From 56bc9832bc8f80604bfddc2c93f81537df6930a1 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Fri, 24 Dec 2010 00:15:10 +0000
Subject: [PATCH] When instantiating a non-type template parameter pack, be
 sure to extract the appropriate argument from the argument pack (based on the
 current substitution index, of course). Simple instantiation of pack
 expansions involving non-type template parameter packs now works.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@122532 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/AST/DeclPrinter.cpp                       |  3 ++
 lib/AST/StmtProfile.cpp                       |  1 +
 lib/Sema/SemaTemplateInstantiate.cpp          | 18 ++++++++---
 lib/Sema/SemaTemplateVariadic.cpp             |  2 +-
 test/CXX/temp/temp.decls/temp.variadic/p4.cpp | 30 +++++++++++++++----
 5 files changed, 44 insertions(+), 10 deletions(-)

diff --git a/lib/AST/DeclPrinter.cpp b/lib/AST/DeclPrinter.cpp
index 95421a494b..8941200969 100644
--- a/lib/AST/DeclPrinter.cpp
+++ b/lib/AST/DeclPrinter.cpp
@@ -681,6 +681,9 @@ void DeclPrinter::VisitTemplateDecl(TemplateDecl *D) {
                  dyn_cast<NonTypeTemplateParmDecl>(Param)) {
       Out << NTTP->getType().getAsString(Policy);
 
+      if (NTTP->isParameterPack() && !isa<PackExpansionType>(NTTP->getType()))
+        Out << "...";
+        
       if (IdentifierInfo *Name = NTTP->getIdentifier()) {
         Out << ' ';
         Out << Name->getName();
diff --git a/lib/AST/StmtProfile.cpp b/lib/AST/StmtProfile.cpp
index 418b241009..66c067b7b1 100644
--- a/lib/AST/StmtProfile.cpp
+++ b/lib/AST/StmtProfile.cpp
@@ -894,6 +894,7 @@ void StmtProfiler::VisitDecl(Decl *D) {
     if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D)) {
       ID.AddInteger(NTTP->getDepth());
       ID.AddInteger(NTTP->getIndex());
+      ID.AddInteger(NTTP->isParameterPack());
       VisitType(NTTP->getType());
       return;
     }
diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 16e1faa7f9..8c9681ffd5 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -638,7 +638,7 @@ namespace {
     ExprResult TransformDeclRefExpr(DeclRefExpr *E);
     ExprResult TransformCXXDefaultArgExpr(CXXDefaultArgExpr *E);
     ExprResult TransformTemplateParmRefExpr(DeclRefExpr *E,
-                                                NonTypeTemplateParmDecl *D);
+                                            NonTypeTemplateParmDecl *D);
 
     QualType TransformFunctionProtoType(TypeLocBuilder &TLB,
                                         FunctionProtoTypeLoc TL);
@@ -836,8 +836,19 @@ TemplateInstantiator::TransformTemplateParmRefExpr(DeclRefExpr *E,
                                         NTTP->getPosition()))
     return SemaRef.Owned(E);
 
-  const TemplateArgument &Arg = TemplateArgs(NTTP->getDepth(),
-                                             NTTP->getPosition());
+  TemplateArgument Arg = TemplateArgs(NTTP->getDepth(), NTTP->getPosition());
+  if (NTTP->isParameterPack()) {
+    assert(Arg.getKind() == TemplateArgument::Pack && 
+           "Missing argument pack");
+    
+    if (getSema().ArgumentPackSubstitutionIndex == -1) {
+      // FIXME: Variadic templates fun case.
+      getSema().Diag(Loc, diag::err_pack_expansion_mismatch_unsupported);
+      return ExprError();
+    }
+    
+    Arg = Arg.pack_begin()[getSema().ArgumentPackSubstitutionIndex];
+  }
 
   // The template argument itself might be an expression, in which
   // case we just return that expression.
@@ -876,7 +887,6 @@ ExprResult
 TemplateInstantiator::TransformDeclRefExpr(DeclRefExpr *E) {
   NamedDecl *D = E->getDecl();
   if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D)) {
-    // FIXME: Variadic templates index substitution.
     if (NTTP->getDepth() < TemplateArgs.getNumLevels())
       return TransformTemplateParmRefExpr(E, NTTP);
     
diff --git a/lib/Sema/SemaTemplateVariadic.cpp b/lib/Sema/SemaTemplateVariadic.cpp
index fe30ba5845..3dac8a0408 100644
--- a/lib/Sema/SemaTemplateVariadic.cpp
+++ b/lib/Sema/SemaTemplateVariadic.cpp
@@ -395,7 +395,7 @@ bool Sema::CheckParameterPacksForExpansion(SourceLocation EllipsisLoc,
     
     // If we don't have a template argument at this depth/index, then we 
     // cannot expand the pack expansion. Make a note of this, but we still 
-    // want to check that any parameter packs we *do* have arguments for.
+    // want to check any parameter packs we *do* have arguments for.
     if (!TemplateArgs.hasTemplateArgument(Depth, Index)) {
       ShouldExpand = false;
       continue;
diff --git a/test/CXX/temp/temp.decls/temp.variadic/p4.cpp b/test/CXX/temp/temp.decls/temp.variadic/p4.cpp
index 7f40e9c438..06a7bf3679 100644
--- a/test/CXX/temp/temp.decls/temp.variadic/p4.cpp
+++ b/test/CXX/temp/temp.decls/temp.variadic/p4.cpp
@@ -1,6 +1,22 @@
 // RUN: %clang_cc1 -std=c++0x -fsyntax-only -fexceptions -verify %s
 
 template<typename... Types> struct tuple;
+template<int I> struct int_c;
+
+template<typename T>
+struct identity {
+  typedef T type;
+};
+
+template<typename T, typename U>
+struct is_same {
+  static const bool value = false;
+};
+
+template<typename T>
+struct is_same<T, T> {
+  static const bool value = true;
+};
 
 // FIXME: Many more bullets to go
 
@@ -18,15 +34,19 @@ struct extract_nested_types {
   typedef tuple<typename Types::type...> types;
 };
 
-template<typename T>
-struct identity {
-  typedef T type;
-};
-
 tuple<int, float> *t_int_float;
 extract_nested_types<identity<int>, identity<float> >::types *t_int_float_2 
   = t_int_float;
 
+template<int ...N>
+struct tuple_of_ints {
+  typedef tuple<int_c<N>...> type;
+};
+
+int check_temp_arg_1[is_same<tuple_of_ints<1, 2, 3, 4, 5>::type, 
+                             tuple<int_c<1>, int_c<2>, int_c<3>, int_c<4>, 
+                                   int_c<5>>>::value? 1 : -1];
+
 // In a dynamic-exception-specification (15.4); the pattern is a type-id.
 template<typename ...Types>
 struct f_with_except {
-- 
2.40.0