[net11.0] [runtime] Register host_runtime_contract callbacks so CoreCLR finds System.Private.CoreLib.dll by rolfbjarne · Pull Request #25562 · dotnet/macios

rolfbjarne · 2026-05-28T07:28:55Z

Description

When CoreCLR starts, AssemblyBinderCommon::BindToSystem loads System.Private.CoreLib.dll. It first looks next to libcoreclr, and if that fails it runs a fallback path. In .NET 11 preview 5, dotnet/runtime#128278 changed the fallback to read CoreLib from the single-file bundle's extraction directory, and gated it on Bundle::AppIsBundle() && Bundle::AppBundle->HasExtractedFiles().

Those two flags are set from the host. AppIsBundle() requires the host to register a bundle_probe callback on host_runtime_contract, and HasExtractedFiles() requires the host to return a path from the BUNDLE_EXTRACTION_PATH runtime property. The primary lookup fails on Apple mobile device, because libcoreclr ships inside Frameworks/libcoreclr.framework/libcoreclr while System.Private.CoreLib.dll lives at the app bundle root, so CoreLib is never next to libcoreclr.

Fix

Register a no-op bundle_probe and provide BUNDLE_EXTRACTION_PATH with the directory containing System.Private.CoreLib.dll (app bundle root, then .xamarin/), so the gate passes and BindToSystem resolves CoreLib from that directory.

Fixes #25542

…ystem.Private.CoreLib.dll dotnet/runtime#128278 (.NET 11 preview 5) gated the BindToSystem CoreLib fallback behind `Bundle::AppIsBundle () && Bundle::AppBundle->HasExtractedFiles ()`. macios doesn't bundle assemblies and never registered `bundle_probe` nor a `BUNDLE_EXTRACTION_PATH` property, so the gate fails and CoreCLR can't locate `System.Private.CoreLib.dll` (which lives at the app bundle root, not next to `libcoreclr.framework/libcoreclr`). The app aborts in `xamarin_vm_initialize` with "Failed to initialize the VM". Fix: register a no-op `bundle_probe` so `Bundle::AppBundle` is non-null, and answer `BUNDLE_EXTRACTION_PATH` from `get_runtime_property` with the directory that actually contains CoreLib (app bundle root, then `.xamarin/<RID>`, matching the TPA probe order). The fallback then finds CoreLib and the VM initializes. Fixes #25542. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

This PR updates the Apple native CoreCLR host shim to provide the host_runtime_contract callbacks CoreCLR now relies on (in .NET 11 preview 5+) to locate System.Private.CoreLib.dll via the bundle/extraction fallback, fixing CoreCLR startup failures on iOS devices where libcoreclr and CoreLib are not colocated.

Changes:

Register a no-op bundle_probe callback so CoreCLR considers the app “bundled” for the fallback gate.
Implement get_runtime_property to answer HOST_PROPERTY_BUNDLE_EXTRACTION_PATH with the directory that actually contains System.Private.CoreLib.dll (bundle root, then .xamarin/<RID>).
Wire these callbacks into the host_runtime_contract passed through HOST_RUNTIME_CONTRACT during xamarin_vm_initialize.

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

vs-mobiletools-engineering-service2 · 2026-05-28T08:00:15Z

✅ [PR Build #0a31d6e] Build passed (Detect API changes) ✅

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vs-mobiletools-engineering-service2 · 2026-05-28T08:18:40Z

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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 )

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vs-mobiletools-engineering-service2 · 2026-05-28T10:17:52Z

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vs-mobiletools-engineering-service2 · 2026-05-28T14:02:14Z

✅ [PR Build #0a31d6e] Build passed (Build macOS tests) ✅

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Hash: 0a31d6e20ad6c1e154ac761d43cd949d81a1c29d [PR build]

vs-mobiletools-engineering-service2 · 2026-05-28T16:33:42Z

🔥 [CI Build #0a31d6e] Test results 🔥

Test results

❌ Tests failed on VSTS: test results

3 tests crashed, 24 tests failed, 132 tests passed.

Failures

❌ dotnettests tests (MacCatalyst)

🔥 Failed catastrophically on VSTS: test results - dotnettests_maccatalyst (no summary found).

Html Report (VSDrops) Download

❌ linker tests (macOS)

🔥 Failed catastrophically on VSTS: test results - linker_macos (no summary found).

Html Report (VSDrops) Download

❌ monotouch tests (iOS) [attempt 2]

24 tests failed, 0 tests passed.

Failed tests

monotouch-test/iOS - simulator/Debug: LaunchTimedOut
monotouch-test/iOS - simulator/Debug (CoreCLR): LaunchTimedOut
monotouch-test/iOS - simulator/Release (CoreCLR, ARM64): LaunchTimedOut
monotouch-test/iOS - simulator/Release (CoreCLR, x64): LaunchTimedOut
monotouch-test/iOS - simulator/Release (CoreCLR, Universal): LaunchTimedOut
monotouch-test/iOS - simulator/Release (link sdk): LaunchTimedOut
monotouch-test/iOS - simulator/Release (link all): LaunchTimedOut
monotouch-test/iOS - simulator/Debug (LinkSdk): LaunchTimedOut
monotouch-test/iOS - simulator/Debug (static registrar): LaunchTimedOut
monotouch-test/iOS - simulator/Release (all optimizations): LaunchTimedOut
monotouch-test/iOS - simulator/Debug (ARM64): LaunchTimedOut
monotouch-test/iOS - simulator/Release (NativeAOT, ARM64): LaunchTimedOut
monotouch-test/iOS - simulator/Release (trimmable static registrar, NativeAOT, ARM64): LaunchTimedOut
monotouch-test/iOS - simulator/Debug (managed static registrar): LaunchTimedOut
monotouch-test/iOS - simulator/Debug (trimmable static registrar): LaunchTimedOut
monotouch-test/iOS - simulator/Release (managed static registrar, all optimizations): LaunchTimedOut
monotouch-test/iOS - simulator/Release (trimmable static registrar, all optimizations): LaunchTimedOut
monotouch-test/iOS - simulator/Release (NativeAOT, x64): LaunchTimedOut
monotouch-test/iOS - simulator/Release (trimmable static registrar, NativeAOT, x64): LaunchTimedOut
monotouch-test/iOS - simulator/Debug (interpreter): LaunchTimedOut
monotouch-test/iOS - simulator/Release (interpreter): LaunchTimedOut
monotouch-test/iOS - simulator/Release (compat inline dlfcn): LaunchTimedOut
monotouch-test/iOS - simulator/Release (strict inline dlfcn, link sdk): LaunchTimedOut
monotouch-test/iOS - simulator/Release (NativeAOT, .NET 11 defaults): LaunchTimedOut

