Repository navigation
check intersection props for never-reduction in a stable order - #64521
Merged
Anders Hejlsberg (ahejlsberg) merged 1 commit intoSep 29, 2026
Merged
Anders Hejlsberg (ahejlsberg) merged 1 commit into
Anders Hejlsberg (ahejlsberg) merged 1 commit into
Conversation
Copy link
Copy Markdown
Contributor
Sorry, something went wrong.
somePropertyReducesToNever ranged over a map, so the combined properties it creates were created in a random order, and when there was more than one candidate, which of them got created before it returned varied between runs. Keep the counts in an OrderedMap so the properties are checked in the order they were found. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Anders Hejlsberg (ahejlsberg)
approved these changes
Sep 29, 2026
Anders Hejlsberg (ahejlsberg)
marked this pull request as ready for review
September 29, 2026 14:18
Copy link
Copy Markdown
Contributor
|
This PR doesn't have any linked issues. Please open an issue that references this PR. From there we can discuss and prioritise. |
Sorry, something went wrong.
Anders Hejlsberg (ahejlsberg)
enabled auto-merge
September 29, 2026 14:18
Copilot started reviewing on behalf of
Anders Hejlsberg (ahejlsberg)
September 29, 2026 14:18
View session
Copy link
Copy Markdown
Contributor
There was a problem hiding this comment.
Copilot review overview
🟢 Approval recommended
The focused change correctly preserves existing behavior while eliminating nondeterministic iteration.
Review effort: Balanced
Findings: None
Makes intersection-property checking deterministic by preserving property discovery order.
Changes:
- Replaces an unordered count map with collections.OrderedMap.
- Checks candidate properties in stable insertion order.
| File | Description |
|---|---|
| tsc/internal/checker/checker.go | Stabilizes property processing during intersection reduction. |
💡 Add a code-review agent skill for context-aware, tailored reviews. Learn more in the docs.
Sorry, something went wrong.
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
Reviewers
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.
follow up to:
somePropertyReducesToNever ranges over a map, so the order it builds the combined properties in is random. when an intersection has more than one candidate, which ones get built before it returns changes from run to run, so the same program does slightly different work each time
on vscode from typescript-benchmarking with --singleThreaded, the symbol count comes out 8557485 / 8557513 / 8557486 on main, and 8557373 every time with this. before that PR it was stable too
diagnostics were the same in everything i ran (the 6 typescript-benchmarking tsc projects give the same output with and without this), but different work run to run is how order dependent output sneaks in, and it makes perf comparisons noisy
this keeps the counts in a collections.OrderedMap so the names are checked in the order they were found
used claude code to help write this, ive reviewed it