Enable use of _Static_assert inside structs and unions in C11 mode (as per C11 6.7.2.1p1).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178632 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Parse/ParseDecl.cpp

@@ -3093,6 +3093,13 @@ void Parser::ParseStructUnionBody(SourceLocation RecordLoc,
       continue;
     }
 
+    // Parse _Static_assert declaration.
+    if (Tok.is(tok::kw__Static_assert)) {
+      SourceLocation DeclEnd;
+      ParseStaticAssertDeclaration(DeclEnd);
+      continue;
+    }
+
     if (!Tok.is(tok::at)) {
       struct CFieldCallback : FieldCallback {
         Parser &P;

test/Sema/static-assert.c

@@ -1,6 +1,10 @@
-// RUN: %clang_cc1 -std=c1x -fsyntax-only -verify %s
+// RUN: %clang_cc1 -std=c11 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -xc++ -std=c++11 -fsyntax-only -verify %s
 
-_Static_assert("foo", "string is nonzero"); // expected-error {{static_assert expression is not an integral constant expression}}
+_Static_assert("foo", "string is nonzero");
+#ifndef __cplusplus
+// expected-error@-2 {{static_assert expression is not an integral constant expression}}
+#endif
 
 _Static_assert(1, "1 is nonzero");
 _Static_assert(0, "0 is nonzero"); // expected-error {{static_assert failed "0 is nonzero"}}
@@ -11,3 +15,28 @@ void foo(void) {
 }
 
 _Static_assert(1, invalid); // expected-error {{expected string literal for diagnostic message in static_assert}}
+
+struct A {
+  int a;
+  _Static_assert(1, "1 is nonzero");
+  _Static_assert(0, "0 is nonzero"); // expected-error {{static_assert failed "0 is nonzero"}}
+};
+
+#ifdef __cplusplus
+#define ASSERT_IS_TYPE(T) __is_same(T, T)
+#else
+#define ASSERT_IS_TYPE(T) __builtin_types_compatible_p(T, T)
+#endif
+
+#define UNION(T1, T2) union { \
+    __typeof__(T1) one; \
+    __typeof__(T2) two; \
+    _Static_assert(ASSERT_IS_TYPE(T1), "T1 is not a type"); \
+    _Static_assert(ASSERT_IS_TYPE(T2), "T2 is not a type"); \
+    _Static_assert(sizeof(T1) == sizeof(T2), "type size mismatch"); \
+  }
+
+typedef UNION(unsigned, struct A) U1;
+UNION(char[2], short) u2 = { .one = { 'a', 'b' } };
+typedef UNION(char, short) U3; // expected-error {{static_assert failed "type size mismatch"}}
+typedef UNION(float, 0.5f) U4; // expected-error {{expected a type}}