今天升了macOS10.15，发现自己编译的llvm和clang坏掉了，重新编译也没用，而自带的/usr/clang是没有问题的，发现是 /usr/include 缺失。
==2020年11月19日：big sur 无法修改/usr/include，==
==2020年11月20日：使用cmake初始化时，添加-DDEFAULT_SYSROOT=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk，重新编译，即可解决==
一、背景
Command Line Tools 10.13系列，是拥有/usr/include目录的，之前一直在用。但是在macOS 10.15上无法安装它，就很气。
Command Line Tools 10.14系列，砍掉了32位的编译环境，也砍掉了/usr/include。
macOS 10.15砍掉了 32 位的运行环境，将 / 挂载为 read-only。
而自己编译的llvm+clang是不会主动去寻找 MacOSXSDK的头文件的，就出现了找不到头文件的情况。
二、修复过程（中英双语，中文更简单、英文更详细）
人肉diff 一下曾经的
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/usr/include |
和 现在的
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/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include |
发现后者比前者多出少量的.h 文件，但缺少 c++目录。
而现在的 c++目录在
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/Library/Developer/CommandLineTools/usr/include/c++ |
因此思路很简单
1、恢复 c++
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sudo ln -s /Library/Developer/CommandLineTools/usr/include/c++ /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++ |
2、重启到 recovery 关掉 SIP
3、重启到操作系统
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sudo mount -uw / sudo ln -s /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include /usr/include |
4、重启到 recovery 开启 SIP
5、效果
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➜ lsa /usr/include lrwxr-xr-x 1 root wheel 63B 10 16 14:31 include -> /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include |
这时候/usr/include 下面就有 c 和 cpp 常用的头文件了，自己编译的 llvm 和 clang 也就可以正常使用了
三、Repair it
Since Command-Line-Tools >= 10.14, there is no /usr/include path.
And after macOS Catalina, ‘/’ partition is read-only. So I finally fix it by myself.
I diff the /usr/include for 10.13 and /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include for 10.15. The only difference is that:
– Most of them are the same.
– 10.15 has more header files, maybe some new feature.
– 10.13 has c++ directory, which is /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++ in macOS 10.15.
So do the following things:
- add c++ headers
sudo ln -s /Library/Developer/CommandLineTools/usr/include/c++ /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++
- reboot to recovery and disable SIP
- reboot to desktop,
sudo mount -uw /
sudo ln -s /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include /usr/include
- reboot to recovery and enable SIP.
- result:
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➜ lsa /usr/include lrwxr-xr-x 1 root wheel 63B 10 16 14:31 include -> /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include ➜ /tmp clang -v test.c clang version 8.0.0 (tags/RELEASE_800/final) Target: x86_64-apple-darwin19.0.0 Thread model: posix ........ #include "..." search starts here: #include <...> search starts here: /usr/local/include /Users/leadroyal/pllvm/r/lib/clang/8.0.0/include /usr/include /System/Library/Frameworks (framework directory) /Library/Frameworks (framework directory) End of search list. |
四、相关链接
https://github.com/Homebrew/homebrew-core/issues/45061
https://discourse.brew.sh/t/clang-can-no-longer-find-usr-include-header-files-fatal-error-stdlib-h-file-not-found/4523/7