Scope MT-specific TaskAnalyzer diagnostics to MT tasks by default by VolPlita · Pull Request #14775 · dotnet/msbuild

VolPlita · 2026-08-21T10:17:18Z

Context

This is a narrow, incremental scope change for MT-specific migration diagnostics. It does not define TaskAnalyzer's complete shipping policy.

MSBuildTask0002, MSBuildTask0003, and related MSBuildTask0005 findings describe MT migration work. Reporting them on every regular task by default can add warnings when customers only update the analyzer package. Always-applicable MSBuildTask0001 and MSBuildTask0004 findings remain active for regular tasks, including through MSBuildTask0005 call chains.

Changes Made

Uses multithreadable_only as the default scope for MSBuildTask0002, MSBuildTask0003, and their transitive MSBuildTask0005 findings.
Keeps direct and transitive MSBuildTask0001/MSBuildTask0004 findings active for regular tasks.
Keeps all as an explicit migration mode.
Recognizes IMultiThreadableTask, [MSBuildMultiThreadableTask], and [MSBuildMultiThreadableTaskAnalyzed] as MT opt-ins.
Reads the supported bare msbuild_task_analyzer.scope global option and removes the unreachable dotted build_property lookup.
Adds real .globalconfig tests for direct and transitive analysis. A section-based .editorconfig intentionally does not set this compilation-wide option.
Verifies all three MT opt-ins for direct and transitive analysis: IMultiThreadableTask, [MSBuildMultiThreadableTask], and [MSBuildMultiThreadableTaskAnalyzed].
Configures Microsoft.Build.Tasks with scope = all only when BuildAnalyzer=true, preserving repository migration coverage.
Updates the scope and severity documentation.

Testing

TaskAnalyzer.Tests: 282 passed, 0 failed, 0 skipped.
Standard repository build: 0 warnings, 0 errors.
Analyzer-enabled repository build: 161 expected TaskAnalyzer warnings, 0 errors.
Confirmed TaskAnalyzer.globalconfig is included only when BuildAnalyzer=true.

Scope Relative to Follow-up PRs

[TaskAnalyzer] Align diagnostic severities and ignore open generic ITaskItem<T> #14811 owns the broader shipping policy, generic false-positive fix, and severity changes. After this PR merges, it should be rebased and its duplicated scope changes removed.
Document and configure TaskAnalyzer #14820 owns stable MSBuild-property propagation and package-consumption configuration tests.
Ship TaskAnalyzer with Microsoft.Build.Framework #14812 owns analyzer packaging.

The direct migration configuration supported by this PR is:

is_global = true
msbuild_task_analyzer.scope = all

Copilot

Pull request overview

Adjusts TaskAnalyzer’s default analysis behavior so multi-threading (MT) diagnostics don’t introduce new warnings for “regular” tasks when the analyzer ships broadly (e.g., with Microsoft.Build.Framework), while still allowing an explicit migration mode to analyze all tasks.

Changes:

Changed the default scope behavior to analyze MT-specific rules only for MT-opted-in tasks, with scope=all enabling migration-mode analysis for all tasks.
Applied scope gating to MSBuildTask0002/MSBuildTask0003 and to task-root selection for MSBuildTask0005, with new/updated tests covering default/all/invalid values.
Updated analyzer documentation/comments to reflect the new default behavior (with a remaining config-mechanism doc mismatch noted in PR comments).

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/TaskAnalyzer/SharedAnalyzerHelpers.cs	Changes scope option parsing to default to MT-only and only enable all-tasks when explicitly set to `all`.
src/TaskAnalyzer/MultiThreadableTaskAnalyzer.cs	Updates scope documentation/comments to match new default behavior.
src/TaskAnalyzer/README.md	Updates public documentation for new default scope and migration-mode behavior.
src/TaskAnalyzer.Tests/TestHelpers.cs	Refactors helpers to make “all” explicit and adds helpers for default-scope runs.
src/TaskAnalyzer.Tests/MultiThreadableTaskAnalyzerTests.cs	Adds tests validating default vs `all` scope behavior and invalid values.
src/TaskAnalyzer.Tests/TransitiveCallChainAnalyzerTests.cs	Adds tests validating MSBuildTask0005 behavior under default vs `all` scope.

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@@ -17,8 +17,8 @@ namespace Microsoft.Build.TaskAuthoring.Analyzer
    /// Roslyn analyzer that detects unsafe API usage in MSBuild task implementations.
    /// 
    /// Scope (controlled by .editorconfig option "msbuild_task_analyzer.scope"):


@@ -18,25 +18,25 @@ internal static class SharedAnalyzerHelpers
    {
        /// <summary>
        /// The .editorconfig key controlling analysis scope.


Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

JanProvaznik · 2026-08-24T12:36:45Z

@VolPlita please resolve the conflict and give this PR a more meaningful title

AR-May · 2026-08-24T12:42:48Z

expert review AI report:
Review complete. Verdict: 🔴 Request changes — direction is right, but the change doesn't achieve its stated goal.

