When we're substituting into a function parameter pack and expect to

get a function parameter pack (but don't due to weird substitutions),
complain. Fixes the last bit of PR11848.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148960 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 30f0de375f3c3aa80211e02e37840c9ae7ff1277..cf77a7e9e5ab4fd0c2de9b7ce66c79a7cbb299cc 100644 (file)
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -5100,7 +5100,8 @@ public:
   ParmVarDecl *SubstParmVarDecl(ParmVarDecl *D,
                             const MultiLevelTemplateArgumentList &TemplateArgs,
                                 int indexAdjustment,
-                                llvm::Optional<unsigned> NumExpansions);
+                                llvm::Optional<unsigned> NumExpansions,
+                                bool ExpectParameterPack);
   bool SubstParmTypes(SourceLocation Loc,
                       ParmVarDecl **Params, unsigned NumParams,
                       const MultiLevelTemplateArgumentList &TemplateArgs,

diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index e183f1f1c1d7d8cbb8fffd08755eb6122a060c1b..dde782672fa173cc96e3fca95cf70cf53a14e3af 100644 (file)
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -778,7 +778,8 @@ namespace {
                                         FunctionProtoTypeLoc TL);
     ParmVarDecl *TransformFunctionTypeParam(ParmVarDecl *OldParm,
                                             int indexAdjustment,
-                                      llvm::Optional<unsigned> NumExpansions);
+                                        llvm::Optional<unsigned> NumExpansions,
+                                            bool ExpectParameterPack);
 
     /// \brief Transforms a template type parameter type by performing
     /// substitution of the corresponding template type argument.
@@ -1194,9 +1195,10 @@ QualType TemplateInstantiator::TransformFunctionProtoType(TypeLocBuilder &TLB,
 ParmVarDecl *
 TemplateInstantiator::TransformFunctionTypeParam(ParmVarDecl *OldParm,
                                                  int indexAdjustment,
-                                       llvm::Optional<unsigned> NumExpansions) {
+                                       llvm::Optional<unsigned> NumExpansions,
+                                                 bool ExpectParameterPack) {
   return SemaRef.SubstParmVarDecl(OldParm, TemplateArgs, indexAdjustment,
-                                  NumExpansions);
+                                  NumExpansions, ExpectParameterPack);
 }
 
 QualType
@@ -1450,7 +1452,8 @@ TypeSourceInfo *Sema::SubstFunctionDeclType(TypeSourceInfo *T,
 ParmVarDecl *Sema::SubstParmVarDecl(ParmVarDecl *OldParm, 
                             const MultiLevelTemplateArgumentList &TemplateArgs,
                                     int indexAdjustment,
-                                    llvm::Optional<unsigned> NumExpansions) {
+                                    llvm::Optional<unsigned> NumExpansions,
+                                    bool ExpectParameterPack) {
   TypeSourceInfo *OldDI = OldParm->getTypeSourceInfo();
   TypeSourceInfo *NewDI = 0;
   
@@ -1471,7 +1474,16 @@ ParmVarDecl *Sema::SubstParmVarDecl(ParmVarDecl *OldParm,
       // Therefore, make its type a pack expansion type.
       NewDI = CheckPackExpansion(NewDI, ExpansionTL.getEllipsisLoc(),
                                  NumExpansions);
-    }
+    } else if (ExpectParameterPack) {
+      // We expected to get a parameter pack but didn't (because the type
+      // itself is not a pack expansion type), so complain. This can occur when
+      // the substitution goes through an alias template that "loses" the
+      // pack expansion.
+      Diag(OldParm->getLocation(), 
+           diag::err_function_parameter_pack_without_parameter_packs)
+        << NewDI->getType();
+      return 0;
+    } 
   } else {
     NewDI = SubstType(OldDI, TemplateArgs, OldParm->getLocation(), 
                       OldParm->getDeclName());
@@ -1506,9 +1518,7 @@ ParmVarDecl *Sema::SubstParmVarDecl(ParmVarDecl *OldParm,
     NewParm->setUninstantiatedDefaultArg(Arg);
 
   NewParm->setHasInheritedDefaultArg(OldParm->hasInheritedDefaultArg());
-
-  // FIXME: When OldParm is a parameter pack and NewParm is not a parameter
-  // pack, we actually have a set of instantiated locations. Maintain this set!
+  
   if (OldParm->isParameterPack() && !NewParm->isParameterPack()) {
     // Add the new parameter to the instantiated parameter pack.
     CurrentInstantiationScope->InstantiatedLocalPackArg(OldParm, NewParm);

diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index c9d2cf6e18ebf0e14412fe9df2855ff646195050..023005cd197fd6d0b37085bab736ebf2a973775e 100644 (file)
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1601,7 +1601,8 @@ Decl *TemplateDeclInstantiator::VisitCXXConversionDecl(CXXConversionDecl *D) {
 
