[macOS][gn] support both x64/arm64 macOS host clang toolchains for ASAN#186669
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This pull request updates the Clang base path in the iOS build configuration to support dynamic host CPU architectures and a new versioned path. Feedback indicates that the updated path structure may be incorrect as it omits standard directory levels and uses an unconventional version number. Additionally, a typo in the TODO's issue number and a spelling error were identified.
When producing ASAN builds, link against the correct ASAN dylib path. Note that ASAN builds for iOS *are not* currently built or tested on CI, and have been broken for some time. Not only did we add a library with the incorrect architecture, but the toolchain path was incorrect. Given that these builds do not receive automated testing for macOS/iOS and are intended purely for local testing, as well as the fact that ASAN builds for macOS/iOS are more limited in what they check for, we should consider whether we want to support ASAN builds for macOS/iOS at all or instead do such testing in Instruments, as Apple suggests. Due to platform differences, ASAN on macOS lacks functionality on Linux such as: * LSAN * Static initialisation order fiasco detection, due to Mach-O loader behaviour. * DWARF symolification (dSYM files instead) * DYLD_INSERT_LIBRARIES support (unlikely any of us use this) Note that if the build is intentionally invoked under Rosetta 2 -- for example by running `arch -x86_64 BUILD_COMMAND`, `host_cpu` will evaluate to `x86_64`. As such, it is still possible to run builds using the x64 toolchain on demand, but the default behaviour is now to build consistently with the appropriate clang toolchain for the host CPU architecture. Issue: flutter#103386
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Note: It looks like our current clang toolchain does NOT include ios/iossim asan dylibs, just osx binaries. I'm fine fixing the path bug here to eliminate the x64 hardcoding, but given that ASAN has never quite worked for iOS builds, doesn't run on CI, and is less useful than on Linux even if we ever do get it working, I'm leaning towards just adding an Thoughts? |
jmagman
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ASAN has indeed been busted for awhile. I wish it worked, I looked into building it in CI at one point. We could use the asan dylib vended in Xcode: #108469 (comment).
I'm okay landing this PR though in the name of #103386, it doesn't make anything worse.
vashworth
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May 18, 2026
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flutter/flutter@3598686...259aeae 2026-05-19 engine-flutter-autoroll@skia.org Roll Skia from 967ddb1aa561 to f1b406860c5e (2 revisions) (flutter/flutter#186731) 2026-05-19 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from 5Ki-dBY4SpWdQMF_3... to -F9Ci3Opxt06MixDl... (flutter/flutter#186727) 2026-05-19 116356835+AbdeMohlbi@users.noreply.github.com Remove unused field in `ResourceExtractor` (flutter/flutter#186629) 2026-05-19 mbrase@google.com Update Fuchsia tests to use realm_builder_server as a subpackage (flutter/flutter#186409) 2026-05-19 engine-flutter-autoroll@skia.org Roll Skia from cebf49d034b8 to 967ddb1aa561 (4 revisions) (flutter/flutter#186720) 2026-05-19 137456488+flutter-pub-roller-bot@users.noreply.github.com Roll pub packages (flutter/flutter#186721) 2026-05-19 chris@bracken.jp [macOS][gn] support both x64/arm64 macOS host clang toolchains for ASAN (flutter/flutter#186669) 2026-05-19 chris@bracken.jp [macOS][gn] Use arm64 clang in generate_coverage.py on arm64 Macs (flutter/flutter#186662) 2026-05-19 awolff@google.com Fix broken link in impeller golden_tests readme (flutter/flutter#186470) 2026-05-19 engine-flutter-autoroll@skia.org Roll Skia from 27f7bba22600 to cebf49d034b8 (37 revisions) (flutter/flutter#186699) 2026-05-19 chris@bracken.jp [macOS][gn] Use arm64 clang in verify_exported.dart on arm64 Macs (flutter/flutter#186664) 2026-05-19 chris@bracken.jp [macOS][gn] Use arm64 clang in sanitizer_suppressions.sh on arm64 Macs (flutter/flutter#186663) 2026-05-19 chris@bracken.jp [macOS][gn] Use arm64 clang in copy_info_plist.py on arm64 Macs (flutter/flutter#186661) 2026-05-19 58529443+srujzs@users.noreply.github.com Complete completer only once in hot restart tests (flutter/flutter#186702) 