Gentoo Websites Logo
Go to: Gentoo Home Documentation Forums Lists Bugs Planet Store Wiki Get Gentoo!
Bug 855677 - dev-libs/dietlibc-0.34 fails to compile (lto): stackgap-common.h:41:12: error: type of [-Werror=lto-type-mismatch]
Summary: dev-libs/dietlibc-0.34 fails to compile (lto): stackgap-common.h:41:12: error...
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: No maintainer - Look at if you want to take care of it
Depends on:
Blocks: lto
  Show dependency tree
Reported: 2022-07-02 07:22 UTC by Agostino Sarubbo
Modified: 2024-03-12 03:31 UTC (History)
0 users

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

build.log (build.log,575.97 KB, text/plain)
2022-07-02 07:22 UTC, Agostino Sarubbo

Note You need to log in before you can comment on or make changes to this bug.
Description Agostino Sarubbo gentoo-dev 2022-07-02 07:22:17 UTC

Issue: dev-libs/dietlibc-0.34 fails to compile (lto).
Discovered on: amd64 (internal ref: lto_tinderbox)

This machine uses lto with CFLAGS=-flto -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing
Comment 1 Agostino Sarubbo gentoo-dev 2022-07-02 07:22:20 UTC
Created attachment 789443 [details]

build log and emerge --info
Comment 2 Agostino Sarubbo gentoo-dev 2022-07-26 09:00:56 UTC
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 3 Larry the Git Cow gentoo-dev 2024-03-12 03:31:18 UTC
The bug has been closed via the following commit(s):

commit 8b80f01f80f7b461c7a2366c10d15f014e4d953f
Author:     Sam James <>
AuthorDate: 2024-03-12 03:25:49 +0000
Commit:     Sam James <>
CommitDate: 2024-03-12 03:30:52 +0000

    dev-libs/dietlibc: filter LTO
    This package is pretty.. special and already disables SA.
    Signed-off-by: Sam James <>

 dev-libs/dietlibc/dietlibc-0.34.ebuild | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)