Skip use_self inside macro expansion of impl Self items

Author: tesuji

clippy_lints/src/use_self.rs

@@ -87,6 +87,7 @@ impl<'tcx> LateLintPass<'tcx> for UseSelf {
             // skip over `ItemKind::OpaqueTy` in order to lint `foo() -> impl <..>`
             return;
         }
+
         // We push the self types of `impl`s on a stack here. Only the top type on the stack is
         // relevant for linting, since this is the self type of the `impl` we're currently in. To
         // avoid linting on nested items, we push `StackItem::NoCheck` on the stack to signal, that
@@ -134,6 +135,14 @@ impl<'tcx> LateLintPass<'tcx> for UseSelf {
     }
 
     fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) {
+        // Checking items of `impl Self` blocks in which macro expands into.
+        // HACK: Nested macros sometimes clears `macro_backtrace` of types in `check_ty`.
+        // To work around this problem, we check if this impl_item is from macro expansions.
+        // Just remember to remove this state again in `check_impl_item_post`.
+        if impl_item.span.from_expansion() {
+            self.stack.push(StackItem::NoCheck);
+            return;
+        }
         // We want to skip types in trait `impl`s that aren't declared as `Self` in the trait
         // declaration. The collection of those types is all this method implementation does.
         if let ImplItemKind::Fn(FnSig { decl, .. }, ..) = impl_item.kind
@@ -189,6 +198,11 @@ impl<'tcx> LateLintPass<'tcx> for UseSelf {
         }
     }
 
+    fn check_impl_item_post(&mut self, _: &LateContext<'_>, _: &hir::ImplItem<'_>) {
+        if let Some(StackItem::NoCheck) = self.stack.last() {
+            self.stack.pop();
+        }
+    }
 
     fn check_ty(&mut self, cx: &LateContext<'tcx>, hir_ty: &Ty<'tcx>) {
         if !hir_ty.span.from_expansion()

tests/ui/use_self.fixed

@@ -682,12 +682,12 @@ mod issue_13092 {
     struct MyStruct;
 
     impl MyStruct {
-        macro_inner_item!(Self);
+        macro_inner_item!(MyStruct);
     }
 
     impl MyStruct {
         thread_local! {
-            static SPECIAL: RefCell<Self> = RefCell::default();
+            static SPECIAL: RefCell<MyStruct> = RefCell::default();
         }
     }
 }

tests/ui/use_self.stderr

@@ -259,25 +259,5 @@ error: unnecessary structure name repetition
 LL |                 E::A => {},
    |                 ^ help: use the applicable keyword: `Self`
 
-error: unnecessary structure name repetition
-  --> tests/ui/use_self.rs:685:27
-   |
-LL |         macro_inner_item!(MyStruct);
-   |                           ^^^^^^^^ help: use the applicable keyword: `Self`
-
-error: unnecessary structure name repetition
-  --> tests/ui/use_self.rs:690:37
-   |
-LL |             static SPECIAL: RefCell<MyStruct> = RefCell::default();
-   |                                     ^^^^^^^^ help: use the applicable keyword: `Self`
-
-error: unnecessary structure name repetition
-  --> tests/ui/use_self.rs:690:37
-   |
-LL |             static SPECIAL: RefCell<MyStruct> = RefCell::default();
-   |                                     ^^^^^^^^ help: use the applicable keyword: `Self`
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 46 previous errors
+error: aborting due to 43 previous errors