In preparation for the deprecation of `stdenv.isX`.
These shorthands are not conducive to cross-compilation because they
hide the platforms.
Darwin might get cross-compilation for which the continued usage of `stdenv.isDarwin` will get in the way
One example of why this is bad and especially affects compiler packages
https://www.github.com/NixOS/nixpkgs/pull/343059
There are too many files to go through manually but a treewide should
get users thinking when they see a `hostPlatform.isX` in a place where it
doesn't make sense.
```
fd --type f "\.nix" | xargs sd --fixed-strings "stdenv.is" "stdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "stdenv'.is" "stdenv'.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "clangStdenv.is" "clangStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "gccStdenv.is" "gccStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "stdenvNoCC.is" "stdenvNoCC.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "inherit (stdenv) is" "inherit (stdenv.hostPlatform) is"
fd --type f "\.nix" | xargs sd --fixed-strings "buildStdenv.is" "buildStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "effectiveStdenv.is" "effectiveStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "originalStdenv.is" "originalStdenv.hostPlatform.is"
```
This focuses on Rust packages, since the most commonly used argument
parser library (clap/structopt) makes the following pattern natural and
thus common:
postInstall = ''
installShellCompletion --cmd foo \
--bash <($out/bin/foo completion bash) \
…
This commit just guards those with
lib.optionalString (stdenv.buildPlatform.canExecute stdenv.hostPlatform)
splitting the string where unrelated actions are performed.
I don't see a reason to override this and with -Dauto_features=enabled (from
our meson setup-hook) the build breaks without explicitly passing -Dxps=disabled.
Otherwise references to the Python interpreter inside the set are wrong, as demonstrated by:
``` nix
with import <nixpkgs> { };
let
python' = python3.override {
packageOverrides = final: prev: { requests = prev.requests.overridePythonAttrs(old: { version = "1337"; }); };
};
in python'.pkgs.python.pkgs.requests
```
which returns the _non_ overriden requests.
And the same with `self`:
```
with import <nixpkgs> { };
let
python' = python3.override {
self = python';
packageOverrides = final: prev: { requests = prev.requests.overridePythonAttrs(old: { version = "1337"; }); };
};
in python'.pkgs.python.pkgs.requests
```
which returns the overriden requests.
This can manifest itself as file collisions when constructing environments or as subtly incorrect dependency graphs.
