dotnet/roslyn

Improve error recovery for explicit implementation lacking return type

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#61,563 opened on May 27, 2022

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Area-CompilersConcept-Diagnostic Clarityhelp wanted

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Description

Version Used: e6b5dd830f1b790bd80e62272129cc040d0a2fdc

Steps to Reproduce:

SharpLab

interface I
{
    void F();
}

class C : I
{
    F() { }
    I.F() { }
}

Expected Behavior: F() { } and I.F() { } both parse as ConstructorDeclaration, which results in a "Method must have a return type" diagnostic.

Actual Behavior: Only F() parses as a ConstructorDeclaration, which results in some not as useful parsing diagnostics for I.F():

error CS1519: Invalid token '(' in class, record, struct, or interface member declaration error CS8124: Tuple must contain at least two elements. error CS1519: Invalid token '{' in class, record, struct, or interface member declaration error CS1022: Type or namespace definition, or end-of-file expected

Contributor guide

Research direction
Investigate the parser logic for explicit interface member implementations to ensure missing return type is properly diagnosed as a constructor declaration, rather than producing confusing error messages.
Tech stack
csharp
Domain
tooling
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.
1-3 hours
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#Git
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55