<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/150039>150039</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [Compiler RT] compiler-rt doesn't cross compile into MacOS
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          mccakit
      </td>
    </tr>
</table>

<pre>
    cmake -S runtimes -B build -G Ninja \
 -DCMAKE_BUILD_TYPE=Release \
 -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;libunwind;compiler-rt" \
 -DLLVM_HOST_TRIPLE=x86_64-unknown-linux-gnu
 -DCMAKE_TOOLCHAIN_FILE=$HOME/toolchains/llvm-macos-x64

Toolchain

---

```
set(CMAKE_SYSTEM_NAME Darwin)
set(CMAKE_SYSTEM_PROCESSOR X86_64)
set(triple x86_64-apple-darwin)

set(CMAKE_C_COMPILER /home/mccakit/dev/llvm/bin/clang)
set(CMAKE_C_COMPILER_TARGET ${triple})
set(CMAKE_CXX_COMPILER /home/mccakit/dev/llvm/bin/clang++)
set(CMAKE_CXX_COMPILER_TARGET ${triple})
set(CMAKE_RC_COMPILER /home/mccakit/dev/llvm/bin/llvm-rc)
set(CMAKE_LINKER_TYPE LLD)
set(CMAKE_AR /home/mccakit/dev/llvm/bin/llvm-ar)
set(CMAKE_RANLIB /home/mccakit/dev/llvm/bin/llvm-ranlib)
set(CMAKE_MT /home/mccakit/dev/llvm/bin/llvm-mt)
set(CMAKE_ASM_COMPILER /home/mccakit/dev/llvm/bin/clang)

set(CMAKE_INSTALL_NAME_TOOL /home/mccakit/dev/llvm/bin/llvm-install-name-tool)
set(CMAKE_OBJC_COMPILER /home/mccakit/dev/llvm/bin/clang)
set(CMAKE_OBJC_COMPILER_TARGET ${triple})
set(CMAKE_OBJCXX_COMPILER /home/mccakit/dev/llvm/bin/clang++)
set(CMAKE_OBJCXX_COMPILER_TARGET ${triple})

set(CMAKE_OSX_SYSROOT /mnt/c/dev/sysroots/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk)
set(CMAKE_OSX_DEPLOYMENT_TARGET 14.0)
set(DARWIN_macosx_OVERRIDE_SDK_VERSION "16.4")
```

Compiler rt tries to use bits/libc-header-start.h wh'ch doesn't exist in MacOS SDK 16.4

FAILED: [code=1] compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins_i386_osx.dir/addsf3.c.o /home/mccakit/dev/llvm/bin/clang --target=x86_64-apple-darwin -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS  -O3 -DNDEBUG -arch i386 -isysroot /mnt/c/dev/sysroots/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk -isysroot / -mmacosx-version-min=10.7 -fPIC -O3 -fvisibility=hidden -DVISIBILITY_HIDDEN -Wall -fomit-frame-pointer -Werror=array-bounds -Werror=uninitialized -Werror=shadow -Werror=empty-body -Werror=sizeof-pointer-memaccess -Werror=sizeof-array-argument -Werror=suspicious-memaccess -Werror=builtin-memcpy-chk-size -Werror=array-bounds-pointer-arithmetic -Werror=return-stack-address -Werror=sizeof-array-decay -Werror=format-insufficient-args -Wformat -Werror=format-nonliteral -DDONT_DEFINE_EPRINTF -arch i386 -MD -MT compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins_i386_osx.dir/addsf3.c.o -MF compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins_i386_osx.dir/addsf3.c.o.d -o compiler-rt/lib/builtins/CMakeFiles/clang_rt.builtins_i386_osx.dir/addsf3.c.o -c /home/mccakit/llvm-project/compiler-rt/lib/builtins/addsf3.c In file included from /home/mccakit/llvm-project/compiler-rt/lib/builtins/addsf3.c:14: In file included from /home/mccakit/llvm-project/compiler-rt/lib/builtins/fp_add_impl.inc:14: In file included from /home/mccakit/llvm-project/compiler-rt/lib/builtins/fp_lib.h:23: In file included from /home/mccakit/llvm-project/compiler-rt/lib/builtins/int_lib.h:93: In file included from /home/mccakit/dev/llvm/lib/clang/21/include/limits.h:25: /usr/include/limits.h:26:10: fatal error: 'bits/libc-header-start.h' file not found 26 | #include <bits/libc-header-start.h> | ^~~~~~~~~~~~~~~~~~~~~~~~~~ 1 error generated. [1695/2915] Building CXX object libunwind/src/CMakeFiles/unwind_static_objects.dir/libunwind.cpp.o ninja: build stopped: subcommand failed. mccakit@DESKTOP-6J44CHE:~/llvm-project$ 

