Enlighten RAR task by AR-May · Pull Request #13319 · dotnet/msbuild

AR-May · 2026-03-03T15:02:45Z

Context

RAR task enlightening. While auditing the inputs in build logs, only StateFile, AppConfigFile, and CandidateAssemblyFiles were obviously unenlightened, but several other inputs (TargetFrameworkDirectories, per-reference HintPath, AssemblyFoldersEx registry values, AssemblyFoldersFromConfig directory entries, …) are also not guaranteed to be absolute. They are now absolutized via TaskEnvironment.GetAbsolutePath.

Changes Made

RAR out-of-proc node now uses the multithreaded TaskEnvironment for proper path resolution (instead of just updating StateFile and AppConfigFile)
Resolvers now take TaskEnvironement object and use them for path absolutization of the inputs that are not absolutized prior.
Some of the inputs now are backed up with AbsolutePath structs instead of strings.

Breaking changes under a ChangeWave:

Empty AppConfigFile resulted before in failure while now it is skipped (as if it was null before)
StateFile.ItemSpec is used for the path instead of StateFile.ToString() which could be otherwise defined in a custom ITaskItem

Testing (in progress)

Checklist:

Copilot

Pull request overview

This PR advances “RAR task enlightening” by routing path resolution and environment access through TaskEnvironment (including in the out-of-proc RAR node), and by upgrading several RAR inputs from strings to AbsolutePath to ensure stable, project-relative-to-absolute resolution in multithreaded builds.

Changes:

RAR and related resolvers now use TaskEnvironment for absolute path conversion and environment variable access.
Out-of-proc RAR node now hydrates a multithreaded TaskEnvironment using the client project directory.
Introduces a new ChangeWave (18.6) and updates task/unit test code to provide TaskEnvironment.

Reviewed changes

Copilot reviewed 51 out of 51 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/Tasks/SystemState.cs	Uses `TaskEnvironment` for state file path handling during precomputed cache load.
src/Tasks/StateFileBase.cs	Clarifies expectation that state file path is absolute.
src/Tasks/RedistList.cs	Moves redist list paths to `AbsolutePath` and enables `TaskEnvironment`-based absolutization.
src/Tasks/InstalledSDKResolver.cs	Caches absolute SDK root paths for resolver probing.
src/Tasks/GetReferenceAssemblyPaths.cs	Marks task as multi-threadable and passes `TaskEnvironment` into GAC resolution.
src/Tasks/AssemblyDependency/Resolver.cs	Adds `TaskEnvironment` to resolver base for consistent path/env usage.
src/Tasks/AssemblyDependency/ResolveAssemblyReference.cs	Converts several inputs to `AbsolutePath`, adds MT task interface, and updates RAR execution to pass `TaskEnvironment` through the pipeline.
src/Tasks/AssemblyDependency/ReferenceTable.cs	Propagates `TaskEnvironment` into resolution pipeline and normalizes resolved paths.
src/Tasks/AssemblyDependency/Reference.cs	Adds `IsFrameworkFile` overload for `AbsolutePath[]` framework paths.
src/Tasks/AssemblyDependency/RawFilenameResolver.cs	Resolves raw filename candidate via `TaskEnvironment`.
src/Tasks/AssemblyDependency/Node/RarNodeExecuteRequest.cs	Captures project directory for out-of-proc node `TaskEnvironment` creation.
src/Tasks/AssemblyDependency/Node/OutOfProcRarNodeEndpoint.cs	Creates a multithreaded `TaskEnvironment` per request using the client project directory.
src/Tasks/AssemblyDependency/HintPathResolver.cs	Resolves hint path using `TaskEnvironment` and canonicalizes.
src/Tasks/AssemblyDependency/GlobalAssemblyCache.cs	Switches env-var access to `TaskEnvironment` and threads it through GetLocation APIs.
src/Tasks/AssemblyDependency/GacResolver.cs	Threads `TaskEnvironment` into GAC resolver construction.
src/Tasks/AssemblyDependency/FrameworkPathResolver.cs	Threads `TaskEnvironment` into framework path resolver construction.
src/Tasks/AssemblyDependency/DirectoryResolver.cs	Caches absolute search path via `TaskEnvironment`.
src/Tasks/AssemblyDependency/CandidateAssemblyFilesResolver.cs	Threads `TaskEnvironment` into candidate assembly files resolver construction.
src/Tasks/AssemblyDependency/AssemblyResolution.cs	Threads `TaskEnvironment` through resolver compilation APIs.
src/Tasks/AssemblyDependency/AssemblyFoldersResolver.cs	Threads `TaskEnvironment` into AssemblyFolders resolver.
src/Tasks/AssemblyDependency/AssemblyFoldersFromConfig/AssemblyFoldersFromConfigResolver.cs	Uses `TaskEnvironment` for cache escape-hatch env var access and passes it into cache.
src/Tasks/AssemblyDependency/AssemblyFoldersFromConfig/AssemblyFoldersFromConfigCache.cs	Uses `TaskEnvironment` for cache escape-hatch env var access.
src/Tasks/AssemblyDependency/AssemblyFoldersExResolver.cs	Uses `TaskEnvironment` for cache escape-hatch env var access and passes it into cache.
src/Tasks.UnitTests/RARPrecomputedCache_Tests.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/HintPathResolver_Tests.cs	Updates resolver test to provide `TaskEnvironment`.
src/Tasks.UnitTests/GetReferencePaths_Tests.cs	Updates task test to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/WinMDTests.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/VerifyTargetFrameworkHigherThanRedist.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/VerifyTargetFrameworkAttribute.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/VerifyIgnoreVersionForFrameworkReference.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/SuggestedRedirects.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/StronglyNamedDependencyAutoUnify.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/StronglyNamedDependencyAppConfig.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/StronglyNamedDependency.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/SpecificVersionPrimary.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/ResolveAssemblyReferenceTestFixture.cs	Updates helper to pass `TaskEnvironment` into GAC resolution.
src/Tasks.UnitTests/AssemblyDependency/Perf.cs	Updates perf tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/NonSpecificVersionStrictPrimary.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/Node/RarNodeExecuteRequest_Tests.cs	Updates node request tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/Node/OutOfProcRarNode_Tests.cs	Updates node tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/Miscellaneous.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/InstalledSDKResolverFixture.cs	Updates resolver fixture to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/GlobalAssemblyCacheTests.cs	Updates cache tests to pass `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/FilePrimary.cs	Updates RAR tests to provide `TaskEnvironment`.
src/Tasks.UnitTests/AssemblyDependency/AssemblyFoldersFromConfig_Tests.cs	Updates tests to provide `TaskEnvironment`.
src/Framework/MultiThreadedTaskEnvironmentDriver.cs	Moves driver into Framework layer and updates env-var comparer dependency.
src/Framework/MultiProcessTaskEnvironmentDriver.cs	Moves driver into Framework layer and routes env-var ops through Framework utilities.
src/Framework/FrameworkCommunicationsUtilities.cs	Adds Framework-local env-var utilities needed by moved drivers.
src/Framework/ChangeWaves.cs	Adds new wave 18.6 and includes it in `AllWaves`.
src/Build/Microsoft.Build.csproj	Removes compilation of drivers from Build project (now in Framework).
src/Build/BackEnd/Components/RequestBuilder/RequestBuilder.cs	Updates comment to reflect new Framework env-var utilities usage.

