By using testProjectFile, we can properly build the test and run it in
checkPhase, as well as not include the test in the derivation output.
This also happens to fix the startup crash as described in #345038.
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"
```
Instead of creating a nuget.config in NIX_BUILD_TOP, and depending on
inheritance from sourceRoot, we'll make the required changes directly in
the latter. This fixes packages where sourceRoot is NIX_BUILD_TOP.
This is done with the following bash script:
```
#!/usr/bin/env bash
process_line() {
local filename=${1%:}
if [[ $4 =~ \"(.*)\"\; ]]; then
local sha256="${BASH_REMATCH[1]}"
fi
[[ -z $sha256 ]] && return 0
local hash=$(nix hash to-sri --type sha256 $sha256)
echo "Processing: $filename"
echo " $sha256 => $hash"
sed -i "s|cargoSha256 = \"$sha256\"|cargoHash = \"$hash\"|"
$filename
}
# split output by line
grep -r 'cargoSha256 = ' . | while IFS= read -r line; do
# split them further by space
read -r -a parts <<< "$line"
process_line "${parts[@]}"
done
```