Tested on x86_64-pc-linux-gnu, pushed as obvious.
-- >8 --
Here's a previously accepted testcase that is now ambiguous after
r16-2771-gb9f1cc4e119da, since the uninstantiated constraints are
equivalent but the partially instantiated constraints aren't, so
the two member functions no longer correspond.
PR c++/121351
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-using6.C: New test.
---
gcc/testsuite/g++.dg/cpp2a/concepts-using6.C | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-using6.C
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-using6.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-using6.C
new file mode 100644
index 000000000000..a40519a30dae
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-using6.C
@@ -0,0 +1,20 @@
+// PR c++/121351
+// { dg-do compile { target c++20 } }
+
+template<class T> concept C = true;
+
+template<class T>
+struct A {
+ template<class U> void f(U) requires C<T>; // #1
+};
+
+template<class T>
+struct B : A<T*> {
+ using A<T*>::f;
+ template<class U> void f(U) requires C<T>; // #2
+};
+
+int main() {
+ B<int> b;
+ b.f(42); // { dg-error "ambiguous" } #1 and #2 don't correspond
+}
--
2.51.0.rc0
