https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117658
Nathaniel Shead <nshead at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=101140
CC| |jason at gcc dot gnu.org,
| |nshead at gcc dot gnu.org
--- Comment #2 from Nathaniel Shead <nshead at gcc dot gnu.org> ---
Specifically, a minimal example would be:
// a.cpp
export module A;
export template <typename T> void test(T t) { foo(t); }
namespace ns {
export struct S {};
/* not exported */ void foo(S) {}
}
// b.cpp
import A;
int main() {
ns::S s;
test(s); // OK?
}
Clang compiles this, but GCC complains:
In module A, imported at b.cpp:1:
a.cpp: In instantiation of 'void test@A(T) [with T = ns::S@A]':
b.cpp:4:7: required from here
4 | test(ns::S{});
| ~~~~^~~~~~~~~
a.cpp:2:50: error: 'foo' was not declared in this scope
2 | export template <typename T> void test(T t) { foo(t); }
| ~~~^~~
If `ns::foo` is exported then GCC also compiles this example.
Relevant seems to be https://eel.is/c++draft/basic.lookup.argdep#4. The first
set of bullet points don't apply, but since `t` is a dependent name lookup
should also be performed from each point in the instantiation context.
This is not an instantiation of a template in an enclosing specialisation, so
it looks to me that the instantiation context here is just the point of
instantiation of `test` (https://eel.is/c++draft/module.context#5), i.e.
main.cpp, but Clang seems to think that it should also include the point at the
end of `a.cpp`. This latter interpretation seems to be supported by the example
here https://eel.is/c++draft/basic.lookup.argdep#5 so I'm probably missing
something!
CCing Jason in case he has any thoughts.
