Microsoft.Extensions.Telemetry.Abstractions nuget package is missing the buildTransitive/netstandard2.0 folder

[CZEMacLeod]

Description

The build and published nuget package supports net462, netstandard2.0, and the stanrdard net8.0, net9.0, and net 10.0 TFMs.
However, the package does not include the buildTransitive/netstandard2.0 folder and associated .targets file.
Using this on a class library targeting netstandard results in problems with conflicting source generators since the DisableMicrosoftExtensionsLoggingSourceGenerator property is not injected into the project.

Reproduction Steps

Create a netstandard2.0 class library.
Install Microsoft.Extensions.Telemetry.Abstractions
Try and use the LoggerMessageAttribute.
You will get an error about ambiguous methods and partial methods cannot have multiple implementations.

Expected behavior

You should be able to use LoggerMessageAttribute etc. to get the enhanced version of the source generator without conflicts.

Actual behavior

The original source generator from Microsoft.Extensions.Logging.Abstractions conflicts and you get error messages and it won't compile.

Regression?

This appears to be the case in all the packages I've looked at from 8.0.0 thru 10.4.0

Known Workarounds

You can manually add the missing property to the class library project.

Configuration

Not really applicable but a netstandard2.0 class using net10 sdk.

Other information

There is some code in the project file which I think is meant to make the build engine add the transitive file but it doesn't appear to work.

extensions/src/Libraries/Microsoft.Extensions.Telemetry.Abstractions/Microsoft.Extensions.Telemetry.Abstractions.csproj

Lines 35 to 44 in b797b53

	<PropertyGroup>
	<_AdditionalNETStandardCompatErrorFileContents>
	<![CDATA[
	<!-- This package should replace the Microsoft.Extensions.Logging.Abstractions source generator, so we set the property to remove the source generator from the project. -->
	<PropertyGroup>
	<DisableMicrosoftExtensionsLoggingSourceGenerator>true</DisableMicrosoftExtensionsLoggingSourceGenerator>
	</PropertyGroup>
	]]>
	</_AdditionalNETStandardCompatErrorFileContents>
	</PropertyGroup>

The lib/netstandard2.0 folder exists and the dll is there.

https://nuget.info/packages/Microsoft.Extensions.Telemetry.Abstractions/10.4.0

There does seem to be some mixing of stuff in the .targets/.props files. There is no net9.0 or net10.0 buildTransitive folder either (I assume it falls back to the net8.0 version).
The net462 version has the property in the .targets file, not a .props file, and the target that removes the analyser is missing there.

[evgenyfedorov2]

might be related #7061

[CZEMacLeod]

Looks like it - and #7062 mentions the _AdditionalNETStandardCompatErrorFileContents - except there is not netstandard file generated.
I think this might be a common fault to quite a few of the Microsoft.Extensions.* packages that multitarget net4x/netstandard2.0/net8.0++...
The have a net462 folder, but no netstandard2.0 folder.
I guess if you compile against netstandard it doesn't warn you until you consume it transitively in an 'unsupported' target framework - e.g. until you consume the netstandard class library in either net framework or net core.
However, in this case there is logic needed at the consuming library compile time, not just the head/executable project compile time.

[CZEMacLeod]

It looks like

extensions/eng/MSBuild/Packaging.targets

Line 22 in 9a8fe6f

<NETStandardCompatError Include="$(ConditionalNet462)"

Sets up the targets file paths, but it is actually writing a net462 tfm although it is named NETStandardCompatError
From the looks of it, there should be a

<NETStandardCompatError Include="netstandard2.0" />

in this package to ensure that the compat contents gets written to both buildTransitive/net462/Microsoft.Extensions.Telemetry.Abstractions.targets and buildTransitive/netstandard2.0/Microsoft.Extensions.Telemetry.Abstractions.targets.
Although, I think that, like the other TFMs, there should be both a .props and a .targets including the full proper logic to disable the analyzer etc. for all the TFMs.

It looks like Microsoft.Extensions.Http.Resilience has better logic, but it too is 'missing' an actual netstandard2.0 folder so this logic doesn't occur in a netstandard2.0 class library.