[Pkg-rust-maintainers] Bug#1134157: Bug#1134157: rustc-src: impossible to satisfy crate dependencies

[Fabian Grünbichler]

Control: severity -1 wishlist
Control: tag -1 +moreinfo

On Fri, Apr 17, 2026, at 9:18 AM, Jonas Smedegaard wrote:
> Source: rustc
> Version: 1.94.1+dfsg1-1~exp3
> Severity: grave

I am not sure what this severity is supposed to mean, given the lack of
justification ;) Downgrading accordingly, but I am willing to reconsider if you
provide a reason.

> In package rust-src, /usr/src/rustc-1.94.1/Cargo.lock and
> usr/src/rustc-1.94.1/library/Cargo.lock are locked at crate
> versions unsatifiable in Debian, e.g. rustc-demangle 0.1.26 and
> object 0.37.3.
>
> Also, /usr/src/rustc-1.94.1/library/std/Cargo.toml requires
> newer-than-Debian crate including object 0.37.1, and
> missing-in-Debian crates including dlmalloc and wasi.

This is intentional. rustc and libstd/libcore are not built using packaged
crates, so the code shipped in rust-src cannot either.

The purpose of rust-src is (at the moment) twofold:
- allow navigating into libstd/libcore sources for IDE and editor integration,
  e.g. via rust-analyzer (as per the package description)
- allow using `-Zbuild-std` when using *just the toolchain* (by pretending to
  be nightly rustc via RUSTC_BOOTSTRAP)

Neither of this requires matching rust-src dependency information with packaged
crates, the latter in fact would not work at all in that case unless rustc
packaging itself is switched over to use packaged crates, which is not really
feasible.

I hope this clears things up, if not - please clearly describe what you want to
do and what doesn't work, maybe we can find a solution.

Thanks,
Fabian