[llvm-dev] "--sdk macosx" argument?

[Keith Smiley via llvm-dev]

On the Apple side I filed this a few years ago as FB7253366
--
Keith Smiley


On Mon, Jun 21, 2021 at 10:52 AM Blumenthal, Uri - 0553 - MITLL via
llvm-dev <llvm-dev at lists.llvm.org> wrote:

> This is about building Clang-12 on MacOS (Big Sur 11.4, in case it
> matters). Some machines have a problem with how LLVM selects the SDK to use
> and pass to compiler as  -isysroot  argument. It appears that the build
> process locates SDK via
>
>
>
> xcrun --sdk macosx –show-sdk-path
>
>
>
> that returns MacOSX11.3.sdk, while
>
>
>
> xcrun --show-sdk-path
>
>
>
> returns MacOSX.sdk.
>
>
>
> I’m bringing this up to your attention, because MacOSX11.3.sdk (that is
> symlink’ed to MacOSX.sdk) seems to fail the build (see
> https://trac.macports.org/ticket/63038#comment:39). It fails to locate an
> SDK-provided header file.
>
>
>
> Here’s what the problem/error looks like:
>
> :info:build [ 11%] Building CXX object
> lib/Target/AArch64/CMakeFiles/LLVMAArch64CodeGen.dir/AArch64TargetMachine.cpp.o
>
> :info:build cd
> opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_llvm-12/clang-12/work/build/lib/Target/AArch64
> && /usr/bin/clang++ -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS
> -D__STDC_LIMIT_MACROS
> -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_llvm-12/clang-12/work/build/lib/Target/AArch64
> -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_llvm-12/clang-12/work/llvm-project-12.0.0.src/llvm/lib/Target/AArch64
> -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_llvm-12/clang-12/work/build/include
> -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_llvm-12/clang-12/work/llvm-project-12.0.0.src/llvm/include
> -isystem /opt/local/include -pipe -Os -DNDEBUG -I/opt/local/include
> -stdlib=libc++
> -isysroot/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk
> -fPIC -fvisibility-inlines-hidden -Werror=date-time
> -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter
> -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic
> -Wno-long-long -Wimplicit-fallthrough -Wcovered-switch-default
> -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor
> -Wsuggest-override -Wstring-conversion -O3 -DNDEBUG -arch x86_64 -isysroot
> /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk
> -mmacosx-version-min=11.0  -fno-exceptions -std=c++14 -o
> CMakeFiles/LLVMAArch64CodeGen.dir/AArch64TargetMachine.cpp.o -c
> /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_llvm-12/clang-12/work/llvm-project-12.0.0.src/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp
>
> :info:build In file included from
> /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_llvm-12/clang-12/work/llvm-project-12.0.0.src/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp:12:
>
> :info:build In file included from
> /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_llvm-12/clang-12/work/llvm-project-12.0.0.src/llvm/lib/Target/AArch64/AArch64TargetMachine.h:16:
>
> :info:build In file included from
> /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_llvm-12/clang-12/work/llvm-project-12.0.0.src/llvm/lib/Target/AArch64/AArch64InstrInfo.h:16:
>
> :info:build In file included from
> /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_llvm-12/clang-12/work/llvm-project-12.0.0.src/llvm/lib/Target/AArch64/AArch64.h:17:
>
> :info:build In file included from
> /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_llvm-12/clang-12/work/llvm-project-12.0.0.src/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCTargetDesc.h:18:
>
> :info:build In file included from
> /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk/usr/include/c++/v1/memory:688:
>
> :info:build
> /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk/usr/include/c++/v1/cassert:20:10:
> fatal error: 'assert.h' file not found
>
> :info:build #include <assert.h>
>
> :info:build          ^~~~~~~~~~
>
> :info:build 1 error generated.
>
>
>
> The workaround for this problem is removing the --sdk macosx  flag. Then
> xcrun locates the “main” MacOSX.sdk rather a symlink to it, and
> everything works fine. This flag is unnecessary to begin with, and harmful
> on some machines.
>
>
>
> Therefore, I’d like to request the maintainers to remove the “--sdk
> macosx”   flag from the build config.
>
>
>
> Thank you!
>
> --
>
> Regards,
>
> Uri Blumenthal                              Voice: (781) 981-1638
>
> Secure Resilient Systems and Technologies   Cell:  (339) 223-5363
>
> MIT Lincoln Laboratory
>
> 244 Wood Street, Lexington, MA  02420-9108
>
>
>
> Web:     https://www.ll.mit.edu/biographies/uri-blumenthal
>
> Root CA: https://www.ll.mit.edu/llrca2.pem
>
>
>
> *There are two ways to design a system. One is to make is so simple there
> are obviously no deficiencies.*
>
> *The other is to make it so complex there are no obvious deficiencies.*
>
> *
>                                                                                                                    -
> C. A. R. Hoare*
>
>
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