[Parse] Let declarations follow labels in -fms-extensions mode

MSVC permits declarations in these places as conforming extension (it is
a constraint violation otherwise).

This fixes PR28782.

llvm-svn: 277352

2 files changed, 11 insertions, 1 deletions

diff --git a/clang/lib/Parse/ParseStmt.cpp b/clang/lib/Parse/ParseStmt.cpp
index 9043ebb9a2b..d0557b8a62b 100644
--- a/clang/lib/Parse/ParseStmt.cpp
+++ b/clang/lib/Parse/ParseStmt.cpp
@@ -206,7 +206,8 @@ Retry:
   }
 
   default: {
-    if ((getLangOpts().CPlusPlus || Allowed == ACK_Any) &&
+    if ((getLangOpts().CPlusPlus || getLangOpts().MicrosoftExt ||
+         Allowed == ACK_Any) &&
         isDeclarationStatement()) {
       SourceLocation DeclStart = Tok.getLocation(), DeclEnd;
       DeclGroupPtrTy Decl = ParseDeclaration(Declarator::BlockContext,
diff --git a/clang/test/Parser/MicrosoftExtensions.c b/clang/test/Parser/MicrosoftExtensions.c
index 39ab51f31fa..2af6c421bcc 100644
--- a/clang/test/Parser/MicrosoftExtensions.c
+++ b/clang/test/Parser/MicrosoftExtensions.c
@@ -106,3 +106,12 @@ __declspec(align(16)) struct align_before_key3 {} *align_before_key3_var;
 _Static_assert(__alignof(struct align_before_key1) == 16, "");
 _Static_assert(__alignof(struct align_before_key2) == 16, "");
 _Static_assert(__alignof(struct align_before_key3) == 16, "");
+
+void PR28782(int i) {
+foo:
+  int n;
+  switch (i) {
+  case 0:
+    int m;
+  }
+}