[bug] `MetalToolchain` causing build error on iOS target

[setoelkahfi]

Describe the bug

I observed this when tying to run a Metal library for machine learning models. I tested by removing my Metal Toolchain and it fixed the build.

Ld /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Products/debug-iphonesimulator/KaroKowe.app/__preview.dylib normal (in target 'app_iOS' from project 'app')
    cd /Users/setoelkahfi/Repositories/splitfire/frontend/karokowe/src-tauri/gen/apple
    /Applications/Xcode-26.2.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -Xlinker -reproducible -target arm64-apple-ios13.0-simulator -dynamiclib -isysroot /Applications/Xcode-26.2.0.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator26.2.sdk -O0 -L/Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Products/debug-iphonesimulator -L/Users/setoelkahfi/Repositories/splitfire/frontend/karokowe/src-tauri/gen/apple/Externals/arm64/debug -L/Applications/Xcode-26.2.0.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator26.2.sdk/usr/lib/swift -L/var/run/com.apple.security.cryptexd/mnt/com.apple.MobileAsset.MetalToolchain-v17.3.48.0.T5h9NI/Metal.xctoolchain/usr/lib/swift/iphonesimulator -L/var/run/com.apple.security.cryptexd/mnt/com.apple.MobileAsset.MetalToolchain-v17.3.48.0.T5h9NI/Metal.xctoolchain/usr/lib/swift-5.0/iphonesimulator -F/Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Products/debug-iphonesimulator -F. -install_name @rpath/KaroKowe.debug.dylib -dead_strip -rdynamic -Xlinker -no_deduplicate -Xlinker -objc_abi_version -Xlinker 2 -Xlinker -dependency_info -Xlinker /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/Objects-normal/arm64/KaroKowe_dependency_info.dat -Xlinker -sectcreate -Xlinker __TEXT -Xlinker __entitlements -Xlinker /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/KaroKowe.app-Simulated.xcent -Xlinker -sectcreate -Xlinker __TEXT -Xlinker __ents_der -Xlinker /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/KaroKowe.app-Simulated.xcent.der -Xlinker -no_adhoc_codesign -o /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Products/debug-iphonesimulator/KaroKowe.app/__preview.dylib
ld: warning: search path '/var/run/com.apple.security.cryptexd/mnt/com.apple.MobileAsset.MetalToolchain-v17.3.48.0.T5h9NI/Metal.xctoolchain/usr/lib/swift/iphonesimulator' not found
ld: warning: search path '/var/run/com.apple.security.cryptexd/mnt/com.apple.MobileAsset.MetalToolchain-v17.3.48.0.T5h9NI/Metal.xctoolchain/usr/lib/swift-5.0/iphonesimulator' not found

CompileC /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/Objects-normal/arm64/main.o /Users/setoelkahfi/Repositories/splitfire/frontend/karokowe/src-tauri/gen/apple/Sources/app/main.mm normal arm64 objective-c++ com.apple.compilers.llvm.clang.1_0.compiler (in target 'app_iOS' from project 'app')
    cd /Users/setoelkahfi/Repositories/splitfire/frontend/karokowe/src-tauri/gen/apple

    Using response file: /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/Objects-normal/arm64/af3fcb34312c57c0f52879cdce924b91-common-args.resp

