AV2210: Require warning level 9999

[bart-degreed]

The highest warning level used to be 4, until C# 9 added warning level 5. Microsoft now recommends to use 9999, which should include all future warning levels.

AV2210 should be updated to require level 9999.

[PaulARoy]

Hi,
We're seeing this warning repeatedly despite having set <WarningLevel>9999</WarningLevel> into the project file.

Could there be any reason why it's still triggering the AV2210?

Thanks,

[bkoelman]

This is a known issue in .NET 5, tracked at dotnet/sdk#21599.

[PaulARoy]

Thank you very much, I did not found that!
What would be the best workaround in your opinion? Completely cancel out AV2210?

(we upgraded to .net5 a few weeks ago and I only got the warning when we updated the nuget package recently so I thought it was coming from it)

[bkoelman]

Use the workaround described in the linked issue.

On my machine, Microsoft.NET.Sdk.Analyzers.targets also contains:

<!-- If the user specified 'preview' we want to pick a very high warning level to opt into the highest possible warning wave -->
<WarningLevel Condition="'$(Language)' == 'C#' And '$(AnalysisLevel)' == 'preview'">9999</WarningLevel>

which means you can select 'preview' too.

[bkoelman]

@PaulARoy I've removed the check on warning level (see 90174ea for motivation), so once the next release has shipped you can remove any earlier workarounds.