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Follow up to the same problem on Mojave.

After upgrading to macOS Catalina, none of the C headers can be found in /usr/include. The reason for this may be found in the Xcode 10 release notes (previous version):

The Command Line Tools package installs the macOS system headers inside the macOS SDK. Software that compiles with the installed tools will search for headers within the macOS SDK provided by either Xcode at:

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk

or the Command Line Tools at:

/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk

[...] As a workaround, an extra package is provided which will install the headers to the base system. In a future release, this package will no longer be provided. [...]

(See the link to the question above for details on this suggested workaround.)

Apparently Apple made good on their threat with Xcode 11. How can one install the C headers to /usr/include on macOS Catalina using Xcode 11?

Context: The clang python binding search the header files in /usr/include per default. According to kkurian's answer and the comment I made (in response to this question), there are multiple ways to control this behaviour, if necessary.

Related question: Can't compile C program on a Mac after upgrade to Mojave.

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  • You don't - your build system needs to point to the correct path
    – mmmmmm
    Oct 9, 2019 at 14:01
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    Unfortunately, the python bindings for clang don't leave you a lot of choice in that matter...
    – mkl
    Oct 9, 2019 at 14:17
  • Sounds liks that should be reported as a bug to clang then
    – mmmmmm
    Oct 9, 2019 at 18:23
  • The particular problem of using the python bindings in macOS Catalina can be solved by adding the compiler flag -isysroot [...] to the cindex.Index.parse call, where [...] is the return value of xcrun --show-sdk-path.
    – mkl
    Oct 13, 2019 at 19:50
  • @mkl Can you provide more details? I'm trying to build a numerical library for python and having this problem, but ... what do you mean by "the cindex.Index.parse call"? Where is this call, and can your fix be made part of some python configuration?
    – Robert P. Goldman
    Dec 28, 2020 at 21:58

1 Answer 1

Reset to default
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Set the CPATH environment variable in your shell (e.g., put this in your .zshrc assuming you're using zsh):

export CPATH=`xcrun --show-sdk-path`/usr/include

And then try to build your project again.

UPDATE

The OP related to how to install the headers in /usr/include, not how to point clang to the headers wherever they may be.

MacOS System Integrity Protection prevents the creation of /usr/include, even by root. See this related answer.

If you disabled SIP (not recommended) then I imagine something like

sudo ln -s `xcrun --show-sdk-path`/usr/include /usr/include

will do the trick.

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  • Thanks for answering! This does indeed work with clang's python bindings, and, therefore, solves my problem. For the sake of correctness, I will not accept this answer, since the original question about how to install the C headers to /usr/include remains unanswered. Again, my thanks!
    – mkl
    Oct 15, 2019 at 8:40
  • Nevermind, clang python brings still have trouble finding some headers, apparently. Anyways, that seems to be the material for a new question. Thanks for helping...
    – mkl
    Oct 15, 2019 at 8:47
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    @mkl I've updated the answer. Thank you for your feedback.
    – kkurian
    Oct 16, 2019 at 7:38
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    Ah, many thanks! I guess this is as close as one can get to writing anything to /usr/include, given that Apple has clearly stated that the workaround mentioned in the question will not be available in future versions of Xcode...
    – mkl
    Oct 16, 2019 at 9:09
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    Is there a way to consume those headers without disableing SIP on catalina ? I am having issue when I try to make Python3.6 source on Catalina :(
    – Muhammad Faizan-Ul-Haq
    Sep 9, 2021 at 7:37

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