PyIterNextOutput> {
+    fn convert(self, py: Python<'_>) -> PyResult<PyIterNextOutput> {
         match self {
             IterNextOutput::Yield(o) => Ok(IterNextOutput::Yield(o.into_py(py))),
             IterNextOutput::Return(o) => Ok(IterNextOutput::Return(o.into_py(py))),
@@ -504,7 +504,7 @@ impl<T> IntoPyCallbackOutput<PyIterNextOutput> for Option<T>
 where
     T: IntoPy<PyObject>,
 {
-    fn convert(self, py: Python) -> PyResult<PyIterNextOutput> {
+    fn convert(self, py: Python<'_>) -> PyResult<PyIterNextOutput> {
         match self {
             Some(o) => Ok(PyIterNextOutput::Yield(o.into_py(py))),
             None => Ok(PyIterNextOutput::Return(py.None())),
@@ -526,7 +526,7 @@ pub enum IterANextOutput<T, U> {
 pub type PyIterANextOutput = IterANextOutput<PyObject, PyObject>;
 
 impl IntoPyCallbackOutput<*mut ffi::PyObject> for PyIterANextOutput {
-    fn convert(self, _py: Python) -> PyResult<*mut ffi::PyObject> {
+    fn convert(self, _py: Python<'_>) -> PyResult<*mut ffi::PyObject> {
         match self {
             IterANextOutput::Yield(o) => Ok(o.into_ptr()),
             IterANextOutput::Return(opt) => {
@@ -541,7 +541,7 @@ where
     T: IntoPy<PyObject>,
     U: IntoPy<PyObject>,
 {
-    fn convert(self, py: Python) -> PyResult<PyIterANextOutput> {
+    fn convert(self, py: Python<'_>) -> PyResult<PyIterANextOutput> {
         match self {
             IterANextOutput::Yield(o) => Ok(IterANextOutput::Yield(o.into_py(py))),
             IterANextOutput::Return(o) => Ok(IterANextOutput::Return(o.into_py(py))),
@@ -553,7 +553,7 @@ impl<T> IntoPyCallbackOutput<PyIterANextOutput> for Option<T>
 where
     T: IntoPy<PyObject>,
 {
-    fn convert(self, py: Python) -> PyResult<PyIterANextOutput> {
+    fn convert(self, py: Python<'_>) -> PyResult<PyIterANextOutput> {
         match self {
             Some(o) => Ok(PyIterANextOutput::Yield(o.into_py(py))),
             None => Ok(PyIterANextOutput::Return(py.None())),

src/pyclass_init.rs

@@ -22,7 +22,7 @@ pub trait PyObjectInit<T>: Sized {
     /// - `subtype` must be a valid pointer to a type object of T or a subclass.
     unsafe fn into_new_object(
         self,
-        py: Python,
+        py: Python<'_>,
         subtype: *mut PyTypeObject,
     ) -> PyResult<*mut ffi::PyObject>;
     private_decl! {}
@@ -34,7 +34,7 @@ pub struct PyNativeTypeInitializer<T: PyTypeInfo>(PhantomData<T>);
 impl<T: PyTypeInfo> PyObjectInit<T> for PyNativeTypeInitializer<T> {
     unsafe fn into_new_object(
         self,
-        py: Python,
+        py: Python<'_>,
         subtype: *mut PyTypeObject,
     ) -> PyResult<*mut ffi::PyObject> {
         let type_object = T::type_object_raw(py);
@@ -197,7 +197,7 @@ impl<T: PyClass> PyClassInitializer<T> {
 
     /// Creates a new PyCell and initializes it.
     #[doc(hidden)]
-    pub fn create_cell(self, py: Python) -> PyResult<*mut PyCell<T>>
+    pub fn create_cell(self, py: Python<'_>) -> PyResult<*mut PyCell<T>>
     where
         T: PyClass,
     {
@@ -212,7 +212,7 @@ impl<T: PyClass> PyClassInitializer<T> {
     #[doc(hidden)]
     pub unsafe fn create_cell_from_subtype(
         self,
-        py: Python,
+        py: Python<'_>,
         subtype: *mut crate::ffi::PyTypeObject,
     ) -> PyResult<*mut PyCell<T>>
     where
@@ -225,7 +225,7 @@ impl<T: PyClass> PyClassInitializer<T> {
 impl<T: PyClass> PyObjectInit<T> for PyClassInitializer<T> {
     unsafe fn into_new_object(
         self,
-        py: Python,
+        py: Python<'_>,
         subtype: *mut PyTypeObject,
     ) -> PyResult<*mut ffi::PyObject> {
         /// Layout of a PyCellBase after base new has been called, but the borrow flag has not
@@ -302,7 +302,7 @@ where
     U: Into<PyClassInitializer<T>>,
 {
     #[inline]
-    fn convert(self, _py: Python) -> PyResult<PyClassInitializer<T>> {
+    fn convert(self, _py: Python<'_>) -> PyResult<PyClassInitializer<T>> {
         Ok(self.into())
     }
 }

src/test_hygiene/pymethods.rs

@@ -114,7 +114,7 @@ impl Dummy {
 
     fn __delitem__(&self, key: u32) {}
 
-    fn __iter__(_: crate::pycell::PyRef<Self>, py: crate::Python) -> crate::Py<DummyIter> {
+    fn __iter__(_: crate::pycell::PyRef<'_, Self>, py: crate::Python<'_>) -> crate::Py<DummyIter> {
         crate::Py::new(py, DummyIter {}).unwrap()
     }
 
@@ -122,7 +122,10 @@ impl Dummy {
         ::std::option::Option::None
     }
 
-    fn __reversed__(slf: crate::pycell::PyRef<Self>, py: crate::Python) -> crate::Py<DummyIter> {
+    fn __reversed__(
+        slf: crate::pycell::PyRef<'_, Self>,
+        py: crate::Python<'_>,
+    ) -> crate::Py<DummyIter> {
         crate::Py::new(py, DummyIter {}).unwrap()
     }
 
@@ -262,19 +265,19 @@ impl Dummy {
 
     fn __ior__(&mut self, other: &Self) {}
 
-    fn __neg__(slf: crate::pycell::PyRef<Self>) -> crate::pycell::PyRef<Self> {
+    fn __neg__(slf: crate::pycell::PyRef<'_, Self>) -> crate::pycell::PyRef<'_, Self> {
         slf
     }
 
-    fn __pos__(slf: crate::pycell::PyRef<Self>) -> crate::pycell::PyRef<Self> {
+    fn __pos__(slf: crate::pycell::PyRef<'_, Self>) -> crate::pycell::PyRef<'_, Self> {
         slf
     }
 
-    fn __abs__(slf: crate::pycell::PyRef<Self>) -> crate::pycell::PyRef<Self> {
+    fn __abs__(slf: crate::pycell::PyRef<'_, Self>) -> crate::pycell::PyRef<'_, Self> {
         slf
     }
 
-    fn __invert__(slf: crate::pycell::PyRef<Self>) -> crate::pycell::PyRef<Self> {
+    fn __invert__(slf: crate::pycell::PyRef<'_, Self>) -> crate::pycell::PyRef<'_, Self> {
         slf
     }
 
@@ -328,7 +331,7 @@ impl Dummy {
     // Awaitable Objects
     //////////////////////
 
-    fn __await__(slf: crate::pycell::PyRef<Self>) -> crate::pycell::PyRef<Self> {
+    fn __await__(slf: crate::pycell::PyRef<'_, Self>) -> crate::pycell::PyRef<'_, Self> {
         slf
     }
 
@@ -337,7 +340,10 @@ impl Dummy {
     // Asynchronous Iterators
     //////////////////////
 
-    fn __aiter__(slf: crate::pycell::PyRef<Self>, py: crate::Python) -> crate::Py<DummyIter> {
+    fn __aiter__(
+        slf: crate::pycell::PyRef<'_, Self>,
+        py: crate::Python<'_>,
+    ) -> crate::Py<DummyIter> {
         crate::Py::new(py, DummyIter {}).unwrap()
     }
 
@@ -508,7 +514,7 @@ impl Dummy {
 
     fn __delitem__(&self, key: u32) {}
 
-    fn __iter__(_: crate::pycell::PyRef<Self>, py: crate::Python) -> crate::Py<DummyIter> {
+    fn __iter__(_: crate::pycell::PyRef<'_, Self>, py: crate::Python<'_>) -> crate::Py<DummyIter> {
         crate::Py::new(py, DummyIter {}).unwrap()
     }
 
