Building with "-flto=auto" causes apps to crash
In openSUSE all packages have by default enabled LTO (but in cases like this it can be easily disabled). Fortunately this is caught by the tests, because helpers/helper_accept_no_peer_addr crashes and a test fails.
This is probably because we're using a custom --version-script:
https://github.com/nixcloud/ip2unix/blob/1083369be4c2a09256f06507bacdf2accadd8d78/meson.build#L85-L92
~~Okay, just tested this and it's not because of the --version-script,~~ investigating...
Sooo, this essentially boils down to a nullptr dereference because the symbols actually resolve to null:
With LTO:
$ nm -D result/lib/libip2unix.so | grep socket
0000000000000000 A socket
Without LTO:
$ nm -D result/lib/libip2unix.so | grep socket
000000000000fed0 T socket
Okay, backtracking on what I wrote earlier, it is the linker script indeed. I accidentally run a isolated test which ran into essentially a no-op without the linker script.