[clang] [Clang] handle [[warn_unused]] attribute for unused private fields (PR #120734)

[Erich Keane via cfe-commits]

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@@ -3307,6 +3307,29 @@ void Sema::CheckShadowInheritedFields(const SourceLocation &Loc,
   }
 }
 
+template <typename AttrType>
+inline static bool HasAttribute(const QualType &T) {
+  if (const TagDecl *TD = T->getAsTagDecl())
+    return TD->hasAttr<AttrType>();
+  if (const TypedefType *TDT = T->getAs<TypedefType>())
+    return TDT->getDecl()->hasAttr<AttrType>();
+  return false;
+}
+
+inline static bool IsUnusedPrivateField(FieldDecl *FD) {
+  if (FD->getAccess() == AS_private && FD->getDeclName()) {
+    QualType FieldType = FD->getType();
+    if (HasAttribute<WarnUnusedAttr>(FieldType))
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erichkeane wrote:

The FieldDecl?  I guess I can't think of any conditions where it could be context dependent/implicit?  Or am I missing something again?

https://github.com/llvm/llvm-project/pull/120734