3.3.x regression: SDL_image's showimage example segfaults on s390x (64-bit big endian)

[smcv]

The Debian packaging for SDL_image has an automated smoke-test which copies out its showimage example into a temporary directory, compiles it, and runs it with the -save and -quit options. This is mainly done to check that the packaging for the development files (-dev package) is usable, but it has the side-effect of doing a simple functional test on the libraries use.d

When using SDL 3.2.x from Debian testing/unstable, this works fine on all of Debian's supported architectures, even s390x (a 64-bit big-endian IBM mainframe). However, when using SDL 3.3 git snapshots (which are packaged in Debian experimental to get early-warning of any regressions) on s390x, the resulting showimage program crashes with a segfault:

 62s + xvfb-run -a -s -screen 0 1280x1024x24 -noreset ./showimage -quit -save debian-logo.bmp debian-logo.png
 62s Segmentation fault

I'll try to get a backtrace for this from a Debian-developer-accessible s390x machine. I don't know whether a precompiled showimage would exhibit the same problem, or whether this is specific to recompiling it - at the moment the smoke-test only tries doing the latter.

s390x-specific bugs are usually because it's a big-endian architecture, unlike everything else that's still relevant in 2025.

[slouken]

Yes, a stack trace would be helpful, thanks!

[smcv]

Unfortunately I was unable to reproduce this in an interactive test environment. It is still reproducible in the non-interactive test environment (on a remote machine that I can't access), so I'll have to try uploading a version that runs the test under gdb, and see whether I can get a backtrace non-interactively that way.