Bug 860423 – media-sound/alsaplayer-0.99.81-r3 fails to compile (lto): queues.c:65:12: error: type of [-Werror=lto-type-mismatch]

• Product: Gentoo Linux
• Status: RESOLVED FIXED

[Description Agostino Sarubbo 2022-07-24 07:47:02 UTC]

https://blogs.gentoo.org/ago/2020/07/04/gentoo-tinderbox/

Issue: media-sound/alsaplayer-0.99.81-r3 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

[Comment 1 Agostino Sarubbo 2022-07-24 07:47:05 UTC]

Created attachment 793691 [details]
build.log

build log and emerge --info

[Comment 2 Agostino Sarubbo 2022-07-26 09:02:44 UTC]

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

[Comment 3 Larry the Git Cow 2024-03-03 07:50:21 UTC]

The bug has been closed via the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=d4e40c626bf4f6e1a52259443bafd767072c62b1

commit d4e40c626bf4f6e1a52259443bafd767072c62b1
Author:     Eli Schwartz <[e-mail]>
AuthorDate: 2024-03-03 07:22:33 +0000
Commit:     Sam James <[e-mail]>
CommitDate: 2024-03-03 07:50:11 +0000

    media-sound/alsaplayer: mark as LTO-unsafe
    
    Closes: https://bugs.gentoo.org/860423
    Signed-off-by: Eli Schwartz <[e-mail]>
    Signed-off-by: Sam James <[e-mail]>

 media-sound/alsaplayer/alsaplayer-0.99.81-r4.ebuild | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

[Comment 4 Sam James 2024-03-03 07:50:46 UTC]

I filed https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114218 for a better GCC warning here.

[Comment 5 Eli Schwartz 2024-03-04 02:49:46 UTC]

*** Bug 876424 has been marked as a duplicate of this bug. ***