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From: "ppalka at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/114600] [14 Regression] [modules] redefinition errors when
 using certain std headers in GMF
Date: Wed, 24 Apr 2024 13:46:31 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114600

--- Comment #12 from Patrick Palka <ppalka at gcc dot gnu.org> ---
(In reply to m.cencora from comment #10)
> Created attachment 57924 [details]
> Full "std' modules with workarounds
>=20
> Here is an improved version of "std" module, with workarounds for:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114683
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114685

Interesting, thanks!

IIUC in light of these 'export using' bugs the most robust way to implement=
 the
std module in GCC 14 is probably:

$ cat std.C
export module std;
export import <bits/stdc++.h>;

$ g++ -fmodules-ts -x c++-system-header bits/stdc++.h -x c++ std.C

This has the disadvantage of exposing implementation-detail entities and
requiring an additional step to build the <bits/stdc++.h> header module, but
should otherwise just work.=