After r11-6614 made cp_walk_subtrees walk into the template of a CTAD
placeholder, we now correctly accept the below testcase. We used to
reject it because find_parameter_packs_r would fail to find the
parameter pack Ts inside the CTAD placeholder within the pack expansion.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/class-deduction77.C: New test.
---
gcc/testsuite/g++.dg/cpp1z/class-deduction77.C | 6 ++++++
1 file changed, 6 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/class-deduction77.C
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction77.C
b/gcc/testsuite/g++.dg/cpp1z/class-deduction77.C
new file mode 100644
index 00000000000..c5462fb4f32
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction77.C
@@ -0,0 +1,6 @@
+// { dg-do compile { target c++17 } }
+
+template <class...> struct A {};
+
+template <template <class> class... Ts>
+using B = A<decltype(Ts{0})...>;
--
2.30.0.155.g66e871b664