Html Report (VSDrops) Download

❌ monotouch tests (MacCatalyst) [attempt 2]

🔥 Failed catastrophically on VSTS: test results - monotouch_maccatalyst (no summary found).

Html Report (VSDrops) Download

Successes

✅ cecil: All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (iOS): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (macOS): All 1 tests passed. (⚠️ Html Report Publish failed ⚠️) 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 Publish failed ⚠️) Download
✅ interdependent-binding-projects: All 4 tests passed. Html Report (VSDrops) Download
✅ introspection: All 9 tests passed. Html Report (VSDrops) Download
✅ linker (iOS): All 11 tests passed. Html Report (VSDrops) Download
✅ linker (MacCatalyst): All 11 tests passed. Html Report (VSDrops) Download
✅ linker (tvOS): All 11 tests passed. Html Report (VSDrops) Download
✅ monotouch (macOS): All 20 tests passed. Html Report (VSDrops) Download
✅ monotouch (tvOS): All 24 tests passed. [attempt 2] Html Report (VSDrops) Download
✅ msbuild: All 2 tests passed. Html Report (VSDrops) Download
✅ sharpie: All 1 tests passed. [attempt 2] 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 Sonoma (14): All 5 tests passed. [attempt 2] Html Report (VSDrops) Download
✅ Tests on macOS Sequoia (15): All 5 tests passed. [attempt 2] Html Report (VSDrops) Download
✅ Tests on macOS Tahoe (26): All 5 tests passed. [attempt 2] Html Report (VSDrops) Download

Linux Build Verification

✅ Linux build succeeded

Pipeline on Agent
Hash: 0a31d6e20ad6c1e154ac761d43cd949d81a1c29d [PR build]

rolfbjarne · 2026-05-28T17:02:44Z

Merging, this targets another PR, and the problem this PR is supposed to fix looks fixed.

…LR finds System.Private.CoreLib.dll (#25562) ### Description When CoreCLR starts, AssemblyBinderCommon::BindToSystem loads System.Private.CoreLib.dll. It first looks next to libcoreclr, and if that fails it runs a fallback path. In .NET 11 preview 5, dotnet/runtime#128278 changed the fallback to read CoreLib from the single-file bundle's extraction directory, and gated it on Bundle::AppIsBundle() && Bundle::AppBundle->HasExtractedFiles(). Those two flags are set from the host. AppIsBundle() requires the host to register a bundle_probe callback on host_runtime_contract, and HasExtractedFiles() requires the host to return a path from the BUNDLE_EXTRACTION_PATH runtime property. The primary lookup fails on Apple mobile device, because libcoreclr ships inside Frameworks/libcoreclr.framework/libcoreclr while System.Private.CoreLib.dll lives at the app bundle root, so CoreLib is never next to libcoreclr. ### Fix Register a no-op bundle_probe and provide BUNDLE_EXTRACTION_PATH with the directory containing System.Private.CoreLib.dll (app bundle root, then .xamarin/<RID>), so the gate passes and BindToSystem resolves CoreLib from that directory. Fixes #25542 --------- Co-authored-by: Milos Kotlar <miloskotlar@github.com> Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: Milos Kotlar <kotlarmilos@gmail.com> Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings May 28, 2026 07:28

Copilot started reviewing on behalf of rolfbjarne May 28, 2026 07:29 View session

rolfbjarne mentioned this pull request May 28, 2026

[runtime] Register host_runtime_contract callbacks so CoreCLR finds System.Private.CoreLib.dll #25561

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kotlarmilos and others added 3 commits May 28, 2026 09:36

Potential fix for pull request finding

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Potential fix for pull request finding

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dalexsoto approved these changes May 28, 2026

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rolfbjarne merged commit c6fabd7 into darc-net11.0-d4fe64b2-8391-403d-bbd7-5e3371f43b46 May 28, 2026
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rolfbjarne commented May 28, 2026

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vs-mobiletools-engineering-service2 commented May 28, 2026

✅ [PR Build #0a31d6e] Build passed (Detect API changes) ✅

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vs-mobiletools-engineering-service2 commented May 28, 2026

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vs-mobiletools-engineering-service2 commented May 28, 2026

✅ [PR Build #0a31d6e] Build passed (Build packages) ✅

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vs-mobiletools-engineering-service2 commented May 28, 2026

✅ [PR Build #0a31d6e] Build passed (Build macOS tests) ✅

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🔥 [CI Build #0a31d6e] Test results 🔥

Test results

Failures

❌ dotnettests tests (MacCatalyst)

❌ linker tests (macOS)

❌ monotouch tests (iOS) [attempt 2]

Failed tests

❌ monotouch tests (MacCatalyst) [attempt 2]

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