rustPlatform.importCargoLock: add allowBuiltinFetchGit option

doc/languages-frameworks/rust.section.md

@@ -186,6 +186,23 @@ added. To find the correct hash, you can first use `lib.fakeSha256` or
 `lib.fakeHash` as a stub hash. Building the package (and thus the
 vendored dependencies) will then inform you of the correct hash.
 
+For usage outside nixpkgs, `allowBuiltinFetchGit` could be used to
+avoid having to specify `outputHashes`. For example:
+
+```nix
+rustPlatform.buildRustPackage rec {
+ pname = "myproject";
+ version = "1.0.0";
+
+ cargoLock = {
+ lockFile = ./Cargo.lock;
+ allowBuiltinFetchGit = true;
+ };
+
+ # ...
+}
+```
+
 ### Cargo features {#cargo-features}
 
 You can disable default features using `buildNoDefaultFeatures`, and

pkgs/build-support/rust/import-cargo-lock.nix

@@ -7,6 +7,9 @@
  # Cargo lock file contents as string
 , lockFileContents ? null
 
+ # Allow `builtins.fetchGit` to be used to not require hashes for git dependencies
+, allowBuiltinFetchGit ? false
+
  # Hashes for git dependencies.
 , outputHashes ? {}
 } @ args:
@@ -38,14 +41,14 @@ let
  # There is no source attribute for the source package itself. But
  # since we do not want to vendor the source package anyway, we can
  # safely skip it.
- depPackages = (builtins.filter (p: p ? "source") packages);
+ depPackages = builtins.filter (p: p ? "source") packages;
 
  # Create dependent crates from packages.
  #
  # Force evaluation of the git SHA -> hash mapping, so that an error is
  # thrown if there are stale hashes. We cannot rely on gitShaOutputHash
  # being evaluated otherwise, since there could be no git dependencies.
- depCrates = builtins.deepSeq (gitShaOutputHash) (builtins.map mkCrate depPackages);
+ depCrates = builtins.deepSeq gitShaOutputHash (builtins.map mkCrate depPackages);
 
  # Map package name + version to git commit SHA for packages with a git source.
  namesGitShas = builtins.listToAttrs (
@@ -117,12 +120,20 @@ let
  If you use `buildRustPackage`, you can add this attribute to the `cargoLock`
  attribute set.
  '';
- sha256 = gitShaOutputHash.${gitParts.sha} or missingHash;
- tree = fetchgit {
- inherit sha256;
- inherit (gitParts) url;
- rev = gitParts.sha; # The commit SHA is always available.
- };
+ tree =
+ if gitShaOutputHash ? ${gitParts.sha} then
+ fetchgit {
+ inherit (gitParts) url;
+ rev = gitParts.sha; # The commit SHA is always available.
+ sha256 = gitShaOutputHash.${gitParts.sha};
+ }
+ else if allowBuiltinFetchGit then
+ builtins.fetchGit {
+ inherit (gitParts) url;
+ rev = gitParts.sha;
+ }
+ else
+ missingHash;
  in runCommand "${pkg.name}-${pkg.version}" {} ''
  tree=${tree}