bug#74217: Bootstrapping Zig with no Binary Blobs

[Efraim Flashner]

On Thu, Nov 14, 2024 at 05:22:17PM +0800, Hilton Chain wrote:
> On Thu, 14 Nov 2024 14:05:52 +0800,
> Hilton Chain wrote:
> >
> > Currently I'm 1. modifying each-lib-rpath option of 'zig build'.  2. passing
> > libc to linker.  I'll write details on this when succeed.
> 
> 1. Modification about each-lib-rpath.
> --8<---------------cut here---------------start------------->8---
> -feach-lib-rpath               Ensure adding rpath for each used dynamic 
> library
> --8<---------------cut here---------------end--------------->8---
> 
> This option is on implicitly for native builds.  This implicity is what our 
> Zig
> currently solely relies on.
> 
> I'm modifying it so that it's also on when CROSS_LIBRARY_PATH or LIBRARY_PATH 
> is
> set.  This approach is better than my previous one since it only adds needed
> libraries.
> 
> 
> 2. Pass libc to Zig's linker
> This was the behavior in 0.9, but changed due to issue on macOS[1].  (btw, our
> CPLUS_INCLUDE_PATH also has issue with macOS target[2]).  RUNPATH for glibc 
> was
> missing because of this, since it's the linker handling each-lib-rpath.
> 
> Since we do not support macOS anyway, can we restore this behavior?

At worst I could see adding a comment that it would likely break future
macOS cross-compiles.  I don't see an issue with either putting it back
unconditionally or trying to make it conditional based on
(%current-system) or the contents of (%current-target-system).

> 
> I also have concern for Zig's relying on /usr/bin/env (Zig uses an ELF file to
> find dynamic linker, env is chosen for it's well-known).  We have patched this
> reference, not sure if it will cause issue for cross-building Zig.

We use search-input-file in the replacement, so it should choose the
cross-binutils for the replacement /bin/env, so it shouldn't be a
problem.

> 
> Thanks
> ---
> [1]: https://github.com/ziglang/zig/issues/10765
> [2]: https://github.com/ziglang/zig/issues/18063

-- 
Efraim Flashner   <efraim@flashner.co.il>   אפרים פלשנר
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