c++/reflection: add fixed test [PR123440]

This test crashed until r16-7330.  The errors are expected.
Let's make sure the crash doesn't come back.

	PR c++/123440

gcc/testsuite/ChangeLog:

	* g++.dg/reflect/extract10.C: New test.

diff --git a/gcc/testsuite/g++.dg/reflect/extract10.C b/gcc/testsuite/g++.dg/reflect/extract10.C
new file mode 100644 (file)
index 0000000..12dc25c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/reflect/extract10.C
@@ -0,0 +1,55 @@
+// PR c++/123440
+// { dg-do compile { target c++26 } }
+// { dg-additional-options "-freflection" }
+
+#include <meta>
+#include <ranges>
+
+using namespace std::meta;
+
+struct test_struct
+{
+    int data_member;
+    void fn1() {}
+    void fn2() {}
+    int getter() { return data_member; }
+    void setter(int i) { data_member = i; }
+    virtual int virtual_fn(char*, bool) { return 0; }
+    virtual int pure_virtual_fn(char*, int) = 0;
+    static int static_member_fn(bool b) { return b ? 42 : 0; }
+};
+template<typename T, size_t I>
+consteval info get_member_at()
+{
+    constexpr auto ctx          = access_context::current();
+    constexpr auto pointable    = [](info i) consteval -> bool {
+        return !is_destructor(i) && !is_constructor(i) && !is_special_member_function(i);
+    };
+    return (members_of(^^T, ctx) | std::views::filter(pointable) | std::ranges::to<std::vector>())[I];
+}
+template<typename T, size_t I>
+consteval info get_member_type() {
+    return type_of(get_member_at<T, I>());
+}
+template<typename T, size_t I>
+consteval auto get_member_ptr() {
+    constexpr info member   = get_member_at<T, I>();
+    constexpr info mem_type = add_pointer(get_member_type<T, I>());
+    using type              = typename[: mem_type :];
+    return extract<type>(member);
+}
+constexpr auto ex_0 = extract<int test_struct::*>(get_member_at<test_struct, 0>());
+constexpr auto ex_1 = extract<void (test_struct::*)()>(get_member_at<test_struct, 1>());
+constexpr auto ex_2 = extract<void (test_struct::*)()>(get_member_at<test_struct, 2>());
+constexpr auto ex_3 = extract<int (test_struct::*)()>(get_member_at<test_struct, 3>());
+constexpr auto ex_4 = extract<void (test_struct::*)(int)>(get_member_at<test_struct, 4>());
+constexpr auto ex_5 = extract<int (test_struct::*)(char*, bool)>(get_member_at<test_struct, 5>());
+constexpr auto ex_6 = extract<int (test_struct::*)(char*, int)>(get_member_at<test_struct, 6>());
+constexpr auto ex_7 = extract<int(*)(bool)>(get_member_at<test_struct, 7>());
+constexpr auto ex_8 = get_member_ptr<test_struct, 7>();
+constexpr auto test_1 = get_member_ptr<test_struct, 1>(); // { dg-error "value cannot be extracted" }
+constexpr auto test_2 = get_member_ptr<test_struct, 2>(); // { dg-error "value cannot be extracted" }
+constexpr auto test_3 = get_member_ptr<test_struct, 3>(); // { dg-error "value cannot be extracted" }
+constexpr auto test_4 = get_member_ptr<test_struct, 4>(); // { dg-error "value cannot be extracted" }
+constexpr auto test_5 = get_member_ptr<test_struct, 5>(); // { dg-error "value cannot be extracted" }
+constexpr auto test_6 = get_member_ptr<test_struct, 6>(); // { dg-error "value cannot be extracted" }