@@ -516,7 +522,10 @@ impl Dummy {
         ::std::option::Option::None
     }
 
-    fn __reversed__(slf: crate::pycell::PyRef<Self>, py: crate::Python) -> crate::Py<DummyIter> {
+    fn __reversed__(
+        slf: crate::pycell::PyRef<'_, Self>,
+        py: crate::Python<'_>,
+    ) -> crate::Py<DummyIter> {
         crate::Py::new(py, DummyIter {}).unwrap()
     }
 
@@ -655,19 +664,19 @@ impl Dummy {
 
     fn __ior__(&mut self, other: &Self) {}
 
-    fn __neg__(slf: crate::pycell::PyRef<Self>) -> crate::pycell::PyRef<Self> {
+    fn __neg__(slf: crate::pycell::PyRef<'_, Self>) -> crate::pycell::PyRef<'_, Self> {
         slf
     }
 
-    fn __pos__(slf: crate::pycell::PyRef<Self>) -> crate::pycell::PyRef<Self> {
+    fn __pos__(slf: crate::pycell::PyRef<'_, Self>) -> crate::pycell::PyRef<'_, Self> {
         slf
     }
 
-    fn __abs__(slf: crate::pycell::PyRef<Self>) -> crate::pycell::PyRef<Self> {
+    fn __abs__(slf: crate::pycell::PyRef<'_, Self>) -> crate::pycell::PyRef<'_, Self> {
         slf
     }
 
-    fn __invert__(slf: crate::pycell::PyRef<Self>) -> crate::pycell::PyRef<Self> {
+    fn __invert__(slf: crate::pycell::PyRef<'_, Self>) -> crate::pycell::PyRef<'_, Self> {
         slf
     }
 
@@ -721,7 +730,7 @@ impl Dummy {
     // Awaitable Objects
     //////////////////////
 
-    fn __await__(slf: crate::pycell::PyRef<Self>) -> crate::pycell::PyRef<Self> {
+    fn __await__(slf: crate::pycell::PyRef<'_, Self>) -> crate::pycell::PyRef<'_, Self> {
         slf
     }
 
@@ -730,7 +739,10 @@ impl Dummy {
     // Asynchronous Iterators
     //////////////////////
 
-    fn __aiter__(slf: crate::pycell::PyRef<Self>, py: crate::Python) -> crate::Py<DummyIter> {
+    fn __aiter__(
+        slf: crate::pycell::PyRef<'_, Self>,
+        py: crate::Python<'_>,
+    ) -> crate::Py<DummyIter> {
         crate::Py::new(py, DummyIter {}).unwrap()
     }
 

src/test_hygiene/pymodule.rs

@@ -9,13 +9,13 @@ fn do_something(x: i32) -> crate::PyResult<i32> {
 
 #[crate::pymodule]
 #[pyo3(crate = "crate")]
-fn foo(_py: crate::Python, _m: &crate::types::PyModule) -> crate::PyResult<()> {
+fn foo(_py: crate::Python<'_>, _m: &crate::types::PyModule) -> crate::PyResult<()> {
     ::std::result::Result::Ok(())
 }
 
 #[crate::pymodule]
 #[pyo3(crate = "crate")]
-fn my_module(_py: crate::Python, m: &crate::types::PyModule) -> crate::PyResult<()> {
+fn my_module(_py: crate::Python<'_>, m: &crate::types::PyModule) -> crate::PyResult<()> {
     m.add_function(crate::wrap_pyfunction!(do_something, m)?)?;
     m.add_wrapped(crate::wrap_pymodule!(foo))?;
 

src/type_object.rs

@@ -52,7 +52,7 @@ pub unsafe trait PyTypeInfo: Sized {
     type AsRefTarget: PyNativeType;
 
     /// PyTypeObject instance for this type.
-    fn type_object_raw(py: Python) -> *mut ffi::PyTypeObject;
+    fn type_object_raw(py: Python<'_>) -> *mut ffi::PyTypeObject;
 
     /// Checks if `object` is an instance of this type or a subclass of this type.
     fn is_type_of(object: &PyAny) -> bool {
@@ -75,14 +75,14 @@ pub unsafe trait PyTypeInfo: Sized {
 /// See also [PyTypeInfo::type_object_raw](trait.PyTypeInfo.html#tymethod.type_object_raw).
 pub unsafe trait PyTypeObject {
     /// Returns the safe abstraction over the type object.
-    fn type_object(py: Python) -> &PyType;
+    fn type_object(py: Python<'_>) -> &PyType;
 }
 
 unsafe impl<T> PyTypeObject for T
 where
     T: PyTypeInfo,
 {
-    fn type_object(py: Python) -> &PyType {
+    fn type_object(py: Python<'_>) -> &PyType {
         unsafe { py.from_borrowed_ptr(Self::type_object_raw(py) as _) }
     }
 }
@@ -107,7 +107,7 @@ impl LazyStaticType {
         }
     }
 
-    pub fn get_or_init<T: PyClass>(&self, py: Python) -> *mut ffi::PyTypeObject {
+    pub fn get_or_init<T: PyClass>(&self, py: Python<'_>) -> *mut ffi::PyTypeObject {
         let type_object = *self.value.get_or_init(py, || create_type_object::<T>(py));
         self.ensure_init(py, type_object, T::NAME, &T::for_all_items);
         type_object
@@ -115,7 +115,7 @@ impl LazyStaticType {
 
     fn ensure_init(
         &self,
-        py: Python,
+        py: Python<'_>,
         type_object: *mut ffi::PyTypeObject,
         name: &str,
         for_all_items: &dyn Fn(&mut dyn FnMut(&PyClassItems)),
@@ -188,7 +188,7 @@ impl LazyStaticType {
 }
 
 fn initialize_tp_dict(
-    py: Python,
+    py: Python<'_>,
     type_object: *mut ffi::PyObject,
     items: Vec<(&'static std::ffi::CStr, PyObject)>,
 ) -> PyResult<()> {

src/types/any.rs

@@ -80,7 +80,7 @@ impl PyAny {
     ///     assert!(any.downcast::<PyList>().is_err());
     /// });
     /// ```
-    pub fn downcast<T>(&self) -> Result<&T, PyDowncastError>
+    pub fn downcast<T>(&self) -> Result<&T, PyDowncastError<'_>>
     where
         for<'py> T: PyTryFrom<'py>,
     {
@@ -658,11 +658,11 @@ impl PyAny {
     /// Casts the PyObject to a concrete Python object type.
     ///
     /// This can cast only to native Python types, not types implemented in Rust.
-    pub fn cast_as<'a, D>(&'a self) -> Result<&'a D, PyDowncastError>
+    pub fn cast_as<'a, D>(&'a self) -> Result<&'a D, PyDowncastError<'_>>
     where
         D: PyTryFrom<'a>,
     {
-        D::try_from(self)
+        <D as PyTryFrom<'_>>::try_from(self)
     }
 
     /// Extracts some type from the Python object.

src/types/boolobject.rs

@@ -13,7 +13,7 @@ pyobject_native_type!(PyBool, ffi::PyObject, ffi::PyBool_Type, #checkfunction=ff
 impl PyBool {
     /// Depending on `val`, returns `true` or `false`.
     #[inline]
-    pub fn new(py: Python, val: bool) -> &PyBool {
+    pub fn new(py: Python<'_>, val: bool) -> &PyBool {
         unsafe { py.from_borrowed_ptr(if val { ffi::Py_True() } else { ffi::Py_False() }) }
     }
 
