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Add type inference for $_ in -replace scriptblock - #28329
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MartinGC94 wants to merge 2 commits into
Open
MartinGC94 wants to merge 2 commits into
MartinGC94 wants to merge 2 commits into
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MartinGC94
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a team,
Patrick Meinecke (SeeminglyScience) and
Dongbo Wang (daxian-dbw)
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November 4, 2026 14:10
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🟡 Changes recommended
Replacement callback detection incorrectly assigns Match to eagerly invoked scriptblocks and misses array-literal callbacks, producing incorrect or missing type inference for $_.
2 open issues
What changed in this PR
Adds type inference for $_ inside -replace scriptblocks, enabling PowerShell’s inference engine to recognize it as System.Text.RegularExpressions.Match.
Changes:
- Detects replacement scriptblock contexts for case-sensitive and case-insensitive replacement operators.
- Adds a regression test for the inferred
Matchtype.
| File | Description |
|---|---|
test/powershell/engine/Api/TypeInference.Tests.ps1 |
Tests $_ type inference inside a replacement callback. |
src/System.Management.Automation/engine/parser/TypeInferenceVisitor.cs |
Adds replacement-context detection and Match inference. |
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PR Summary
This PR adds type inference for $_ when used inside a scriptblock for the
-replaceoperator.For example when it's used like this:
"123" -replace '2', {[int]$_.Value + 2}PR Context
Yesterday I found out that you could use a scriptblock for
-replacebut there was no type inference for$_in this particular case, so I decided to add it.PR Checklist
.h,.cpp,.cs,.ps1and.psm1files have the correct copyright header