Some programs (e.g. nvfetcher) parse the output of nix-prefetch-git as
JSON. However, there is a pushd/popd command in nix-prefetch-git that
outputs the directory name, breaking the structure of the result JSON.
We suppressed it with `>/dev/null`.
Passingly fixes a mixuse of tab and spaces.
This script needs to support being run both as part of a `fetchgit`
derivation and as a standalone, command-line tool.
The use of `$NIX_BUILD_TOP` only works when used in `fetchgit` but not when
invoked as a standalone tool. Instead we try to respect `$NETRC` so that
the command-line invocation behaves more like standard tools and the
`fetchgit` derivation can explicitly set `$NETRC` when `netrcPhase` is used
to avoid all ambiguity.
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.
Before this commit, cc-wrapper/default.nix was using
`isGccArchSupported` to validate `-mtune=` values. This has two
problems:
- On x86, `-mtune=` can take the same values as `-march`, plus two
additional values `generic` and `intel` which are not valid for
`-march`.
- On ARM, `-mtune=` does not take the same values as `-march=`;
instead it takes the same values as `-mcpu`.
This commit fixes these two problems by adding a new
`isGccTuneSupported` function. For `isx86` this returns `true` for
the two special values and otherwise defers to `isGccArchSupported`.
This commit also adds support for `-mtune=` on Aarch64.
Unfortunately on Aarch64, Clang does not accept as wide a variety of
`-mtune=` values as Gcc does. In particular, Clang does not tune
for big.LITTLE mixed-model chips like the very popular RK3399, which
is targeted using `-march=cortex-a72.cortex-a53` in gcc.
To address this problem, this commit also adds a function
`findBestTuneApproximation` which can be used to map
clang-unsupported tunings like `cortex-a72.cortex-a53` to
less-precise tunings like `cortex-a53`.
The work which led to this commit arose because we now have
packages, like `crosvm`, which use *both* `clang` *and* `gcc`.
Previously I had been using `overrideAttrs` to set
`NIX_CFLAGS_COMPILE` on a package-by-package basis based on which
compiler that package used. Since we now have packages which use
*both* compilers, this strategy no longer works.
I briefly considered splitting `NIX_CFLAGS_COMPILE` into
`NIX_CFLAGS_COMPILE_GCC` and `NIX_CFLAGS_COMPILE_CLANG`, but since
`NIX_CFLAGS_COMPILE` is sort of a hack to begin with I figured that
adding the logic to `cc-wrapper` would be preferable.
