Bug 877711 – =media-libs/zvbi-0.2.35-r2: undefined behavior with aggressive loop optimizations

• Status: UNCONFIRMED
• Product: Gentoo Linux

[Description Jocelyn Mayer 2022-10-20 05:26:22 UTC]

While building zvbi using gcc (clang untested) with
 -faggressive-loop-optimizations CFLAG set, I get this kind of message:
iteration 24 invokes undefined behavior in src/xds_demux.c

Then, forcing adding -fno-aggressive-loop-optimizations
and -fno--unsafe-loop-optimizations too all flags (for safety) solves the issue.

Reproducible: Always

Steps to Reproduce:
1.Put -faggressive-loop-optimizations -Wno-aggressive-loop-optimizations in compilation flags
2. Emerge media-libs/zvbi
3. See the output
Actual Results:  
I got the 'undefined behavior' warning message

Expected Results:  
It seems better not to have any undefined behavior.

Seems like it has been long reported upstream:
https://sourceforge.net/p/zapping/bugs/201/

[Comment 1 Jocelyn Mayer 2022-10-20 05:28:10 UTC]

Created attachment 824823 [details]
Output from emerge --info =media-libs/zvbi-0.2.35-r2

[Comment 2 Jocelyn Mayer 2022-10-20 05:29:10 UTC]

Created attachment 824825 [details]
Emerge failure build log

[Comment 3 Jocelyn Mayer 2022-10-20 05:30:50 UTC]

The thing I did to solve this issue is to create a file in /etc/portage/env with the following and use it for zvbi adding a reference in /etc/portage/package.env

ADD_FLAGS="-fno-aggressive-loop-optimizations -fno-unsafe-loop-optimizations"
CFLAGS="${CFLAGS} ${ADD_FLAGS} "
CXXFLAGS="${CXXFLAGS} ${ADD_FLAGS}"
FCFLAGS="${FCFLAGS} ${ADD_FLAGS}"
FFLAGS="${FFLAGS} ${ADD_FLAGS}"
LDFLAGS="${LDFLAGS} ${ADD_FLAGS}"