I highly recommend this article written by my colleagues Serge Guelton and Yannis Juglaret about a truly hard-to-parse issue that affected #Firefox users on old Ubuntu installations.

It's a cautionary tale about how complex builds can be affected by subtle compiler/linker flags. Also, C++ is hard and making modern C++ work on older platforms is painful and full of pitfalls.

https://hacks.mozilla.org/2024/01/option-soup-the-subtle-pitfalls-of-combining-compiler-flags/

Option Soup: the subtle pitfalls of combining compiler flags - Mozilla Hacks - the Web developer blog

During the Firefox 120 beta cycle, a new crash signature appeared on our radars. Engineers explored the pitfalls of combining compiler flags.

^{Serge Guelton (Mozilla Hacks - the Web developer blog)}