[msbuild] Fix app crash at launch when _ExportSymbolsExplicitly=false. Fixes #25491 by rolfbjarne · Pull Request #25494 · dotnet/macios

rolfbjarne · 2026-05-21T17:31:56Z

When _ExportSymbolsExplicitly=false, the strip command was running without any flags on the main executable, stripping all symbols including ones the runtime needs, causing the app to crash at launch.

Changes

msbuild/Xamarin.Shared/Xamarin.Shared.targets — Always pass the symbol file to strip (revert the condition from PR [msbuild] Don't pass symbol file to strip when _ExportSymbolsExplicitly=false. Fixes #24582. #24800 that removed it when _ExportSymbolsExplicitly=false).
msbuild/Xamarin.MacDev.Tasks/Tasks/SymbolStrip.cs — Implement GetAdditionalItemsToBeCopied() to ensure the symbol file is transferred to the remote Mac for Windows→Mac builds, so remote builds behave identically to local builds.
tests/dotnet/UnitTests/ProjectTest.cs — Add StrippedWithExportSymbolsExplicitlyFalse test that builds with _ExportSymbolsExplicitly=false, executes the app, and verifies required symbols remain in the binary.

Root cause

PR #24800 fixed a build failure for remote Windows builds by removing the symbol file from the strip command when _ExportSymbolsExplicitly=false. However, running bare strip (without -i -s <symbolfile>) removes all symbols from the main executable, including ones the .NET runtime needs at launch.

Fix approach

Instead of conditionally omitting the symbol file, we now:

Always pass the symbol file to strip (it's always written unconditionally by WriteLinesToFile)
Ensure it gets transferred to the remote Mac via GetAdditionalItemsToBeCopied()

This ensures consistent behavior between local and remote builds.

Fixes #25491

🤖 Pull request created by Copilot

…Fixes #25491. When _ExportSymbolsExplicitly=false, the strip command was running without any flags on the main executable, which strips all symbols including ones the runtime needs, causing the app to crash at launch. Fix by: 1. Always passing the symbol file to strip (reverting the condition from PR #24800). 2. Making the SymbolStrip task resilient: if the symbol file doesn't exist (e.g. Windows remote builds), fall back to '-S -x' (strip debug and local symbols only) instead of bare 'strip'. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Instead of falling back to different strip behavior when the symbol file is missing, ensure the file is always transferred to the remote Mac by implementing GetAdditionalItemsToBeCopied in the SymbolStrip task. This ensures remote builds behave identically to local builds. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The GetAdditionalItemsToBeCopied() method needs the local (Windows) path to know which file to copy to the remote Mac build server. Added a SymbolFileLocalPath property that holds the local path while SymbolFile retains the Mac-resolved path for the actual strip command. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Fixes a launch-time crash caused by invoking strip without arguments when _ExportSymbolsExplicitly=false, by ensuring the exported-symbol list is still used during symbol stripping (and is available in remote builds).

Changes:

Always provide the symbols list file to the post-processing strip step (regardless of _ExportSymbolsExplicitly).
Extend the SymbolStrip MSBuild task to include the symbols list among files copied to the remote Mac (Windows→Mac builds).
Add a unit test validating that required runtime symbols remain after stripping with _ExportSymbolsExplicitly=false.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
`msbuild/Xamarin.Shared/Xamarin.Shared.targets`	Always supplies the symbol list to `SymbolStrip` and threads through a local-path metadata for remote copy support.
`msbuild/Xamarin.MacDev.Tasks/Tasks/SymbolStrip.cs`	Adds `SymbolFileLocalPath` and begins implementing remote-copy support via `GetAdditionalItemsToBeCopied()`.
`tests/dotnet/UnitTests/ProjectTest.cs`	Adds a regression test for stripping with `_ExportSymbolsExplicitly=false`.

vs-mobiletools-engineering-service2 · 2026-06-25T18:15:57Z

✅ [PR Build #9170dd6] Build passed (Detect API changes) ✅

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vs-mobiletools-engineering-service2 · 2026-06-25T18:20:44Z

✅ [PR Build #9170dd6] Build passed (Build packages) ✅

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vs-mobiletools-engineering-service2 · 2026-06-25T18:31:59Z

✅ 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

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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 )

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vs-mobiletools-engineering-service2 · 2026-06-25T18:45:09Z

✅ [PR Build #9170dd6] Build passed (Build macOS tests) ✅

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Hash: 9170dd6037b287df3da1658030e7e148d9d39364 [PR build]

vs-mobiletools-engineering-service2 · 2026-06-26T13:38:15Z

🚀 [CI Build #9170dd6] Test results 🚀

Test results

✅ All tests passed on VSTS: test results.

🎉 All 199 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 18 tests passed. [attempt 2] Html Report (VSDrops) Download
✅ monotouch (MacCatalyst): All 17 tests passed. Html Report (VSDrops) Download
✅ monotouch (macOS): All 18 tests passed. Html Report (VSDrops) Download
✅ monotouch (tvOS): All 18 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

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✅ Linux build succeeded

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Hash: 9170dd6037b287df3da1658030e7e148d9d39364 [PR build]

rolfbjarne and others added 2 commits May 21, 2026 19:30

rolfbjarne added the copilot label May 21, 2026

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rolfbjarne marked this pull request as ready for review June 25, 2026 10:47

Merge branch 'main' into dev/rolf/issue-25491-strip-exported-symbols

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rolfbjarne requested a review from mauroa as a code owner June 25, 2026 10:47

Copilot AI review requested due to automatic review settings June 25, 2026 10:47

Copilot started reviewing on behalf of rolfbjarne June 25, 2026 10:48 View session

Copilot AI reviewed Jun 25, 2026

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Comment thread msbuild/Xamarin.MacDev.Tasks/Tasks/SymbolStrip.cs

Comment thread tests/dotnet/UnitTests/ProjectTest.cs

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dalexsoto approved these changes Jun 25, 2026

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Merge branch 'main' into dev/rolf/issue-25491-strip-exported-symbols

9170dd6

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rolfbjarne commented May 21, 2026

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vs-mobiletools-engineering-service2 commented Jun 25, 2026

✅ [PR Build #9170dd6] Build passed (Detect API changes) ✅

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vs-mobiletools-engineering-service2 commented Jun 25, 2026

✅ [PR Build #9170dd6] Build passed (Build packages) ✅

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vs-mobiletools-engineering-service2 commented Jun 25, 2026

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vs-mobiletools-engineering-service2 commented Jun 25, 2026

✅ [PR Build #9170dd6] Build passed (Build macOS tests) ✅

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vs-mobiletools-engineering-service2 commented Jun 26, 2026

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