Index: lib/AST/DeclBase.cpp
===================================================================
--- lib/AST/DeclBase.cpp
+++ lib/AST/DeclBase.cpp
@@ -131,11 +131,12 @@
 
 void Decl::setInvalidDecl(bool Invalid) {
   InvalidDecl = Invalid;
-  assert(!isa<TagDecl>(this) || !cast<TagDecl>(this)->isCompleteDefinition());
   if (!Invalid) {
     return;
   }
 
+  assert(!isa<TagDecl>(this) || !cast<TagDecl>(this)->isCompleteDefinition());
+
   if (!isa<ParmVarDecl>(this)) {
     // Defensive maneuver for ill-formed code: we're likely not to make it to
     // a point where we set the access specifier, so default it to "public"