ChangeDocumentationFileForPackaging causes incremental build issues inside VS

[ViktorHofer]

This target picks the intellisense file from the Microsoft.Private.Intellisense package :

runtime/eng/intellisense.targets

Lines 43 to 51 in 88f2547

	<!-- Replace the compiler generated xml file in the obj folder with the one that comes from the intellisense package. -->
	<Target Name="ChangeDocumentationFileForPackaging"
	BeforeTargets="CopyFilesToOutputDirectory;DocumentationProjectOutputGroup"
	Condition="'$(UseCompilerGeneratedDocXmlFile)' != 'true' and '$(IntellisensePackageXmlFilePath)' != ''">
	<ItemGroup>
	<DocFileItem Remove="@(DocFileItem)" />
	<DocFileItem Include="$(IntellisensePackageXmlFilePath)" />
	</ItemGroup>
	</Target>

Because of using that prebuilt asset, the earliest output in the output directory dates back to when the package was last updated which results in incremental build issues.

WARNING: Potential build performance issue in 'System.Text.RegularExpressions.csproj'. The project does not appear up-to-date after a successful build: Input 'C:\git\runtime2\Directory.Build.props' is newer (10/3/2023 3:15:00 PM) than earliest output 'C:\git\runtime2\artifacts\bin\System.Text.RegularExpressions\Debug\net9.0\System.Text.RegularExpressions.xml' (9/18/2023 11:26:32 PM), not up-to-date. See https://aka.ms/incremental-build-failure.

@carlossanlop @ericstj

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Issue Details

---

This target picks the intellisense file from the Microsoft.Private.Intellisense package :

runtime/eng/intellisense.targets

Lines 43 to 51 in 88f2547

	<!-- Replace the compiler generated xml file in the obj folder with the one that comes from the intellisense package. -->
	<Target Name="ChangeDocumentationFileForPackaging"
	BeforeTargets="CopyFilesToOutputDirectory;DocumentationProjectOutputGroup"
	Condition="'$(UseCompilerGeneratedDocXmlFile)' != 'true' and '$(IntellisensePackageXmlFilePath)' != ''">
	<ItemGroup>
	<DocFileItem Remove="@(DocFileItem)" />
	<DocFileItem Include="$(IntellisensePackageXmlFilePath)" />
	</ItemGroup>
	</Target>

Because of using that prebuilt asset, the earliest output in the output directory dates back to when the package was last updated which results in incremental build issues.

WARNING: Potential build performance issue in 'System.Text.RegularExpressions.csproj'. The project does not appear up-to-date after a successful build: Input 'C:\git\runtime2\Directory.Build.props' is newer (10/3/2023 3:15:00 PM) than earliest output 'C:\git\runtime2\artifacts\bin\System.Text.RegularExpressions\Debug\net9.0\System.Text.RegularExpressions.xml' (9/18/2023 11:26:32 PM), not up-to-date. See https://aka.ms/incremental-build-failure.

@carlossanlop @ericstj

Author:	ViktorHofer
Assignees:	-
Labels:	area-Infrastructure-libraries
Milestone:	-

[ericstj]

Are we ever using that file for an up-to-date check or is this just a false-positive tooling issue?

I don't see inputs/outputs on the target you mention, so I'm inclined to think the latter.

Regardless, if we want to quiet this warning we should just use Touch on the copied file.

[ViktorHofer]

This is a warning emitted by the up-to-date check by VS, not the incremental build feature from msbuild. cc @drewnoakes

[ericstj]

@ViktorHofer why not try setting UpToDateCheckInput="false" metadata on that DocFileItem as suggested in the doc and see if it resolves the issue?

Alternatively you can add a Touch to a target that would update the timestamp after the file is copied out of the package.

[ViktorHofer]

While the warning is emitted by the up-to-date check feature, I believe this really prevents msbuild to not requeue a build:

Even with putting UpToDateCheckInput="false" on that item, VS always builds the project (incrementally) instead of skipping it (because it should be up-to-date).

[ericstj]

I see, well if we can't get that suppression to work, then the right thing to do would be to have that target copy it and touch the copy. It should put it somewhere in a subfolder in obj so that we can still preserve the compiler-emitted one.

[ViktorHofer]

@carlossanlop can you help with that? The target should be in intellisense.targets.