When mapping from a function parameter pack to the set of function

parameters it expanded to, map exactly the number of function
parameters that were expanded rather than just running to the end of
the instantiated parameter list. This finishes the implementation of
the last sentence of C++0x [temp.deduct.call]p1.

llvm-svn: 123213

clang/include/clang/Sema/Sema.h

@@ -3383,6 +3383,15 @@ public:
                                        bool &RetainExpansion,
                                        unsigned &NumExpansions);
 
+  /// \brief Determine the number of arguments in the given pack expansion
+  /// type.
+  ///
+  /// This routine already assumes that the pack expansion type can be
+  /// expanded and that the number of arguments in the expansion is
+  /// consistent across all of the unexpanded parameter packs in its pattern.
+  unsigned getNumArgumentsInExpansion(QualType T, 
+                            const MultiLevelTemplateArgumentList &TemplateArgs);
+  
   /// \brief Determine whether the given declarator contains any unexpanded
   /// parameter packs.
   ///

clang/lib/Sema/SemaTemplateInstantiateDecl.cpp

@@ -1894,9 +1894,10 @@ TemplateDeclInstantiator::SubstFunctionType(FunctionDecl *D,
         // Parameter pack: make the instantiation an argument pack.
         SemaRef.CurrentInstantiationScope->MakeInstantiatedLocalArgPack(
                                                                       OldParam);
-        // FIXME: Variadic templates. Figure out how many arguments are in the
-        // expansion of OldParam, so we don't gobble all of the arguments here.
-        while (NewIdx < NumNewParams) {
+        unsigned NumArgumentsInExpansion
+          = SemaRef.getNumArgumentsInExpansion(OldParam->getType(),
+                                               TemplateArgs);
+        while (NumArgumentsInExpansion--) {
           ParmVarDecl *NewParam = NewProtoLoc->getArg(NewIdx++);
           Params.push_back(NewParam);
           SemaRef.CurrentInstantiationScope->InstantiatedLocalPackArg(OldParam,

clang/lib/Sema/SemaTemplateVariadic.cpp

@@ -536,6 +536,50 @@ bool Sema::CheckParameterPacksForExpansion(SourceLocation EllipsisLoc,
   return false;
 }
 
+unsigned Sema::getNumArgumentsInExpansion(QualType T, 
+                          const MultiLevelTemplateArgumentList &TemplateArgs) {
+  QualType Pattern = cast<PackExpansionType>(T)->getPattern();
+  llvm::SmallVector<UnexpandedParameterPack, 2> Unexpanded;
+  CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseType(Pattern);
+
+  for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
+    // Compute the depth and index for this parameter pack.
+    unsigned Depth;
+    unsigned Index;
+    
+    if (const TemplateTypeParmType *TTP
+          = Unexpanded[I].first.dyn_cast<const TemplateTypeParmType *>()) {
+      Depth = TTP->getDepth();
+      Index = TTP->getIndex();
+    } else {      
+      NamedDecl *ND = Unexpanded[I].first.get<NamedDecl *>();
+      if (isa<ParmVarDecl>(ND)) {
+        // Function parameter pack.
+        typedef LocalInstantiationScope::DeclArgumentPack DeclArgumentPack;
+        
+        llvm::PointerUnion<Decl *, DeclArgumentPack *> *Instantiation
+          = CurrentInstantiationScope->findInstantiationOf(
+                                        Unexpanded[I].first.get<NamedDecl *>());
+        if (Instantiation && Instantiation->is<DeclArgumentPack *>())
+          return Instantiation->get<DeclArgumentPack *>()->size();
+        
+        continue;
+      }
+      
+      llvm::tie(Depth, Index) = getDepthAndIndex(ND);        
+    }
+    if (Depth >= TemplateArgs.getNumLevels() ||
+        !TemplateArgs.hasTemplateArgument(Depth, Index))
+      continue;
+    
+    // Determine the size of the argument pack.
+    return TemplateArgs(Depth, Index).pack_size();
+  }
+  
+  llvm_unreachable("No unexpanded parameter packs in type expansion.");
+  return 0;
+}
+
 bool Sema::containsUnexpandedParameterPacks(Declarator &D) {
   const DeclSpec &DS = D.getDeclSpec();
   switch (DS.getTypeSpecType()) {

clang/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p1-0x.cpp

@@ -78,8 +78,6 @@ void test_pair_deduction(int *ip, float *fp, double *dp) {
 // For a function parameter pack that does not occur at the end of the
 // parameter-declaration-list, the type of the parameter pack is a
 // non-deduced context.
-// FIXME: We're not in a position to handle this yet.
-#if 0
 template<typename ...Types> struct tuple { };
 
 template<typename ...Types>
@@ -88,4 +86,3 @@ void pack_not_at_end(tuple<Types...>, Types... values, int);
 void test_pack_not_at_end(tuple<int*, double*> t2) {
   pack_not_at_end(t2, 0, 0, 0);
 }
-#endif