nixpkgs/pkgs/build-support/fetchgit/builder.sh
Maximilian Bosch 8bc5104a6e
treewide: refactor .attrs.sh detection
When specifying the `builder` attribute in `stdenv.mkDerivation`, this
will be effectively transformed into

    builtins.derivation {
      builder = stdenv.shell;
      args = [ "-e" builder ];
    }

This also means that `default-builder.sh` is never sourced and as a
result it's not guaranteed that `$NIX_ATTRS_SH_FILE` is set to a correct
location[1].

Also, we need to source `.attrs.sh` to source `$stdenv`. So, the
following is done now:

* If `$NIX_ATTRS_SH_FILE` points to a correct location, then use it.
  Directly using `.attrs.sh` is problematic for `nix-shell(1)` usage
  (see previous commit for more context), so prefer the environment
  variable if possible.

* Otherwise, if `.attrs.sh` exists, then use it. See [1] for when this
  can happen.

* If neither applies, it can be assumed that `__structuredAttrs` is
  turned off and thus nothing needs to be done.

[1] It's possible that it doesn't exist at all - in case of Nix 2.3 or
    it can point to a wrong location on older Nix versions with a bug in
    `__structuredAttrs`.
2023-10-04 18:36:57 +02:00

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# tested so far with:
# - no revision specified and remote has a HEAD which is used
# - revision specified and remote has a HEAD
# - revision specified and remote without HEAD
#
if [ -e "$NIX_ATTRS_SH_FILE" ]; then . "$NIX_ATTRS_SH_FILE"; elif [ -f .attrs.sh ]; then . .attrs.sh; fi
source $stdenv/setup
echo "exporting $url (rev $rev) into $out"
$SHELL $fetcher --builder --url "$url" --out "$out" --rev "$rev" \
${leaveDotGit:+--leave-dotGit} \
${fetchLFS:+--fetch-lfs} \
${deepClone:+--deepClone} \
${fetchSubmodules:+--fetch-submodules} \
${sparseCheckout:+--sparse-checkout "$sparseCheckout"} \
${nonConeMode:+--non-cone-mode} \
${branchName:+--branch-name "$branchName"}
runHook postFetch