From 4d2abba63ede7dde686892a20865245ed355aeb1 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Thu, 16 Dec 2010 15:36:43 +0000
Subject: [PATCH] Delay the check for unexpanded parameter packs in the types
 of non-type template parameters until we know that we have an actual template
 declaration of some sort. This cannot be tested yet, but will become
 important when we have template template parameter packs.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@121967 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaTemplate.cpp | 49 ++++++++++++++++++++++++++++++++-------
 1 file changed, 41 insertions(+), 8 deletions(-)

diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index f94f34626d..5df84d66a4 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -626,16 +626,10 @@ Decl *Sema::ActOnNonTypeTemplateParameter(Scope *S, Declarator &D,
                                                            PrevDecl);
   }
 
-  if (DiagnoseUnexpandedParameterPack(D.getIdentifierLoc(), TInfo, 
-                                      UPPC_NonTypeTemplateParameterType)) {
+  T = CheckNonTypeTemplateParameterType(T, D.getIdentifierLoc());
+  if (T.isNull()) {
     T = Context.IntTy; // Recover with an 'int' type.
     Invalid = true;
-  } else {  
-    T = CheckNonTypeTemplateParameterType(T, D.getIdentifierLoc());
-    if (T.isNull()) {
-      T = Context.IntTy; // Recover with an 'int' type.
-      Invalid = true;
-    }
   }
   
   NonTypeTemplateParmDecl *Param
@@ -1049,6 +1043,30 @@ static bool DiagnoseDefaultTemplateArgument(Sema &S,
   return false;
 }
 
+/// \brief Check for unexpanded parameter packs within the template parameters
+/// of a template template parameter, recursively.
+bool DiagnoseUnexpandedParameterPacks(Sema &S, TemplateTemplateParmDecl *TTP){
+  TemplateParameterList *Params = TTP->getTemplateParameters();
+  for (unsigned I = 0, N = Params->size(); I != N; ++I) {
+    NamedDecl *P = Params->getParam(I);
+    if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P)) {
+      if (S.DiagnoseUnexpandedParameterPack(NTTP->getLocation(), 
+                                            NTTP->getTypeSourceInfo(),
+                                      Sema::UPPC_NonTypeTemplateParameterType))
+        return true;
+      
+      continue;
+    }
+    
+    if (TemplateTemplateParmDecl *InnerTTP 
+                                        = dyn_cast<TemplateTemplateParmDecl>(P))
+      if (DiagnoseUnexpandedParameterPacks(S, InnerTTP))
+        return true;
+  }
+    
+  return false;
+}
+
 /// \brief Checks the validity of a template parameter list, possibly
 /// considering the template parameter list from a previous
 /// declaration.
@@ -1153,6 +1171,14 @@ bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
         MissingDefaultArg = true;
     } else if (NonTypeTemplateParmDecl *NewNonTypeParm
                = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
+      // Check for unexpanded parameter packs.
+      if (DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
+                                          NewNonTypeParm->getTypeSourceInfo(), 
+                                          UPPC_NonTypeTemplateParameterType)) {
+        Invalid = true;
+        continue;
+      }
+
       // Check the presence of a default argument here.
       if (NewNonTypeParm->hasDefaultArgument() && 
           DiagnoseDefaultTemplateArgument(*this, TPC, 
@@ -1191,6 +1217,13 @@ bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
       // Check the presence of a default argument here.
       TemplateTemplateParmDecl *NewTemplateParm
         = cast<TemplateTemplateParmDecl>(*NewParam);
+      
+      // Check for unexpanded parameter packs, recursively.
+      if (DiagnoseUnexpandedParameterPacks(*this, NewTemplateParm)) {
+        Invalid = true;
+        continue;
+      }
+      
       if (NewTemplateParm->hasDefaultArgument() && 
           DiagnoseDefaultTemplateArgument(*this, TPC, 
                                           NewTemplateParm->getLocation(), 
-- 
2.40.0