Don't let -Xarch_x86_64 break Apple builds that use -Werror - #134
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CMAKE_OSX_ARCHITECTURES is only an upper bound on the slices Xcode actually compiles: it picks slices per SDK at build time. An iOS build configured for "arm64;x86_64" (leetal/ios-cmake's OS64COMBINED, where x86_64 is the simulator slice) compiles only arm64 against the iphoneos SDK, so the -Xarch_x86_64 applies to nothing and clang reports it as an unused argument -- fatal for projects building with -Werror. Pair the flag with -Wno-unused-command-line-argument so the SSE minspec still reaches every x86_64 slice that is built, without breaking the slices that aren't.
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Verified on real iOS CISince bgfx.cmake has no CI of its own, I validated this against the build that actually reproduces the failure. I pointed a throwaway BabylonNative branch's
Same runner image, same Xcode 26.4.1, same |
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What
Fixes
-Xarch_x86_64 -msse4.2breaking Apple builds that compile with-Werror.Why
#133 made the SSE minspec arch-aware, using
-Xarch_x86_64for universal builds so the flag only reaches the x86_64 slice. That is correct whenCMAKE_OSX_ARCHITECTURESdescribes the slices that actually get compiled -- which holds for a macOS universal build, but not for Xcode in general.Xcode picks slices per SDK at build time, so
CMAKE_OSX_ARCHITECTURESis only an upper bound. An iOS build configured through leetal/ios-cmake'sOS64COMBINEDreportsarm64;x86_64(x86_64 being the simulator slice), yet theiphoneosbuild compiles arm64 only. clang then sees an-Xarch_x86_64that applies to nothing:This reproduces in BabylonNative's iOS CI (BabylonJS/BabylonNative#1795), which builds with
-Werror.How
Pair the flag with
-Wno-unused-command-line-argument, scoped to the universal-build branch only. Every x86_64 slice that is actually compiled still gets the SSE4.2 minspec; slices that aren't no longer fail the build. Single-slice builds are untouched -- they pass a plain-msse4.2with no-Xarch_and so cannot hit this.