https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119203
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
For the original example, clang says what's wrong:
arrow.cc:14:7: error: no viable overloaded 'operator->'
14 | iter->i;
| ~~~~^
arrow.cc:6:8: note: candidate function not viable: constraints not satisfied
6 | auto operator->() const requires(t.operator->()) { return
t.operator->(); }
| ^
arrow.cc:6:38: note: because substituted constraint expression is ill-formed:
no member named 'operator->' in 'S'
6 | auto operator->() const requires(t.operator->()) { return
t.operator->(); }
| ^
1 error generated.
But EDG has the same problem as GCC:
"arrow.cc", line 14: error: operator -> or ->* applied to "Iter<S>" instead of
to a pointer type
iter->i;
^
"arrow.cc", line 14: warning: variable "iter" is used before its value is set
iter->i;
^
1 error detected in the compilation of "arrow.cc".