@@ -27,7 +27,7 @@ impl PyBool {
 /// Converts a Rust `bool` to a Python `bool`.
 impl ToPyObject for bool {
     #[inline]
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         unsafe {
             PyObject::from_borrowed_ptr(
                 py,
@@ -43,7 +43,7 @@ impl ToPyObject for bool {
 
 impl IntoPy<PyObject> for bool {
     #[inline]
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         PyBool::new(py, self).into()
     }
 }

src/types/bytearray.rs

@@ -44,7 +44,7 @@ impl PyByteArray {
     /// })
     /// # }
     /// ```
-    pub fn new_with<F>(py: Python, len: usize, init: F) -> PyResult<&PyByteArray>
+    pub fn new_with<F>(py: Python<'_>, len: usize, init: F) -> PyResult<&PyByteArray>
     where
         F: FnOnce(&mut [u8]) -> PyResult<()>,
     {

src/types/bytes.rs

@@ -50,7 +50,7 @@ impl PyBytes {
     /// })
     /// # }
     /// ```
-    pub fn new_with<F>(py: Python, len: usize, init: F) -> PyResult<&PyBytes>
+    pub fn new_with<F>(py: Python<'_>, len: usize, init: F) -> PyResult<&PyBytes>
     where
         F: FnOnce(&mut [u8]) -> PyResult<()>,
     {
@@ -125,7 +125,7 @@ impl<I: SliceIndex<[u8]>> Index<I> for PyBytes {
 }
 
 impl<'a> IntoPy<PyObject> for &'a [u8] {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         PyBytes::new(py, self).to_object(py)
     }
 }

src/types/capsule.rs

@@ -167,7 +167,7 @@ impl PyCapsule {
     /// assert_eq!(rx.recv(), Ok("Destructor called!".to_string()));
     /// ```
     #[allow(clippy::not_unsafe_ptr_arg_deref)]
-    pub fn set_context(&self, py: Python, context: *mut c_void) -> PyResult<()> {
+    pub fn set_context(&self, py: Python<'_>, context: *mut c_void) -> PyResult<()> {
         let result = unsafe { ffi::PyCapsule_SetContext(self.as_ptr(), context) as u8 };
         if result != 0 {
             Err(PyErr::fetch(py))
@@ -178,7 +178,7 @@ impl PyCapsule {
 
     /// Gets the current context stored in the capsule. If there is no context, the pointer
     /// will be null.
-    pub fn get_context(&self, py: Python) -> PyResult<*mut c_void> {
+    pub fn get_context(&self, py: Python<'_>) -> PyResult<*mut c_void> {
         let ctx = unsafe { ffi::PyCapsule_GetContext(self.as_ptr()) };
         if ctx.is_null() && self.is_valid() && PyErr::occurred(py) {
             Err(PyErr::fetch(py))

