[gcc r12-4217] c++: One more spaceship test.

[gcc r12-4217] c++: One more spaceship test.

[Jason Merrill]

https://gcc.gnu.org/g:6aab794614d26007d6886d7440f2e8124a08416a

commit r12-4217-g6aab794614d26007d6886d7440f2e8124a08416a
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Oct 6 17:12:02 2021 -0400

    c++: One more spaceship test.
    
    Jakub suggested adding a variant where we actually try to call the
    implicitly deleted operator.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp2a/spaceship-synth8a.C: New test.

Diff:
---
 gcc/testsuite/g++.dg/cpp2a/spaceship-synth8a.C | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/gcc/testsuite/g++.dg/cpp2a/spaceship-synth8a.C b/gcc/testsuite/g++.dg/cpp2a/spaceship-synth8a.C
new file mode 100644
index 00000000000..42a32da77f9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/spaceship-synth8a.C
@@ -0,0 +1,25 @@
+// PR c++/94907
+// { dg-do compile { target c++20 } }
+
+namespace std { struct strong_ordering {
+  int _v;
+  constexpr strong_ordering (int v) :_v(v) {}
+  constexpr operator int (void) const { return _v; }
+  static const strong_ordering less;
+  static const strong_ordering equal;
+  static const strong_ordering greater;
+};
+constexpr strong_ordering strong_ordering::less = -1;
+constexpr strong_ordering strong_ordering::equal = 0;
+constexpr strong_ordering strong_ordering::greater = 1;
+}
+
+struct E;
+struct D {
+  virtual std::strong_ordering operator<=>(const struct E&) const = 0;
+};
+struct E : D {							       // { dg-error "no match" }
+  std::strong_ordering operator<=>(const E&) const override = default; // { dg-message "default" }
+};
+
+auto x = E() <=> E();		// { dg-error "deleted" }