[VSCodeSweeper MVP — test only] lsp signature_helper Activity parameter highlight position error

[egamma]

⚠️ VSCodeSweeper MVP — test only. This draft PR was generated by an AI experiment
(vscodesweeper) inside a personal fork. It is
not intended for microsoft/vscode and is not a contribution proposal.

Upstream issue: microsoft#246019

Change summary

Signature help highlights the wrong parameter position when the parameter name string appears multiple times in the signature label.

Validation

Write a unit test in parameterHintsWidget tests that creates a signature where a parameter name (e.g., 'len') also appears in an earlier parameter or the function name, and assert the highlight offsets point to the Nth occurrence matching the activeParameterIndex, not the first.

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Branch vscodesweeper/fix-246019 · generated fix · review loop runs separately (codex review).

[egamma]

🤖 copilot /review — round 1

VSCodeSweeper MVP self-review (fork-only experiment).

● Get commits on branch (shell)
│ cd && git log main...HEAD --oneline
└ 2 lines…

● Get diff stats (shell)
│ cd && git diff main...HEAD --stat
└ 4 lines…

● Get full diff (shell)
│ cd && git diff main...HEAD
└ 201 lines…

No significant issues found in the reviewed changes.

The logic correctly handles:

• Setting regex.lastIndex with the g flag properly instructs test() to search from that position
• When test() returns false (no match), lastIndex resets to 0, making idx negative, which fails the idx >= searchStart check and returns [0, 0]
• The word-boundary regex (\W|^)..(?=\W|$) correctly prevents matching substrings within identifiers
• The sequential searchStart advancement correctly handles duplicate parameter names by finding each occurrence in order● Code-review(claude-opus-4.6) Review parameter hints fix
  │ Check git status (shell)
  │ │ cd && git --no-pager diff --staged
  │ 2>/dev/null |
  │ │ head -5; git --no-pager diff 2>/dev/null | head -5; git --no-pager log --oneline -3
  │ └ 3 lines…
  └ Read parameterHintsWidget.ts
  │ src/vs/editor/contrib/parameterHints/browser/parameterHintsWidget.ts
  └ L350:396 (46 lines read)

Code Review Summary

Commit: fix #246019: lsp signature_helper Activity parameter highlight position error

What it does: Fixes parameter highlighting in signature help when a parameter name appears as a substring of the function name (e.g., "len" incorrectly highlighted inside "strlen"). The fix computes a searchStart offset from previous parameters so the regex skips earlier occurrences.

Verdict: Looks good ✅ — no bugs or logic errors found.

Minor observations:

• The searchStart loop is O(n²) for string-labeled parameters, but parameter lists are small in practice — not a concern.
• If regex.test() returns false for the target parameter, lastIndex resets to 0, making idx negative, which correctly triggers the [0, 0] fallback via the idx >= searchStart guard.
• Tests are well-structured and cover the key scenarios including the original bug, duplicates, mixed label types, and edge cases.

[egamma]

✅ Round 1: no actionable findings — the review loop converged.