src/types/cls.rs

@@ -0,0 +1,584 @@
+// Copyright (c) 2017-present PyO3 Project and Contributors
+
+//! Defines conversions between Rust and Python types.
+use crate::err::{self, PyDowncastError, PyResult};
+use crate::type_object::PyTypeInfo;
+use crate::types::PyTuple;
+use crate::{
+    ffi, gil, Py, PyAny, PyCell, PyClass, PyNativeType, PyObject, PyRef, PyRefMut, Python,
+};
+use std::ptr::NonNull;
+
+/// This trait represents that **we can do zero-cost conversion from the object
+/// to a FFI pointer**.
+///
+/// This trait is implemented for types that internally wrap a pointer to a Python object.
+///
+/// # Examples
+///
+/// ```
+/// use pyo3::{prelude::*, AsPyPointer};
+/// Python::with_gil(|py| {
+///     let dict = pyo3::types::PyDict::new(py);
+///     // All native object wrappers implement AsPyPointer!!!
+///     assert_ne!(dict.as_ptr(), std::ptr::null_mut());
+/// });
+/// ```
+pub trait AsPyPointer {
+    /// Retrieves the underlying FFI pointer (as a borrowed pointer).
+    fn as_ptr(&self) -> *mut ffi::PyObject;
+}
+
+/// This trait allows retrieving the underlying FFI pointer from Python objects.
+pub trait IntoPyPointer {
+    /// Retrieves the underlying FFI pointer. Whether pointer owned or borrowed
+    /// depends on implementation.
+    fn into_ptr(self) -> *mut ffi::PyObject;
+}
+
+/// Convert `None` into a null pointer.
+impl<T> AsPyPointer for Option<T>
+where
+    T: AsPyPointer,
+{
+    #[inline]
+    fn as_ptr(&self) -> *mut ffi::PyObject {
+        self.as_ref()
+            .map_or_else(std::ptr::null_mut, |t| t.as_ptr())
+    }
+}
+
+/// Convert `None` into a null pointer.
+impl<T> IntoPyPointer for Option<T>
+where
+    T: IntoPyPointer,
+{
+    #[inline]
+    fn into_ptr(self) -> *mut ffi::PyObject {
+        self.map_or_else(std::ptr::null_mut, |t| t.into_ptr())
+    }
+}
+
+impl<'a, T> IntoPyPointer for &'a T
+where
+    T: AsPyPointer,
+{
+    fn into_ptr(self) -> *mut ffi::PyObject {
+        unsafe { ffi::_Py_XNewRef(self.as_ptr()) }
+    }
+}
+
+/// Conversion trait that allows various objects to be converted into `PyObject`.
+pub trait ToPyObject {
+    /// Converts self into a Python object.
+    fn to_object(&self, py: Python<'_>) -> PyObject;
+}
+
+/// This trait has two implementations: The slow one is implemented for
+/// all [ToPyObject] and creates a new object using [ToPyObject::to_object],
+/// while the fast one is only implemented for AsPyPointer (we know
+/// that every AsPyPointer is also ToPyObject) and uses [AsPyPointer::as_ptr()]
+pub trait ToBorrowedObject: ToPyObject {
+    /// Converts self into a Python object and calls the specified closure
+    /// on the native FFI pointer underlying the Python object.
+    ///
+    /// May be more efficient than `to_object` because it does not need
+    /// to touch any reference counts when the input object already is a Python object.
+    fn with_borrowed_ptr<F, R>(&self, py: Python<'_>, f: F) -> R
+    where
+        F: FnOnce(*mut ffi::PyObject) -> R,
+    {
+        let ptr = self.to_object(py).into_ptr();
+        let result = f(ptr);
+        unsafe {
+            ffi::Py_XDECREF(ptr);
+        }
+        result
+    }
+}
+
+impl<T> ToBorrowedObject for T where T: ToPyObject {}
+
+/// Defines a conversion from a Rust type to a Python object.
+///
+/// It functions similarly to std's [`Into`](std::convert::Into) trait,
+/// but requires a [GIL token](Python) as an argument.
+/// Many functions and traits internal to PyO3 require this trait as a bound,
+/// so a lack of this trait can manifest itself in different error messages.
+///
+/// # Examples
+/// ## With `#[pyclass]`
+/// The easiest way to implement `IntoPy` is by exposing a struct as a native Python object
+/// by annotating it with [`#[pyclass]`](crate::prelude::pyclass).
+///
+/// ```rust
+/// use pyo3::prelude::*;
+///
+/// #[pyclass]
+/// struct Number {
+///     #[pyo3(get, set)]
+///     value: i32,
+/// }
+/// ```
+/// Python code will see this as an instance of the `Number` class with a `value` attribute.
+///
+/// ## Conversion to a Python object
+///
+/// However, it may not be desirable to expose the existence of `Number` to Python code.
+/// `IntoPy` allows us to define a conversion to an appropriate Python object.
+/// ```rust
+/// use pyo3::prelude::*;
+///
+/// struct Number {
+///     value: i32,
+/// }
+///
+/// impl IntoPy<PyObject> for Number {
+///     fn into_py(self, py: Python<'_>) -> PyObject {
+///         // delegates to i32's IntoPy implementation.
+///         self.value.into_py(py)
+///     }
+/// }
+/// ```
+/// Python code will see this as an `int` object.
+///
+/// ## Dynamic conversion into Python objects.
+/// It is also possible to return a different Python object depending on some condition.
+/// This is useful for types like enums that can carry different types.
+///
+/// ```rust
+/// use pyo3::prelude::*;
+///
+/// enum Value {
+///     Integer(i32),
+///     String(String),
+///     None,
+/// }
+///
+/// impl IntoPy<PyObject> for Value {
+///     fn into_py(self, py: Python<'_>) -> PyObject {
+///         match self {
+///             Self::Integer(val) => val.into_py(py),
+///             Self::String(val) => val.into_py(py),
+///             Self::None => py.None(),
+///         }
+///     }
+/// }
+/// # fn main() {
+/// #     Python::with_gil(|py| {
+/// #         let v = Value::Integer(73).into_py(py);
+/// #         let v = v.extract::<i32>(py).unwrap();
+/// #
+/// #         let v = Value::String("foo".into()).into_py(py);
+/// #         let v = v.extract::<String>(py).unwrap();
+/// #
+/// #         let v = Value::None.into_py(py);
+/// #         let v = v.extract::<Option<Vec<i32>>>(py).unwrap();
+/// #     });
+/// # }
+/// ```
+/// Python code will see this as any of the `int`, `string` or `None` objects.
+#[cfg_attr(docsrs, doc(alias = "IntoPyCallbackOutput"))]
+pub trait IntoPy<T>: Sized {
+    /// Performs the conversion.
+    fn into_py(self, py: Python<'_>) -> T;
+}
+
+/// `FromPyObject` is implemented by various types that can be extracted from
+/// a Python object reference.
+///
+/// Normal usage is through the helper methods `Py::extract` or `PyAny::extract`:
+///
+/// ```rust,ignore
+/// let obj: Py<PyAny> = ...;
+/// let value: &TargetType = obj.extract(py)?;
+///
+/// let any: &PyAny = ...;
+/// let value: &TargetType = any.extract()?;
+/// ```
+///
+/// Note: depending on the implementation, the lifetime of the extracted result may
+/// depend on the lifetime of the `obj` or the `prepared` variable.
+///
+/// For example, when extracting `&str` from a Python byte string, the resulting string slice will
+/// point to the existing string data (lifetime: `'source`).
+/// On the other hand, when extracting `&str` from a Python Unicode string, the preparation step
+/// will convert the string to UTF-8, and the resulting string slice will have lifetime `'prepared`.
+/// Since which case applies depends on the runtime type of the Python object,
+/// both the `obj` and `prepared` variables must outlive the resulting string slice.
+///
+/// The trait's conversion method takes a `&PyAny` argument but is called
+/// `FromPyObject` for historical reasons.
+pub trait FromPyObject<'source>: Sized {
+    /// Extracts `Self` from the source `PyObject`.
+    fn extract(ob: &'source PyAny) -> PyResult<Self>;
+}
+
+/// Identity conversion: allows using existing `PyObject` instances where
+/// `T: ToPyObject` is expected.
+impl<T: ?Sized + ToPyObject> ToPyObject for &'_ T {
+    #[inline]
+    fn to_object(&self, py: Python<'_>) -> PyObject {
+        <T as ToPyObject>::to_object(*self, py)
+    }
+}
+
+/// `Option::Some<T>` is converted like `T`.
+/// `Option::None` is converted to Python `None`.
+impl<T> ToPyObject for Option<T>
+where
+    T: ToPyObject,
+{
+    fn to_object(&self, py: Python<'_>) -> PyObject {
+        self.as_ref()
+            .map_or_else(|| py.None(), |val| val.to_object(py))
+    }
+}
+
+impl<T> IntoPy<PyObject> for Option<T>
+where
+    T: IntoPy<PyObject>,
+{
+    fn into_py(self, py: Python<'_>) -> PyObject {
+        self.map_or_else(|| py.None(), |val| val.into_py(py))
+    }
+}
+
+/// `()` is converted to Python `None`.
+impl ToPyObject for () {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
+        py.None()
+    }
+}
+
+impl IntoPy<PyObject> for () {
+    fn into_py(self, py: Python<'_>) -> PyObject {
+        py.None()
+    }
+}
+
+impl<T> IntoPy<PyObject> for &'_ T
+where
+    T: AsPyPointer,
+{
+    #[inline]
+    fn into_py(self, py: Python<'_>) -> PyObject {
+        unsafe { PyObject::from_borrowed_ptr(py, self.as_ptr()) }
+    }
+}
+
+impl<'a, T> FromPyObject<'a> for &'a PyCell<T>
+where
+    T: PyClass,
+{
+    fn extract(obj: &'a PyAny) -> PyResult<Self> {
+        PyTryFrom::try_from(obj).map_err(Into::into)
+    }
+}
+
+impl<'a, T> FromPyObject<'a> for T
+where
+    T: PyClass + Clone,
+{
+    fn extract(obj: &'a PyAny) -> PyResult<Self> {
+        let cell: &PyCell<Self> = PyTryFrom::try_from(obj)?;
+        Ok(unsafe { cell.try_borrow_unguarded()?.clone() })
+    }
+}
+
+impl<'a, T> FromPyObject<'a> for PyRef<'a, T>
+where
+    T: PyClass,
+{
+    fn extract(obj: &'a PyAny) -> PyResult<Self> {
+        let cell: &PyCell<T> = PyTryFrom::try_from(obj)?;
+        cell.try_borrow().map_err(Into::into)
+    }
+}
+
+impl<'a, T> FromPyObject<'a> for PyRefMut<'a, T>
+where
+    T: PyClass,
+{
+    fn extract(obj: &'a PyAny) -> PyResult<Self> {
+        let cell: &PyCell<T> = PyTryFrom::try_from(obj)?;
+        cell.try_borrow_mut().map_err(Into::into)
+    }
+}
+
