We keep running into situations where we can't get the right
combination of rustc flags through build systems into rustc.
RUSTFLAGS is the only variable supported across build systems, but if
RUSTFLAGS is set, Cargo will ignore all other ways of specifying rustc
flags, including the target-specific ones, which we need to make
dynamic musl builds work. (This is why pkgsCross.musl64.crosvm is
currently broken — it works if you unset separateDebugInfo, which
causes RUSTFLAGS not to be set.)
So, we need to do the same thing we do for C and C++ compilers, and
add a compiler wrapper so we can inject the flags we need, regardless
of the build system.
Currently the wrapper only supports a single mechanism for injecting
flags — the NIX_RUSTFLAGS environment variable. As time goes on,
we'll probably want to add additional features, like target-specific
environment variables.
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.
Rust is not yet able to target the n32 ABI on mips64.
Let's add `isMips64n32` to the `meta.badPlatforms` of all
derivations created by buildRustPackage.
I use this to automatically detect which packages on my system can
be built for n32 (almost all of them) and build those using n32, and
the few packages (mainly those that depend on boost or rust) that
can't for n64.
Rust is not yet able to target the n32 ABI on mips64.
Let's add `isMips64n32` to the `meta.badPlatforms` of all
derivations created by buildRustCrate.
I use this to automatically detect which packages on my system can
be built for n32 (almost all of them) and build those using n32, and
the few packages (mainly those that depend on boost or rust) that
can't for n64.
Cargo will never need to link for the target platform — that'd be for
the package being built to do at runtime. Cargo should know about the
build and host linkers.
This fixes e.g. pkgsCross.musl64.fd from x86_64-linux.
Fixes: 67a4f828b4 ("rust: hooks: fix cross compilation")
This upgrade unfortunately removes MIPS support, as it has been
dropped to Tier 3[1] and so bootstrap tarballs are no longer provided.
It looks like it was dropped due to multiple codegen bugs, and lack of
maintenance, so bringing it back would probably involve engaging with
Rust/LLVM upstream on those.
[1]: https://github.com/rust-lang/compiler-team/issues/648
> 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.
Currently there is a state of severe confusion in
pkgs/build-support/rust/hooks/ regarding host vs target; right now
there is only "host" defined, but whether it means "host" or
"target" seems to fluctuate.
This commit corrects that, ensuring that all variables come in all
three flavors (build, host, target) and are used consistently with
the nixpkgs convention.
This also fixes the cross-compilation of packages which use
`maturinBuildHook` -- hooks go in `nativeBuildInputs` and are
phase-shifted backwards by one platform, so they need to be careful
about distinguishing between build and host.
Closes#247441
armv6l-linux was incorrectly added to the list of platforms without host
tools in #227987. arm-unknown-linux-gnueabihf is present in the list of
Tier 2 targets with host tools, and this target corresponds to our
armv6l-linux platform.
Members of the [package] table in Cargo.toml can be either subtables, or
values like strings and bools. Python is happy to check for membership
of "workspace" in a string, since Python strings are iterables, but if
the value is a bool, Python will throw an exception.
rustc supports way more platforms than Linux and Darwin. We might not
be able to build it for every platform at the moment, but that's what
meta.broken is for.
There are other platforms that rustc can produce binaries for, but
can't run on itself, so those are listed in the defaults for
buildRustPackage.
