Gentoo Websites Logo
Go to: Gentoo Home Documentation Forums Lists Bugs Planet Store Wiki Get Gentoo!
Bug 864127 - www-client/elinks-0.13.5-r100 fails to compile (lto): lists.h:181:20: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
Summary: www-client/elinks-0.13.5-r100 fails to compile (lto): lists.h:181:20: error: ...
Status: RESOLVED FIXED
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: All Linux
: Normal normal
Assignee: Felix Janda
URL:
Whiteboard:
Keywords:
Depends on:
Blocks: lto
  Show dependency tree
 
Reported: 2022-08-07 05:39 UTC by Agostino Sarubbo
Modified: 2024-02-29 00:27 UTC (History)
1 user (show)

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


Attachments
build.log (build.log,262.23 KB, text/plain)
2022-08-07 05:39 UTC, Agostino Sarubbo
Details

Note You need to log in before you can comment on or make changes to this bug.
Description Agostino Sarubbo gentoo-dev 2022-08-07 05:39:44 UTC
https://blogs.gentoo.org/ago/2020/07/04/gentoo-tinderbox/

Issue: www-client/elinks-0.13.5-r100 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 gentoo-dev 2022-08-07 05:39:47 UTC
Created attachment 798424 [details]
build.log

build log and emerge --info
Comment 2 Larry the Git Cow gentoo-dev 2022-10-13 01:51:43 UTC
The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=60077257913d961895b343c5126ee4bdeb77ca3c

commit 60077257913d961895b343c5126ee4bdeb77ca3c
Author:     Sam James <sam@gentoo.org>
AuthorDate: 2022-10-13 01:50:51 +0000
Commit:     Sam James <sam@gentoo.org>
CommitDate: 2022-10-13 01:51:18 +0000

    www-client/elinks: add 0.15.1
    
    Bug: https://bugs.gentoo.org/635110
    Bug: https://bugs.gentoo.org/864127
    Closes: https://bugs.gentoo.org/780672
    Signed-off-by: Sam James <sam@gentoo.org>

 www-client/elinks/Manifest             |   1 +
 www-client/elinks/elinks-0.15.1.ebuild | 148 ++++++++++++++++++++++++++++++
 www-client/elinks/elinks-9999.ebuild   | 162 ++++++++++++++++-----------------
 3 files changed, 228 insertions(+), 83 deletions(-)
Comment 3 Eli Schwartz gentoo-dev 2024-02-28 23:45:50 UTC
Was fixed, see above comment.
Comment 4 Larry the Git Cow gentoo-dev 2024-02-29 00:27:57 UTC
The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=c30f795e25db71ca03d85a7ccfd0a085f5e9a1c6

commit c30f795e25db71ca03d85a7ccfd0a085f5e9a1c6
Author:     Eli Schwartz <eschwartz93@gmail.com>
AuthorDate: 2024-02-29 00:05:16 +0000
Commit:     Sam James <sam@gentoo.org>
CommitDate: 2024-02-29 00:27:48 +0000

    www-client/elinks: mark LTO-unsafe
    
    Upstream acknowledges the project is a walking strict-aliasing
    violation, and activates -fno-strict-aliasing.
    
    Given this, we shouldn't trust it to generate valid code with LTO
    either.
    
    Bug: https://bugs.gentoo.org/864127
    Signed-off-by: Eli Schwartz <eschwartz93@gmail.com>
    Signed-off-by: Sam James <sam@gentoo.org>

 www-client/elinks/elinks-0.16.1.1-r2.ebuild | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)