Bug 871999 – dev-ruby/google-protobuf-3.24.4 fails to compile (lto): <artificial>:(.text+0x1357): undefined reference to __wrap_memcpy

• Product: Gentoo Linux
• Status: CONFIRMED ---

[Description Agostino Sarubbo 2022-09-20 08:23:29 UTC]

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

Issue: dev-ruby/google-protobuf-3.19.3 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 2022-09-20 08:23:32 UTC]

Created attachment 813052 [details]
build.log

build log and emerge --info

[Comment 2 Agostino Sarubbo 2022-09-20 08:23:34 UTC]

Error(s) that match a know pattern in addition to what has been reported in the summary:


/usr/lib/gcc/x86_64-pc-linux-gnu/12.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: <artificial>:(.text+0x1ba6): undefined reference to `__wrap_memcpy'
/usr/lib/gcc/x86_64-pc-linux-gnu/12.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: <artificial>:(.text+0x3680): undefined reference to `__wrap_memcpy'
<artificial>:(.text+0x1357): undefined reference to `__wrap_memcpy'
<artificial>:(.text+0x3526): undefined reference to `__wrap_memcpy'
<artificial>:(.text+0x3642): undefined reference to `__wrap_memcpy'
collect2: error: ld returned 1 exit status

[Comment 3 Agostino Sarubbo 2024-02-27 08:59:00 UTC]

lto_tinderbox has reproduced this issue with version 3.24.4 - Updating summary.