The unwrapped version doesn't know where to look for libraries, so
this is required to e.g. build anything that uses openssl-sys with
OPENSSL_NO_VENDOR. A randomly chosen example package that's fixed by
this change is pkgsStatic.gitoxide.
We're already using pkgsBuildBuild, and we'll soon be using
pkgsBuildTarget, so for consistency, change buildPackages and
targetPackages to their corresponding two-component names.
We need this stuff to be available in lib so make-derivation.nix can
access it to construct the Meson cross file.
This has a couple of other advantages:
- It makes Rust less special. Now figuring out what Rust calls a
platform is the same as figuring out what Linux or QEMU call it.
- We can unify the schema used to define Rust targets, and the schema
used to access those values later. Just like you can set "config"
or "system" in a platform definition, and then access those same
keys on the elaborated platform, you can now set "rustcTarget" in
your crossSystem, and then access "stdenv.hostPlatform.rustcTarget"
in your code.
"rustcTarget", "rustcTargetSpec", "cargoShortTarget", and
"cargoEnvVarTarget" have the "rustc" and "cargo" prefixes because
these are not exposed to code by the compiler, and are not
standardized. The arch/os/etc. variables are all named to match the
forms in the Rust target spec JSON.
The new rust.target-family only takes a list, since we don't need to
worry about backwards compatibility when that name is used.
The old APIs are all still functional with no warning for now, so that
it's possible for external code to use a single API on both 23.05 and
23.11. We can introduce the warnings once 23.05 is EOL, and make them
hard errors when 23.11 is EOL.
> If using a target spec JSON file, the <triple> value is the filename
> stem. For example --target foo/bar.json would match [target.bar].
- https://doc.rust-lang.org/cargo/reference/config.html#target
I've also exposed toRustTargetSpecShort as a public function, because
it's useful to be able to know what the target subdirectory will be.
Used in cases where you need to get the vendor of a target. Such as when
you need to perform dependency resolution outside of Cargo (eg in
Kolloch's crate2nix).
`toTargetArch` in `pkgs/build-support/rust/lib/default.nix` is used to
set `CARGO_CFG_TARGET_ARCH`. This environment variable is supposed to
be the `<arch>` portion of an LLVM-style platform name:
```
<arch><sub>-<kernel>-<libc><abi>
```
Note that the pointer-width (the "64" in "x86_64" and "mips64") is
part of `<arch>`, but the endianness (the `_be` in `aarch64_be`) is
*not*.
Unfortunately at the moment nixpkgs' parsed `cpuType` has no way to
query for the three subparts (name, pointer-width, and
subarch/endianness), nor any way to ask for just the first two parts.
For now, this commit simply fixes the problem in the two cases that
matter: `mips64el` and `powerpc64le`, which I believe are the only two
platforms supported by both rust and nixpkgs which have a
"subarchitecture".
- `toRustTarget` and friends pulled out from rust tools into rust
library. Since they don't depend on any packages they can be more
widely useable.
- `build-rust-package` gets its own directory
- `fetch-cargo-tarball` gets its own directory
