Seeing the following new warnings pop up on stderr when cargo was bumped
to 1.78:
```
warning: `/build/.cargo/config` is deprecated in favor of `config.toml`
note: if you need to support cargo 1.38 or earlier, you can symlink `config` to `config.toml`
```
which happens to break commitmsgfmt builds in nix (#320294).
closes#320294
Seeing the following new warnings pop up on stderr when cargo was bumped
to 1.78:
```
warning: `/build/.cargo/config` is deprecated in favor of `config.toml`
note: if you need to support cargo 1.38 or earlier, you can symlink `config` to `config.toml`
```
which happens to break commitmsgfmt builds in nix (#320294).
closes#320294
unpackFile doesn't dereference symlinks if cargoDeps is a directory, and
some cargo builds run into permission issues because the files the
symlinks point to are not writable.
Currently cargo-setup-hook instructs the builder upon cargoSha256 or
cargoHash being out-of-date compared to the Cargo.lock file.
The instructions can be simplified a bit, because nowadays it is fine to
keep a hash empty, instead of filling it with
`0000000000000000000000000000000000000000000000000000`.
Nix nowadays outputs SRI hashes, which should usually be placed in
`cargoHash` instead of `cargoSha256`, but the instructions are still
only referring to `cargoSha256`.
Lastly, the output of Nix doesn't include `got: sha256: ` anymore, as it
now outputs `got: sha256-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX=`.
It would be nice to make it clear that the trailing `=` is important as
well, so the full example SRI hash is mentioned.
This change switches to using GCC 11 by default on aarch64-linux, as well as passing `-lgcc` to the linker, per #201485.
See #201254 and #208412 for wider context on the issue.
This breaks the builder when a nix-shell or keepBuildTree is used. The
issue occurs because paths to cargo lockfiles are read with NIX_BUILD_TOP,
which is not reliable.
This breaks a nix-shell because NIX_BUILD_TOP simply is not set, causing
an invalid path to be used. This can be worked around using
NIX_BUILD_TOP=$PWD, but that obviously is not great.
This breaks keepBuildTree because it changes the working directory to a
different path than NIX_BUILD_TOP. Since the lockfiles are copied based
on the working directory, but read based on NIX_BUILD_TOP, this causes
the hook to not be able to find them.
This was solved by both reading these files based on the working directory,
using absolute paths to avoid having to traverse back in the directory tree.
Fixes: #138554
