diff --git a/src/conversion.rs b/src/conversion.rs
index 8ec196f8..b07fef42 100644
--- a/src/conversion.rs
+++ b/src/conversion.rs
@@ -94,16 +94,6 @@ 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
-    where
-        F: FnOnce(*mut ffi::PyObject) -> R;
-}
-
-#[cfg(feature = "nightly")]
-impl<T> ToBorrowedObject for T
-where
-    T: ToPyObject,
-{
-    default fn with_borrowed_ptr<F, R>(&self, py: Python, f: F) -> R
     where
         F: FnOnce(*mut ffi::PyObject) -> R,
     {
@@ -116,12 +106,12 @@ where
     }
 }
 
-#[cfg(not(feature = "nightly"))]
 impl<T> ToBorrowedObject for T
 where
     T: ToPyObject,
 {
-    fn with_borrowed_ptr<F, R>(&self, py: Python, f: F) -> R
+    #[cfg(feature = "nightly")]
+    default fn with_borrowed_ptr<F, R>(&self, py: Python, f: F) -> R
     where
         F: FnOnce(*mut ffi::PyObject) -> R,
     {
diff --git a/src/types/sequence.rs b/src/types/sequence.rs
index b8aedb3c..97dd819e 100644
--- a/src/types/sequence.rs
+++ b/src/types/sequence.rs
@@ -1,7 +1,5 @@
 // Copyright (c) 2017-present PyO3 Project and Contributors
 
-#[cfg(feature = "nightly")]
-use crate::buffer;
 use crate::err::{self, PyDowncastError, PyErr, PyResult};
 use crate::exceptions;
 use crate::ffi::{self, Py_ssize_t};
@@ -262,24 +260,19 @@ impl PySequence {
 macro_rules! array_impls {
     ($($N:expr),+) => {
         $(
-            #[cfg(feature = "nightly")]
             impl<'a, T> FromPyObject<'a> for [T; $N]
             where
                 T: Copy + Default + FromPyObject<'a>,
             {
-                default fn extract(obj: &'a PyAny) -> PyResult<Self> {
+                #[cfg(not(feature = "nightly"))]
+                fn extract(obj: &'a PyAny) -> PyResult<Self> {
                     let mut array = [T::default(); $N];
                     extract_sequence_into_slice(obj, &mut array)?;
                     Ok(array)
                 }
-            }
 
-            #[cfg(not(feature = "nightly"))]
-            impl<'a, T> FromPyObject<'a> for [T; $N]
-            where
-                T: Copy + Default + FromPyObject<'a>,
-            {
-                fn extract(obj: &'a PyAny) -> PyResult<Self> {
+                #[cfg(feature = "nightly")]
+                default fn extract(obj: &'a PyAny) -> PyResult<Self> {
                     let mut array = [T::default(); $N];
                     extract_sequence_into_slice(obj, &mut array)?;
                     Ok(array)
@@ -289,12 +282,12 @@ macro_rules! array_impls {
             #[cfg(feature = "nightly")]
             impl<'source, T> FromPyObject<'source> for [T; $N]
             where
-                for<'a> T: Copy + Default + FromPyObject<'a> + buffer::Element,
+                for<'a> T: Default + FromPyObject<'a> + crate::buffer::Element,
             {
                 fn extract(obj: &'source PyAny) -> PyResult<Self> {
                     let mut array = [T::default(); $N];
                     // first try buffer protocol
-                    if let Ok(buf) = buffer::PyBuffer::get(obj) {
+                    if let Ok(buf) = crate::buffer::PyBuffer::get(obj) {
                         if buf.dimensions() == 1 && buf.copy_to_slice(obj.py(), &mut array).is_ok() {
                             buf.release(obj.py());
                             return Ok(array);
@@ -315,21 +308,15 @@ array_impls!(
     26, 27, 28, 29, 30, 31, 32
 );
 
-#[cfg(not(feature = "nightly"))]
 impl<'a, T> FromPyObject<'a> for Vec<T>
 where
     T: FromPyObject<'a>,
 {
+    #[cfg(not(feature = "nightly"))]
     fn extract(obj: &'a PyAny) -> PyResult<Self> {
         extract_sequence(obj)
     }
-}
-
-#[cfg(feature = "nightly")]
-impl<'a, T> FromPyObject<'a> for Vec<T>
-where
-    T: FromPyObject<'a>,
-{
+    #[cfg(feature = "nightly")]
     default fn extract(obj: &'a PyAny) -> PyResult<Self> {
         extract_sequence(obj)
     }
@@ -338,11 +325,11 @@ where
 #[cfg(feature = "nightly")]
 impl<'source, T> FromPyObject<'source> for Vec<T>
 where
-    for<'a> T: FromPyObject<'a> + buffer::Element + Copy,
+    for<'a> T: FromPyObject<'a> + crate::buffer::Element,
 {
     fn extract(obj: &'source PyAny) -> PyResult<Self> {
         // first try buffer protocol
-        if let Ok(buf) = buffer::PyBuffer::get(obj) {
+        if let Ok(buf) = crate::buffer::PyBuffer::get(obj) {
             if buf.dimensions() == 1 {
                 if let Ok(v) = buf.to_vec(obj.py()) {
                     buf.release(obj.py());
diff --git a/tests/test_compile_error.rs b/tests/test_compile_error.rs
index 465922b5..f9a18eda 100644
--- a/tests/test_compile_error.rs
+++ b/tests/test_compile_error.rs
@@ -1,22 +1,20 @@
+#[rustversion::stable]
 #[test]
 fn test_compile_errors() {
     let t = trybuild::TestCases::new();
-    testcase_common(&t);
-    testcase_latest_stable(&t);
+    t.compile_fail("tests/ui/invalid_macro_args.rs");
+    t.compile_fail("tests/ui/invalid_property_args.rs");
+    t.compile_fail("tests/ui/invalid_pyclass_args.rs");
+    t.compile_fail("tests/ui/missing_clone.rs");
+    t.compile_fail("tests/ui/reject_generics.rs");
+    t.compile_fail("tests/ui/wrong_aspyref_lifetimes.rs");
+
+    skip_min_stable(&t);
 
-    fn testcase_common(t: &trybuild::TestCases) {
-        t.compile_fail("tests/ui/invalid_macro_args.rs");
-        t.compile_fail("tests/ui/invalid_property_args.rs");
-        t.compile_fail("tests/ui/invalid_pyclass_args.rs");
-        t.compile_fail("tests/ui/missing_clone.rs");
-        t.compile_fail("tests/ui/reject_generics.rs");
-        t.compile_fail("tests/ui/wrong_aspyref_lifetimes.rs");
-        t.compile_fail("tests/ui/invalid_pymethod_names.rs");
-    }
     #[rustversion::since(1.43)]
-    fn testcase_latest_stable(t: &trybuild::TestCases) {
+    fn skip_min_stable(t: &trybuild::TestCases) {
         t.compile_fail("tests/ui/static_ref.rs");
     }
     #[rustversion::before(1.43)]
-    fn testcase_latest_stable(_t: &trybuild::TestCases) {}
+    fn skip_min_stable(_t: &trybuild::TestCases) {}
 }