Fix some clippy and dead code warnings.

pyo3-build-config/src/impl_.rs

@@ -885,7 +885,7 @@ fn search_lib_dir(path: impl AsRef<Path>, cross: &CrossCompileConfig) -> Vec<Pat
     } else {
         "python3.".into()
     };
-    for f in fs::read_dir(path).expect("Path does not exist").into_iter() {
+    for f in fs::read_dir(path).expect("Path does not exist") {
         sysconfig_paths.extend(match &f {
             // Python 3.7+ sysconfigdata with platform specifics
             Ok(f) if starts_with(f, "_sysconfigdata_") && ends_with(f, "py") => vec![f.path()],

pyo3-macros-backend/src/pyclass.rs

@@ -392,7 +392,7 @@ pub fn build_py_enum(
     let variants: Vec<PyClassEnumVariant> = enum_
         .variants
         .iter()
-        .map(|v| extract_variant_data(v))
+        .map(extract_variant_data)
         .collect::<syn::Result<_>>()?;
     impl_enum(enum_, args, variants, method_type)
 }

pyo3-macros-backend/src/utils.rs

@@ -77,11 +77,7 @@ pub fn get_doc(
     syn::token::Bracket(Span::call_site()).surround(&mut tokens, |tokens| {
         if let Some((python_name, text_signature)) = text_signature {
             // create special doc string lines to set `__text_signature__`
-            let signature_lines = format!(
-                "{}{}\n--\n\n",
-                python_name.to_string(),
-                text_signature.lit.value()
-            );
+            let signature_lines = format!("{}{}\n--\n\n", python_name, text_signature.lit.value());
             signature_lines.to_tokens(tokens);
             comma.to_tokens(tokens);
         }

src/err/mod.rs

@@ -440,7 +440,7 @@ impl PyErr {
     pub fn cause(&self, py: Python) -> Option<PyErr> {
         let ptr = unsafe { ffi::PyException_GetCause(self.pvalue(py).as_ptr()) };
         let obj = unsafe { py.from_owned_ptr_or_opt::<PyAny>(ptr) };
-        obj.map(|x| Self::from_instance(x))
+        obj.map(Self::from_instance)
     }
 
     /// Set the cause associated with the exception, pass `None` to clear it.

tests/test_frompyobject.rs

@@ -194,6 +194,7 @@ struct PyBaz {
 }
 
 #[derive(Debug, FromPyObject)]
+#[allow(dead_code)]
 struct Baz<U, T> {
     e: E<U, T>,
     tup: Tuple,