Several improvements to template argument deduction:

  - Once we have deduced template arguments for a class template partial
    specialization, we use exactly those template arguments for instantiating
    the definition of the class template partial specialization.
  - Added template argument deduction for non-type template parameters.
  - Added template argument deduction for dependently-sized array types.

With these changes, we can now implement, e.g., the remove_reference
type trait. Also, Daniel's Ackermann template metaprogram now compiles
properly.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72909 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 37 insertions, 0 deletions

diff --git a/test/SemaTemplate/ackermann.cpp b/test/SemaTemplate/ackermann.cpp
new file mode 100644
index 0000000000..48fbbbb3cf
--- /dev/null
+++ b/test/SemaTemplate/ackermann.cpp
@@ -0,0 +1,37 @@
+// RUN: clang-cc -fsyntax-only -ftemplate-depth=1000 -verify %s
+
+// template<unsigned M, unsigned N>
+// struct Ackermann {
+//   enum {
+//     value = M ? (N ? Ackermann<M-1, Ackermann<M-1, N-1> >::value
+//                    : Ackermann<M-1, 1>::value)
+//               : N + 1
+//   };
+// };
+
+template<unsigned M, unsigned N>
+struct Ackermann {
+ enum {
+   value = Ackermann<M-1, Ackermann<M, N-1>::value >::value
+ };
+};
+
+template<unsigned M> struct Ackermann<M, 0> {
+ enum {
+   value = Ackermann<M-1, 1>::value
+ };
+};
+
+template<unsigned N> struct Ackermann<0, N> {
+ enum {
+   value = N + 1
+ };
+};
+
+template<> struct Ackermann<0, 0> {
+ enum {
+   value = 1
+ };
+};
+
+int g0[Ackermann<3, 8>::value == 2045 ? 1 : -1];