Comments suppressed due to low confidence (1)

src/Tasks/AssemblyDependency/ReferenceTable.cs:496

When assemblyFileName is relative, reference.FullPath is made absolute via TaskEnvironment, but the subsequent _fileExists, _directoryExists, _getAssemblyName, and ResolvedSearchPath logic still uses the original (potentially relative) assemblyFileName. In multithreaded/out-of-proc scenarios this can probe the wrong directory and fail to resolve assemblies. Use the resolved absolute path (e.g., reference.FullPath) consistently for file system checks and assembly name probing.

…read safe.

…nment.

AR-May · 2026-03-13T12:33:42Z

I separated moving drivers to the Framework project to another PR: #13380.
Merge this changes after #13380 is merged. There would be build errors meanwhile.

…on as it is expensive and would be done in ReferenceTable centrally.

…ool)

…solver.

AR-May · 2026-04-16T13:15:25Z

/review

JanProvaznik

review point 1 before I get to the juicy stuff:
pls remove everywhere t.TaskEnvironment = TaskEnvironmentHelper.CreateForTest(); which will make the PR also optically smaller

…est() from tests and change Wave18_6 to Wave18_8 Remove property-assignment-style TaskEnvironmentHelper.CreateForTest() additions from test files where they were not required by production API changes. Keep method argument additions where production code signatures require them. Change ChangeWave from 18_6 to 18_8 and add Wave18_8 definition. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

JanProvaznik

a few things to improve but seems solid on the high level

…rror message indicating that these modes cannot be used together.

AR-May · 2026-05-11T16:59:38Z

For the OOP + MT issues, I will remember this feedback and investigate those, but for now we will move fixing the OOP + MT fully to another PR. In this PR I will only make the current OOP code work through task environment, as I can not separate those changes.

NEW1_StringsInitialize_HasPublicationRace

fixed, thank you!

NEW4 StateFile / AppConfigFile no longer absolutized at the wire boundary

The StateFile and AppConfigFile are getting resolved through task environment which we start sending through the boundary, so it does not matter anymore whether they are relative or not, thus I removed the absolutization.

JanProvaznik

1 race condition candidate and 1 usage of clear API
otherwise more feedback is low severity and I am OK with merging it

Unit test coverage for -mt path is not great, have you at least run it on artificial solutions with high parallelism?

