clang: Fix static_assert in a few contexts in microsoft mode

[thakis]

Summary

Follow-up to D17444. Fixes PR48904. See bug for details.

[rsmith]

Looks good, and I think we should also backport this to Clang 12.

clang/lib/Parse/ParseDecl.cpp

4234

Use isOneOf.

clang/lib/Parse/ParseDecl.cpp

while (!tryParseMisplacedModuleImport() && Tok.isNot(tok::r_brace) &&
 
     // Check for extraneous top-level semicolon.
     if (Tok.is(tok::semi)) {
       ConsumeExtraSemi(InsideStruct, TagType);
       continue;
     }
 
     // Parse _Static_assert declaration.
-    if (Tok.is(tok::kw__Static_assert)) {
+    if (Tok.isOneOf(tok::kw__Static_assert, tok::kw_static_assert)) {
       SourceLocation DeclEnd;
       ParseStaticAssertDeclaration(DeclEnd);
       continue;
     }
 
     if (Tok.is(tok::annot_pragma_pack)) {
       HandlePragmaPack();
       continue;
case tok::kw__Noreturn:
 
     // alignment-specifier
   case tok::kw__Alignas:
 
     // friend keyword.
   case tok::kw_friend:
 
     // static_assert-declaration
+  case tok::kw_static_assert:
   case tok::kw__Static_assert:
 
     // GNU typeof support.
   case tok::kw_typeof:
 
     // GNU attributes.
   case tok::kw___attribute:
 

clang/test/Sema/static-assert.c

 // RUN: %clang_cc1 -std=c11 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fms-compatibility -DMS -fsyntax-only -verify %s
 // RUN: %clang_cc1 -std=c99 -pedantic -fsyntax-only -verify=expected,ext %s
 // RUN: %clang_cc1 -xc++ -std=c++11 -pedantic -fsyntax-only -verify=expected,ext,cxx %s
 
 _Static_assert("foo", "string is nonzero"); // ext-warning {{'_Static_assert' is a C11 extension}}
 #ifndef __cplusplus
 // expected-error@-2 {{static_assert expression is not an integral constant expression}}
 #endif
 
 _Static_assert(1, "1 is nonzero"); // ext-warning {{'_Static_assert' is a C11 extension}}
 _Static_assert(0, "0 is nonzero"); // expected-error {{static_assert failed "0 is nonzero"}} \
                                    // ext-warning {{'_Static_assert' is a C11 extension}}
 
+#ifdef MS
+static_assert(1, "1 is nonzero");
+#endif
+
 void foo(void) {
   _Static_assert(1, "1 is nonzero"); // ext-warning {{'_Static_assert' is a C11 extension}}
   _Static_assert(0, "0 is nonzero"); // expected-error {{static_assert failed "0 is nonzero"}} \
                                      // ext-warning {{'_Static_assert' is a C11 extension}}
+#ifdef MS
+  static_assert(1, "1 is nonzero");
+#endif
 }
 
 _Static_assert(1, invalid); // expected-error {{expected string literal for diagnostic message in static_assert}} \
                             // ext-warning {{'_Static_assert' is a C11 extension}}
 
 struct A {
   int a;
   _Static_assert(1, "1 is nonzero"); // ext-warning {{'_Static_assert' is a C11 extension}}
   _Static_assert(0, "0 is nonzero"); // expected-error {{static_assert failed "0 is nonzero"}} \
                                      // ext-warning {{'_Static_assert' is a C11 extension}}
+#ifdef MS
+  static_assert(1, "1 is nonzero");
+#endif
 };
 
 #ifdef __cplusplus
 #define ASSERT_IS_TYPE(T) __is_same(T, T)
 #else
 #define ASSERT_IS_TYPE(T) __builtin_types_compatible_p(T, T)
 #endif