    /Applications/Xcode-26.2.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -x objective-c++ -ivfsstatcache /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/SDKStatCaches.noindex/iphonesimulator26.2-23C53-3885c01c3e6b6a337905948deab2002e396ea2e52eee30dc3ef691f54c5a881e.sdkstatcache -fmessage-length\=214 -fdiagnostics-show-note-include-stack -fmacro-backtrace-limit\=0 -fcolor-diagnostics -fmodules-prune-interval\=86400 -fmodules-prune-after\=345600 -fbuild-session-file\=/Users/setoelkahfi/Library/Developer/Xcode/DerivedData/ModuleCache.noindex/Session.modulevalidation -fmodules-validate-once-per-build-session -Wnon-modular-include-in-framework-module -Werror\=non-modular-include-in-framework-module -Wno-trigraphs -Wno-missing-field-initializers -Wno-missing-prototypes -Werror\=return-type -Wdocumentation -Wunreachable-code -Wquoted-include-in-framework-header -Wno-implicit-atomic-properties -Werror\=deprecated-objc-isa-usage -Wno-objc-interface-ivars -Werror\=objc-root-class -Wno-arc-repeated-use-of-weak -Wimplicit-retain-self -Wno-non-virtual-dtor -Wno-overloaded-virtual -Wno-exit-time-destructors -Wduplicate-method-match -Wno-missing-braces -Wparentheses -Wswitch -Wunused-function -Wno-unused-label -Wno-unused-parameter -Wunused-variable -Wunused-value -Wempty-body -Wuninitialized -Wconditional-uninitialized -Wno-unknown-pragmas -Wno-shadow -Wno-four-char-constants -Wno-conversion -Wconstant-conversion -Wint-conversion -Wbool-conversion -Wenum-conversion -Wno-float-conversion -Wnon-literal-null-conversion -Wobjc-literal-conversion -Wshorten-64-to-32 -Wno-newline-eof -Wno-selector -Wno-strict-selector-match -Wundeclared-selector -Wdeprecated-implementations -Wno-c++11-extensions -Wno-implicit-fallthrough -fstrict-aliasing -Wprotocol -Wdeprecated-declarations -Winvalid-offsetof -Wno-sign-conversion -Winfinite-recursion -Wmove -Wcomma -Wblock-capture-autoreleasing -Wstrict-prototypes -Wrange-loop-analysis -Wno-semicolon-before-method-body -Wunguarded-availability -index-store-path /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Index.noindex/DataStore @/Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/Objects-normal/arm64/af3fcb34312c57c0f52879cdce924b91-common-args.resp -MMD -MT dependencies -MF /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/Objects-normal/arm64/main.d --serialize-diagnostics /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/Objects-normal/arm64/main.dia -c /Users/setoelkahfi/Repositories/splitfire/frontend/karokowe/src-tauri/gen/apple/Sources/app/main.mm -o /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/Objects-normal/arm64/main.o -index-unit-output-path /app.build/debug-iphonesimulator/app_iOS.build/Objects-normal/arm64/main.o

CompileAssetCatalogVariant thinned /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Products/debug-iphonesimulator/KaroKowe.app /Users/setoelkahfi/Repositories/splitfire/frontend/karokowe/src-tauri/gen/apple/Assets.xcassets (in target 'app_iOS' from project 'app')
    cd /Users/setoelkahfi/Repositories/splitfire/frontend/karokowe/src-tauri/gen/apple
    /Applications/Xcode-26.2.0.app/Contents/Developer/usr/bin/actool /Users/setoelkahfi/Repositories/splitfire/frontend/karokowe/src-tauri/gen/apple/Assets.xcassets --compile /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/assetcatalog_output/thinned --output-format human-readable-text --notices --warnings --export-dependency-info /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/assetcatalog_dependencies_thinned --output-partial-info-plist /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/assetcatalog_generated_info.plist_thinned --app-icon AppIcon --compress-pngs --enable-on-demand-resources YES --filter-for-thinning-device-configuration iPhone18,1 --filter-for-device-os-version 26.2 --development-region en --target-device iphone --target-device ipad --minimum-deployment-target 13.0 --platform iphonesimulator

