Allow us to transform pack expansion expressions.

llvm-svn: 123349

2 files changed, 24 insertions, 2 deletions

diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index f601d5c047c..43d89e2875e 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -6787,8 +6787,14 @@ TreeTransform<Derived>::TransformCXXNoexceptExpr(CXXNoexceptExpr *E) {
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformPackExpansionExpr(PackExpansionExpr *E) {
-  llvm_unreachable("pack expansion expression in unhandled context");
-  return ExprError();
+  ExprResult Pattern = getDerived().TransformExpr(E->getPattern());
+  if (Pattern.isInvalid())
+    return ExprError();
+  
+  if (!getDerived().AlwaysRebuild() && Pattern.get() == E->getPattern())
+    return SemaRef.Owned(E);
+
+  return getDerived().RebuildPackExpansion(Pattern.get(), E->getEllipsisLoc());
 }
 
 template<typename Derived>
diff --git a/clang/test/CXX/temp/temp.decls/temp.variadic/injected-class-name.cpp b/clang/test/CXX/temp/temp.decls/temp.variadic/injected-class-name.cpp
index 36621ecf5ae..a76ef8067df 100644
--- a/clang/test/CXX/temp/temp.decls/temp.variadic/injected-class-name.cpp
+++ b/clang/test/CXX/temp/temp.decls/temp.variadic/injected-class-name.cpp
@@ -56,4 +56,20 @@ namespace rdar8848837 {
 
   X<int(float, double)> xif;
 
+  template<unsigned> struct unsigned_c { };
+  template<typename ...ArgTypes> int g(ArgTypes...);
+
+  template<typename F> struct X1;
+
+  template<typename R, typename ...ArgTypes>
+  struct X1<R(ArgTypes...)> {
+    unsigned_c<sizeof(1 + g(ArgTypes()...))> f();
+  };
+
+  template<typename R, typename ...ArgTypes>
+  unsigned_c<sizeof(1 + g(ArgTypes()...))> X1<R(ArgTypes...)>::f() { 
+    return unsigned_c<sizeof(int)>();
+  }
+
+  X1<int(float, double)> xif2;
 }