Fix behavior of [[gnu::]] function attributes. Per g++'s behavior, these

attributes appertain to a declaration, even though they would be much more
naturally modelled as appertaining to a function type. Previously, we would
try to distribute them from the declarator to the function type, then
reject them for being at an incorrect location. Now, we just distribute them
as far as the declarator; the existing attribute handling code can actually
apply them there just fine.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172504 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaType.cpp

@@ -463,6 +463,15 @@ distributeFunctionTypeAttrFromDeclSpec(TypeProcessingState &state,
                                        QualType &declSpecType) {
   state.saveDeclSpecAttrs();
 
+  // C++11 attributes before the decl specifiers actually appertain to
+  // the declarators. Move them straight there. We don't support the
+  // 'put them wherever you like' semantics we allow for GNU attributes.
+  if (attr.isCXX11Attribute()) {
+    moveAttrFromListToList(attr, state.getCurrentAttrListRef(),
+                           state.getDeclarator().getAttrListRef());
+    return;
+  }
+
   // Try to distribute to the innermost.
   if (distributeFunctionTypeAttrToInnermost(state, attr,
                                             state.getCurrentAttrListRef(),
@@ -512,6 +521,11 @@ static void distributeTypeAttrsFromDeclarator(TypeProcessingState &state,
   do {
     next = attr->getNext();
 
+    // Do not distribute C++11 attributes. They have strict rules for what
+    // they appertain to.
+    if (attr->isCXX11Attribute())
+      continue;
+
     switch (attr->getKind()) {
     OBJC_POINTER_TYPE_ATTRS_CASELIST:
       distributeObjCPointerTypeAttrFromDeclarator(state, *attr, declSpecType);

test/Parser/objcxx11-attributes.mm

@@ -44,7 +44,7 @@ void f(X *noreturn) {
   int e2(); // expected-warning {{interpreted as a function declaration}} expected-note{{}}
 
   // A function taking a noreturn function.
-  int(f)([[noreturn]] int()); // expected-note {{here}}
+  int(f)([[gnu::noreturn]] int ()); // expected-note {{here}}
   f(e);
   f(e2); // expected-error {{cannot initialize a parameter of type 'int (*)() __attribute__((noreturn))' with an lvalue of type 'int ()'}}
 

test/SemaCXX/cxx11-gnu-attrs.cpp

@@ -39,7 +39,17 @@ void deprecated3() {
 
 void nonnull [[gnu::nonnull]] (); // expected-warning {{applied to function with no pointer arguments}}
 
+// [[gnu::noreturn]] appertains to a declaration, and marks the innermost
+// function declarator in that declaration as being noreturn.
 int noreturn [[gnu::noreturn]]; // expected-warning {{'noreturn' only applies to function types}}
+int noreturn_fn_1();
+int noreturn_fn_2() [[gnu::noreturn]]; // expected-warning {{cannot be applied to a type}}
+int noreturn_fn_3 [[gnu::noreturn]] ();
+[[gnu::noreturn]] int noreturn_fn_4();
+int (*noreturn_fn_ptr_1 [[gnu::noreturn]])() = &noreturn_fn_1; // expected-error {{cannot initialize}}
+int (*noreturn_fn_ptr_2 [[gnu::noreturn]])() = &noreturn_fn_3;
+[[gnu::noreturn]] int (*noreturn_fn_ptr_3)() = &noreturn_fn_1; // expected-error {{cannot initialize}}
+[[gnu::noreturn]] int (*noreturn_fn_ptr_4)() = &noreturn_fn_3;
 
 struct [[gnu::packed]] packed { char c; int n; };
 static_assert(sizeof(packed) == sizeof(char) + sizeof(int), "not packed");