5 files changed, 19 insertions, 16 deletions

diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 3703500e76b..db7c562c49f 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -5647,7 +5647,8 @@ public:
                              SourceLocation TemplateLoc,
                              SourceLocation LAngleLoc,
                              ArrayRef<Decl *> Params,
-                             SourceLocation RAngleLoc);
+                             SourceLocation RAngleLoc,
+                             Expr *RequiresClause);
 
   /// \brief The context in which we are checking a template parameter list.
   enum TemplateParamListContext {
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index cbe3d913679..6b7ffb64fae 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -2004,7 +2004,7 @@ Decl *Parser::ParseDeclarationAfterDeclaratorAndAttributes(
         TemplateParameterLists FakedParamLists;
         FakedParamLists.push_back(Actions.ActOnTemplateParameterList(
             0, SourceLocation(), TemplateInfo.TemplateLoc, LAngleLoc, None,
-            LAngleLoc));
+            LAngleLoc, nullptr));
 
         ThisDecl =
             Actions.ActOnTemplateDeclarator(getCurScope(), FakedParamLists, D);
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 6849eb9a6c5..049e9ceae70 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -1670,7 +1670,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
           // template specialization.
           FakedParamLists.push_back(Actions.ActOnTemplateParameterList(
               0, SourceLocation(), TemplateInfo.TemplateLoc, LAngleLoc, None,
-              LAngleLoc));
+              LAngleLoc, nullptr));
           TemplateParams = &FakedParamLists;
         }
       }
diff --git a/clang/lib/Parse/ParseTemplate.cpp b/clang/lib/Parse/ParseTemplate.cpp
index 61da159ae02..6cf7b6d3dc5 100644
--- a/clang/lib/Parse/ParseTemplate.cpp
+++ b/clang/lib/Parse/ParseTemplate.cpp
@@ -122,20 +122,15 @@ Parser::ParseTemplateDeclarationOrSpecialization(unsigned Context,
       return nullptr;
     }
 
-    ParamLists.push_back(
-      Actions.ActOnTemplateParameterList(CurTemplateDepthTracker.getDepth(), 
-                                         ExportLoc,
-                                         TemplateLoc, LAngleLoc,
-                                         TemplateParams, RAngleLoc));
-
+    ExprResult OptionalRequiresClauseConstraintER;
     if (!TemplateParams.empty()) {
       isSpecialization = false;
       ++CurTemplateDepthTracker;
 
       if (TryConsumeToken(tok::kw_requires)) {
-        ExprResult ER =
+        OptionalRequiresClauseConstraintER =
             Actions.CorrectDelayedTyposInExpr(ParseConstraintExpression());
-        if (!ER.isUsable()) {
+        if (!OptionalRequiresClauseConstraintER.isUsable()) {
           // Skip until the semi-colon or a '}'.
           SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
           TryConsumeToken(tok::semi);
@@ -145,6 +140,10 @@ Parser::ParseTemplateDeclarationOrSpecialization(unsigned Context,
     } else {
       LastParamListWasEmpty = true;
     }
+
+    ParamLists.push_back(Actions.ActOnTemplateParameterList(
+        CurTemplateDepthTracker.getDepth(), ExportLoc, TemplateLoc, LAngleLoc,
+        TemplateParams, RAngleLoc, OptionalRequiresClauseConstraintER.get()));
   } while (Tok.isOneOf(tok::kw_export, tok::kw_template));
 
   unsigned NewFlags = getCurScope()->getFlags() & ~Scope::TemplateParamScope;
@@ -287,7 +286,7 @@ Parser::ParseSingleDeclarationAfterTemplate(
         TemplateParameterLists FakedParamLists;
         FakedParamLists.push_back(Actions.ActOnTemplateParameterList(
             0, SourceLocation(), TemplateInfo.TemplateLoc, LAngleLoc, None,
-            LAngleLoc));
+            LAngleLoc, nullptr));
 
         return ParseFunctionDefinition(
             DeclaratorInfo, ParsedTemplateInfo(&FakedParamLists,
@@ -638,7 +637,7 @@ Parser::ParseTemplateTemplateParameter(unsigned Depth, unsigned Position) {
     Actions.ActOnTemplateParameterList(Depth, SourceLocation(),
                                        TemplateLoc, LAngleLoc,
                                        TemplateParams,
-                                       RAngleLoc);
+                                       RAngleLoc, nullptr);
 
   // Grab a default argument (if available).
   // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 3833e2c3f07..9d3bf1c1605 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -817,18 +817,21 @@ Decl *Sema::ActOnTemplateTemplateParameter(Scope* S,
   return Param;
 }
 
-/// ActOnTemplateParameterList - Builds a TemplateParameterList that
-/// contains the template parameters in Params/NumParams.
+/// ActOnTemplateParameterList - Builds a TemplateParameterList, optionally
+/// constrained by RequiresClause, that contains the template parameters in
+/// Params.
 TemplateParameterList *
 Sema::ActOnTemplateParameterList(unsigned Depth,
                                  SourceLocation ExportLoc,
                                  SourceLocation TemplateLoc,
                                  SourceLocation LAngleLoc,
                                  ArrayRef<Decl *> Params,
-                                 SourceLocation RAngleLoc) {
+                                 SourceLocation RAngleLoc,
+                                 Expr *RequiresClause) {
   if (ExportLoc.isValid())
     Diag(ExportLoc, diag::warn_template_export_unsupported);
 
+  // FIXME: store RequiresClause
   return TemplateParameterList::Create(
       Context, TemplateLoc, LAngleLoc,
       llvm::makeArrayRef((NamedDecl *const *)Params.data(), Params.size()),