2026-05-18 30870216+gaaclarke@users.noreply.github.com Testing autosubmit bot -- updating testowners (flutter/flutter#185226) 2026-05-18 chris@bracken.jp [ios] Correct handling for CADisplayLink paused-to-unpaused transitions (flutter/flutter#186457) 2026-05-18 chris@bracken.jp [Android][macOS][gn] support both x64/arm64 macOS host clang toolchains (flutter/flutter#186660) 2026-05-18 engine-flutter-autoroll@skia.org Roll Packages from 32c84d6 to b9bdd37 (2 revisions) (flutter/flutter#186683) 2026-05-18 jesswon@google.com [AGP 9] Upgrade Flutter Test Apps to AGP 9 (flutter/flutter#186200) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC stuartmorgan@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
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…r#11737) flutter/flutter@3598686...259aeae 2026-05-19 engine-flutter-autoroll@skia.org Roll Skia from 967ddb1aa561 to f1b406860c5e (2 revisions) (flutter/flutter#186731) 2026-05-19 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from 5Ki-dBY4SpWdQMF_3... to -F9Ci3Opxt06MixDl... (flutter/flutter#186727) 2026-05-19 116356835+AbdeMohlbi@users.noreply.github.com Remove unused field in `ResourceExtractor` (flutter/flutter#186629) 2026-05-19 mbrase@google.com Update Fuchsia tests to use realm_builder_server as a subpackage (flutter/flutter#186409) 2026-05-19 engine-flutter-autoroll@skia.org Roll Skia from cebf49d034b8 to 967ddb1aa561 (4 revisions) (flutter/flutter#186720) 2026-05-19 137456488+flutter-pub-roller-bot@users.noreply.github.com Roll pub packages (flutter/flutter#186721) 2026-05-19 chris@bracken.jp [macOS][gn] support both x64/arm64 macOS host clang toolchains for ASAN (flutter/flutter#186669) 2026-05-19 chris@bracken.jp [macOS][gn] Use arm64 clang in generate_coverage.py on arm64 Macs (flutter/flutter#186662) 2026-05-19 awolff@google.com Fix broken link in impeller golden_tests readme (flutter/flutter#186470) 2026-05-19 engine-flutter-autoroll@skia.org Roll Skia from 27f7bba22600 to cebf49d034b8 (37 revisions) (flutter/flutter#186699) 2026-05-19 chris@bracken.jp [macOS][gn] Use arm64 clang in verify_exported.dart on arm64 Macs (flutter/flutter#186664) 2026-05-19 chris@bracken.jp [macOS][gn] Use arm64 clang in sanitizer_suppressions.sh on arm64 Macs (flutter/flutter#186663) 2026-05-19 chris@bracken.jp [macOS][gn] Use arm64 clang in copy_info_plist.py on arm64 Macs (flutter/flutter#186661) 2026-05-19 58529443+srujzs@users.noreply.github.com Complete completer only once in hot restart tests (flutter/flutter#186702) 2026-05-18 30870216+gaaclarke@users.noreply.github.com Testing autosubmit bot -- updating testowners (flutter/flutter#185226) 2026-05-18 chris@bracken.jp [ios] Correct handling for CADisplayLink paused-to-unpaused transitions (flutter/flutter#186457) 2026-05-18 chris@bracken.jp [Android][macOS][gn] support both x64/arm64 macOS host clang toolchains (flutter/flutter#186660) 2026-05-18 engine-flutter-autoroll@skia.org Roll Packages from 32c84d6 to b9bdd37 (2 revisions) (flutter/flutter#186683) 2026-05-18 jesswon@google.com [AGP 9] Upgrade Flutter Test Apps to AGP 9 (flutter/flutter#186200) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC stuartmorgan@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
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When producing ASAN builds, link against the correct ASAN dylib path. Note that ASAN builds for iOS are not currently built or tested on CI, and have been broken for some time. Not only did we add a library with the incorrect architecture, but the toolchain path was incorrect.
Given that these builds do not receive automated testing for macOS/iOS and are intended purely for local testing, as well as the fact that ASAN builds for macOS/iOS are more limited in what they check for, we should consider whether we want to support ASAN builds for macOS/iOS at all or instead do such testing in Instruments, as Apple suggests. Due to platform differences, ASAN on macOS lacks functionality on Linux such as:
Note that if the build is intentionally invoked under Rosetta 2 -- for example by running
arch -x86_64 BUILD_COMMAND,host_cpuwill evaluate tox86_64. As such, it is still possible to run builds using the x64 toolchain on demand, but the default behaviour is now to build consistently with the appropriate clang toolchain for the host CPU architecture.Issue: #103386
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