+impl<'a, T> FromPyObject<'a> for Option<T>
+where
+    T: FromPyObject<'a>,
+{
+    fn extract(obj: &'a PyAny) -> PyResult<Self> {
+        if obj.as_ptr() == unsafe { ffi::Py_None() } {
+            Ok(None)
+        } else {
+            T::extract(obj).map(Some)
+        }
+    }
+}
+
+/// Trait implemented by Python object types that allow a checked downcast.
+/// If `T` implements `PyTryFrom`, we can convert `&PyAny` to `&T`.
+///
+/// This trait is similar to `std::convert::TryFrom`
+pub trait PyTryFrom<'v>: Sized + PyNativeType {
+    /// Cast from a concrete Python object type to PyObject.
+    fn try_from<V: Into<&'v PyAny>>(value: V) -> Result<&'v Self, PyDowncastError<'v>>;
+
+    /// Cast from a concrete Python object type to PyObject. With exact type check.
+    fn try_from_exact<V: Into<&'v PyAny>>(value: V) -> Result<&'v Self, PyDowncastError<'v>>;
+
+    /// Cast a PyAny to a specific type of PyObject. The caller must
+    /// have already verified the reference is for this type.
+    ///
+    /// # Safety
+    ///
+    /// Callers must ensure that the type is valid or risk type confusion.
+    unsafe fn try_from_unchecked<V: Into<&'v PyAny>>(value: V) -> &'v Self;
+}
+
+/// Trait implemented by Python object types that allow a checked downcast.
+/// This trait is similar to `std::convert::TryInto`
+pub trait PyTryInto<T>: Sized {
+    /// Cast from PyObject to a concrete Python object type.
+    fn try_into(&self) -> Result<&T, PyDowncastError<'_>>;
+
+    /// Cast from PyObject to a concrete Python object type. With exact type check.
+    fn try_into_exact(&self) -> Result<&T, PyDowncastError<'_>>;
+}
+
+// TryFrom implies TryInto
+impl<U> PyTryInto<U> for PyAny
+where
+    U: for<'v> PyTryFrom<'v>,
+{
+    fn try_into(&self) -> Result<&U, PyDowncastError<'_>> {
+        <U as PyTryFrom<'_>>::try_from(self)
+    }
+    fn try_into_exact(&self) -> Result<&U, PyDowncastError<'_>> {
+        U::try_from_exact(self)
+    }
+}
+
+impl<'v, T> PyTryFrom<'v> for T
+where
+    T: PyTypeInfo + PyNativeType,
+{
+    fn try_from<V: Into<&'v PyAny>>(value: V) -> Result<&'v Self, PyDowncastError<'v>> {
+        let value = value.into();
+        unsafe {
+            if T::is_type_of(value) {
+                Ok(Self::try_from_unchecked(value))
+            } else {
+                Err(PyDowncastError::new(value, T::NAME))
+            }
+        }
+    }
+
+    fn try_from_exact<V: Into<&'v PyAny>>(value: V) -> Result<&'v Self, PyDowncastError<'v>> {
+        let value = value.into();
+        unsafe {
+            if T::is_exact_type_of(value) {
+                Ok(Self::try_from_unchecked(value))
+            } else {
+                Err(PyDowncastError::new(value, T::NAME))
+            }
+        }
+    }
+
+    #[inline]
+    unsafe fn try_from_unchecked<V: Into<&'v PyAny>>(value: V) -> &'v Self {
+        Self::unchecked_downcast(value.into())
+    }
+}
+
+impl<'v, T> PyTryFrom<'v> for PyCell<T>
+where
+    T: 'v + PyClass,
+{
+    fn try_from<V: Into<&'v PyAny>>(value: V) -> Result<&'v Self, PyDowncastError<'v>> {
+        let value = value.into();
+        unsafe {
+            if T::is_type_of(value) {
+                Ok(Self::try_from_unchecked(value))
+            } else {
+                Err(PyDowncastError::new(value, T::NAME))
+            }
+        }
+    }
+    fn try_from_exact<V: Into<&'v PyAny>>(value: V) -> Result<&'v Self, PyDowncastError<'v>> {
+        let value = value.into();
+        unsafe {
+            if T::is_exact_type_of(value) {
+                Ok(Self::try_from_unchecked(value))
+            } else {
+                Err(PyDowncastError::new(value, T::NAME))
+            }
+        }
+    }
+    #[inline]
+    unsafe fn try_from_unchecked<V: Into<&'v PyAny>>(value: V) -> &'v Self {
+        Self::unchecked_downcast(value.into())
+    }
+}
+
+/// Converts `()` to an empty Python tuple.
+impl IntoPy<Py<PyTuple>> for () {
+    fn into_py(self, py: Python<'_>) -> Py<PyTuple> {
+        PyTuple::empty(py).into()
+    }
+}
+
+/// Raw level conversion between `*mut ffi::PyObject` and PyO3 types.
+///
+/// # Safety
+///
+/// See safety notes on individual functions.
+pub unsafe trait FromPyPointer<'p>: Sized {
+    /// Convert from an arbitrary `PyObject`.
+    ///
+    /// # Safety
+    ///
+    /// Implementations must ensure the object does not get freed during `'p`
+    /// and ensure that `ptr` is of the correct type.
+    /// Note that it must be safe to decrement the reference count of `ptr`.
+    unsafe fn from_owned_ptr_or_opt(py: Python<'p>, ptr: *mut ffi::PyObject) -> Option<&'p Self>;
+    /// Convert from an arbitrary `PyObject` or panic.
+    ///
+    /// # Safety
+    ///
+    /// Relies on [`from_owned_ptr_or_opt`](#method.from_owned_ptr_or_opt).
+    unsafe fn from_owned_ptr_or_panic(py: Python<'p>, ptr: *mut ffi::PyObject) -> &'p Self {
+        Self::from_owned_ptr_or_opt(py, ptr).unwrap_or_else(|| err::panic_after_error(py))
+    }
+    /// Convert from an arbitrary `PyObject` or panic.
+    ///
+    /// # Safety
+    ///
+    /// Relies on [`from_owned_ptr_or_opt`](#method.from_owned_ptr_or_opt).
+    unsafe fn from_owned_ptr(py: Python<'p>, ptr: *mut ffi::PyObject) -> &'p Self {
+        Self::from_owned_ptr_or_panic(py, ptr)
+    }
+    /// Convert from an arbitrary `PyObject`.
+    ///
+    /// # Safety
+    ///
+    /// Relies on [`from_owned_ptr_or_opt`](#method.from_owned_ptr_or_opt).
+    unsafe fn from_owned_ptr_or_err(py: Python<'p>, ptr: *mut ffi::PyObject) -> PyResult<&'p Self> {
+        Self::from_owned_ptr_or_opt(py, ptr).ok_or_else(|| err::PyErr::fetch(py))
+    }
+    /// Convert from an arbitrary borrowed `PyObject`.
+    ///
+    /// # Safety
+    ///
+    /// Implementations must ensure the object does not get freed during `'p` and avoid type confusion.
+    unsafe fn from_borrowed_ptr_or_opt(py: Python<'p>, ptr: *mut ffi::PyObject)
+        -> Option<&'p Self>;
+    /// Convert from an arbitrary borrowed `PyObject`.
+    ///
+    /// # Safety
+    ///
+    /// Relies on unsafe fn [`from_borrowed_ptr_or_opt`](#method.from_borrowed_ptr_or_opt).
+    unsafe fn from_borrowed_ptr_or_panic(py: Python<'p>, ptr: *mut ffi::PyObject) -> &'p Self {
+        Self::from_borrowed_ptr_or_opt(py, ptr).unwrap_or_else(|| err::panic_after_error(py))
+    }
+    /// Convert from an arbitrary borrowed `PyObject`.
+    ///
+    /// # Safety
+    ///
+    /// Relies on unsafe fn [`from_borrowed_ptr_or_opt`](#method.from_borrowed_ptr_or_opt).
+    unsafe fn from_borrowed_ptr(py: Python<'p>, ptr: *mut ffi::PyObject) -> &'p Self {
+        Self::from_borrowed_ptr_or_panic(py, ptr)
+    }
+    /// Convert from an arbitrary borrowed `PyObject`.
+    ///
+    /// # Safety
+    ///
+    /// Relies on unsafe fn [`from_borrowed_ptr_or_opt`](#method.from_borrowed_ptr_or_opt).
+    unsafe fn from_borrowed_ptr_or_err(
+        py: Python<'p>,
+        ptr: *mut ffi::PyObject,
+    ) -> PyResult<&'p Self> {
+        Self::from_borrowed_ptr_or_opt(py, ptr).ok_or_else(|| err::PyErr::fetch(py))
+    }
+}
+
+unsafe impl<'p, T> FromPyPointer<'p> for T
+where
+    T: 'p + crate::PyNativeType,
+{
+    unsafe fn from_owned_ptr_or_opt(py: Python<'p>, ptr: *mut ffi::PyObject) -> Option<&'p Self> {
+        gil::register_owned(py, NonNull::new(ptr)?);
+        Some(&*(ptr as *mut Self))
+    }
+    unsafe fn from_borrowed_ptr_or_opt(
+        _py: Python<'p>,
+        ptr: *mut ffi::PyObject,
+    ) -> Option<&'p Self> {
+        NonNull::new(ptr as *mut Self).map(|p| &*p.as_ptr())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::types::{IntoPyDict, PyAny, PyDict, PyList};
+    use crate::{AsPyPointer, PyObject, Python, ToPyObject};
+
+    use super::PyTryFrom;
+
+    #[test]
+    fn test_try_from() {
+        Python::with_gil(|py| {
+            let list: &PyAny = vec![3, 6, 5, 4, 7].to_object(py).into_ref(py);
+            let dict: &PyAny = vec![("reverse", true)].into_py_dict(py).as_ref();
+
+            assert!(<PyDict as PyTryFrom<'_>>::try_from(list).is_ok());
+            assert!(<PyDict as PyTryFrom<'_>>::try_from(dict).is_ok());
+
+            assert!(<PyAny as PyTryFrom<'_>>::try_from(list).is_ok());
+            assert!(<PyAny as PyTryFrom<'_>>::try_from(dict).is_ok());
+        });
+    }
+
+    #[test]
+    fn test_try_from_exact() {
+        Python::with_gil(|py| {
+            let list: &PyAny = vec![3, 6, 5, 4, 7].to_object(py).into_ref(py);
+            let dict: &PyAny = vec![("reverse", true)].into_py_dict(py).as_ref();
+
+            assert!(PyList::try_from_exact(list).is_ok());
+            assert!(PyDict::try_from_exact(dict).is_ok());
+
+            assert!(PyAny::try_from_exact(list).is_err());
+            assert!(PyAny::try_from_exact(dict).is_err());
+        });
+    }
+
+    #[test]
+    fn test_try_from_unchecked() {
+        Python::with_gil(|py| {
+            let list = PyList::new(py, &[1, 2, 3]);
+            let val = unsafe { <PyList as PyTryFrom>::try_from_unchecked(list.as_ref()) };
+            assert!(list.is(val));
+        });
+    }
+
+    #[test]
+    fn test_option_as_ptr() {
+        Python::with_gil(|py| {
+            let mut option: Option<PyObject> = None;
+            assert_eq!(option.as_ptr(), std::ptr::null_mut());
+
+            let none = py.None();
+            option = Some(none.clone());
+
+            let ref_cnt = none.get_refcnt(py);
+            assert_eq!(option.as_ptr(), none.as_ptr());
+
+            // Ensure ref count not changed by as_ptr call
+            assert_eq!(none.get_refcnt(py), ref_cnt);
+        });
+    }
+}

