https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122279
Bug ID: 122279
Summary: Non-exported using-directives not visible across TUs
within the same module
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gulackeg at gmail dot com
Target Milestone: ---
Test code:
// https://godbolt.org/z/fxsP1Wejh
// M.cpp
export module M;
namespace N {
void f() {}
}
using namespace N;
export void g();
// M-impl.cpp
module M;
void g() {
// - Clang: OK
// - GCC: error: 'f' was not declared in this scope
f();
}
GCC accepts the code if we add `export` to `using namespace N;`. But according
to [basic.lookup.general]/2.3[1]:
- either *X* is exported or else *D* and *L* are part of the same
module and *X* does not inhabit a namespace with internal linkage
or declare a name with internal linkage.
`export` is not needed here because the TUs `M.cpp` and `M-impl.cpp` are part
of the same module `M`.
[1]: https://timsong-cpp.github.io/cppwp/n4950/basic.lookup.general#2.3
