reproducible builds issue

[bmwiedemann]

While working on reproducible builds for openSUSE (sponsored by the NLnet NGI0 fund), I found that our pop-launcher package build produces different results between a 1-core-VM and a VM with 2+ cores. This could be an indicator of some race-condition or poorly defined build-dependencies.

https://rb.zq1.de/other/pop-launcher/strings.diff.txt
shows that some symbols have variations in the ID at the end.
e.g.

-_ZN4core3ptr43drop_in_place$LT$zvariant..value..Value$GT$17he5bf3c79d5d19a4aE.28032
+_ZN4core3ptr43drop_in_place$LT$zvariant..value..Value$GT$17he5bf3c79d5d19a4aE.28050

The two full binaries are also available in the same directory.

[mmstick]

Rust projects will always have different binaries when building with a different number of codegen units. You can configure your build system to 1 if you want it to use only one.

[bmwiedemann]

Indeed. #231 seems to avoid that issue.

Others do the same already:

• https://github.com/getzola/zola/blob/b97f8a1/Cargo.toml#L62
• https://github.com/sharkdp/bat/blob/6fc5882/Cargo.toml#L123
• https://gitlab.gnome.org/GNOME/loupe/-/blob/ff869412/Cargo.toml#L10