Ld /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Products/debug-iphonesimulator/KaroKowe.app/KaroKowe.debug.dylib normal (in target 'app_iOS' from project 'app')
    cd /Users/setoelkahfi/Repositories/splitfire/frontend/karokowe/src-tauri/gen/apple
    /Applications/Xcode-26.2.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -Xlinker -reproducible -target arm64-apple-ios13.0-simulator -dynamiclib -isysroot /Applications/Xcode-26.2.0.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator26.2.sdk -O0 -L/Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/EagerLinkingTBDs/debug-iphonesimulator -L/Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Products/debug-iphonesimulator -L/Users/setoelkahfi/Repositories/splitfire/frontend/karokowe/src-tauri/gen/apple/Externals/arm64/debug -L/Applications/Xcode-26.2.0.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator26.2.sdk/usr/lib/swift -L/var/run/com.apple.security.cryptexd/mnt/com.apple.MobileAsset.MetalToolchain-v17.3.48.0.T5h9NI/Metal.xctoolchain/usr/lib/swift/iphonesimulator -L/var/run/com.apple.security.cryptexd/mnt/com.apple.MobileAsset.MetalToolchain-v17.3.48.0.T5h9NI/Metal.xctoolchain/usr/lib/swift-5.0/iphonesimulator -F/Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/EagerLinkingTBDs/debug-iphonesimulator -F/Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Products/debug-iphonesimulator -F. -filelist /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/Objects-normal/arm64/KaroKowe.LinkFileList -install_name @rpath/KaroKowe.debug.dylib -Xlinker -rpath -Xlinker @executable_path/Frameworks -dead_strip -Xlinker -object_path_lto -Xlinker /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/Objects-normal/arm64/KaroKowe_lto.o -rdynamic -Xlinker -no_deduplicate -Xlinker -objc_abi_version -Xlinker 2 -Xlinker -dependency_info -Xlinker /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Intermediates.noindex/app.build/debug-iphonesimulator/app_iOS.build/Objects-normal/arm64/KaroKowe_dependency_info.dat -stdlib\=libc++ -fobjc-arc -fobjc-link-runtime -Xlinker -alias -Xlinker _main -Xlinker ___debug_main_executable_dylib_entry_point -lapp -framework CoreGraphics -framework Metal -framework MetalKit -framework QuartzCore -framework Security -framework UIKit -framework AudioToolbox -framework AVFoundation -framework AVFAudio -framework CoreAudio -framework OpenAL -framework WebKit -Xlinker -no_adhoc_codesign -o /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Products/debug-iphonesimulator/KaroKowe.app/KaroKowe.debug.dylib
ld: warning: search path '/var/run/com.apple.security.cryptexd/mnt/com.apple.MobileAsset.MetalToolchain-v17.3.48.0.T5h9NI/Metal.xctoolchain/usr/lib/swift/iphonesimulator' not found
ld: warning: search path '/var/run/com.apple.security.cryptexd/mnt/com.apple.MobileAsset.MetalToolchain-v17.3.48.0.T5h9NI/Metal.xctoolchain/usr/lib/swift-5.0/iphonesimulator' not found
ld: warning: Could not find or use auto-linked library 'swiftCompatibility56': library 'swiftCompatibility56' not found
ld: warning: Could not find or use auto-linked library 'swiftCompatibilityConcurrency': library 'swiftCompatibilityConcurrency' not found
ld: warning: Could not find or use auto-linked library 'swiftCompatibilityPacks': library 'swiftCompatibilityPacks' not found
ld: warning: Could not find or use auto-linked framework 'CoreAudioTypes': framework 'CoreAudioTypes' not found
ld: warning: Could not find or use auto-linked framework 'UIUtilities': framework 'UIUtilities' not found
ld: warning: Could not parse or use implicit file '/Applications/Xcode-26.2.0.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/System/Library/Frameworks/SwiftUICore.framework/SwiftUICore.tbd': cannot link directly with 'SwiftUICore' because product being built is not an allowed client of it
Undefined symbols for architecture arm64:
  "__swift_FORCE_LOAD_$_swiftCompatibility56", referenced from:
      __swift_FORCE_LOAD_$_swiftCompatibility56_$_SwiftRs in libapp.a[260](lib.swift.o)
      __swift_FORCE_LOAD_$_swiftCompatibility56_$_Tauri in libapp.a[261](Channel.swift.o)
      __swift_FORCE_LOAD_$_swiftCompatibility56_$_tauri_plugin_haptics in libapp.a[269](HapticsPlugin.swift.o)
      __swift_FORCE_LOAD_$_swiftCompatibility56_$_tauri_plugin_clipboard_manager in libapp.a[281](ClipboardPlugin.swift.o)
      __swift_FORCE_LOAD_$_swiftCompatibility56_$_tauri_plugin_opener in libapp.a[292](OpenerPlugin.swift.o)
      __swift_FORCE_LOAD_$_swiftCompatibility56_$_tauri_plugin_log in libapp.a[1192](LogPlugin.swift.o)
  "__swift_FORCE_LOAD_$_swiftCompatibilityConcurrency", referenced from:
      __swift_FORCE_LOAD_$_swiftCompatibilityConcurrency_$_SwiftRs in libapp.a[260](lib.swift.o)
      __swift_FORCE_LOAD_$_swiftCompatibilityConcurrency_$_Tauri in libapp.a[261](Channel.swift.o)
      __swift_FORCE_LOAD_$_swiftCompatibilityConcurrency_$_tauri_plugin_haptics in libapp.a[269](HapticsPlugin.swift.o)
      __swift_FORCE_LOAD_$_swiftCompatibilityConcurrency_$_tauri_plugin_clipboard_manager in libapp.a[281](ClipboardPlugin.swift.o)
      __swift_FORCE_LOAD_$_swiftCompatibilityConcurrency_$_tauri_plugin_opener in libapp.a[292](OpenerPlugin.swift.o)
      __swift_FORCE_LOAD_$_swiftCompatibilityConcurrency_$_tauri_plugin_log in libapp.a[1192](LogPlugin.swift.o)
ld: symbol(s) not found for architecture arm64
clang++: error: linker command failed with exit code 1 (use -v to see invocation)

