[PATCH] D52421: [Sema] Diagnose parameter names that shadow inherited field names

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman created this revision.
aaron.ballman added reviewers: lebedev.ri, rsmith, dblaikie.

This patch diagnoses parameter names that shadow the names of inherited fields 
under -Wshadow-field. It addresses PR34120. Note, unlike GCC, we take into 
account the accessibility of the field when deciding whether to warn or not.


https://reviews.llvm.org/D52421

Files:
  include/clang/Basic/DiagnosticSemaKinds.td
  include/clang/Sema/Sema.h
  lib/Sema/SemaDecl.cpp
  lib/Sema/SemaDeclCXX.cpp
  test/SemaCXX/warn-shadow.cpp


Index: test/SemaCXX/warn-shadow.cpp
===================================================================
--- test/SemaCXX/warn-shadow.cpp
+++ test/SemaCXX/warn-shadow.cpp
@@ -222,3 +222,23 @@
   };
 }
 }
+
+namespace PR34120 {
+struct A {
+  int B; // expected-note {{declared here}}
+};
+
+class C : public A {
+  void D(int B) {} // expected-warning {{parameter 'B' shadows member inherited from type 'A'}}
+  void E() {
+    extern void f(int B); // Ok
+  }
+};
+
+class Private {
+  int B;
+};
+class Derived : Private {
+  void D(int B) {} // Ok
+};
+}
Index: lib/Sema/SemaDeclCXX.cpp
===================================================================
--- lib/Sema/SemaDeclCXX.cpp
+++ lib/Sema/SemaDeclCXX.cpp
@@ -2852,7 +2852,8 @@
 // Check if there is a field shadowing.
 void Sema::CheckShadowInheritedFields(const SourceLocation &Loc,
                                       DeclarationName FieldName,
-                                      const CXXRecordDecl *RD) {
+                                      const CXXRecordDecl *RD,
+                                      bool DeclIsField) {
   if (Diags.isIgnored(diag::warn_shadow_field, Loc))
     return;
 
@@ -2892,7 +2893,7 @@
     if (AS_none !=
         CXXRecordDecl::MergeAccess(P.Access, BaseField->getAccess())) {
       Diag(Loc, diag::warn_shadow_field)
-        << FieldName << RD << Base;
+        << FieldName << RD << Base << DeclIsField;
       Diag(BaseField->getLocation(), diag::note_shadow_field);
       Bases.erase(It);
     }
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -12379,6 +12379,13 @@
     }
   }
 
+  if (LangOpts.CPlusPlus && II) {
+    DeclarationNameInfo DNI = GetNameForDeclarator(D);
+    if (auto *RD = dyn_cast<CXXRecordDecl>(CurContext))
+      CheckShadowInheritedFields(DNI.getLoc(), DNI.getName(), RD,
+                                 /*DeclIsField*/ false);
+  }
+
   // Temporarily put parameter variables in the translation unit, not
   // the enclosing context.  This prevents them from accidentally
   // looking like class members in C++.
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -10524,7 +10524,8 @@
   /// Check if there is a field shadowing.
   void CheckShadowInheritedFields(const SourceLocation &Loc,
                                   DeclarationName FieldName,
-                                  const CXXRecordDecl *RD);
+                                  const CXXRecordDecl *RD,
+                                  bool DeclIsField = true);
 
   /// Check if the given expression contains 'break' or 'continue'
   /// statement that produces control flow different from GCC.
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -9418,10 +9418,9 @@
   "__final is a GNU extension, consider using C++11 final">,
   InGroup<GccCompat>;
 
-def warn_shadow_field :
-  Warning<"non-static data member %0 of %1 shadows member inherited from "
-  "type %2">,
-  InGroup<ShadowField>, DefaultIgnore;
+def warn_shadow_field : Warning<
+  "%select{parameter|non-static data member}3 %0 %select{|of %1 }3shadows "
+  "member inherited from type %2">, InGroup<ShadowField>, DefaultIgnore;
 def note_shadow_field : Note<"declared here">;
 
 def err_multiversion_required_in_redecl : Error<

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