Bug 864409 – x11-libs/cmrt-1.0.6-r3 fails to compile (lto): cm_task_internal.cpp:546:66: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]

• Product: Gentoo Linux
• Status: RESOLVED FIXED

[Description Agostino Sarubbo 2022-08-08 12:07:40 UTC]

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

Issue: x11-libs/cmrt-1.0.6-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

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 2022-08-08 12:07:43 UTC]

Created attachment 798865 [details]
build.log

build log and emerge --info

[Comment 2 Agostino Sarubbo 2024-03-29 07:46:41 UTC]

lto_tinderbox has reproduced this issue with version 1.0.6-r3 - Updating summary.

[Comment 3 Larry the Git Cow 2024-05-08 19:21:21 UTC]

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

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=0518bf825c5834935484f672dabd5afcb08cc530

commit 0518bf825c5834935484f672dabd5afcb08cc530
Author:     Eli Schwartz <[e-mail]>
AuthorDate: 2024-05-08 03:26:23 +0000
Commit:     Sam James <[e-mail]>
CommitDate: 2024-05-08 19:19:30 +0000

    x11-libs/cmrt: mark as LTO-unsafe, strict-aliasing unsafe
    
    The software is dead upstream. In August 2022 (almost immediately after
    the package was added to the tree), the README.md was updated to say:
    
    > Intel has ceased development and contributions including, but not
    > limited to, maintenance, bug fixes, new releases, or updates, to this
    > project.
    >
    > Intel no longer accepts patches to this project.
    
    and the github repository was marked as archived.
    
    No point in reporting anything, because you can't even if you want to.
    Just mark it as unsafe and move on.
    
    Closes: https://bugs.gentoo.org/864409
    Signed-off-by: Eli Schwartz <[e-mail]>
    Signed-off-by: Sam James <[e-mail]>

 x11-libs/cmrt/cmrt-1.0.6-r3.ebuild | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)