Bofore this change, NUM_JOBS was set to 1. Some crates for building
C/C++ code (e.g. the cc and cmake crates), rely on this variable to
set the number of jobs. As a consequence, we were compiling embedded
libraries serially. Change this to NIX_BUILD_CORES to permit parallel
builds.
Prior discussion:
https://github.com/NixOS/nixpkgs/pull/50452#issuecomment-439407547
Cargo sets `CARGO_FEATURE_*` for all features when running a build
script:
https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-build-scripts
Some crates have build scripts (e.g. openblas-src) that rely on the
feature variables being properly set.
Since we now need several representations of features, this change
also updates `createFeatures` to be a list of features, rather than
`rustc` feature arguments. `configureCrate` and `buildCrate` then
build the required representations as-needed.
Fixes#68978
According to the Cargo documentation:
> The build script does not have access to the dependencies listed in
> the dependencies or dev-dependencies section (they’re not built
> yet!). Also, build dependencies are not available to the package
> itself unless also explicitly added in the [dependencies] table.
https://doc.rust-lang.org/cargo/reference/build-scripts.html
This change separates linkage of regular dependencies and build
dependencies.
* Make errors include the crate name and make them much more prominent.
* Move more code into lib.sh
* Already source generated logging code and lib.sh in configure
We can just use `lib` instead of `builtins` in all cases but the
`hashString` case. Also changed a few lines to make use of some optional
helpers from lib.
Quoting from the splitString docstring:
NOTE: this function is not performant and should never be used.
This replaces trivial uses of splitString for splitting version
strings with the (potentially builtin) splitVersion.
Before this change, buildRustCrate always called rustc with
--extern libName=[...]libName[...]
However, Cargo permits using a different name under which a dependency
is known to a crate. For example, rand 0.7.0 uses:
[dependencies]
getrandom_package = { version = "0.1.1", package = "getrandom", optional = true }
Which introduces the getrandom dependency such that it is known as
getrandom_package to the rand crate. In this case, the correct extern
flag is of the form
--extern getrandom_package=[...]getrandom[...]
which is currently not supported. In order to support such cases, this
change introduces a crateRenames argument to buildRustCrate. This
argument is an attribute set of dependencies that should be renamed. In
this case, crateRenames would be:
{
"getrandom" = "getrandom_package";
}
The extern options are then built such that if the libName occurs as
an attribute in this set, it value will be used as the local
name. Otherwise libName will be used as before.
While it is not obvious from the source, cargo sets CARGO_MANIFEST_DIR to an absolute directory. This let to a build problem with the popular "tera" crate using the "pest" crate.
## Cargo details
The variable is set here:
f7c91ba622/src/cargo/core/compiler/compilation.rs (L229)
and computed from the `manifest_path`:
f7c91ba622/src/cargo/core/package.rs (L163)
The manifest path is also exported via `cargo metadata` where you can see that it is absolute.
The build expression got quiet large over time and to make it a bit
easier to grasp the different scripts involved in the build are now
separated from the nix file.
