Also treat impl definition parent as transparent regarding modules

Author: Urgau

compiler/rustc_lint/src/non_local_def.rs

@@ -284,8 +284,8 @@ fn path_has_local_parent(
         .is_some_and(|did| did_has_local_parent(did, cx.tcx, impl_parent, outermost_impl_parent))
 }
 
-/// Given a def id this checks if the parent def id (modulo modules) correspond to
-/// the def id of the parent impl definition (the direct one and the outermost one).
+/// Given a def if we check if the parent def id (modulo modules and const-anons) correspond
+/// to the def id of the parent impl definition (the direct parent or the outermost one).
 #[inline]
 fn did_has_local_parent(
     did: DefId,
@@ -301,13 +301,21 @@ fn did_has_local_parent(
         return false;
     };
 
-    peel_parent_while(tcx, parent_did, |tcx, did| {
-        tcx.def_kind(did) == DefKind::Mod
-            || (tcx.def_kind(did) == DefKind::Const
-                && tcx.opt_item_name(did) == Some(kw::Underscore))
-    })
-    .map(|parent_did| parent_did == impl_parent || Some(parent_did) == outermost_impl_parent)
-    .unwrap_or(false)
+    // Peel modules
+    peel_parent_while(tcx, parent_did, |tcx, did| tcx.def_kind(did) == DefKind::Mod)
+        // Peel const-anons
+        .map(|parent_did| {
+            peel_parent_while(tcx, parent_did, |tcx, did| {
+                tcx.def_kind(did) == DefKind::Const
+                    && tcx.opt_item_name(did) == Some(kw::Underscore)
+            })
+        })
+        .flatten()
+        // Check if parent def if is either equal to:
+        //  - the `impl` parent
+        //  - or the outermost `impl` parent
+        .map(|parent_did| parent_did == impl_parent || Some(parent_did) == outermost_impl_parent)
+        .unwrap_or(false)
 }
 
 /// Given a `DefId` checks if it satisfies `f` if it does check with it's parent and continue

tests/ui/lint/non-local-defs/convoluted-locals-132427.rs

@@ -0,0 +1,54 @@
+// Regression tests for https://github.com/rust-lang/rust/issues/132427
+
+//@ check-pass
+
+// original
+mod auth {
+    const _: () = {
+        pub enum ArbitraryContext {}
+
+        const _: () = {
+            impl ArbitraryContext {}
+        };
+    };
+}
+
+const _: () = {
+    mod auth {
+        const _: () = {
+            pub enum ArbitraryContext {}
+
+            const _: () = {
+                impl ArbitraryContext {}
+            };
+        };
+    }
+};
+
+mod a {
+    mod b {
+        const _: () = {
+            pub enum ArbitraryContext {}
+
+            const _: () = {
+                impl ArbitraryContext {}
+            };
+        };
+    }
+}
+
+mod foo {
+    const _: () = {
+        mod auth {
+            const _: () = {
+                pub enum ArbitraryContext {}
+
+                const _: () = {
+                    impl ArbitraryContext {}
+                };
+            };
+        }
+    };
+}
+
+fn main() {}