[gcc r12-10129] c++: op== defaulted outside class [PR110084]

[Jason Merrill <jason@gcc.gnu.org>]

https://gcc.gnu.org/g:28f95c81382243fc4e6f1b22741d258f5fd7541f

commit r12-10129-g28f95c81382243fc4e6f1b22741d258f5fd7541f
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Feb 2 12:04:11 2024 -0500

    c++: op== defaulted outside class [PR110084]
    
    defaulted_late_check is for checks that need to happen after the class is
    complete; we shouldn't call it sooner.
    
            PR c++/110084
    
    gcc/cp/ChangeLog:
    
            * pt.cc (tsubst_function_decl): Only check a function defaulted
            outside the class if the class is complete.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp2a/spaceship-synth-neg3.C: Check error message.
            * g++.dg/cpp2a/spaceship-eq16.C: New test.
    
    (cherry picked from commit e17a122d417fc0d606bcb3a3705b93ee81745cab)

Diff:
---
 gcc/cp/pt.cc                                      |  1 +
 gcc/testsuite/g++.dg/cpp2a/spaceship-eq16.C       | 11 +++++++++++
 gcc/testsuite/g++.dg/cpp2a/spaceship-synth-neg3.C |  2 +-
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index dc8121e1b4b3..ed4dbe06179e 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -14444,6 +14444,7 @@ tsubst_function_decl (tree t, tree args, tsubst_flags_t complain,
     }
   determine_visibility (r);
   if (DECL_DEFAULTED_OUTSIDE_CLASS_P (r)
+      && COMPLETE_TYPE_P (DECL_CONTEXT (r))
       && !processing_template_decl)
     defaulted_late_check (r);
 
diff --git a/gcc/testsuite/g++.dg/cpp2a/spaceship-eq16.C b/gcc/testsuite/g++.dg/cpp2a/spaceship-eq16.C
new file mode 100644
index 000000000000..e5538ea98901
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/spaceship-eq16.C
@@ -0,0 +1,11 @@
+// PR c++/110084
+// { dg-do compile { target c++20 } }
+
+template <class T>
+class BadTuple {
+  constexpr bool operator==(const BadTuple&) const;
+};
+template<class T>
+constexpr bool BadTuple<T>::operator==(const BadTuple<T>&) const = default;
+
+BadTuple<int> a;
diff --git a/gcc/testsuite/g++.dg/cpp2a/spaceship-synth-neg3.C b/gcc/testsuite/g++.dg/cpp2a/spaceship-synth-neg3.C
index a4d8b32922fb..aaa0264e7b34 100644
--- a/gcc/testsuite/g++.dg/cpp2a/spaceship-synth-neg3.C
+++ b/gcc/testsuite/g++.dg/cpp2a/spaceship-synth-neg3.C
@@ -5,7 +5,7 @@ template<auto V>
 struct A {};
 
 struct B {
-    constexpr auto operator<=>(const B&) const = default; // { dg-error "" }
+    constexpr auto operator<=>(const B&) const = default; // { dg-error "strong_ordering" }
     int value;
 };