Add extra tests for [[gnu::...]] attributes, missed from r172382.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172391 91177308-0d34-0410-b5e6-96231b3b80d8

test/SemaCXX/cxx11-gnu-attrs.cpp

+// RUN: %clang -cc1 -std=c++11 -verify %s
+
+// Error cases.
+
+[[gnu::this_attribute_does_not_exist]] int unknown_attr;
+// expected-warning@-1 {{unknown attribute 'this_attribute_does_not_exist' ignored}}
+int [[gnu::unused]] attr_on_type;
+// expected-warning@-1 {{attribute 'unused' ignored, because it is not attached to a declaration}}
+int *[[gnu::unused]] attr_on_ptr;
+// expected-warning@-1 {{attribute 'unused' ignored, because it cannot be applied to a type}}
+
+// Valid cases.
+
+void alias1() {}
+void alias2 [[gnu::alias("_Z6alias1v")]] ();
+
+[[gnu::aligned(8)]] int aligned;
+void aligned_fn [[gnu::aligned(32)]] ();
+struct [[gnu::aligned(8)]] aligned_struct {};
+
+[[gnu::malloc, gnu::alloc_size(1,2)]] void *alloc_size(int a, int b);
+
+void always_inline [[gnu::always_inline]] ();
+
+__thread int tls_model [[gnu::tls_model("local-exec")]];
+
+void cleanup(int *p) {
+  int n [[gnu::cleanup(cleanup)]];
+}
+
+void deprecated1 [[gnu::deprecated]] (); // expected-note {{here}}
+[[gnu::deprecated("custom message")]] void deprecated2(); // expected-note {{here}}
+void deprecated3() {
+  deprecated1(); // expected-warning {{deprecated}}
+  deprecated2(); // expected-warning {{custom message}}
+}
+
+[[gnu::naked(1,2,3)]] void naked(); // expected-error {{takes no arguments}}
+
+void nonnull [[gnu::nonnull]] (); // expected-warning {{applied to function with no pointer arguments}}
+
+int noreturn [[gnu::noreturn]]; // expected-warning {{'noreturn' only applies to function types}}
+
+struct [[gnu::packed]] packed { char c; int n; };
+static_assert(sizeof(packed) == sizeof(char) + sizeof(int), "not packed");