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

Mon Jun 21 11:25:48 PDT 2021

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

I see. Glad you did – and sorry it did not get the appropriate reaction.

Can the LLVM maintainers here make this change (which would be the best/simplest)? Or does it have to come from the Apple side (which appears to be far harder to reach)?

TNX

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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