https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101140
--- Comment #5 from Nathaniel Shead <nshead at gcc dot gnu.org> ---
(In reply to Patrick Palka from comment #4)
> FWIW I was thinking we might want to perform two-phase name lookup for
> new-expressions like we do for other operator expressions, wherein
> unqualified lookup is performed at template definition time, saved inside
> the expression (via DEPENDENT_OPERATOR_TYPE) and then reused at
> instantiation time.
I actually wonder if this is even correct. [basic.argdep.lookup] p4 says:
> If the lookup is for a dependent name ([temp.dep], [temp.dep.candidate]), the
> above lookup is also performed from each point in the instantiation context
> ([module.context]) of the lookup, additionally ignoring any declaration that
> appears in another translation unit, is attached to the global module, and is
> either discarded ([module.global.frag]) or has internal linkage.
And the instantiation context is defined to include ([module.context] p3):
> ...if the template is defined in a module interface unit of a module M and
> the point of instantiation is not in a module interface unit of M, the point
> at the end of the declaration-seq of the primary module interface unit of M
> (prior to the private-module-fragment, if any).
Which implies to me that the following sample should work:
export module M;
export template <typename T>
void f(T t) { g(t); }
namespace ns {
export struct X {};
void g(X);
}
//
import M;
int main() {
f(ns::X{}); // should compile?
}
but we currently error. Whether this is a sensible thing to support is another
question...
