Building ILC causes double writes in the runtime build

[ViktorHofer]

Repro: build.cmd/sh clr+libs /bl

Inspect the binary log and find the following double write:

This is problematic as it makes the build slower as it needs to be and might break the incremental build feature in msbuild. After fixing this issue, we should consider adding CI protection to guard against double writes by doing something similar to https://www.meziantou.net/detecting-double-writes-in-msbuild-using-the-binlog.htm. AFAIK the roslyn team already does that.

cc @MichalStrehovsky

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Issue Details

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Repro: build.cmd/sh clr+libs /bl

Inspect the binary log and find the following double write:

This is problematic as it makes the build slower as it needs to be and might break the incremental build feature in msbuild. After fixing this issue, we should consider adding CI protection to guard against double writes by doing something similar to https://www.meziantou.net/detecting-double-writes-in-msbuild-using-the-binlog.htm. AFAIK the roslyn team already does that.

Author:	ViktorHofer
Assignees:	-
Labels:	area-Infrastructure-coreclr, untriaged
Milestone:	-

[MichalStrehovsky]

This is related to/same as #79575. The SDK dumps an apphost there that we then need to delete:

runtime/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Publish.targets

Lines 93 to 110 in e43cba3

	<Target Name="CopyNativeBinary" AfterTargets="Publish">
	<!-- replace apphost with binary we generated during native compilation -->
	<Delete Files="$(PublishDir)\$(TargetName)$(NativeBinaryExt)" />
	<Copy SourceFiles="$(NativeOutputPath)$(TargetName)$(NativeBinaryExt)" DestinationFolder="$(PublishDir)" />
	<!-- dotnet CLI produces managed debug symbols, which we will delete and copy native symbols instead -->
	<Delete Files="$(PublishDir)\$(TargetName).pdb" />
	<PropertyGroup>
	<_symbolExt Condition="'$(OS)' == 'Windows_NT'">$(NativeSymbolExt)</_symbolExt>
	<_symbolExt Condition="'$(OS)' != 'Windows_NT'">$(NativeBinaryExt)$(NativeSymbolExt)</_symbolExt>
	</PropertyGroup>
	<!-- replace native symbol file if it exists -->
	<Delete Files="$(PublishDir)\$(TargetName)$(_symbolExt)" />
	<Copy SourceFiles="$(NativeOutputPath)$(TargetName)$(_symbolExt)" DestinationFolder="$(PublishDir)"
	Condition="Exists('$(NativeOutputPath)$(TargetName)$(_symbolExt)') and '$(CopyOutputSymbolsToPublishDirectory)' == 'true'" />
	</Target>

This code originates from times when we couldn't put customizations into SDK because native AOT was an experimental project. It's no longer so.

[ViktorHofer]

I see. Do you know if there's something that we can do in runtime meanwhile to avoid the double write?

[MichalStrehovsky]

I don't like that we do that in the product itself either. I don't think there's anything we can do from here besides patching the SDK targets in the nuget cache after they restore.

The SDK gets really mad if UseAppHost is false on something it considers self-contained. I was trying to fix this in dotnet/sdk#33229 that you're Cc'd on but it's currently in limbo because I'm sure it will break something else and I'm not mentally capable to deal with the worms from that can at this time. I'll be taking some time off soon so maybe after that.