AR-May · 2026-05-18T16:26:50Z

Running the exp insertion to check the latest changes and should be merging as soon as possible after it.

AR-May self-assigned this Mar 4, 2026

AR-May commented Mar 4, 2026

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Comment thread src/Framework/FrameworkCommunicationsUtilities.cs Outdated

AR-May marked this pull request as ready for review March 4, 2026 13:48

Copilot AI review requested due to automatic review settings March 4, 2026 13:48

Copilot started reviewing on behalf of AR-May March 4, 2026 13:49 View session

Copilot AI reviewed Mar 4, 2026

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JanProvaznik reviewed Mar 6, 2026

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AR-May added 5 commits March 13, 2026 13:04

Make RAR as a service use TaskEnvironment. Make OutOfProcRarClient th…

b743044

…read safe.

Absolutize RAR task inputs. ReferenceTable should use the task enviro…

f5caaff

…nment.

Make resolvers use task environemnt.

f090cef

Enlighten GetReferenceAssemblyPaths

84ed710

Fix tests.

fdd2f52

AR-May force-pushed the enlighten-RAR-2 branch from 2c6a029 to fdd2f52 Compare March 13, 2026 12:31

Set default driver to enlightened tasks.

b669d97

SimaTian reviewed Mar 24, 2026

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Comment thread src/Tasks.UnitTests/AssemblyDependency/GlobalAssemblyCacheTests.cs Outdated

SimaTian reviewed Mar 24, 2026

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Comment thread src/Tasks/AssemblyDependency/Node/OutOfProcRarNodeEndpoint.cs

SimaTian reviewed Mar 24, 2026

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Comment thread src/Tasks/AssemblyDependency/AssemblyFoldersFromConfig/AssemblyFoldersFromConfigCache.cs Outdated

SimaTian reviewed Mar 24, 2026

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Comment thread src/Tasks/AssemblyDependency/AssemblyFoldersFromConfig/AssemblyFoldersFromConfigResolver.cs

AR-May added 10 commits April 15, 2026 12:20

Merge branch 'main' into enlighten-RAR-2

c818294

Fix bug with sdk paths comparer.

6e770db

Added AbsolutePath overload for SerializeCache.

161d875

Ensure that resolvers absolutize the inputs. Do not do canonicalizati…

a7da484

…on as it is expensive and would be done in ReferenceTable centrally.

Disambiguated the cref to SerializeCache(string, TaskLoggingHelper, b…

f6f5292

…ool)

Be defensive and absolutize in AssemblyFoldersFromConfig cache and re…

92f997c

…solver.

Add comment.

c4653dd

defensively assign empty arrays as values if null value is passed.

77ea94b

Removed the redundant _taskEnvironment field

0688f80

Add tests for the AppConfigFile in RAR

5186ee4

JanProvaznik reviewed Apr 28, 2026

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JanProvaznik and others added 4 commits May 4, 2026 11:41

changewave number

b8295a5

Merge origin/main and resolve conflicts

80bec33

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Fix stale Wave 18.6 comments to Wave 18.8

4d72a84

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

JanProvaznik reviewed May 4, 2026

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AR-May added 9 commits May 6, 2026 17:41

Add ChangeWaves documentation and add more tests.

797c567

Make the canonicalization error message more clear.

389a621

Minor refactoring

95346fb

Refactor AbsolutePath array conversions.

27de13c

Localize temporary message.

06bafbf

GAC should not work through the TaskEnvironment.

df7544d

Fix empty paths handling in resolvers.

ec60559

Fix race condition in Strings.Initialize

8db2cd0

Revert fixes for OOP RAR client support in MT mode, and add a clear e…

e814358

…rror message indicating that these modes cannot be used together.

Remove redundant TaskEnvironmentHelper.CreateForTest()

4db964f

rainersigwald reviewed May 12, 2026

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Address pr comments: minor refactorings.

cf673f8

JanProvaznik reviewed May 12, 2026

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Comment thread src/Tasks/AssemblyDependency/ResolveAssemblyReference.cs Outdated

Comment thread src/Tasks/SystemState.cs Outdated

AR-May added 2 commits May 13, 2026 13:48

Use public API for setting default TaskEnvironment.

1fa6f6d

Fix race condition in SystemState.

2f8ee2c

JanProvaznik approved these changes May 13, 2026

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Merge branch 'main' into enlighten-RAR-2

cc8e522

rainersigwald approved these changes May 14, 2026

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Drop wave gate for empty-path handling in RAR resolvers. Remove tests.

1787f42

JanProvaznik approved these changes May 18, 2026

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AR-May merged commit d9c38b1 into dotnet:main May 19, 2026
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dotnet-maestro Bot mentioned this pull request May 20, 2026

[main] Source code updates from dotnet/msbuild dotnet/dotnet#6704

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AR-May commented Mar 13, 2026

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AR-May commented Apr 16, 2026

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