[runtime] Generate trusted platform assemblies at build time Fixes #16744 by rolfbjarne · Pull Request #26245 · dotnet/macios

rolfbjarne · 2026-07-22T16:38:54Z

Generate the trusted platform assembly list from final publish items for non-debug builds, avoiding app bundle enumeration during startup.

Retain runtime discovery for debug builds to minimize build overhead, optimize single-RID path expansion, and preserve universal bundle handling on supported platforms.

Fixes #16744

🤖 Pull request created by Copilot

Generate trusted platform assembly data from final publish items for non-debug builds while retaining runtime discovery for debug builds. Optimize single-RID startup and preserve universal bundle handling on supported platforms. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

…he dylib Commit fae4375 made the runtime reference three symbols that are generated at app build time (GenerateTrustedPlatformAssemblySource): xamarin_trusted_platform_assemblies, xamarin_trusted_platform_assembly_count and xamarin_is_multi_rid_build. They're declared weak_import in main.h, with a runtime null-check fallback for debug builds where they aren't generated. The compiler correctly emits them as weak external undefined, but the Xcode 26 linker still errors ("Undefined symbols ...") when building the standalone libxamarin-dotnet.dylib, because no linked dylib exports them. Pass -Wl,-U for each of these symbols so they're allowed to be undefined (resolved via dynamic lookup) in the runtime dylib. The final app link provides the real definitions, and debug builds keep resolving them to NULL via weak_import. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 4aa93657-2767-43e8-ab51-f761657b87fd

Copilot

Pull request overview

This PR reduces startup overhead by generating the trusted platform assemblies (TPA) list at build time for non-Debug builds, so the runtime can avoid enumerating the app bundle on startup (fixing #16744). Debug builds keep the existing runtime discovery behavior to avoid extra build work.

Changes:

Add an MSBuild task to generate per-architecture native source containing the TPA names and count, and compile it into the native executable inputs.
Update the runtime to prefer the build-time generated TPA list (with a fallback to runtime discovery when symbols aren’t present).
Document the new GenerateTrustedPlatformAssemblies build property and add task-level unit tests.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tests/msbuild/Xamarin.MacDev.Tasks.Tests/TaskTests/GenerateTrustedPlatformAssemblySourceTests.cs	Adds unit tests validating filtering, ordering, escaping, and Multi-RID behavior of the generated TPA source.
runtime/xamarin/main.h	Declares weak-imported build-time TPA symbols and introduces a platform macro for universal-build support.
runtime/runtime.m	Switches `xamarin_compute_trusted_platform_assemblies` to use build-time TPA symbols when available, with Multi-RID handling on supported platforms.
runtime/Makefile	Allows weak undefined references to the new build-time TPA symbols when building the runtime dylib.
msbuild/Xamarin.MacDev.Tasks/Tasks/GenerateTrustedPlatformAssemblySource.cs	New task that generates native source for the TPA list/count and optional Multi-RID flag.
dotnet/targets/Xamarin.Shared.Sdk.targets	Wires in the new task/target, defaults property based on Debug, compiles generated sources, and forces export of the new native symbols.
docs/building-apps/build-properties.md	Documents `GenerateTrustedPlatformAssemblies` and its default behavior.

Comments suppressed due to low confidence (2)

runtime/xamarin/main.h:139

Use the corrected macro name here as well ("SUPPORTS_UNIVERSAL_BUILDS"), to match the definition and avoid inconsistencies.

#if defined (SUPPORTS_UNIVERAL_BUILDS)
extern const bool xamarin_is_multi_rid_build __attribute__ ((weak_import));
#endif

runtime/runtime.m:2406

Typo in the macro name: "UNIVERAL" should be "UNIVERSAL" (and match the header + generated source).

