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Bug 880589 - sys-libs/slang-2.3.3 fails to compile (LTO-SYSTEM): chksum_sha2.c:485:47: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
Summary: sys-libs/slang-2.3.3 fails to compile (LTO-SYSTEM): chksum_sha2.c:485:47: err...
Status: RESOLVED FIXED
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: CJK Team
URL:
Whiteboard:
Keywords:
Depends on: 927753
Blocks: lto
  Show dependency tree
 
Reported: 2022-11-09 11:39 UTC by Agostino Sarubbo
Modified: 2024-03-24 21:27 UTC (History)
4 users (show)

See Also:
Package list:
Runtime testing required: ---


Attachments
build.log (build.log,92.80 KB, text/plain)
2022-11-09 11:39 UTC, Agostino Sarubbo
Details
sys-libs\:slang-2.3.3\:20230912-101355.log (sys-libs:slang-2.3.3:20230912-101355.log,46.59 KB, text/x-log)
2023-09-12 09:37 UTC, Pietro
Details
emerge --info (file_880589.txt,6.67 KB, text/plain)
2023-09-12 09:38 UTC, Pietro
Details

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Description Agostino Sarubbo gentoo-dev 2022-11-09 11:39:41 UTC
https://blogs.gentoo.org/ago/2020/07/04/gentoo-tinderbox/

Issue: sys-libs/slang-2.3.3 fails to compile (LTO-SYSTEM).
Discovered on: amd64 (internal ref: lto_tinderbox)

NOTE:
(LTO-SYSTEM) in the summary means that bug was found on a machine that runs lto but this bug MAY or MAY NOT BE related to lto.

This machine uses lto with CFLAGS=-flto -Werror=odr -Werror=lto-type-mismatch -Werror=strict-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
Comment 1 Agostino Sarubbo gentoo-dev 2022-11-09 11:39:43 UTC
Created attachment 830003 [details]
build.log

build log and emerge --info
Comment 2 Pietro 2023-09-12 09:37:27 UTC
Created attachment 870332 [details]
sys-libs\:slang-2.3.3\:20230912-101355.log

I am being hit by the same issue. Error log is attached
Comment 3 Pietro 2023-09-12 09:38:12 UTC
Created attachment 870333 [details]
emerge --info
Comment 4 Larry the Git Cow gentoo-dev 2023-09-14 04:43:38 UTC
The bug has been closed via the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=10a68be525074c92f0d96ef0b3c14052b47ee2ba

commit 10a68be525074c92f0d96ef0b3c14052b47ee2ba
Author:     Sam James <sam@gentoo.org>
AuthorDate: 2023-09-14 04:42:53 +0000
Commit:     Sam James <sam@gentoo.org>
CommitDate: 2023-09-14 04:43:07 +0000

    sys-libs/slang: filter-lto, -fno-strict-aliasing
    
    Not worth trying to fix the violations here.
    
    Closes: https://bugs.gentoo.org/880589
    Signed-off-by: Sam James <sam@gentoo.org>

 sys-libs/slang/slang-2.3.3-r1.ebuild | 87 ++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)