Expose builtins.fetchFinalTree to the user #14634
Draft
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
We don't care if the user (or more likely the lock file) specifies an incorrect value for revCount, since it doesn't matter for security (unlikely content hashes like narHash).
Same as revCount.
builtins.fetchTree was setting `shallow = true` when fetching from git. That's bad because it makes it behave inconsistently from non-fetchTree fetches, e.g. when updating an input. Instead, the Git fetcher now will do a shallow fetch automatically if `revCount` is already set (e.g. when fetching a lock). Fixes #14588.
This fixes the issue where updating a Git input does a non-shallow fetch, and then a subsequent eval does a shallow refetch because the revCount is already known. Now the subsequent eval will use the repo used in the first fetch.
This may be more efficient than fetchTree since it allows substitution from binary caches if `narHash` is specified in the input attributes. This is what call-flake.nix already used internally.
github-actions
bot
added
with-tests
roberth
reviewed
Dec 7, 2025
Comment on lines
+368
to
+369
| Like `fetchTree`, but does not return any additional fetcher attributes (like `revCount`). | ||
| This allows inputs to be substituted if `narHash` is specified. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Motivation
This may be more efficient than
fetchTreesince it allows substitution from binary caches ifnarHashis specified in the input attributes. This is whatcall-flake.nixalready used internally.Depends on #14633.
Corresponding PR to flake-compat: NixOS/flake-compat#79
Context
Add 👍 to pull requests you find important.
The Nix maintainer team uses a GitHub project board to schedule and track reviews.