</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJzMWF1zo7gS_TXyi0qUEdgeP_gBG5hhYxuXYWaSJ0qAsLUBiZJEPvZhf_stgZM4H5Pa3Du5tSlXBUvd55yWutXCRCl24JQuwGQJJv6IdPoo5KIpCnLN9CgX5f2iaMg1hSiBsuOaNVRBtIR5x-oSoq9wy_ifBILJCow9iPzVxrsIsuX3aO1n6dUuAI6_pzUlij7ZrNc_Nlmw9ZbrINt_36bRJkiA4wOMa5YXd3fAWQ4PJGfDc8dvGS-BsyxE07KaSiQ1wPgF5Lc4SbN0H-3WhvbuyzSbuqjj11zcclQz3t2hA-_OdaZxvF5986JtFka9E8Dut3gTABxqIeriSBhXAId1fdOghhRCobupC8YeGHvpg8HwFSE0PIDp-PQZe4pqgL8MXMlVkgabbOttAugTecs4wPO3bXb7eBUkSbyHl30Q54Zasram8BQdaduaovIM7gXiKlvFm120DvYQ4PAoGgpweNpegMOS3pzCAzjMDUZY1IQfXkt7AspSb_81SCHALpgtBz1g5r_hcnn537Iv-897gP9Yxf7jS9BvtyxeY62j7YWhvtoFcL1-g8z7GAeRb-j1tuto-TGphNcsfw21ST8E0-g3Ako2_0sGvUCLtknqrdd9EfTF9yF9jCtN6hpx0lBk6vO13Hj5x2_L-GdY_zjdjNfvzvsXmO9qeemaXJpTZR_HfS403PAXjxrUvZJCaHPGXRaipA__LdK2AIcrwTXl_bRPb2gtWioBDnc10ZWQjRnfkCJOLq32NPTCMvEvzoxUef1GcMll5ge7dXy1CbbpQ2y2a43PbX1v_zPaZv0ZfJfFP4L9PvKDLPEvsh_BPoniLQQY21PLBRifVuLsIAZjb3VqHVBqqCWjCmoBO0VhzvoATctBR0pKKpHSRGrrCG-PAM-KIywFVRzgmYb0jikNGYd9SDDxL2BP2lOEXrQOfOB4EEyW_XI6vg0mPnzWtsK-VkPTQfXQXlYbck1DVlP1kAmZ1NaDQcacL9NMqDurZGZNSVmqyrEKS3wouSBCmsgD1U-98bx7QORnWZL6JuVNlW7TbOOt9nHyNBHG-433engdbaLHUYhiByJ_6wfL718hIrI4QqMfInbKtX9FGj6XA1EzJBa6oVIxwVHDuNm7sTWDqNpFqyGs6oYplrOa6Xvg-EdWltSs248oiZbROkqvsm-R7wdbiH6SuoaoEg3TqJLmvGoF45pKiH5SKYUEjk-kJPcoFx0v1dlwxxlnmpGa_UXLs3F1JKW4PRugTauNf3l_bsX-oqJ6YEMNbUhRUKVemwz0RB66hnJ9Pt-plhVMdOpN91NamrmivUfF8RoZxF8E9qiESKaPDdWsOLOUVHeSm3IrrhEpS_mO0pIW5DxSs81Em6bQVRUrGOXaRGP8h6nXtlzwmmkqSQ2R78fbNPODMNoGWbDbR9s0fJavGx-iTfpppYs24WdhWyVE4vOEF28eO32HbqX4kxZ9bb_P_oAHIw4rVlPIeFF3JS1hJUXzGwmA49muOZE_i6hqM1KWGWva2mL8_8JXs9w6AsfDzmcSMa4fmeYfZHrWgwbk0wUnxHaP3SP0kw3Taghn0ndOHHZK_tJmahZ4bAwrokkNTxVu_Ga_buQAzwbpXGhYmYMJ4ikEsxUE2DkRQeCs3kFwgsF-Evz9qz9oD3LggXIqiaalZS4C9nQ-MYHP7Ym5CyzNmzPjB7i6vIQiN5sBn15xcajMi8fz8hzmMqWJZkU2-KhTZT66WkXbWgJy8z5uFmR4Q1datC0tzYDq8kI0DeElrAirjbqHHXPHfpBcpPEOTf9w3dW3ADje368yxoVg7I3KhVPOnTkZ0YU9mzj2fOa6zui4yJ2STsbEnhauW9mujSe4dCe5M7bt3J5P7RFb4DGejGcY2xN7hh2rnFYVLedV-SWvprgqgDumDWG1ZWgtIQ8jplRHF_ZkPHbmo5rktFb9LxUYc3oL-1lz3Zv4I7notebdQQF3XDOl1ROMZrruf-J4vAPu0xfXsrMrXiGFUg9zkHEthsveqJP14qh1q4DjARwCHB6YPna5VYjmLN2fV1kv0mziKYqbBf5PAAAA___o-p81">