Re-enabled support for the Subjects for the weak attribute. This changes the diagnostic involved to be more accurate -- for C++ code, it will now report that weak applies to variables, functions or classes. Added additional test case for this.

llvm-svn: 196120

clang/include/clang/Basic/Attr.td

@@ -870,7 +870,7 @@ def WarnUnusedResult : InheritableAttr {
 
 def Weak : InheritableAttr {
   let Spellings = [GNU<"weak">, CXX11<"gnu", "weak">];
-//  let Subjects = SubjectList<[Var, Function, CXXRecord]>;
+  let Subjects = SubjectList<[Var, Function, CXXRecord]>;
 }
 
 def WeakImport : InheritableAttr {

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -2037,7 +2037,7 @@ def warn_attribute_wrong_decl_type : Warning<
   "variables and fields|variables, data members and tag types|"
   "types and namespaces|Objective-C interfaces|methods and properties|"
   "struct or union|struct, union or class|types|"
-  "Objective-C instance methods}1">,
+  "Objective-C instance methods|variables, functions and classes}1">,
   InGroup<IgnoredAttributes>;
 def err_attribute_wrong_decl_type : Error<
   "%0 attribute only applies to %select{functions|unions|"
@@ -2049,7 +2049,7 @@ def err_attribute_wrong_decl_type : Error<
   "variables and fields|variables, data members and tag types|"
   "types and namespaces|Objective-C interfaces|methods and properties|"
   "struct or union|struct, union or class|types|"
-  "Objective-C instance methods}1">;
+  "Objective-C instance methods|variables, functions and classes}1">;
 def warn_type_attribute_wrong_type : Warning<
   "'%0' only applies to %select{function|pointer|"
   "Objective-C object or block pointer}1 types; type here is %2">,

clang/include/clang/Sema/AttributeList.h

@@ -859,7 +859,8 @@ enum AttributeDeclKind {
   ExpectedStructOrUnion,
   ExpectedStructOrUnionOrClass,
   ExpectedType,
-  ExpectedObjCInstanceMethod
+  ExpectedObjCInstanceMethod,
+  ExpectedFunctionVariableOrClass
 };
 
 }  // end namespace clang

clang/lib/Sema/SemaDeclAttr.cpp

@@ -2243,24 +2243,6 @@ static void handleWarnUnusedResult(Sema &S, Decl *D, const AttributeList &Attr)
                                   Attr.getAttributeSpellingListIndex()));
 }
 
-static void handleWeakAttr(Sema &S, Decl *D, const AttributeList &Attr) {
-  if (!isa<VarDecl>(D) && !isa<FunctionDecl>(D)) {
-    if (isa<CXXRecordDecl>(D)) {
-      D->addAttr(::new (S.Context) WeakAttr(Attr.getRange(), S.Context));
-      return;
-    }
-    S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
-      << Attr.getName() << ExpectedVariableOrFunction;
-    return;
-  }
-
-  NamedDecl *nd = cast<NamedDecl>(D);
-
-  nd->addAttr(::new (S.Context)
-              WeakAttr(Attr.getRange(), S.Context,
-                       Attr.getAttributeSpellingListIndex()));
-}
-
 static void handleWeakImportAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   // weak_import only applies to variable & function declarations.
   bool isDef = false;
@@ -4168,7 +4150,8 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
     handleSimpleAttribute<WarnUnusedAttr>(S, D, Attr); break;
   case AttributeList::AT_WarnUnusedResult: handleWarnUnusedResult(S, D, Attr);
     break;
-  case AttributeList::AT_Weak:        handleWeakAttr        (S, D, Attr); break;
+  case AttributeList::AT_Weak:
+    handleSimpleAttribute<WeakAttr>(S, D, Attr); break;
   case AttributeList::AT_WeakRef:     handleWeakRefAttr     (S, D, Attr); break;
   case AttributeList::AT_WeakImport:  handleWeakImportAttr  (S, D, Attr); break;
   case AttributeList::AT_TransparentUnion:

clang/test/SemaCXX/attr-weak.cpp

@@ -3,7 +3,7 @@
 static int test0 __attribute__((weak)); // expected-error {{weak declaration cannot have internal linkage}}
 static void test1() __attribute__((weak)); // expected-error {{weak declaration cannot have internal linkage}}
 
-namespace test2 __attribute__((weak)) { // expected-warning {{'weak' attribute only applies to variables and functions}}
+namespace test2 __attribute__((weak)) { // expected-warning {{'weak' attribute only applies to variables, functions and classes}}
 }
 
 namespace {
@@ -34,3 +34,5 @@ int Test7<T>::var;
 namespace { class Internal; }
 template struct Test7<Internal>;
 template struct Test7<int>;
+
+class __attribute__((weak)) Test8 {}; // OK

clang/utils/TableGen/ClangAttrEmitter.cpp

@@ -1797,6 +1797,12 @@ static std::string CalculateDiagnostic(const Record &S) {
     case Func | FuncTemplate:
     case Func | ObjCMethod: return "ExpectedFunctionOrMethod";
     case Func | Var: return "ExpectedVariableOrFunction";
+
+    // If not compiling for C++, the class portion does not apply.
+    case Func | Var | Class:
+      return "(S.getLangOpts().CPlusPlus ? ExpectedFunctionVariableOrClass : "
+                                           "ExpectedVariableOrFunction)";
+
     case ObjCMethod | ObjCProp: return "ExpectedMethodOrProperty";
     case Field | Var: return "ExpectedFieldOrGlobalVar";
   }