dotnet/roslyn

Remove extraneous branch for empty strings in interpolated string handler CFG

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#57,611 opened on Nov 5, 2021

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 (0 comments) (0 reactions) (1 assignee)C# (4,257 forks)batch import
Area-CompilersBugFeature - IOperationFeature - Interpolated String Improvementshelp wanted

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Description

When an interpolated string handler is created for an empty string, and the constructor of the handler uses an out bool success parameter, we generate an unnecessary branch in the CFG for the code, demonstrated in the InterpolatedStringHandlerConversionFlow_16 test. We could take the approach Aleksey detailed in his review to remove that branch, but we will have to wire a CreateDiscardSymbol method through the semantic model to be able to create an IDiscardOperation for the parameter value. This is presently undone.

Contributor guide

Research direction
Study the test InterpolatedStringHandlerConversionFlow 16 to understand the current CFG generation. Implement CreateDiscardSymbol in the semantic model and use it to avoid the unnecessary branch, following the review suggestion.
Tech stack
csharp
Domain
None
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C#Roslyn compiler internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40