🐛 fix(builder): validate backend-path entries exist on disk#1016
Merged
gaborbernat merged 2 commits intoApr 9, 2026
Conversation
Early-fail with a clear error when backend-path entries in pyproject.toml don't exist or aren't directories, instead of surfacing an opaque BackendUnavailable from the subprocess. Closes pypa#145
gaborbernat
force-pushed
the
fix/validate-in-tree-backend-path
branch
from
723d5e6 to
2cba2de
Compare
Signed-off-by: Henry Schreiner <henryfs@princeton.edu>
henryiii
approved these changes
Apr 9, 2026
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
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
When
backend-pathinpyproject.tomlpoints to a nonexistent directory (typo, missing checkout, wrong relative path), the error only surfaces deep inside a subprocess as an opaqueBackendUnavailableexception frompyproject_hooks. This makes it hard to diagnose what went wrong.This adds early validation in
ProjectBuilder.__init__that checks eachbackend-pathentry resolves to an existing directory relative to the source directory. When it doesn't, aBuildSystemTableValidationErroris raised immediately with a clear message identifying the bad path. This is consistent with the existing type validation already performed on[build-system]table fields.Closes #145