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Bug 881461 - x11-plugins/wmcalendar-0.5.2-r2 fails to compile (LTO-SYSTEM): calendar.c:362:10: error: type of [-Werror=lto-type-mismatch]
Summary: x11-plugins/wmcalendar-0.5.2-r2 fails to compile (LTO-SYSTEM): calendar.c:362...
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: Bernard Cafarelli
Depends on:
Blocks: lto
  Show dependency tree
Reported: 2022-11-16 07:43 UTC by Agostino Sarubbo
Modified: 2024-04-28 06:55 UTC (History)
0 users

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

build.log (build.log,67.25 KB, text/plain)
2022-11-16 07:43 UTC, Agostino Sarubbo

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Description Agostino Sarubbo gentoo-dev 2022-11-16 07:43:00 UTC

Issue: x11-plugins/wmcalendar-0.5.2-r2 fails to compile (LTO-SYSTEM).
Discovered on: amd64 (internal ref: lto_tinderbox)

(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:

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.

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

Used to find possible runtime issues in packages. These bugs are a problem anyway but may be even worse when combined with LTO.

- 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:
Comment 1 Agostino Sarubbo gentoo-dev 2022-11-16 07:43:03 UTC
Created attachment 832881 [details]

build log and emerge --info
Comment 2 Larry the Git Cow gentoo-dev 2024-04-28 06:55:03 UTC
The bug has been closed via the following commit(s):

commit 054d5d2c0cfd27716cf924e7f5b335a43dcf1217
Author:     Eli Schwartz <>
AuthorDate: 2024-04-28 05:42:46 +0000
Commit:     Sam James <>
CommitDate: 2024-04-28 06:54:26 +0000

    x11-plugins/wmcalendar: add patches to fix horrible missing function decls
    We kill two birds with one stone. It fails the c99 porting tracker and
    will not compile with Modern C compilers such as gcc 14 or clang 16, and
    it ALSO fixes LTO errors since -Werror=lto-type-mismatch complained when
    the implicit function declaration's assumed type was incorrect and
    didn't match the type of the actual live instance of the function.
    While we are at it, fix some additional (memory access) errors
    discovered by LTO in the form of -Waggressive-loop-optimizations.
    Signed-off-by: Eli Schwartz <>
    Signed-off-by: Sam James <>

 ...-typo-causing-out-of-bounds-memory-access.patch | 27 ++++++++++
 x11-plugins/wmcalendar/files/wmcalendar-c99.patch  | 63 ++++++++++++++++++++++
 x11-plugins/wmcalendar/wmcalendar-0.5.2-r3.ebuild  | 39 ++++++++++++++
 3 files changed, 129 insertions(+)