P2085 clarified that a defaulted comparison operator must be the first
declaration of the function. Rejecting that avoids the ICE trying to
compare the noexcept-specifications.
Tested x86_64-pc-linux-gnu, applying to trunk.
gcc/cp/ChangeLog
2020-04-24 Jason Merrill <ja...@redhat.com>
PR c++/94583
* decl.c (redeclaration_error_message): Reject defaulted comparison
operator that has been previously declared.
---
gcc/cp/decl.c | 8 ++++++++
gcc/testsuite/g++.dg/cpp2a/spaceship-synth6.C | 11 +++++++++++
2 files changed, 19 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/spaceship-synth6.C
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index c8c2f080763..31b5884ca3a 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -2972,6 +2972,14 @@ redeclaration_error_message (tree newdecl, tree olddecl)
}
}
+ /* [class.compare.default]: A definition of a comparison operator as
+ defaulted that appears in a class shall be the first declaration of
+ that function. */
+ special_function_kind sfk = special_function_p (olddecl);
+ if (sfk == sfk_comparison && DECL_DEFAULTED_FN (newdecl))
+ return G_("comparison operator %q+D defaulted after "
+ "its first declaration");
+
check_abi_tag_redeclaration
(olddecl, lookup_attribute ("abi_tag", DECL_ATTRIBUTES (olddecl)),
lookup_attribute ("abi_tag", DECL_ATTRIBUTES (newdecl)));
diff --git a/gcc/testsuite/g++.dg/cpp2a/spaceship-synth6.C
b/gcc/testsuite/g++.dg/cpp2a/spaceship-synth6.C
new file mode 100644
index 00000000000..e8296bbb60a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/spaceship-synth6.C
@@ -0,0 +1,11 @@
+// PR c++/94583
+// { dg-do compile { target c++2a } }
+
+namespace std { struct strong_ordering { }; }
+
+bool operator==(const struct Q&, const struct Q&);
+struct Q {
+ // { dg-error "defaulted after its first declaration" "" { target *-*-* }
.+1 }
+ friend std::strong_ordering operator<=>(const Q&, const Q&) = default;
+};
+bool b = Q() == Q();
base-commit: cbd2a10dd9edadb262934aed64c0959339da68d1
--
2.18.1
