dotnet/roslyn

IDE0059 (unnecessary assignment to a value) false positive for VB catch statement

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#45,896 opened on Jul 10, 2020

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Area-IDEBugFeature - IDE0059IDE-CodeStylehelp wanted

Description

See https://github.com/dotnet/roslyn/pull/45847/commits/c54743b71f398738408cbb4be860ab1a53d8e7cc#diff-aeaeb48464894aa3843d1bda663ad7fbR98

e1 is flagged with IDE0059, but there is no way to remove it: https://github.com/dotnet/roslyn/blob/e5a8db4ff486983f531ab56adc585c191cf95885/src/EditorFeatures/VisualBasicTest/EditAndContinue/VisualBasicEditAndContinueAnalyzerTests.vb#L91-L110

Contributor guide

Tech stack
None
Domain
tooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
familiarity with Roslyn analyzerunderstanding of VB catch syntax
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Investigate the IDE0059 analyzer's handling of catch statements in Visual Basic. Look at the test file at src/EditorFeatures/VisualBasicTest/EditAndContinue/VisualBasicEditAndContinueAnalyzerTests.vb lines 91-110 to understand the pattern. The analyzer should not flag the exception variable assigned in a Catch block as unnecessary. Consider checking if the variable is used in a Catch clause context.