dotnet/roslyn

Improve error message reported when attempting to declare `ref` field in a `ref struct`

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#37,597 opened on Jul 30, 2019

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Area-CompilersBugConcept-Diagnostic ClarityLanguage-C#help wanted

Description

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Current error message:

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Seems like the code is parsed as method declaration. It would be better to parse as field declaration and report error on ref keyword.

Contributor guide

Tech stack
csharp
Domain
backenddeveloper experience
Issue type
bug
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.
clear
Prerequisites
C# ref structsRoslyn parser basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Investigate the Roslyn parser's handling of field declarations in ref structs. The current code likely parses `ref int x;` as a method declaration. Modify the parser to recognize it as a field declaration and emit an error on the `ref` keyword. Look at files like `Lexer.cs`, `Parser.cs`, or `SyntaxParser.cs` in the CSharp parser directory.