note: Run script build phase 'Build Rust Code' will be run during every build because the option to run the script phase "Based on dependency analysis" is unchecked. (in target 'app_iOS' from project 'app')
** BUILD FAILED **


The following build commands failed:
	Ld /Users/setoelkahfi/Library/Developer/Xcode/DerivedData/app-ahswwcdiberlnuagoaidlgufkpbt/Build/Products/debug-iphonesimulator/KaroKowe.app/KaroKowe.debug.dylib normal (in target 'app_iOS' from project 'app')
	Building workspace app with scheme app_iOS and configuration debug
(2 failures)
       Error failed to run iOS app: failed to build with xcodebuild: command ["xcodebuild"] exited with code 65

Reproduction

1. Install metal toolchain: xcodebuild -downloadComponent MetalToolchain
2. Build a Tauri app for iOS.
3. Build fail.

Expected behavior

Build should succeed with the existence of Metal Toolchain.

Full tauri info output

[✔] Environment
    - OS: Mac OS 26.2.0 arm64 (X64)
    ✔ Xcode Command Line Tools: installed
    ✔ Xcode: 26.2
    ✔ rustc: 1.92.0 (ded5c06cf 2025-12-08)
    ✔ cargo: 1.92.0 (344c4567c 2025-10-21)
    ✔ rustup: 1.28.2 (e4f3ad6f8 2025-04-28)
    ✔ Rust toolchain: 1.92-aarch64-apple-darwin (overridden by environment variable RUSTUP_TOOLCHAIN)
    - node: 24.9.0
    - pnpm: 10.25.0
    - yarn: 1.22.22
    - npm: 11.6.0
    - bun: 1.3.3
    - deno: deno 2.5.6

[-] Packages
    - tauri 🦀: 2.9.5
    - tauri-build 🦀: 2.5.3
    - wry 🦀: 0.53.5, (outdated, latest: 0.54.1)
    - tao 🦀: 0.34.5
    - tauri-cli 🦀: 2.9.6
    - @tauri-apps/api  ⱼₛ: 2.9.1
    - @tauri-apps/cli  ⱼₛ: 2.9.6

[-] Plugins
    - tauri-plugin-opener 🦀: 2.5.3
    - @tauri-apps/plugin-opener  ⱼₛ: 2.5.3
    - tauri-plugin-fs 🦀: 2.4.5
    - @tauri-apps/plugin-fs  ⱼₛ: 2.4.5
    - tauri-plugin-haptics 🦀: 2.3.2
    - @tauri-apps/plugin-haptics  ⱼₛ: 2.3.2
    - tauri-plugin-deep-link 🦀: 2.4.6
    - @tauri-apps/plugin-deep-link  ⱼₛ: 2.4.6
    - tauri-plugin-store 🦀: 2.4.2
    - @tauri-apps/plugin-store  ⱼₛ: 2.4.2
    - tauri-plugin-clipboard-manager 🦀: 2.3.2
    - @tauri-apps/plugin-clipboard-manager  ⱼₛ: 2.3.2
    - tauri-plugin-single-instance 🦀: 2.3.7
    - @tauri-apps/plugin-single-instance  ⱼₛ: not installed!
    - tauri-plugin-os 🦀: 2.3.2
    - @tauri-apps/plugin-os  ⱼₛ: 2.3.2
    - tauri-plugin-log 🦀: 2.8.0
    - @tauri-apps/plugin-log  ⱼₛ: 2.8.0

[-] App
    - build-type: bundle
    - CSP: unset
    - frontendDist: ../dist
    - devUrl: http://localhost:1420/
    - framework: React
    - bundler: Vite

Stack trace

Additional context

Xcode 26.2

No response