dotnet/roslyn

Improve parser error recovery for misplaced `ref` modifier of a struct declaration

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#84,734 opened on Aug 2, 2026

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 (5 comments) (0 reactions) (0 assignees)C# (4,257 forks)batch import
Area-CompilersFeature - Ref Fieldshelp wanted

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Description

Case 1:

Snippet:

ref public struct MyStruct;

Expected: ref is in the modifiers list for MyStruct, error about its misplacement

Actual: ref is a part of RefTypeSyntax of IncompleteMemberSyntax while StructDeclarationSyntax starts from a public token. The error is 'Type expected' on public token

Case 2:

Snippet:

partial ref struct MyStruct;

Expected: partial is in the modifiers list for MyStruct, error about its misplacement

Actual: partial is its own IncompleteMemberSyntax. The error is on ref keyword saying about its misplacement instead

Contributor guide

Research direction
Reproduce the issue with the given snippets. Trace the Roslyn parser's handling of struct declarations and modifiers. Look at how the 'ref' keyword is parsed and why it ends up in RefTypeSyntax rather than the modifier list. Examine the parser's error recovery for misplaced tokens. Review existing tests for parser error recovery.
Tech stack
csharp
Domain
compilers
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
GitC#
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55