[committed] C++ PATCH to add test for c++/87523

[Marek Polacek]

Tested x86_64-linux, applying to trunk.

2018-12-01  Marek Polacek  <pola...@redhat.com>

        PR c++/87523
        * g++.dg/cpp1y/lambda-generic-87523.C: New test.

diff --git gcc/testsuite/g++.dg/cpp1y/lambda-generic-87523.C 
gcc/testsuite/g++.dg/cpp1y/lambda-generic-87523.C
new file mode 100644
index 00000000000..ecba1cfc322
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp1y/lambda-generic-87523.C
@@ -0,0 +1,32 @@
+// PR c++/87523
+// { dg-do compile { target c++14 } }
+
+template <typename T, T v>
+struct my_integer_constant {
+    constexpr my_integer_constant() {}
+    constexpr operator T() const { return v; }
+    constexpr T operator()() const { return v; }
+};
+
+template <typename T, T... u>
+struct constant_call {
+    template <typename Callback>
+    static void call(T v, Callback f) {
+        char dummy[sizeof...(u)] = { ( (v == u) ? (f(my_integer_constant<T, 
u>{}), static_cast<char>(0)) : static_cast<char>(0))... };
+        (void)dummy;
+    }
+};
+
+void f(bool reverse_in, bool other_bool_in) {
+    auto helper = [&] (auto reverse_t) {
+        bool constexpr reverse_v = reverse_t;
+        (void)reverse_v;
+        constant_call<bool, true, false>::call(other_bool_in,
+                                               [&] (auto newb) {
+                                                   bool reverse_v_dyn = 
reverse_v;
+                                               });
+    };
+    constant_call<bool, true, false>::call(reverse_in, [&] (auto reverse_t) {
+            helper(reverse_t);
+        });
+}