src/types/complex.rs

@@ -20,7 +20,7 @@ pyobject_native_type!(
 
 impl PyComplex {
     /// Creates a new `PyComplex` from the given real and imaginary values.
-    pub fn from_doubles(py: Python, real: c_double, imag: c_double) -> &PyComplex {
+    pub fn from_doubles(py: Python<'_>, real: c_double, imag: c_double) -> &PyComplex {
         unsafe {
             let ptr = ffi::PyComplex_FromDoubles(real, imag);
             py.from_owned_ptr(ptr)

src/types/datetime.rs

@@ -26,7 +26,7 @@ use crate::types::PyTuple;
 use crate::{AsPyPointer, PyAny, PyObject, Python, ToPyObject};
 use std::os::raw::c_int;
 
-fn ensure_datetime_api(_py: Python) -> &'static PyDateTime_CAPI {
+fn ensure_datetime_api(_py: Python<'_>) -> &'static PyDateTime_CAPI {
     unsafe {
         if pyo3_ffi::PyDateTimeAPI().is_null() {
             PyDateTime_IMPORT()
@@ -173,7 +173,7 @@ pyobject_native_type!(
 
 impl PyDate {
     /// Creates a new `datetime.date`.
-    pub fn new(py: Python, year: i32, month: u8, day: u8) -> PyResult<&PyDate> {
+    pub fn new(py: Python<'_>, year: i32, month: u8, day: u8) -> PyResult<&PyDate> {
         unsafe {
             let ptr = (ensure_datetime_api(py).Date_FromDate)(
                 year,
@@ -188,7 +188,7 @@ impl PyDate {
     /// Construct a `datetime.date` from a POSIX timestamp
     ///
     /// This is equivalent to `datetime.date.fromtimestamp`
-    pub fn from_timestamp(py: Python, timestamp: i64) -> PyResult<&PyDate> {
+    pub fn from_timestamp(py: Python<'_>, timestamp: i64) -> PyResult<&PyDate> {
         let time_tuple = PyTuple::new(py, &[timestamp]);
 
         // safety ensure that the API is loaded
@@ -466,7 +466,7 @@ pyobject_native_type!(
 impl PyDelta {
     /// Creates a new `timedelta`.
     pub fn new(
-        py: Python,
+        py: Python<'_>,
         days: i32,
         seconds: i32,
         microseconds: i32,
@@ -501,7 +501,7 @@ impl PyDeltaAccess for PyDelta {
 }
 
 // Utility function
-fn opt_to_pyobj(py: Python, opt: Option<&PyObject>) -> *mut ffi::PyObject {
+fn opt_to_pyobj(py: Python<'_>, opt: Option<&PyObject>) -> *mut ffi::PyObject {
     // Convenience function for unpacking Options to either an Object or None
     match opt {
         Some(tzi) => tzi.as_ptr(),

src/types/dict.rs

@@ -27,7 +27,7 @@ pyobject_native_type!(
 
 impl PyDict {
     /// Creates a new empty dictionary.
-    pub fn new(py: Python) -> &PyDict {
+    pub fn new(py: Python<'_>) -> &PyDict {
         unsafe { py.from_owned_ptr::<PyDict>(ffi::PyDict_New()) }
     }
 
@@ -39,7 +39,7 @@ impl PyDict {
     /// Returns an error on invalid input. In the case of key collisions,
     /// this keeps the last entry seen.
     #[cfg(not(PyPy))]
-    pub fn from_sequence(py: Python, seq: PyObject) -> PyResult<&PyDict> {
+    pub fn from_sequence(py: Python<'_>, seq: PyObject) -> PyResult<&PyDict> {
         unsafe {
             let dict = py.from_owned_ptr::<PyDict>(ffi::PyDict_New());
             err::error_on_minusone(
@@ -172,7 +172,7 @@ impl PyDict {
     ///
     /// Note that it's unsafe to use when the dictionary might be changed by
     /// other code.
-    pub fn iter(&self) -> PyDictIterator {
+    pub fn iter(&self) -> PyDictIterator<'_> {
         PyDictIterator {
             dict: self.as_ref(),
             pos: 0,
@@ -236,7 +236,7 @@ where
     V: ToPyObject,
     H: hash::BuildHasher,
 {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         IntoPyDict::into_py_dict(self, py).into()
     }
 }
@@ -246,7 +246,7 @@ where
     K: cmp::Eq + ToPyObject,
     V: ToPyObject,
 {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         IntoPyDict::into_py_dict(self, py).into()
     }
 }
@@ -257,7 +257,7 @@ where
     V: IntoPy<PyObject>,
     H: hash::BuildHasher,
 {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         let iter = self
             .into_iter()
             .map(|(k, v)| (k.into_py(py), v.into_py(py)));
@@ -270,7 +270,7 @@ where
     K: cmp::Eq + IntoPy<PyObject>,
     V: IntoPy<PyObject>,
 {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         let iter = self
             .into_iter()
             .map(|(k, v)| (k.into_py(py), v.into_py(py)));
@@ -283,7 +283,7 @@ where
 pub trait IntoPyDict {
     /// Converts self into a `PyDict` object pointer. Whether pointer owned or borrowed
     /// depends on implementation.
-    fn into_py_dict(self, py: Python) -> &PyDict;
+    fn into_py_dict(self, py: Python<'_>) -> &PyDict;
 }
 
 impl<T, I> IntoPyDict for I
@@ -291,7 +291,7 @@ where
     T: PyDictItem,
     I: IntoIterator<Item = T>,
 {
-    fn into_py_dict(self, py: Python) -> &PyDict {
+    fn into_py_dict(self, py: Python<'_>) -> &PyDict {
         let dict = PyDict::new(py);
         for item in self {
             dict.set_item(item.key(), item.value())

src/types/floatob.rs

@@ -35,13 +35,13 @@ impl PyFloat {
 }
 
 impl ToPyObject for f64 {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         PyFloat::new(py, *self).into()
     }
 }
 
 impl IntoPy<PyObject> for f64 {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         PyFloat::new(py, self).into()
     }
 }
@@ -63,13 +63,13 @@ impl<'source> FromPyObject<'source> for f64 {
 }
 
 impl ToPyObject for f32 {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         PyFloat::new(py, f64::from(*self)).into()
     }
 }
 
 impl IntoPy<PyObject> for f32 {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         PyFloat::new(py, f64::from(self)).into()
     }
 }

src/types/function.rs

@@ -104,7 +104,7 @@ impl PyCFunction {
     ///     py_run!(py, add_one, "assert add_one(42) == 43");
     /// });
     /// ```
-    pub fn new_closure<F, R>(f: F, py: Python) -> PyResult<&PyCFunction>
+    pub fn new_closure<F, R>(f: F, py: Python<'_>) -> PyResult<&PyCFunction>
     where
         F: Fn(&types::PyTuple, Option<&types::PyDict>) -> R + Send + 'static,
         R: crate::callback::IntoPyCallbackOutput<*mut ffi::PyObject>,
@@ -131,7 +131,7 @@ impl PyCFunction {
     #[doc(hidden)]
     fn internal_new_from_pointers(
         method_def: PyMethodDef,
-        py: Python,
+        py: Python<'_>,
         mod_ptr: *mut ffi::PyObject,
         module_name: *mut ffi::PyObject,
     ) -> PyResult<&Self> {
@@ -150,7 +150,7 @@ impl PyCFunction {
     #[doc(hidden)]
     pub fn internal_new(
         method_def: PyMethodDef,
-        py_or_module: PyFunctionArguments,
+        py_or_module: PyFunctionArguments<'_>,
     ) -> PyResult<&Self> {
         let (py, module) = py_or_module.into_py_and_maybe_module();
         let (mod_ptr, module_name) = if let Some(m) = module {

src/types/iterator.rs

@@ -99,7 +99,7 @@ impl Py<PyIterator> {
     /// Similar to [`as_ref`](#method.as_ref), and also consumes this `Py` and registers the
     /// Python object reference in PyO3's object storage. The reference count for the Python
     /// object will not be decreased until the GIL lifetime ends.
-    pub fn into_ref(self, py: Python) -> &PyIterator {
+    pub fn into_ref(self, py: Python<'_>) -> &PyIterator {
         unsafe { py.from_owned_ptr(self.into_ptr()) }
     }
 }
@@ -212,7 +212,8 @@ def fibonacci(target):
     fn iterator_try_from() {
         Python::with_gil(|py| {
             let obj: Py<PyAny> = vec![10, 20].to_object(py).as_ref(py).iter().unwrap().into();
-            let iter: &PyIterator = PyIterator::try_from(obj.as_ref(py)).unwrap();
+            let iter: &PyIterator =
+                <PyIterator as PyTryFrom<'_>>::try_from(obj.as_ref(py)).unwrap();
             assert!(obj.is(iter));
         });
     }

src/types/list.rs

@@ -21,7 +21,10 @@ pyobject_native_type_core!(PyList, ffi::PyList_Type, #checkfunction=ffi::PyList_
 
