Short-circuit a couple of queries (and avoid corrupting
the linkage cache) when type-checking static local
variables.

There's a very deep problem here where the linkage of
a declaration can suddenly massively change as soon as
it's given a typedef name; these fixes, while optimizations
in their own right, are really just targeted workarounds.

rdar://15928125

llvm-svn: 200380
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index a70bece..a054adf 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -8773,7 +8773,13 @@
     }
   }
 
+  // Warn about externally-visible variables being defined without a
+  // prior declaration.  We only want to do this for global
+  // declarations, but we also specifically need to avoid doing it for
+  // class members because the linkage of an anonymous class can
+  // change if it's later given a typedef name.
   if (var->isThisDeclarationADefinition() &&
+      var->getDeclContext()->getRedeclContext()->isFileContext() &&
       var->isExternallyVisible() && var->hasLinkage() &&
       getDiagnostics().getDiagnosticLevel(
                        diag::warn_missing_variable_declarations,
@@ -8910,7 +8916,7 @@
   const DeclContext *DC = VD->getDeclContext();
   // If there's a #pragma GCC visibility in scope, and this isn't a class
   // member, set the visibility of this variable.
-  if (!DC->isRecord() && VD->isExternallyVisible())
+  if (DC->getRedeclContext()->isFileContext() && VD->isExternallyVisible())
     AddPushedVisibilityAttribute(VD);
 
   if (VD->isFileVarDecl())