 ParmVarDecl *TemplateDeclInstantiator::VisitParmVarDecl(ParmVarDecl *D) {
   return SemaRef.SubstParmVarDecl(D, TemplateArgs, /*indexAdjustment*/ 0,
-                                  llvm::Optional<unsigned>());
+                                  llvm::Optional<unsigned>(),
+                                  /*ExpectParameterPack=*/false);
 }
 
 Decl *TemplateDeclInstantiator::VisitTemplateTypeParmDecl(

diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index 2ddba4710fdcff3f93bc44bb8b00b188c4a704a3..f5fc3b7cb8426ce5dbce7ff168e23a27ee8cb572 100644 (file)
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -530,7 +530,8 @@ public:
   ///   scope index;  can be negative
   ParmVarDecl *TransformFunctionTypeParam(ParmVarDecl *OldParm,
                                           int indexAdjustment,
-                                        llvm::Optional<unsigned> NumExpansions);
+                                        llvm::Optional<unsigned> NumExpansions,
+                                          bool ExpectParameterPack);
 
   QualType TransformReferenceType(TypeLocBuilder &TLB, ReferenceTypeLoc TL);
 
@@ -3814,12 +3815,14 @@ template<typename Derived>
 ParmVarDecl *
 TreeTransform<Derived>::TransformFunctionTypeParam(ParmVarDecl *OldParm,
                                                    int indexAdjustment,
-                                       llvm::Optional<unsigned> NumExpansions) {
+                                         llvm::Optional<unsigned> NumExpansions,
+                                                   bool ExpectParameterPack) {
   TypeSourceInfo *OldDI = OldParm->getTypeSourceInfo();
   TypeSourceInfo *NewDI = 0;
   
   if (NumExpansions && isa<PackExpansionType>(OldDI->getType())) {
     // If we're substituting into a pack expansion type and we know the 
+    // length we want to expand to, just substitute for the pattern.
     TypeLoc OldTL = OldDI->getTypeLoc();
     PackExpansionTypeLoc OldExpansionTL = cast<PackExpansionTypeLoc>(OldTL);
     
@@ -3916,7 +3919,8 @@ bool TreeTransform<Derived>::
             ParmVarDecl *NewParm 
               = getDerived().TransformFunctionTypeParam(OldParm,
                                                         indexAdjustment++,
-                                                        OrigNumExpansions);
+                                                        OrigNumExpansions,
+                                                /*ExpectParameterPack=*/false);
             if (!NewParm)
               return true;
             
@@ -3932,7 +3936,8 @@ bool TreeTransform<Derived>::
             ParmVarDecl *NewParm 
               = getDerived().TransformFunctionTypeParam(OldParm,
                                                         indexAdjustment++,
-                                                        OrigNumExpansions);
+                                                        OrigNumExpansions,
+                                                /*ExpectParameterPack=*/false);
             if (!NewParm)
               return true;
             
@@ -3956,11 +3961,13 @@ bool TreeTransform<Derived>::
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
         NewParm = getDerived().TransformFunctionTypeParam(OldParm,
                                                           indexAdjustment,
-                                                          NumExpansions);
+                                                          NumExpansions,
+                                                  /*ExpectParameterPack=*/true);
       } else {
         NewParm = getDerived().TransformFunctionTypeParam(OldParm,
                                                           indexAdjustment,
-                                                  llvm::Optional<unsigned>());
+                                                          llvm::Optional<unsigned>(),
+                                                /*ExpectParameterPack=*/false);
       }
 
       if (!NewParm)

diff --git a/test/SemaTemplate/alias-templates.cpp b/test/SemaTemplate/alias-templates.cpp
index c0f9e21b3530c3bec44678a28e06e4301257e1bf..75615ee29517e78b00ccc634056904a3107cf43a 100644 (file)
--- a/test/SemaTemplate/alias-templates.cpp
+++ b/test/SemaTemplate/alias-templates.cpp
@@ -85,7 +85,7 @@ namespace PR11848 {
   template<typename T>
   struct Hidden1 {
     template<typename ...Ts>
-    Hidden1(typename T::template U<Ts> ...ts);
+    Hidden1(typename T::template U<Ts> ...ts); // expected-error{{type 'typename Hide::U<Ts>' (aka 'int') of function parameter pack does not contain any unexpanded parameter packs}}
   };
 
   template<typename T, typename ...Ts>
@@ -97,7 +97,6 @@ namespace PR11848 {
     template<typename T> using U = int;
   };
 
-  // FIXME: This case crashes clang at the moment.
-  //Hidden1<Hide> h1;
+  Hidden1<Hide> h1;  // expected-note{{in instantiation of template class 'PR11848::Hidden1<PR11848::Hide>' requested here}}
   Hidden2<Hide, double, char> h2(1, 2);
 }