Support enums with a fixed underlying type in all language modes.

Previously we supported these in C++, ObjC, and C with -fms-extensions.

rdar://43831380

Differential revision: https://reviews.llvm.org/D52339

llvm-svn: 343360
diff --git a/clang/test/Sema/fixed-enum.c b/clang/test/Sema/fixed-enum.c
new file mode 100644
index 0000000..60a4bc4
--- /dev/null
+++ b/clang/test/Sema/fixed-enum.c
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -Weverything -xc++ -std=c++11 -DCXX11 -verify %s
+// RUN: %clang_cc1 -Weverything -xc++ -std=c++03 -DCXX03 -verify %s
+// RUN: %clang_cc1 -Weverything -xobjective-c -DOBJC -verify %s
+// RUN: %clang_cc1 -Weverything -std=c11 -xc -DC11 -verify %s
+// RUN: %clang_cc1 -Weverything -std=c11 -xc -fms-extensions -DMS -verify %s
+
+enum X : int {e};
+#if defined(CXX11)
+// expected-warning@-2{{enumeration types with a fixed underlying type are incompatible with C++98}}
+#elif defined(CXX03)
+// expected-warning@-4{{enumeration types with a fixed underlying type are a C++11 extension}}
+#elif defined(OBJC)
+// expected-no-diagnostics
+#elif defined(C11)
+// expected-warning@-8{{enumeration types with a fixed underlying type are a Clang extension}}
+#elif defined(MS)
+// expected-warning@-10{{enumeration types with a fixed underlying type are a Microsoft extension}}
+#endif