1 files changed, 49 insertions, 0 deletions
diff --git a/gcc/testsuite/g++.dg/cpp1z/pr122185.C b/gcc/testsuite/g++.dg/cpp1z/pr122185.C
new file mode 100644
index 00000000000..73cba761b01
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/pr122185.C
@@ -0,0 +1,49 @@
+// PR c++/122185
+// { dg-do compile { target c++17 } }
+// { dg-options "-w -O2" }
+
+namespace std {
+template <typename _Tp> struct remove_reference {
+  using type = __remove_reference(_Tp);
+};
+template <typename _Tp> _Tp forward(typename remove_reference<_Tp>::type);
+}
+template <typename T> struct static_const {
+  static constexpr T value{};
+};
+template <typename, typename> struct adl_serializer;
+template <template <typename, typename> class = adl_serializer>
+class basic_json;
+struct from_json_fn {
+  template <typename BasicJsonType, typename T>
+  void operator()(BasicJsonType, T) const;
+};
+template <typename, typename> struct adl_serializer {
+  template <typename BasicJsonType, typename TargetType>
+  static void from_json(BasicJsonType &&j, TargetType val) {
+    static_const<from_json_fn>::value(std::forward<BasicJsonType>(j), val);
+  }
+};
+struct iter_impl {
+  basic_json<> operator*();
+  void operator++();
+  bool operator!=(iter_impl);
+};
+template <template <typename, typename = void> class JSONSerializer>
+struct basic_json {
+  template <typename> using iter_impl = iter_impl;
+  using iterator = iter_impl<basic_json>;
+  template <typename> void get_impl(int) {
+    auto ret = int();
+    JSONSerializer<int>::from_json(*this, ret);
+  }
+  template <typename> void get() { get_impl<int>({}); }
+  iterator begin();
+  iterator end();
+  char type_name;
+};
+void _ValidateSignatureFile() {
+  basic_json signatures;
+  for (auto signature : signatures)
+    signature.get<int>();
+}