https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114867
Bug ID: 114867
Summary: [modules] name lookup issues when a function overload
set is exported from GMF
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: m.cencora at gmail dot com
Target Milestone: ---
$ cat future.cpp
module;
namespace std {
template<class _Tp>
void swap(_Tp& a, _Tp& b);
namespace __exception_ptr {
class exception_ptr
{};
void swap(exception_ptr&, exception_ptr&);
}
using __exception_ptr::swap;
template < typename _Tp> struct shared_ptr {
void swap(shared_ptr& other) { std::swap(_M_ptr, other._M_ptr); }
_Tp *_M_ptr;
};
struct future {
shared_ptr< void > _M_state;
void operator=(future& other) { _M_state.swap(other._M_state); }
};
} // std
export module std;
namespace std {
using std::swap;
}
$ g++ -std=c++2b -fmodules-ts -Wno-global-module future.cpp
<source>: In instantiation of 'void
std::shared_ptr<_Tp>::swap(std::shared_ptr<_Tp>&) [with _Tp = void]':
<source>:23:48: required from here
23 | void operator=(future& other) { _M_state.swap(other._M_state); }
| ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~
<source>:17:44: error: invalid initialization of reference of type
'std::__exception_ptr::exception_ptr&' from expression of type 'void*'
17 | void swap(shared_ptr& other) { std::swap(_M_ptr, other._M_ptr); }
| ^~~~~~
<source>:10:11: note: in passing argument 1 of 'void
std::__exception_ptr::swap(exception_ptr&, exception_ptr&)'
10 | void swap(exception_ptr&, exception_ptr&);
| ^~~~~~~~~~~~~~
<source>:27:8: warning: not writing module 'std' due to errors
27 | export module std;
| ^~~~~~
This is reduced code from an issue found when creating std
module(https://gcc.gnu.org/PR114600#c10)
module;
#include <future>
export module std;
export namespace std
{
using std::swap;
}
The problem seems to be that using __exception_ptr::swap; hides any other
previous declaration of swap function.
The workarounds is to move decl of template swap after the using
__exception_ptr::swap;
Also this compiles fine if we change shared_ptr::_M_ptr to not become a
template dependent type.
