[marcpopMSFT]

🤖 Disable the default rollout of optimized Native AOT publish in .NET 11 while compatibility issues are addressed.

Changes

• Default UseOptimizedPublish to false for Native AOT publish, restoring full Build execution and build hooks unless explicitly opted in.
• Retain UseOptimizedPublish=true opt-in, the non-AOT guard, and NoBuild behavior.
• Cover unset, explicit false, and explicit true values with and without NoBuild; assert build hooks, managed build outputs, and runnable native publish output. Keep the optimized project-reference test explicitly opted in.
• Update the optimization documentation to describe the .NET 11 opt-in behavior.

This is an independent change based on release/11.0.1xx, not stacked on #56650. It does not change main, schedule .NET 12 activation, or incorporate #56620, #56649, or #56650.

Related customer reports: #56618 and #56645. This defers the default rollout rather than replacing the fixes needed for explicit opt-in.

Validation

• Built a fresh isolated Debug redist SDK with build.cmd -skipCrossgen -skipInstallers.
• Targeted Microsoft.NET.Publish.Tests: 9 passed, including all six default/false/true × build/no-build cases, optimized project references, unsupported publish modes, and the CoreBuild target-chain guard.
• Configured ILLink scope: TrimmingOptions_are_defaulted_correctly_on_trimmed_apps, 7 passed.
• Targeted runs retained TRX results and build binlogs under artifacts/log/targeted-tests/.

Validation was on Windows x64; the full test suite was not run. The redist build succeeded with existing unrelated NU1902/NU1903 warnings for System.Security.Cryptography.Pkcs 8.0.1 in ApiCompat projects; focused test builds had no warnings.

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Tactics

Summary

Optimized Native AOT publish (UseOptimizedPublish, introduced in #54515) skips parts of the normal Build target chain, which breaks build hooks and resource/doc-file handling for AOT apps (#56618, #56645). This PR changes the default in Microsoft.NET.Publish.targets so UseOptimizedPublish is false for Native AOT publish, restoring full Build unless explicitly opted in. The explicit opt-in, non-AOT guard and NoBuild behavior are retained, and docs are updated. Deferring the default is a small, low-blast-radius change suited to servicing; fixes for opt-in remain separate.

Customer Impact

Native AOT publish in .NET 11 pre-release SDKs can fail (e.g. MSB3030 for the XML documentation file when GenerateDocumentationFile is true, #56618) or skip BeforeTargets="ResolveReferences" resource targets (#56645). Affects Native AOT publish scenarios by default. Workaround: set UseOptimizedPublish=false. This change makes that the default.

Regression?

Yes, introduced in #54515 (optimized AOT publish enabled by default).

Testing

• Unit/integration tests in GivenThatWeWantToPublishAnAotApp.cs cover unset/false/true × build/no-build, asserting build hooks, managed build outputs and runnable native output; project-reference test explicitly opts in.
• Author reports targeted Microsoft.NET.Publish.Tests (9 passed) and ILLink scope test (7 passed) on Windows x64 with a fresh redist SDK build.
• Full suite not run locally; PR CI pipelines were started. Approved by baronfel.

Risk

Low. Three files changed (+83/-26): a two-line default change in targets, tests and docs. It reverts to the long-standing full Build behavior; users who explicitly opt in are unaffected.

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[Copilot]

🟢 Approval recommended

The narrow default change preserves existing alternatives, has focused regression coverage, and has no unresolved findings.

0 open findings

What changed in this PR

Makes optimized Native AOT publishing opt-in for .NET 11, restoring full Build behavior by default while compatibility fixes remain separate.

Changes:

• Defaults UseOptimizedPublish to false, preserving explicit opt-in and NoBuild behavior.
• Expands regression coverage for property combinations, build hooks, outputs, and native execution.
• Documents the opt-in behavior.

File	Description
test/​Microsoft.NET.Publish.Tests/​GivenThatWeWantToPublishAnAotApp.cs	Covers default, override, and no-build scenarios.
src/​Tasks/​Microsoft.NET.Build.Tasks/​targets/​Microsoft.NET.Publish.targets	Disables optimized AOT publishing by default.
documentation/​general/​publish-build-optimization.md	Explains .NET 11 opt-in behavior.

🧠 Review effort: Balanced

[marcpopMSFT]

/tactics