https://blogs.gentoo.org/ago/2020/07/04/gentoo-tinderbox/ Issue: games-fps/darkplaces-20140513-r2 fails to compile (lto). Discovered on: amd64 (internal ref: lto_tinderbox) NOTE: This machine uses lto with CFLAGS=-flto -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing
Created attachment 792098 [details] build.log build log and emerge --info
Error(s) that match a know pattern in addition to what has been reported in the summary: Package 'alsa', required by 'virtual:world', not found ../../../mathlib.h:36:29: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing[https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wstrict-aliasing]]
Here is a bit of explanation: -Werror=lto-type-mismatch: User to find possible runtime issues in packages. It likely means the package is unsafe to build & use with LTO. For projects using the same identifier but with different types across different files, they must be fixed to be consistent across the codebase. -Werror=odr: Used to find possible runtime issues in packages. These bugs are a problem anyway but may be even worse when combined with LTO. C++ code must comply with the One Definition Rule (ODR) - see https://en.cppreference.com/w/cpp/language/definition#One_Definition_Rule. -Werror=strict-aliasing: Used to find possible runtime issues in packages. These bugs are a problem anyway but may be even worse when combined with LTO. Workarounds: - If upstream is friendly and still active, file a bug upstream. For emulators, codecs, games, or multimedia packages, it may be worth just applying a workaround instead, as upstreams sometimes aren't receptive to these bugs (VALID FOR ALL). - Use the new 'filter-lto' from flag-o-matic.eclass as it's likely to be unsafe with LTO (VALID FOR lto-type-mismatch - odr). - Fix it yourself if interested, of course (VALID FOR ALL). - Append-flags -fno-strict-aliasing (VALID FOR strict-aliasing). - Use memcpy() but a union is sometimes suitable too (VALID FOR strict-aliasing). - -fstrict-aliasing is implied by -O2, so this must be addressed in some form (VALID FOR strict-aliasing). See also: https://marc.info/?l=gentoo-dev&m=165639574126280&w=2
Looks fixed in git: https://github.com/DarkPlacesEngine/darkplaces/commit/1c5e917527c135ba00c06a49800d57870020f7c2. There's a bunch of stuff that would have to be backported though, so let's filter for now, and put a comment to revisit.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=036ffaac92fed0a29389e8b04ea13f9f8320ec97 commit 036ffaac92fed0a29389e8b04ea13f9f8320ec97 Author: Sam James <sam@gentoo.org> AuthorDate: 2024-03-06 06:13:19 +0000 Commit: Sam James <sam@gentoo.org> CommitDate: 2024-03-06 06:13:19 +0000 games-fps/darkplaces: filter LTO, no SA There's a lot of SA fixes in git, add a comment in the ebuild about that to revisit later. But not going to backport them right now. Closes: https://bugs.gentoo.org/858740 Signed-off-by: Sam James <sam@gentoo.org> games-fps/darkplaces/darkplaces-20140513-r2.ebuild | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