#if defined (SUPPORTS_UNIVERAL_BUILDS)
	if (xamarin_is_multi_rid_build) {

Resolve the overlapping bundler-debug defaults, correct the universal-build macro spelling, and safely fall back when generated weak TPA symbols are incomplete. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

Define runtime defaults for trusted platform assembly data and initialize the final single-RID value from the generated main source. Keep runtime path adjustment only for universal builds and remove the extra native source compilation. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

Return a caller-owned copy of the generated trusted platform assembly string so xamarin_vm_initialize can free it safely. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

Embed a constant array of assembly filenames in generated main and construct full trusted platform assembly paths at runtime. Probe for RID-specific paths only in multi-RID builds. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

…esult

vs-mobiletools-engineering-service2 · 2026-08-03T19:27:16Z

⚠️ AppSizeTest expected files changed ⚠️

The AppSizeTest detected changes in the expected app size files.

To update the expected files, add a comment with the following command:

/apply-gist https://gist.github.com/vs-mobiletools-engineering-service2/82656f3e08a68677bf8bd19e3f2b5ff8

Updated files

iOS-MonoVM-size.txt
MacOSX-CoreCLR-Interpreter-TrimmableStatic-size.txt
MacOSX-NativeAOT-size.txt

Pipeline on Agent
Hash: 903770a1ed793b2409e0f4f8c7adca03a76588fd [PR build]

Preserve external linkage for the runtime trusted platform assembly discovery helper. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

Apply the expected size updates produced by AppSizeTest for the current PR build. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

…ue-16744-generate-the-result

vs-mobiletools-engineering-service2 · 2026-08-06T14:15:02Z

✅ API diff for current PR / commit

NET (empty diffs)

iOS: vsdrops gist ( No breaking changes )
tvOS: vsdrops gist ( No breaking changes )
MacCatalyst: vsdrops gist ( No breaking changes )
macOS: vsdrops gist ( No breaking changes )

✅ API diff vs stable

NET (empty diffs)

iOS: vsdrops gist ( No breaking changes )
tvOS: vsdrops gist ( No breaking changes )
MacCatalyst: vsdrops gist ( No breaking changes )
macOS: vsdrops gist ( No breaking changes )

ℹ️ Generator diff

Generator Diff: vsdrops (html) vsdrops (raw diff) gist (raw diff) - Please review changes)

Pipeline on Agent
Hash: d218bdde31a9ff6685dfef6c6634c1bdb9e6c814 [PR build]

vs-mobiletools-engineering-service2 · 2026-08-06T16:06:09Z

🚀 [CI Build #d218bdd] Test results 🚀

Test results

✅ All tests passed on VSTS: test results.

🎉 All 204 tests passed 🎉

Tests counts

✅ assembly-processing: All 1 tests passed. Html Report (VSDrops) Download
✅ cecil: All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (iOS): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (MacCatalyst): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (macOS): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (Multiple platforms): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (tvOS): All 1 tests passed. Html Report (VSDrops) Download
✅ framework: All 2 tests passed. Html Report (VSDrops) Download
✅ fsharp: All 4 tests passed. Html Report (VSDrops) Download
✅ generator: All 5 tests passed. Html Report (VSDrops) Download
✅ interdependent-binding-projects: All 4 tests passed. Html Report (VSDrops) Download
✅ introspection: All 4 tests passed. Html Report (VSDrops) Download
✅ linker (iOS): All 15 tests passed. Html Report (VSDrops) Download
✅ linker (MacCatalyst): All 15 tests passed. Html Report (VSDrops) Download
✅ linker (macOS): All 21 tests passed. Html Report (VSDrops) Download
✅ linker (tvOS): All 15 tests passed. Html Report (VSDrops) Download
✅ monotouch (iOS): All 19 tests passed. Html Report (VSDrops) Download
✅ monotouch (MacCatalyst): All 18 tests passed. Html Report (VSDrops) Download
✅ monotouch (macOS): All 20 tests passed. Html Report (VSDrops) Download
✅ monotouch (tvOS): All 19 tests passed. Html Report (VSDrops) Download
✅ msbuild: All 2 tests passed. Html Report (VSDrops) Download
✅ sharpie: All 1 tests passed. Html Report (VSDrops) Download
✅ windows: All 3 tests passed. Html Report (VSDrops) Download
✅ xcframework: All 4 tests passed. Html Report (VSDrops) Download
✅ xtro: All 1 tests passed. Html Report (VSDrops) Download

macOS tests

✅ Tests on macOS Monterey (12): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Ventura (13): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Sonoma (14): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Sequoia (15): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Tahoe (26): All 5 tests passed. Html Report (VSDrops) Download

