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jakebailey
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Jan 31, 2026
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Pull request overview
This PR fixes nondeterminism in module specifier generation that was causing test flakiness when handling redirected or deduplicated files. The root cause is that Go's map iteration order is intentionally randomized, so sorting results from maps.Values() requires a fully deterministic comparison function.
Changes:
- Added a deterministic tiebreaker (filename string comparison) to the path comparison function when paths have the same redirect status and directory depth
- Changed from
SortStableFunctoSortFuncsince the comparison function now provides total ordering
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| internal/modulespecifiers/util.go | Enhanced comparison function to add filename comparison as a tiebreaker for deterministic sorting |
| internal/modulespecifiers/specifiers.go | Removed misleading stable sort calls since map iteration order is inherently random in Go |
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| useCaseSensitiveFileNames := info.UseCaseSensitiveFileNames | ||
| comparePaths := func(a, b ModulePath) int { |
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This doesn't actually allocate, right? I assume it'll keep everything on the stack.
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Yeah, or at worst it'll be a single slot on the stack for the closure object
DanielRosenwasser
approved these changes
Feb 2, 2026
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Noticed this in #1604 (and in other CI jobs with dedupes). Without this, redirected / deduplicated files randomly swap ordering because the inputs are randomly ordered.
The comparison change is the real fix, but I have also removed the stable sorts since that is misleading;
allFileNamesis a map!