Most stdenv wrappers already work like this -- it allows greater
customisation. We just have to be careful to remove arguments we're
using that shouldn't be passed to stdenv. I've been conservative
here, because fetchcargo checksums shouldn't change lightly.
The previous lines were only different in the kind of dependencies but
otherwise exactly the same. It makes the entire thing a bit more
readable by moving this into a function that takes care of this.
We can get rid of a bunch of workarounds that were in the build script
before by just passing on the `crateBin` attribute.
Before we converted the list of attributes to a string only to convert
it back in bash during the build phase. We can do the entire looping
through builds in Nix and thus need no conversion and parsing of
attributes over and over again.
The big part that still remains bash is the heuristic that cargo
introduced and that we can't do at eval time.
That code had been in the derivation for a while but no explanation was
given why that is needed. It might be helpful to our future selfs to
document why things are done the way they are.
The expression is already long and confusing enough without the color
stuff sprinkled in. Moving it to a dedicated file makes sense.
I switched a bit of the color support code to pure Nix since there
wasn't much point in doing that in bash while we can just do it in Nix.
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.
This cuts down the dependency tree on some rust builds where a crate not
just exposes a binary but also a library. `$out/lib` contained a bunch
of extra support files that among other information carry linker flags
(including the full path to link-time dependencies). Worst case this led
to some binary outputs depending on the full build closure of rust
crates.
Moving all the `$out/lib` files to `$lib/lib` solves this nicely.
`lib` might be a bit weird here as they are most of the time just rlib
files (rust libraries). Those are essential only required during
compilation but they can also be shared objects (like with traditional
C-style packages). Which is why I went with `lib` for the new output.
One of the caveats we are running into here is that we do not (always)
know ahead of time of a crate produces just a library or just a binary.
Cargo allows for some ambiguity regarding whether or not a crate
provides one, two, … binaries and libraries as it's outputs. Ideally we
would be able to rely on the `crateType` entirely but so far that isn't
the case. More work on that area might show how difficult that actually
is.
One issue with cargoSha256 is that it's hard to detect when it needs to
be updated or not. It's possible to upgrade a package and forget to
update cargoSha256 and run with old versions of the program or
libraries.
This commit introduces `verifyCargoDeps` which, when enabled, will check
that the Cargo.lock is not out of date in the cargoDeps by comparing it
with the package source.
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.
