comparison to LLVM libc and its use cases and more advanced linking use cases

[matu3ba]

Video of LLVM libc: https://www.youtube.com/watch?t=38&v=OpY4lnpnbq4&feature=youtu.be
tldr;

• link order variable to overwrite system libs or prefer system libs.
• configurable (perf, size) only use what you need

more advanced linking use cases for which SONAME sounds useful once you get into dynamic linking (libstd linker script support?).
https://fzakaria.com/2022/09/12/making-runpath-redundant-for-nix.html
https://www.youtube.com/watch?v=HZKFe4mCkr4
tldr;

• 1. RUN_PATH / LD_LIBRARY_PATH currently still used, even though nix has the complete dependency graph and could use SONAME. Could we do the same for packages "that we control" ? Can we patch SONAME for abi compatibility?
• 2. Storing the elf info not in a file, but make it distributable sounds potentially advanterous. No idea for outside nix, but might be lit for folks hacking on nix or linkers in general.
• 3. "nix needs its own dynamic linker".
     QA: Extending elf too cumbersome.

Point 1 sounds like a startup perf optimization. Point 2 sounds like a subset of your database lookup for multi-target versioning (for elf info). Point 3 added for completeness.