Diagnose GNU-style attributes preceding virt-specifiers, but only when the attribute is known to GCC. Clang accepts attributes in this position, but

GCC does not, so this is a GCC-compat warning. If the attribute is not known to GCC, then the diagnostic is suppressed.

llvm-svn: 214730

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -167,6 +167,9 @@ def err_expected_fn_body : Error<
 def warn_attribute_on_function_definition : Warning<
   "GCC does not allow %0 attribute in this position on a function definition">, 
   InGroup<GccCompat>;
+def warn_gcc_attribute_location : Warning<
+  "GCC does not allow an attribute in this position on a function declaration">, 
+  InGroup<GccCompat>;
 def warn_attribute_no_decl : Warning<
   "attribute %0 ignored, because it is not attached to a declaration">, 
   InGroup<IgnoredAttributes>;

clang/lib/Parse/ParseDeclCXX.cpp

@@ -1953,10 +1953,19 @@ void Parser::ParseCXXMemberDeclaratorBeforeInitializer(
 
   // For compatibility with code written to older Clang, also accept a
   // virt-specifier *after* the GNU attributes.
-  // FIXME: If we saw any attributes that are known to GCC followed by a
-  // virt-specifier, issue a GCC-compat warning.
-  if (BitfieldSize.isUnset() && VS.isUnset())
+  if (BitfieldSize.isUnset() && VS.isUnset()) {
     ParseOptionalCXX11VirtSpecifierSeq(VS, getCurrentClass().IsInterface);
+    if (!VS.isUnset()) {
+      // If we saw any GNU-style attributes that are known to GCC followed by a
+      // virt-specifier, issue a GCC-compat warning.
+      const AttributeList *Attr = DeclaratorInfo.getAttributes();
+      while (Attr) {
+        if (Attr->isKnownToGCC() && !Attr->isCXX11Attribute())
+          Diag(Attr->getLoc(), diag::warn_gcc_attribute_location);
+        Attr = Attr->getNext();
+      }
+    }
+  }
 }
 
 /// ParseCXXClassMemberDeclaration - Parse a C++ class member declaration.

clang/test/SemaCXX/attr-gnu.cpp

@@ -11,3 +11,19 @@ void f() {
 }
 
 void g(int a[static [[]] 5]); // expected-error {{static array size is a C99 feature, not permitted in C++}}
+
+namespace {
+class B {
+public:
+  virtual void test() {}
+  virtual void test2() {}
+  virtual void test3() {}
+};
+
+class D : public B {
+public:
+  void test() __attribute__((deprecated)) final {} // expected-warning {{GCC does not allow an attribute in this position on a function declaration}}
+  void test2() [[]] override {} // Ok
+  void test3() __attribute__((cf_unknown_transfer)) override {} // Ok, not known to GCC.
+};
+}