From d409b5c700e1789a5b2d0b1dd1bd996bfd8bb320 Mon Sep 17 00:00:00 2001
From: Jason Newcomb <jsnewcomb@pm.me>
Date: Tue, 11 Jun 2024 02:03:09 -0400
Subject: [PATCH] `extra_unused_type_parameters`: * Inline
 `is_empty_exported_or_macro`. * Check if there are any generic parameters
 before walking the signature.

---
 .../src/extra_unused_type_parameters.rs       | 30 ++++++++-----------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/clippy_lints/src/extra_unused_type_parameters.rs b/clippy_lints/src/extra_unused_type_parameters.rs
index 7484f772e..843ab9d5d 100644
--- a/clippy_lints/src/extra_unused_type_parameters.rs
+++ b/clippy_lints/src/extra_unused_type_parameters.rs
@@ -50,21 +50,6 @@ impl ExtraUnusedTypeParameters {
             avoid_breaking_exported_api,
         }
     }
-
-    /// Don't lint external macros or functions with empty bodies. Also, don't lint exported items
-    /// if the `avoid_breaking_exported_api` config option is set.
-    fn is_empty_exported_or_macro(
-        &self,
-        cx: &LateContext<'_>,
-        span: Span,
-        def_id: LocalDefId,
-        body_id: BodyId,
-    ) -> bool {
-        let body = cx.tcx.hir().body(body_id).value;
-        let fn_empty = matches!(&body.kind, ExprKind::Block(blk, None) if blk.stmts.is_empty() && blk.expr.is_none());
-        let is_exported = cx.effective_visibilities.is_exported(def_id);
-        in_external_macro(cx.sess(), span) || fn_empty || (is_exported && self.avoid_breaking_exported_api)
-    }
 }
 
 impl_lint_pass!(ExtraUnusedTypeParameters => [EXTRA_UNUSED_TYPE_PARAMETERS]);
@@ -266,10 +251,17 @@ impl<'cx, 'tcx> Visitor<'tcx> for TypeWalker<'cx, 'tcx> {
     }
 }
 
+fn is_empty_body(cx: &LateContext<'_>, body: BodyId) -> bool {
+    matches!(cx.tcx.hir().body(body).value.kind, ExprKind::Block(b, _) if b.stmts.is_empty() && b.expr.is_none())
+}
+
 impl<'tcx> LateLintPass<'tcx> for ExtraUnusedTypeParameters {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
         if let ItemKind::Fn(_, generics, body_id) = item.kind
-            && !self.is_empty_exported_or_macro(cx, item.span, item.owner_id.def_id, body_id)
+            && !generics.params.is_empty()
+            && !is_empty_body(cx, body_id)
+            && (!self.avoid_breaking_exported_api || !cx.effective_visibilities.is_exported(item.owner_id.def_id))
+            && !in_external_macro(cx.sess(), item.span)
             && !is_from_proc_macro(cx, item)
         {
             let mut walker = TypeWalker::new(cx, generics);
@@ -281,8 +273,12 @@ impl<'tcx> LateLintPass<'tcx> for ExtraUnusedTypeParameters {
     fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx ImplItem<'tcx>) {
         // Only lint on inherent methods, not trait methods.
         if let ImplItemKind::Fn(.., body_id) = item.kind
+            && !item.generics.params.is_empty()
             && trait_ref_of_method(cx, item.owner_id.def_id).is_none()
-            && !self.is_empty_exported_or_macro(cx, item.span, item.owner_id.def_id, body_id)
+            && !is_empty_body(cx, body_id)
+            && (!self.avoid_breaking_exported_api || !cx.effective_visibilities.is_exported(item.owner_id.def_id))
+            && !in_external_macro(cx.sess(), item.span)
+            && !is_from_proc_macro(cx, item)
         {
             let mut walker = TypeWalker::new(cx, item.generics);
             walk_impl_item(&mut walker, item);