dotnet/roslyn

VB compiler should not "optimize" Select statements during initial binding

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#374 opened on Feb 10, 2015

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Area-CompilersBugConcept-Design DebtLanguage-VBhelp wanted

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Description

The VB compiler "optimizes" Select statements during initial binding, generating and storing a lowered form for the cases depending on the structure of the whole select statement.

Generally speaking such transformations belong in lowering. Since it operates at the level of the whole Select statement after all of the parts have been bound, it can be moved en masse to a later phase. I recommend the local lowering phase.

Any intermediate phases that depend on the lowering having taken place are likely buggy, since different lowered forms may be generated in different circumstances.

[ported from TFS DevDiv 941313]

Contributor guide

Research direction
Move the VB Select statement optimization from initial binding to the lowering phase to ensure consistent lowering.
Tech stack
csharp
Domain
backend
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.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
None
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20