Implicitly expand argument packs when performing template argument

deduction. Unify all of the looping over template arguments for
deduction purposes into a single place, where argument pack expansion
occurs; this is also the hook for deducing from pack expansions, which
itself is not yet implemented.

For now, at least we can handle a basic "count" metafunction written
with variadics. See the new test for the formulation that works.

llvm-svn: 122418

1 files changed, 17 insertions, 0 deletions

diff --git a/clang/test/CXX/temp/temp.decls/temp.variadic/count.cpp b/clang/test/CXX/temp/temp.decls/temp.variadic/count.cpp
new file mode 100644
index 00000000000..aa880a5370a
--- /dev/null
+++ b/clang/test/CXX/temp/temp.decls/temp.variadic/count.cpp
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -std=c++0x -fsyntax-only -verify %s
+
+template<typename Head, typename ...Tail>
+struct count {
+  static const unsigned value = 1 + count<Tail...>::value;
+};
+
+template<typename T>
+struct count<T> {
+  static const unsigned value = 1;
+};
+
+int check1[count<int>::value == 1? 1 : -1];
+int check2[count<float, double>::value == 2? 1 : -1];
+int check3[count<char, signed char, unsigned char>::value == 3? 1 : -1];
+
+