Blocking

Goal not met: only 0002/0003/0005 are gated. MSBuildTask0001 (Error), 0004, 0009 (Warning), 0010 (Error) still fire on every regular ITask — a customer updating Microsoft.Build.Framework gets build-breaking errors with no opt-out. UnsupportedTaskItemTypeAnalyzer never even reads the scope option. Either gate everything on MT opt-in, or narrow the PR's claim explicitly.
The opt-in is unreachable: build_property.msbuild_task_analyzer.scope requires an MSBuild property named with a dot — impossible — and no CompilerVisibleProperty / build/*.props is packed. All scope=all tests seed exactly that dead key; the bare-key .globalconfig path the README documents has zero coverage.

Major

• Config path (your question #2): ship + build/*.props . Avoid per-tree .editorconfig — MSBuildTask0005 filters at CompilationEnd and has no syntax tree, so scopes would disagree.
• TestHelpers now routes the whole legacy ~250-test suite through ScopeAll , so the new shipping default is the least-tested config.
• Five XML comments still say .editorconfig , contradicting the README's .globalconfig .

Moderate

• Transitive analyzer builds the full compilation call graph, then discards it at CompilationEnd under the new default — pure cost for the common case.
• Your question #1: MSBuildTask0005 shouldn't be blanket-suppressed for regular roots — filter by violation category, so transitive 0001/0004 still report. But if you take the "gate everything" route in B1, the current root filter becomes correct and this dissolves. Answer B1 first.

Nits: title typo ("nt" → "mt"), missing newline at EOF, ImplementsInterface helper open-coded.

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

…askItem<T> (#14811) Part of #14078. ### Summary Aligns TaskAnalyzer descriptor severities with the documented intent and prevents an unsupported-type false positive when a task uses an open generic `ITaskItem<T>` property. This PR intentionally does **not** change `msbuild_task_analyzer.scope`. The scope-policy implementation and tests belong to #14775 and are excluded from this PR. ### Changes - Changes MSBuildTask0006, MSBuildTask0007, and MSBuildTask0008 from **Warning** to **Info**. These rules provide modernization suggestions with code fixes; they do not report invalid task definitions. - Changes MSBuildTask0010 from **Error** to **Warning**. `Convert.ChangeType` binding succeeds, but its invariant-culture behavior may not match the task's intended parsing semantics. - Keeps MSBuildTask0009 as **Warning**, avoiding a new unconditional build break for existing analyzer consumers. - Skips MSBuildTask0009 for open generic `ITaskItem<T>` properties because an unresolved type parameter does not provide enough information to determine whether the closed task parameter will be supported. - Updates `DiagnosticDescriptors.cs`, `AnalyzerReleases.Unshipped.md`, the README, and analyzer tests so all severity declarations agree. - Adds coverage showing typed task-item diagnostics apply to regular tasks independently of MT opt-in and that open generic task-item properties do not produce a diagnostic. ### Compatibility The severity changes only reduce diagnostics from Warning/Error to Info/Warning. No new warning or error is introduced, and analyzer scope behavior is unchanged. ### Testing - `.dotnet\dotnet.exe test src\TaskAnalyzer.Tests\TaskAnalyzer.Tests.csproj -c Release`: 250 passed, 0 failed, 0 skipped. - `.\build.cmd -v quiet`: succeeded with 0 warnings and 0 errors. ### Related - #14775 owns the analyzer scope-policy change and is not reimplemented here. - MSBuildTask0005 redesign remains follow-up work in #14777. --------- Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

AR-May · 2026-08-27T07:37:52Z

/azp run

azure-pipelines · 2026-08-27T07:38:01Z

Azure Pipelines will not run the associated pipelines, because the pull request was updated after the run command was issued. Review the pull request again and issue a new run command.

AR-May · 2026-08-27T07:40:44Z

@copilot resolve the merge conflicts in this pull request

default nt only

c7ee92a

VolPlita requested a lite review from Copilot August 21, 2026 10:17

Copilot started reviewing on behalf of VolPlita August 21, 2026 10:17 View session

Copilot AI reviewed Aug 21, 2026

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VolPlita mentioned this pull request Aug 24, 2026

[TaskAnalyzer] Align diagnostic severities and ignore open generic ITaskItem<T> #14811

Merged

Potential fix for pull request finding

44c521a

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

VolPlita marked this pull request as ready for review August 24, 2026 12:13

VolPlita changed the title ~~default nt only~~ Default TaskAnalyzer scope to multithreadable tasks only Aug 25, 2026

VolPlita changed the title ~~Default TaskAnalyzer scope to multithreadable tasks only~~ Limit MSBuildTask0002, 0003, and 0005 to MT tasks by default Aug 25, 2026

Fix TaskAnalyzer scope configuration and coverage

00cd7b0

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

VolPlita changed the title ~~Limit MSBuildTask0002, 0003, and 0005 to MT tasks by default~~ Scope MT-specific TaskAnalyzer diagnostics to MT tasks by default Aug 25, 2026

VolPlita and others added 2 commits August 26, 2026 01:23

Merge branch 'main' into vplita-mt-only-default

0877e4a

Clarify TaskAnalyzer global scope configuration

672974e

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

VolPlita enabled auto-merge (squash) August 26, 2026 11:29

Merge branch 'main' into vplita-mt-only-default

cd22ce0

AR-May disabled auto-merge August 26, 2026 11:44

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Scope MT-specific TaskAnalyzer diagnostics to MT tasks by default - #14775

Scope MT-specific TaskAnalyzer diagnostics to MT tasks by default#14775
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VolPlita commented Aug 21, 2026 •

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VolPlita commented Aug 21, 2026 •

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