Linux Build Verification

✅ Linux build succeeded

Pipeline on Agent
Hash: d218bdde31a9ff6685dfef6c6634c1bdb9e6c814 [PR build]

rolfbjarne added the copilot label Jul 22, 2026

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rolfbjarne marked this pull request as ready for review July 27, 2026 18:12

rolfbjarne requested a review from mauroa as a code owner July 27, 2026 18:12

Copilot AI review requested due to automatic review settings July 27, 2026 18:12

Copilot started reviewing on behalf of rolfbjarne July 27, 2026 18:12 View session

Copilot AI reviewed Jul 27, 2026

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Comment thread runtime/xamarin/main.h

Comment thread runtime/runtime.m

Comment thread msbuild/Xamarin.MacDev.Tasks/Tasks/GenerateTrustedPlatformAssemblySource.cs Outdated

rolfbjarne commented Aug 3, 2026

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Comment thread runtime/xamarin/main.h Outdated

Comment thread runtime/runtime.m Outdated

Comment thread msbuild/Xamarin.MacDev.Tasks/Tasks/GenerateTrustedPlatformAssemblySource.cs Outdated

rolfbjarne requested a review from dalexsoto as a code owner August 3, 2026 11:42

rolfbjarne commented Aug 3, 2026

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Comment thread runtime/runtime.m Outdated

Duplicate generated TPA result

4b9f2bd

Return a caller-owned copy of the generated trusted platform assembly string so xamarin_vm_initialize can free it safely. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

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rolfbjarne enabled auto-merge (squash) August 3, 2026 16:53

Merge branch 'main' into dev/rolf/dev-rolf-issue-16744-generate-the-r…

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rolfbjarne commented Aug 3, 2026

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Comment thread runtime/runtime.m Outdated

rolfbjarne added 2 commits August 3, 2026 22:02

Keep runtime TPA discovery externally linked

aeeb06f

Preserve external linkage for the runtime trusted platform assembly discovery helper. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

[tests] Update expected app size files

72ddf2b

Apply the expected size updates produced by AppSizeTest for the current PR build. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

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rolfbjarne and others added 3 commits August 4, 2026 08:00

Fix single-entry RuntimeIdentifiers builds

7f9e894

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: b6c903d4-d655-47d4-9e0c-636bea8e7d37

Merge remote-tracking branch 'origin/main' into dev/rolf/dev-rolf-iss…

9430d76

…ue-16744-generate-the-result

[tests] Update expected sizes.

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rolfbjarne added the ready-to-review This PR is ready to review/merge. label Aug 4, 2026

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dalexsoto previously approved these changes Aug 4, 2026

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rolfbjarne added 2 commits August 4, 2026 19:11

Merge remote-tracking branch 'origin/main' into dev/rolf/dev-rolf-iss…

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…ue-16744-generate-the-result

[tests] Update expected sizes.

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rolfbjarne dismissed dalexsoto’s stale review via d0420a2 August 4, 2026 17:42

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rolfbjarne removed the ready-to-review This PR is ready to review/merge. label Aug 5, 2026

rolfbjarne added 2 commits August 6, 2026 14:29

Merge remote-tracking branch 'origin/main' into dev/rolf/dev-rolf-iss…

2c89fad

…ue-16744-generate-the-result

[tests] Update expected sizes.

d218bdd

rolfbjarne added the ready-to-review This PR is ready to review/merge. label Aug 6, 2026

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vs-mobiletools-engineering-service2 commented Aug 3, 2026

⚠️ AppSizeTest expected files changed ⚠️

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vs-mobiletools-engineering-service2 commented Aug 6, 2026

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vs-mobiletools-engineering-service2 commented Aug 6, 2026

🚀 [CI Build #d218bdd] Test results 🚀

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