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Bug 860057 - [guru] media-gfx/azpainter-3.0.4 fails to compile (lto): draw_image.c:801:55: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
Summary: [guru] media-gfx/azpainter-3.0.4 fails to compile (lto): draw_image.c:801:55:...
Status: RESOLVED FIXED
Alias: None
Product: GURU
Classification: Unclassified
Component: Package issues (show other bugs)
Hardware: All Linux
: Normal normal
Assignee: Haelwenn (lanodan) Monnier
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2022-07-22 11:32 UTC by Agostino Sarubbo
Modified: 2024-02-01 22:00 UTC (History)
1 user (show)

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


Attachments
build.log (build.log,51.68 KB, text/plain)
2022-07-22 11:32 UTC, Agostino Sarubbo
Details

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Description Agostino Sarubbo gentoo-dev 2022-07-22 11:32:10 UTC
https://blogs.gentoo.org/ago/2020/07/04/gentoo-tinderbox/

Issue: media-gfx/azpainter-3.0.4 fails to compile (lto).
Discovered on: amd64 (internal ref: guru_tinderbox)

NOTE:
This machine uses lto with CFLAGS=-flto -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing
Comment 1 Agostino Sarubbo gentoo-dev 2022-07-22 11:32:12 UTC
Created attachment 793151 [details]
build.log

build log and emerge --info
Comment 2 Agostino Sarubbo gentoo-dev 2022-07-26 09:08:52 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 gentoo-dev 2024-02-01 22:00:26 UTC
The bug has been closed via the following commit(s):

https://gitweb.gentoo.org/repo/proj/guru.git/commit/?id=8315d328efc493b4cb5b3fcf8e917cbd70d54752

commit 8315d328efc493b4cb5b3fcf8e917cbd70d54752
Author:     Takuya Wakazono <pastalian46@gmail.com>
AuthorDate: 2024-02-01 10:52:00 +0000
Commit:     Takuya Wakazono <pastalian46@gmail.com>
CommitDate: 2024-02-01 10:58:09 +0000

    media-gfx/azpainter: add 3.0.7
    
    Closes: https://bugs.gentoo.org/860057
    Signed-off-by: Takuya Wakazono <pastalian46@gmail.com>

 media-gfx/azpainter/Manifest                       |  1 +
 media-gfx/azpainter/azpainter-3.0.7.ebuild         | 62 ++++++++++++++++++++++
 .../files/azpainter-3.0.7-strict-aliasing.patch    | 61 +++++++++++++++++++++
 3 files changed, 124 insertions(+)