Introduce a new type, PackExpansionType, to capture types that are

pack expansions, e.g. given

  template<typename... Types> struct tuple;

  template<typename... Types>
  struct tuple_of_refs {
    typedef tuple<Types&...> types;
  };

the type of the "types" typedef is a PackExpansionType whose pattern
is Types&. 

This commit introduces support for creating pack expansions for
template type arguments, as above, but not for any other kind of pack
expansion, nor for any form of instantiation.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@122223 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 26 insertions, 0 deletions

diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index e9d8c0f304..94038418df 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -2216,6 +2216,32 @@ ASTContext::getDependentTemplateSpecializationType(
   return QualType(T, 0);
 }
 
+QualType ASTContext::getPackExpansionType(QualType Pattern) {
+  llvm::FoldingSetNodeID ID;
+  PackExpansionType::Profile(ID, Pattern);
+
+  assert(Pattern->containsUnexpandedParameterPack() &&
+         "Pack expansions must expand one or more parameter packs");
+  void *InsertPos = 0;
+  PackExpansionType *T
+    = PackExpansionTypes.FindNodeOrInsertPos(ID, InsertPos);
+  if (T)
+    return QualType(T, 0);
+
+  QualType Canon;
+  if (!Pattern.isCanonical()) {
+    Canon = getPackExpansionType(getCanonicalType(Pattern));
+
+    // Find the insert position again.
+    PackExpansionTypes.FindNodeOrInsertPos(ID, InsertPos);
+  }
+
+  T = new (*this) PackExpansionType(Pattern, Canon);
+  Types.push_back(T);
+  PackExpansionTypes.InsertNode(T, InsertPos);
+  return QualType(T, 0);  
+}
+
 /// CmpProtocolNames - Comparison predicate for sorting protocols
 /// alphabetically.
 static bool CmpProtocolNames(const ObjCProtocolDecl *LHS,