Bug 861866 – net-voip/mumble-1.4.230-r3 fails to compile (lto): Channel.h:26:7: error: type struct Channel violates the C++ One Definition Rule [-Werror=odr]

• Product: Gentoo Linux
• Status: RESOLVED FIXED

[Description Agostino Sarubbo 2022-07-29 07:13:07 UTC]

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

Issue: net-voip/mumble-1.4.230-r3 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 2022-07-29 07:13:09 UTC]

Created attachment 795386 [details]
build.log

build log and emerge --info

[Comment 2 Agostino Sarubbo 2022-07-29 07:13:11 UTC]

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


FAILED: mumble 
/var/tmp/portage/net-voip/mumble-1.4.230-r3/work/mumble-1.4.230_build/src/mumble/mumble_autogen/VNU7RW3YIC/../../../../../mumble-1.4.230.src/src/Channel.h:26:7: error: type ‘struct Channel’ violates the C++ One Definition Rule [-Werror=odr]

[Comment 3 Sam James 2022-08-27 16:38:12 UTC]

https://github.com/mumble-voip/mumble/commit/ade77f3c1499e591ba6ac38449c437f1d80af17a

[Comment 4 Larry the Git Cow 2022-08-31 14:52:27 UTC]

The bug has been closed via the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=ab93e23f412bc588c0ea60a06a0de67e0f405b53

commit ab93e23f412bc588c0ea60a06a0de67e0f405b53
Author:     Kenton Groombridge <[e-mail]>
AuthorDate: 2022-08-31 14:04:26 +0000
Commit:     Kenton Groombridge <[e-mail]>
CommitDate: 2022-08-31 14:50:18 +0000

    net-voip/mumble: fix ODR violations
    
    Closes: https://bugs.gentoo.org/861866
    Signed-off-by: Kenton Groombridge <[e-mail]>

 net-voip/mumble/Manifest                                            | 1 +
 net-voip/mumble/{mumble-1.4.274.ebuild => mumble-1.4.274-r1.ebuild} | 6 ++++--
 2 files changed, 5 insertions(+), 2 deletions(-)