 #[inline]
 #[track_caller]
-fn new_from_iter(py: Python, elements: &mut dyn ExactSizeIterator<Item = PyObject>) -> Py<PyList> {
+fn new_from_iter(
+    py: Python<'_>,
+    elements: &mut dyn ExactSizeIterator<Item = PyObject>,
+) -> Py<PyList> {
     unsafe {
         // PyList_New checks for overflow but has a bad error message, so we check ourselves
         let len: Py_ssize_t = elements
@@ -90,7 +93,7 @@ impl PyList {
     }
 
     /// Constructs a new empty list.
-    pub fn empty(py: Python) -> &PyList {
+    pub fn empty(py: Python<'_>) -> &PyList {
         unsafe { py.from_owned_ptr::<PyList>(ffi::PyList_New(0)) }
     }
 
@@ -264,7 +267,7 @@ impl PyList {
     }
 
     /// Returns an iterator over this list's items.
-    pub fn iter(&self) -> PyListIterator {
+    pub fn iter(&self) -> PyListIterator<'_> {
         PyListIterator {
             list: self,
             index: 0,
@@ -351,7 +354,7 @@ impl<T> IntoPy<PyObject> for Vec<T>
 where
     T: IntoPy<PyObject>,
 {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         let mut iter = self.into_iter().map(|e| e.into_py(py));
         let list = new_from_iter(py, &mut iter);
         list.into()
@@ -853,7 +856,7 @@ mod tests {
         }
 
         impl ToPyObject for Bad {
-            fn to_object(&self, py: Python) -> Py<PyAny> {
+            fn to_object(&self, py: Python<'_>) -> Py<PyAny> {
                 self.to_owned().into_py(py)
             }
         }

src/types/mapping.rs

@@ -142,7 +142,7 @@ impl Py<PyMapping> {
     /// Similar to [`as_ref`](#method.as_ref), and also consumes this `Py` and registers the
     /// Python object reference in PyO3's object storage. The reference count for the Python
     /// object will not be decreased until the GIL lifetime ends.
-    pub fn into_ref(self, py: Python) -> &PyMapping {
+    pub fn into_ref(self, py: Python<'_>) -> &PyMapping {
         unsafe { py.from_owned_ptr(self.into_ptr()) }
     }
 }

src/types/mod.rs

@@ -39,7 +39,7 @@ macro_rules! pyobject_native_type_base(
         unsafe impl<$($generics,)*> $crate::PyNativeType for $name {}
 
         impl<$($generics,)*> ::std::fmt::Debug for $name {
-            fn fmt(&self, f: &mut ::std::fmt::Formatter)
+            fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>)
                    -> ::std::result::Result<(), ::std::fmt::Error>
             {
                 let s = self.repr().or(::std::result::Result::Err(::std::fmt::Error))?;
@@ -48,7 +48,7 @@ macro_rules! pyobject_native_type_base(
         }
 
         impl<$($generics,)*> ::std::fmt::Display for $name {
-            fn fmt(&self, f: &mut ::std::fmt::Formatter)
+            fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>)
                    -> ::std::result::Result<(), ::std::fmt::Error>
             {
                 let s = self.str().or(::std::result::Result::Err(::std::fmt::Error))?;
@@ -59,7 +59,7 @@ macro_rules! pyobject_native_type_base(
         impl<$($generics,)*> $crate::ToPyObject for $name
         {
             #[inline]
-            fn to_object(&self, py: $crate::Python) -> $crate::PyObject {
+            fn to_object(&self, py: $crate::Python<'_>) -> $crate::PyObject {
                 use $crate::AsPyPointer;
                 unsafe { $crate::PyObject::from_borrowed_ptr(py, self.as_ptr()) }
             }
@@ -101,7 +101,7 @@ macro_rules! pyobject_native_type_named (
 
         impl<$($generics,)*> $crate::IntoPy<$crate::Py<$name>> for &'_ $name {
             #[inline]
-            fn into_py(self, py: $crate::Python) -> $crate::Py<$name> {
+            fn into_py(self, py: $crate::Python<'_>) -> $crate::Py<$name> {
                 use $crate::AsPyPointer;
                 unsafe { $crate::Py::from_borrowed_ptr(py, self.as_ptr()) }
             }
@@ -135,7 +135,7 @@ macro_rules! pyobject_native_type_info(
             const MODULE: ::std::option::Option<&'static str> = $module;
 
             #[inline]
-            fn type_object_raw(_py: $crate::Python) -> *mut $crate::ffi::PyTypeObject {
+            fn type_object_raw(_py: $crate::Python<'_>) -> *mut $crate::ffi::PyTypeObject {
                 // Create a very short lived mutable reference and directly
                 // cast it to a pointer: no mutable references can be aliasing
                 // because we hold the GIL.
@@ -191,7 +191,7 @@ macro_rules! pyobject_native_type_sized {
     ($name:ty, $layout:path $(;$generics:ident)*) => {
         unsafe impl $crate::type_object::PyLayout<$name> for $layout {}
         impl $crate::type_object::PySizedLayout<$name> for $layout {}
-        impl<'a, $($generics,)*> $crate::impl_::pyclass::PyClassBaseType for $name {
+        impl<$($generics,)*> $crate::impl_::pyclass::PyClassBaseType for $name {
             type LayoutAsBase = $crate::pycell::PyCellBase<$layout>;
             type BaseNativeType = $name;
             type ThreadChecker = $crate::impl_::pyclass::ThreadCheckerStub<$crate::PyObject>;

src/types/module.rs

@@ -221,7 +221,7 @@ impl PyModule {
     /// use pyo3::prelude::*;
     ///
     /// #[pymodule]
-    /// fn my_module(_py: Python, module: &PyModule) -> PyResult<()> {
+    /// fn my_module(_py: Python<'_>, module: &PyModule) -> PyResult<()> {
     ///     module.add("c", 299_792_458)?;
     ///     Ok(())
     /// }
@@ -265,7 +265,7 @@ impl PyModule {
     /// struct Foo { /* fields omitted */ }
     ///
     /// #[pymodule]
-    /// fn my_module(_py: Python, module: &PyModule) -> PyResult<()> {
+    /// fn my_module(_py: Python<'_>, module: &PyModule) -> PyResult<()> {
     ///     module.add_class::<Foo>()?;
     ///     Ok(())
     /// }
@@ -324,7 +324,7 @@ impl PyModule {
     /// use pyo3::prelude::*;
     ///
     /// #[pymodule]
-    /// fn my_module(py: Python, module: &PyModule) -> PyResult<()> {
+    /// fn my_module(py: Python<'_>, module: &PyModule) -> PyResult<()> {
     ///     let submodule = PyModule::new(py, "submodule")?;
     ///     submodule.add("super_useful_constant", "important")?;
     ///
@@ -367,7 +367,7 @@ impl PyModule {
     ///     println!("Hello world!")
     /// }
     /// #[pymodule]
-    /// fn my_module(_py: Python, module: &PyModule) -> PyResult<()> {
+    /// fn my_module(_py: Python<'_>, module: &PyModule) -> PyResult<()> {
     ///     module.add_function(wrap_pyfunction!(say_hello, module)?)
     /// }
     /// ```

