Don't crash while trying to diagnose a function declared at block scope with an
incomplete return type.

llvm-svn: 148088
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 4dcf1db..20309ee 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -4945,7 +4945,8 @@
         // Empty parens mean value-initialization, and no parens mean default
         // initialization. These are equivalent if the default constructor is
         // user-provided, or if zero-initialization is a no-op.
-        if (RD && (RD->isEmpty() || RD->hasUserProvidedDefaultConstructor()))
+        if (RD && RD->hasDefinition() &&
+            (RD->isEmpty() || RD->hasUserProvidedDefaultConstructor()))
           Diag(C.Loc, diag::note_empty_parens_default_ctor)
             << FixItHint::CreateRemoval(ParenRange);
         else if (const char *Init = getFixItZeroInitializerForType(T))