dotnet/roslyn

Simplify logic for deconstruction variables in ExpressionVariableFinder

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#15,064 opened on Nov 7, 2016

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Area-CompilersConcept-Design DebtFeature - Tupleshelp wanted

Description

Per discussion in PR https://github.com/dotnet/roslyn/pull/14871

  • Maybe we don't need MakeOutVariable and MakeDeconstructionVariable, instead one may suffice, by looking up the syntax tree.
  • Maybe we don't need CollectVariablesFromDeconstruction in ExpressionVariableFinder, instead we just need a VisitVariableDesignation which looks up the syntax tree to determine if it is an out or a deconstruction variable.
  • Then maybe we can re-use ExpressionVariableFinder instead of ForEachLoopBinder.CollectLocalsFromDeconstruction.

Contributor guide

Tech stack
csharp
Domain
tooling
Issue type
refactor
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
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.
mostly clear
Prerequisites
C# knowledgeUnderstanding of Roslyn syntax tree
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Examine the linked PR (dotnet/roslyn#14871) to understand the context. Focus on ExpressionVariableFinder.cs and ForEachLoopBinder.cs. Look at methods MakeOutVariable, MakeDeconstructionVariable, and CollectVariablesFromDeconstruction. The discussion suggests merging them into a single VisitVariableDesignation method. Investigate whether the syntax tree can be used to distinguish out vs deconstruction variables instead of separate methods.