GeezerVison

Pull request overview

Adds a new built-in PSScriptAnalyzer rule to detect catch/finally blocks used without a preceding try, with accompanying documentation and Pester tests to validate behavior.

Changes:

• Introduces the new MissingTryBlock built-in rule implementation and localized strings.
• Adds rule documentation and registers it in the rules documentation index.
• Adds a dedicated Pester test suite for violation, compliant, and suppression scenarios.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 6 comments.

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Thanks again iRon7 for working through this with Liam Peters (@liamjpeters). The severity mismatch is fixed and the implementation is tight (using StringConstantExpressionAst as the bareword detection is the right approach for this scenario).

One context note that may be useful: this rule was explicitly endorsed upstream in PowerShell/PowerShell#25491 by the engine working group as something that belongs in PSSA rather than the parser. Good signal that there's appetite for landing it.

Three things before I'm comfortable merging:

The // Find all FunctionDefinitionAst in the Ast comment. GitHub's review bot flagged this and you replied "Outdated?" — but the comment is still in Rules/MissingTryBlock.cs on the current head and it's misleading: the code is finding StringConstantExpressionAst, not FunctionDefinitionAst. Could you replace it with something like // Find bareword "catch" or "finally" tokens that are not part of a TryStatementAst?

Opt-in by default. Same convention point as the other rules: please derive from ConfigurableRule with Enable = false so users can opt in, and update docs/Rules/README.md.

Doc the false-positive. This rule will fire on user code like:

function catch { param([scriptblock]$body) & $body }
catch { Write-Host 'hi' }

which is legal PowerShell (catch is not a reserved word at the command position). Worth a short note in docs/Rules/MissingTryBlock.md so users know they may need to suppress in unusual cases. Doesn't change the implementation.

Once those are sorted, I'd like Liam Peters (@liamjpeters) to take a quick second look since he did the bulk of the original review.

Drafted by Copilot (Claude Opus 4.7)

Looks good to me but agree to fix things from previous comment

Just some small cosmetic/hygiene changes. The actual rule and test coverage is looking really good 👍

Thanks iRon7 — and thanks Liam Peters (@liamjpeters) for the careful second pass. All five of Liam's 2026-05-15 line-level asks landed at the new head: the PSMissingTryBlock = @{ settings example, the "Doesn't emit a violation" rename, the duplicate <summary> block above the class, the dead helper, and Closes #1700 and Fixes #2098 in the PR body.

CI is green on Linux, macOS, and Windows. Approving.

Drafted by Copilot (Claude Opus 4.7)