Teach TreeTransform how to transform a pack expansion type into

another pack expansion type. This can happen when rebuilding types in
the current instantiation.

Fixes <rdar://problem/8848837> (Clang crashing on libc++ <functional>).

llvm-svn: 123316

1 files changed, 21 insertions, 10 deletions

diff --git a/clang/lib/Sema/SemaTemplateVariadic.cpp b/clang/lib/Sema/SemaTemplateVariadic.cpp
index 63a8394d67a..473dcb7d1fa 100644
--- a/clang/lib/Sema/SemaTemplateVariadic.cpp
+++ b/clang/lib/Sema/SemaTemplateVariadic.cpp
@@ -377,18 +377,13 @@ TypeResult Sema::ActOnPackExpansion(ParsedType Type,
 
 TypeSourceInfo *Sema::CheckPackExpansion(TypeSourceInfo *Pattern,
                                          SourceLocation EllipsisLoc) {
-  // C++0x [temp.variadic]p5:
-  //   The pattern of a pack expansion shall name one or more
-  //   parameter packs that are not expanded by a nested pack
-  //   expansion.
-  if (!Pattern->getType()->containsUnexpandedParameterPack()) {
-    Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
-      << Pattern->getTypeLoc().getSourceRange();
+  // Create the pack expansion type and source-location information.
+  QualType Result = CheckPackExpansion(Pattern->getType(), 
+                                       Pattern->getTypeLoc().getSourceRange(),
+                                       EllipsisLoc);
+  if (Result.isNull())
     return 0;
-  }
   
-  // Create the pack expansion type and source-location information.
-  QualType Result = Context.getPackExpansionType(Pattern->getType());
   TypeSourceInfo *TSResult = Context.CreateTypeSourceInfo(Result);
   PackExpansionTypeLoc TL = cast<PackExpansionTypeLoc>(TSResult->getTypeLoc());
   TL.setEllipsisLoc(EllipsisLoc);
@@ -400,6 +395,22 @@ TypeSourceInfo *Sema::CheckPackExpansion(TypeSourceInfo *Pattern,
   return TSResult;
 }
 
+QualType Sema::CheckPackExpansion(QualType Pattern,
+                                  SourceRange PatternRange,
+                                  SourceLocation EllipsisLoc) {
+  // C++0x [temp.variadic]p5:
+  //   The pattern of a pack expansion shall name one or more
+  //   parameter packs that are not expanded by a nested pack
+  //   expansion.
+  if (!Pattern->containsUnexpandedParameterPack()) {
+    Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
+      << PatternRange;
+    return QualType();
+  }
+
+  return Context.getPackExpansionType(Pattern);
+}
+
 ExprResult Sema::ActOnPackExpansion(Expr *Pattern, SourceLocation EllipsisLoc) {
   if (!Pattern)
     return ExprError();