src/types/num.rs

@@ -14,12 +14,12 @@ macro_rules! int_fits_larger_int {
     ($rust_type:ty, $larger_type:ty) => {
         impl ToPyObject for $rust_type {
             #[inline]
-            fn to_object(&self, py: Python) -> PyObject {
+            fn to_object(&self, py: Python<'_>) -> PyObject {
                 (*self as $larger_type).into_py(py)
             }
         }
         impl IntoPy<PyObject> for $rust_type {
-            fn into_py(self, py: Python) -> PyObject {
+            fn into_py(self, py: Python<'_>) -> PyObject {
                 (self as $larger_type).into_py(py)
             }
         }
@@ -48,12 +48,12 @@ pyobject_native_type_core!(PyLong, ffi::PyLong_Type, #checkfunction=ffi::PyLong_
 macro_rules! int_fits_c_long {
     ($rust_type:ty) => {
         impl ToPyObject for $rust_type {
-            fn to_object(&self, py: Python) -> PyObject {
+            fn to_object(&self, py: Python<'_>) -> PyObject {
                 unsafe { PyObject::from_owned_ptr(py, ffi::PyLong_FromLong(*self as c_long)) }
             }
         }
         impl IntoPy<PyObject> for $rust_type {
-            fn into_py(self, py: Python) -> PyObject {
+            fn into_py(self, py: Python<'_>) -> PyObject {
                 unsafe { PyObject::from_owned_ptr(py, ffi::PyLong_FromLong(self as c_long)) }
             }
         }
@@ -82,13 +82,13 @@ macro_rules! int_convert_u64_or_i64 {
     ($rust_type:ty, $pylong_from_ll_or_ull:expr, $pylong_as_ll_or_ull:expr) => {
         impl ToPyObject for $rust_type {
             #[inline]
-            fn to_object(&self, py: Python) -> PyObject {
+            fn to_object(&self, py: Python<'_>) -> PyObject {
                 unsafe { PyObject::from_owned_ptr(py, $pylong_from_ll_or_ull(*self)) }
             }
         }
         impl IntoPy<PyObject> for $rust_type {
             #[inline]
-            fn into_py(self, py: Python) -> PyObject {
+            fn into_py(self, py: Python<'_>) -> PyObject {
                 unsafe { PyObject::from_owned_ptr(py, $pylong_from_ll_or_ull(self)) }
             }
         }
@@ -152,12 +152,12 @@ mod fast_128bit_int_conversion {
         ($rust_type: ty, $is_signed: expr) => {
             impl ToPyObject for $rust_type {
                 #[inline]
-                fn to_object(&self, py: Python) -> PyObject {
+                fn to_object(&self, py: Python<'_>) -> PyObject {
                     (*self).into_py(py)
                 }
             }
             impl IntoPy<PyObject> for $rust_type {
-                fn into_py(self, py: Python) -> PyObject {
+                fn into_py(self, py: Python<'_>) -> PyObject {
                     unsafe {
                         // Always use little endian
                         let bytes = self.to_le_bytes();
@@ -211,13 +211,13 @@ mod slow_128bit_int_conversion {
         ($rust_type: ty, $half_type: ty) => {
             impl ToPyObject for $rust_type {
                 #[inline]
-                fn to_object(&self, py: Python) -> PyObject {
+                fn to_object(&self, py: Python<'_>) -> PyObject {
                     (*self).into_py(py)
                 }
             }
 
             impl IntoPy<PyObject> for $rust_type {
-                fn into_py(self, py: Python) -> PyObject {
+                fn into_py(self, py: Python<'_>) -> PyObject {
                     let lower = self as u64;
                     let upper = (self >> SHIFT) as $half_type;
                     unsafe {
@@ -262,7 +262,7 @@ mod slow_128bit_int_conversion {
 }
 
 fn err_if_invalid_value<T: PartialEq>(
-    py: Python,
+    py: Python<'_>,
     invalid_value: T,
     actual_value: T,
 ) -> PyResult<T> {

src/types/sequence.rs

@@ -330,7 +330,7 @@ impl Py<PySequence> {
     /// Similar to [`as_ref`](#method.as_ref), and also consumes this `Py` and registers the
     /// Python object reference in PyO3's object storage. The reference count for the Python
     /// object will not be decreased until the GIL lifetime ends.
-    pub fn into_ref(self, py: Python) -> &PySequence {
+    pub fn into_ref(self, py: Python<'_>) -> &PySequence {
         unsafe { py.from_owned_ptr(self.into_ptr()) }
     }
 }

src/types/set.rs

@@ -37,7 +37,7 @@ impl PySet {
     }
 
     /// Creates a new empty set.
-    pub fn empty(py: Python) -> PyResult<&PySet> {
+    pub fn empty(py: Python<'_>) -> PyResult<&PySet> {
         unsafe { py.from_owned_ptr_or_err(ffi::PySet_New(ptr::null_mut())) }
     }
 
@@ -111,7 +111,7 @@ impl PySet {
     /// Returns an iterator of values in this set.
     ///
     /// Note that it can be unsafe to use when the set might be changed by other code.
-    pub fn iter(&self) -> PySetIterator {
+    pub fn iter(&self) -> PySetIterator<'_> {
         PySetIterator::new(self)
     }
 }
@@ -123,7 +123,7 @@ pub struct PySetIterator<'p> {
 
 #[cfg(Py_LIMITED_API)]
 impl PySetIterator<'_> {
-    fn new(set: &PyAny) -> PySetIterator {
+    fn new(set: &PyAny) -> PySetIterator<'_> {
         PySetIterator {
             it: PyIterator::from_object(set.py(), set).unwrap(),
         }
@@ -148,7 +148,7 @@ pub struct PySetIterator<'py> {
 
 #[cfg(not(Py_LIMITED_API))]
 impl PySetIterator<'_> {
-    fn new(set: &PyAny) -> PySetIterator {
+    fn new(set: &PyAny) -> PySetIterator<'_> {
         PySetIterator { set, pos: 0 }
     }
 }
@@ -195,7 +195,7 @@ where
     T: hash::Hash + Eq + ToPyObject,
     S: hash::BuildHasher + Default,
 {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         let set = PySet::new::<T>(py, &[]).expect("Failed to construct empty set");
         {
             for val in self {
@@ -210,7 +210,7 @@ impl<T> ToPyObject for collections::BTreeSet<T>
 where
     T: hash::Hash + Eq + ToPyObject,
 {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         let set = PySet::new::<T>(py, &[]).expect("Failed to construct empty set");
         {
             for val in self {
@@ -226,7 +226,7 @@ where
     K: IntoPy<PyObject> + Eq + hash::Hash,
     S: hash::BuildHasher + Default,
 {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         let set = PySet::empty(py).expect("Failed to construct empty set");
         {
             for val in self {
@@ -252,7 +252,7 @@ impl<K> IntoPy<PyObject> for BTreeSet<K>
 where
     K: IntoPy<PyObject> + cmp::Ord,
 {
-    fn into_py(self, py: Python) -> PyObject {
+    fn into_py(self, py: Python<'_>) -> PyObject {
         let set = PySet::empty(py).expect("Failed to construct empty set");
         {
             for val in self {
@@ -283,7 +283,7 @@ impl PyFrozenSet {
     }
 
     /// Creates a new empty frozen set
-    pub fn empty(py: Python) -> PyResult<&PyFrozenSet> {
+    pub fn empty(py: Python<'_>) -> PyResult<&PyFrozenSet> {
         unsafe { py.from_owned_ptr_or_err(ffi::PyFrozenSet_New(ptr::null_mut())) }
     }
 
@@ -317,7 +317,7 @@ impl PyFrozenSet {
     /// Returns an iterator of values in this frozen set.
     ///
     /// Note that it can be unsafe to use when the set might be changed by other code.
-    pub fn iter(&self) -> PySetIterator {
+    pub fn iter(&self) -> PySetIterator<'_> {
         PySetIterator::new(self.as_ref())
     }
 }

src/types/slice.rs

@@ -39,7 +39,7 @@ impl PySliceIndices {
 
 impl PySlice {
     /// Constructs a new slice with the given elements.
-    pub fn new(py: Python, start: isize, stop: isize, step: isize) -> &PySlice {
+    pub fn new(py: Python<'_>, start: isize, stop: isize, step: isize) -> &PySlice {
         unsafe {
             let ptr = ffi::PySlice_New(
                 ffi::PyLong_FromLong(start as c_long),
@@ -84,7 +84,7 @@ impl PySlice {
 }
 
 impl ToPyObject for PySliceIndices {
-    fn to_object(&self, py: Python) -> PyObject {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
         PySlice::new(py, self.start, self.stop, self.step).into()
     }
 }