[Sema] Suppress a warning about a forward-declared fixed enum in C mode

As of r343360, we support fixed-enums in C. This lead to some
warnings in project headers where a fixed enum is forward declared
then later defined. In C++, this is fine, the forward declaration is
treated as a complete type even though the definition isn't present.
We use this rule in C too, but still warn about the forward
declaration anyways. This patch suppresses the warning.

rdar://problem/47356469

Differential revision: https://reviews.llvm.org/D56879

llvm-svn: 351595

1 files changed, 1 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 03061eab359..a5a4833a5c1 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -14747,8 +14747,7 @@ CreateNewDecl:
     // If this is an undefined enum, warn.
     if (TUK != TUK_Definition && !Invalid) {
       TagDecl *Def;
-      if (IsFixed && (getLangOpts().CPlusPlus11 || getLangOpts().ObjC) &&
-          cast<EnumDecl>(New)->isFixed()) {
+      if (IsFixed && cast<EnumDecl>(New)->isFixed()) {
         // C++0x: 7.2p2: opaque-enum-declaration.
         // Conflicts are diagnosed above. Do nothing.
       }