Implement pack expansions whose pattern is a base-specifier.

llvm-svn: 122782

3 files changed, 77 insertions, 8 deletions

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 0021c798235..10d04fa9a31 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -464,7 +464,8 @@ CXXBaseSpecifier *
 Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
                          SourceRange SpecifierRange,
                          bool Virtual, AccessSpecifier Access,
-                         TypeSourceInfo *TInfo) {
+                         TypeSourceInfo *TInfo,
+                         SourceLocation EllipsisLoc) {
   QualType BaseType = TInfo->getType();
 
   // C++ [class.union]p1:
@@ -475,10 +476,17 @@ Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
     return 0;
   }
 
+  if (EllipsisLoc.isValid() && 
+      !TInfo->getType()->containsUnexpandedParameterPack()) {
+    Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
+      << TInfo->getTypeLoc().getSourceRange();
+    EllipsisLoc = SourceLocation();
+  }
+  
   if (BaseType->isDependentType())
     return new (Context) CXXBaseSpecifier(SpecifierRange, Virtual,
                                           Class->getTagKind() == TTK_Class,
-                                          Access, TInfo);
+                                          Access, TInfo, EllipsisLoc);
 
   SourceLocation BaseLoc = TInfo->getTypeLoc().getBeginLoc();
 
@@ -527,7 +535,7 @@ Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
   // Create the base specifier.
   return new (Context) CXXBaseSpecifier(SpecifierRange, Virtual,
                                         Class->getTagKind() == TTK_Class,
-                                        Access, TInfo);
+                                        Access, TInfo, EllipsisLoc);
 }
 
 /// ActOnBaseSpecifier - Parsed a base specifier. A base specifier is
@@ -538,7 +546,8 @@ Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
 BaseResult
 Sema::ActOnBaseSpecifier(Decl *classdecl, SourceRange SpecifierRange,
                          bool Virtual, AccessSpecifier Access,
-                         ParsedType basetype, SourceLocation BaseLoc) {
+                         ParsedType basetype, SourceLocation BaseLoc,
+                         SourceLocation EllipsisLoc) {
   if (!classdecl)
     return true;
 
@@ -550,12 +559,14 @@ Sema::ActOnBaseSpecifier(Decl *classdecl, SourceRange SpecifierRange,
   TypeSourceInfo *TInfo = 0;
   GetTypeFromParser(basetype, &TInfo);
 
-  if (DiagnoseUnexpandedParameterPack(SpecifierRange.getBegin(), TInfo, 
+  if (EllipsisLoc.isInvalid() &&
+      DiagnoseUnexpandedParameterPack(SpecifierRange.getBegin(), TInfo, 
                                       UPPC_BaseType))
     return true;
-
+  
   if (CXXBaseSpecifier *BaseSpec = CheckBaseSpecifier(Class, SpecifierRange,
-                                                      Virtual, Access, TInfo))
+                                                      Virtual, Access, TInfo,
+                                                      EllipsisLoc))
     return BaseSpec;
 
   return true;
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 8c9681ffd5a..77d3e64a157 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1155,6 +1155,58 @@ Sema::SubstBaseSpecifiers(CXXRecordDecl *Instantiation,
       continue;
     }
 
+    SourceLocation EllipsisLoc;
+    if (Base->isPackExpansion()) {
+      // This is a pack expansion. See whether we should expand it now, or
+      // wait until later.
+      llvm::SmallVector<UnexpandedParameterPack, 2> Unexpanded;
+      collectUnexpandedParameterPacks(Base->getTypeSourceInfo()->getTypeLoc(),
+                                      Unexpanded);
+      bool ShouldExpand = false;
+      unsigned NumExpansions = 0;
+      if (CheckParameterPacksForExpansion(Base->getEllipsisLoc(), 
+                                          Base->getSourceRange(),
+                                          Unexpanded.data(), Unexpanded.size(),
+                                          TemplateArgs, ShouldExpand, 
+                                          NumExpansions)) {
+        continue;
+        Invalid = true;
+      }
+      
+      // If we should expand this pack expansion now, do so.
+      if (ShouldExpand) {
+        for (unsigned I = 0; I != NumExpansions; ++I) {
+            Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this, I);
+          
+          TypeSourceInfo *BaseTypeLoc = SubstType(Base->getTypeSourceInfo(),
+                                                  TemplateArgs,
+                                              Base->getSourceRange().getBegin(),
+                                                  DeclarationName());
+          if (!BaseTypeLoc) {
+            Invalid = true;
+            continue;
+          }
+          
+          if (CXXBaseSpecifier *InstantiatedBase
+                = CheckBaseSpecifier(Instantiation,
+                                     Base->getSourceRange(),
+                                     Base->isVirtual(),
+                                     Base->getAccessSpecifierAsWritten(),
+                                     BaseTypeLoc,
+                                     SourceLocation()))
+            InstantiatedBases.push_back(InstantiatedBase);
+          else
+            Invalid = true;
+        }
+      
+        continue;
+      }
+      
+      // The resulting base specifier will (still) be a pack expansion.
+      EllipsisLoc = Base->getEllipsisLoc();
+    }
+    
+    Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this, -1);
     TypeSourceInfo *BaseTypeLoc = SubstType(Base->getTypeSourceInfo(),
                                             TemplateArgs,
                                             Base->getSourceRange().getBegin(),
@@ -1169,7 +1221,8 @@ Sema::SubstBaseSpecifiers(CXXRecordDecl *Instantiation,
                                Base->getSourceRange(),
                                Base->isVirtual(),
                                Base->getAccessSpecifierAsWritten(),
-                               BaseTypeLoc))
+                               BaseTypeLoc,
+                               EllipsisLoc))
       InstantiatedBases.push_back(InstantiatedBase);
     else
       Invalid = true;
diff --git a/clang/lib/Sema/SemaTemplateVariadic.cpp b/clang/lib/Sema/SemaTemplateVariadic.cpp
index a3e308fe11f..92df1fd8636 100644
--- a/clang/lib/Sema/SemaTemplateVariadic.cpp
+++ b/clang/lib/Sema/SemaTemplateVariadic.cpp
@@ -294,6 +294,11 @@ void Sema::collectUnexpandedParameterPacks(QualType T,
   CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseType(T);  
 }  
 
+void Sema::collectUnexpandedParameterPacks(TypeLoc TL,
+                   llvm::SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
+  CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseTypeLoc(TL);  
+}  
+
 ParsedTemplateArgument 
 Sema::ActOnPackExpansion(const ParsedTemplateArgument &Arg,
                          SourceLocation EllipsisLoc) {