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.

3 files changed, 13 insertions, 1 deletions

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 9d30a27..355e960 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -14812,6 +14812,7 @@ tsubst_function_decl (tree t, tree args, tsubst_flags_t complain,
   if (DECL_SECTION_NAME (t))
     set_decl_section_name (r, t);
   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 0000000..e5538ea
--- /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 a4d8b32..aaa0264 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;
 };