1 files changed, 10 insertions, 0 deletions
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index d978c389b2..ea084b49ee 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -2867,6 +2867,16 @@ bool Sema::CheckTemplateArgumentList(TemplateDecl *Template,
     if ((*Param)->isTemplateParameterPack())
       break;
 
+    // If our template is a template template parameter that hasn't acquired
+    // its proper context yet (e.g., because we're using the template template
+    // parameter in the signature of a function template, before we've built
+    // the function template itself), don't attempt substitution of default
+    // template arguments at this point: we don't have enough context to
+    // do it properly.
+    if (isTemplateTemplateParameter && 
+        Template->getDeclContext()->isTranslationUnit())
+      break;
+    
     // We have a default template argument that we will use.
     TemplateArgumentLoc Arg;