dotnet/roslyn

Message for BC30560 should include what assemblies the ambiguous types come from

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#10,811 opened on Apr 23, 2016

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Area-CompilersBugConcept-Diagnostic Clarityhelp wanted

Description

Create two projects with the same type name N.Class1 by compiling the following into two different libraries:

Namespace Global.N
    Public Class Class1
    End Class
End Namespace

Then reference them both and refer to the

Imports N

Module Module1
    Sub Main()
        Dim c As New Class1
    End Sub
End Module

Result: The error message is error BC30560: 'Class1' is ambiguous in the namespace 'N'., which doesn't tell you anything about where the ambiguities come from so you can try to fix it.

Note: C# gives a much better error message: error CS0433: The type 'Class1' exists in both 'ClassLibrary1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' and 'ClassLibrary2, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'

Contributor guide

Tech stack
csharp
Domain
developer experience
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
Basic understanding of C#Familiarity with Roslyn compiler architecture
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Locate the VB compiler's error reporting code for BC30560. Search for the string 'BC30560' in the Roslyn source code. Compare with C# error CS0433 implementation to understand how assembly information is included. Modify the VB error generation to include assembly names as done in C#. Reference the issue for expected behavior.