Bug#1119850: netpbm-free: FTBFS on arm* (testsuite error) with gcc-15

[Andreas Metzler]

On 2025-11-01 Andreas Metzler <ametzler at bebt.de> wrote:
> On 2025-11-01 Andreas Metzler <ametzler at bebt.de> wrote:
>> Source: netpbm-free
>> Version: 2:11.11.01-1
>> Severity: serious
>> Tags: ftbfs
>> Justification: fails to build from source (but built successfully in the past)
>> X-Debbugs-Cc: debian-arm at lists.debian.org
>> User: debian-arm at lists.debian.org
>> Usertags: arm64 armel armhf

>> netpbm-free (both the version in forky and the current version in sid)
>> FTBFS with segfaults when running the testsuite. There is only a single
>> segfault on arm64 (stdin-pam1.test, when running pamtilt)) and multiple
>> ones on armel armhf.

>> I have tried debugging on amdahl.debian.org:
>> This started with the upgrade to gcc-15, building with gcc-14 still
>> works.
>> Building with -O0 or -O1 (instead of -O2) makes the problem go away.
>> The exact failing command on arm64 is
>> analyzer/pamtilt /path/to/small.pbm

>> (small.pbm is generated with 
>> ./generator/pbmmake -g 5 5 > /path/to/small.pbm
>> attached for simplicity)
> [...]

> Disabling optimization just for parseCommandLine() ...

> #pragma GCC push_options
> #pragma GCC optimize ("O0")
> static void
> parseCommandLine(... 
> #pragma GCC pop_options

> ... lets the arm64 build succeed.

Also setting either no-schedule-insns2 or no-strict-aliasing for this
function (instead of O1) for a -O2 build lets the arm64 build succeed.

cu Andreas

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