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Logging Source Generator fails with a NullReferenceException #52277
Description
Repro
- Create a new ClassLibrary
- Add
<PackageReference Include="Microsoft.Extensions.Logging" Version="6.0.0-preview.4.21222.10" /> - Write the following code in
Class1.cs
using System;
using Microsoft.Extensions.Logging;
namespace ClassLibrary1
{
public partial class Class1
{
private ILogger _logger;
public Class1(ILogger logger) => _logger = logger;
internal static class EventIds
{
public const int HealthCheckErrorId = 100;
}
[LoggerMessage(EventId = HealthCheckErrorId, Level = LogLevel.Error, Message = "Health check {HealthCheckName} threw an unhandled exception after {ElapsedMilliseconds}ms")]
private partial void HealthCheckError(string HealthCheckName, double ElapsedMilliseconds, Exception exception);
}
}- Build
Actual results
I'm seeing the following warning in my Error List
Severity Code Description Project File Line Suppression State
Warning CS8785 Generator 'LoggerMessageGenerator' failed to generate source. It will not contribute to the output and compilation errors may occur as a result. Exception was of type 'NullReferenceException' with message 'Object reference not set to an instance of an object.' ClassLibrary1 C:\Users\eerhardt\source\repos\ClassLibrary1\ClassLibrary1\CSC 1 Active
Expected results
I only expect my compile error (here I didn't put EventIds. in front of HealthCheckErrorId in the LoggerMessage attribute) to exist in the Error List. I don't expect the Logging Source Generator to fail and add more errors.
Activity
ericstj commentedon May 5, 2021
Agree with @eerhardt that we need to ensure our source generators are resilient to bad syntax in user's source files (cc @layomia in case similar concerns apply to Json). We probably need test cases for invalid source to ensure our generators handle these cases well.
maryamariyan commentedon Jun 23, 2021
Closed via PR #54305