C++ PATCH to add a test for c++/83644

[Marek Polacek]

Another fixed PR, another additional test.

Tested on x86_64-linux, ok for trunk?

2018-01-02  Marek Polacek  <pola...@redhat.com>

        PR c++/83644
        * g++.dg/cpp1z/pr83644.C: New test.

diff --git gcc/testsuite/g++.dg/cpp1z/pr83644.C 
gcc/testsuite/g++.dg/cpp1z/pr83644.C
index e69de29bb2d..493d8c7cbe4 100644
--- gcc/testsuite/g++.dg/cpp1z/pr83644.C
+++ gcc/testsuite/g++.dg/cpp1z/pr83644.C
@@ -0,0 +1,12 @@
+// PR c++/83644
+// { dg-do compile }
+// { dg-options -std=c++17 }
+
+namespace std {
+template <typename> bool is_invocable_v;
+}
+template <typename F> auto compose(F) {
+  [](auto... objs) noexcept(std::is_invocable_v<decltype(objs)...>){};
+}
+
+auto f() { compose(3); }

        Marek