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macos - 从命令行使用 Homebrew 的 clang

问题描述

我曾经brew install llvm安装 LLVM 8，我想使用命令行工具。我已经按照 Homebrew 的建议设置了clang可执行文件（in /usr/local/opt/llvm/bin）的路径，并按照他们的建议设置了 LDFLAGS 和 CPPFLAGS 。当我编译一个简单的程序时，我得到

x.c:1:10: fatal error: 'stdio.h' file not found
#include <stdio.h>
         ^~~~~~~~~
1 error generated.

阅读文档xcrun，xcode-select我觉得应该有一种简单的方法来选择我的 LLVM 工具链，但我无法弄清楚。我试过改变TOOLCHAINSandSDKROOT没有成功。

clang -v -c x.cHomebrew 的 llvm-8 的输出

clang version 8.0.0 (tags/RELEASE_800/final)
Target: x86_64-apple-darwin18.5.0
Thread model: posix
InstalledDir: /usr/local/opt/llvm/bin
 "/usr/local/Cellar/llvm/8.0.0/bin/clang-8" -cc1 -triple x86_64-apple-macosx10.14.0 -Wdeprecated-objc-isa-usage -Werror=deprecated-objc-isa-usage -emit-obj -mrelax-all -disable-free -disable-llvm-verifier -discard-value-names -main-file-name x.c -mrelocation-model pic -pic-level 2 -mthread-model posix -mdisable-fp-elim -masm-verbose -munwind-tables -target-cpu penryn -dwarf-column-info -debugger-tuning=lldb -ggnu-pubnames -target-linker-version 409.12 -v -coverage-notes-file /tmp/x.gcno -resource-dir /usr/local/Cellar/llvm/8.0.0/lib/clang/8.0.0 -fdebug-compilation-dir /tmp -ferror-limit 19 -fmessage-length 80 -stack-protector 1 -fblocks -fencode-extended-block-signature -fregister-global-dtors-with-atexit -fobjc-runtime=macosx-10.14.0 -fmax-type-align=16 -fdiagnostics-show-option -fcolor-diagnostics -o x.o -x c x.c
clang -cc1 version 8.0.0 based upon LLVM 8.0.0 default target x86_64-apple-darwin18.5.0
ignoring nonexistent directory "/usr/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include
 /usr/local/Cellar/llvm/8.0.0/lib/clang/8.0.0/include
 /System/Library/Frameworks (framework directory)
 /Library/Frameworks (framework directory)
End of search list.
x.c:1:10: fatal error: 'stdio.h' file not found
#include <stdio.h>
         ^~~~~~~~~
1 error generated.

系统叮当的输出：

Apple LLVM version 10.0.1 (clang-1001.0.46.3)
Target: x86_64-apple-darwin18.5.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang" -cc1 -triple x86_64-apple-macosx10.14.0 -Wdeprecated-objc-isa-usage -Werror=deprecated-objc-isa-usage -emit-obj -mrelax-all -disable-free -disable-llvm-verifier -discard-value-names -main-file-name x.c -mrelocation-model pic -pic-level 2 -mthread-model posix -mdisable-fp-elim -fno-strict-return -masm-verbose -munwind-tables -target-sdk-version=10.14 -target-cpu penryn -dwarf-column-info -debugger-tuning=lldb -target-linker-version 450.3 -v -coverage-notes-file /tmp/x.gcno -resource-dir /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/10.0.1 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -I/usr/local/include -Wno-atomic-implicit-seq-cst -Wno-framework-include-private-from-public -Wno-atimport-in-framework-header -Wno-quoted-include-in-framework-header -fdebug-compilation-dir /tmp -ferror-limit 19 -fmessage-length 80 -stack-protector 1 -fblocks -fencode-extended-block-signature -fregister-global-dtors-with-atexit -fobjc-runtime=macosx-10.14.0 -fmax-type-align=16 -fdiagnostics-show-option -fcolor-diagnostics -o x.o -x c x.c
clang -cc1 version 10.0.1 (clang-1001.0.46.3) default target x86_64-apple-darwin18.5.0
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/usr/local/include"
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/Library/Frameworks"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/10.0.1/include
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
 /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/usr/include
 /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/System/Library/Frameworks (framework directory)
End of search list.

标签： macosclanghomebrew

解决方案

您应该按照此问题中的说明安装缺少的标头/库。

或者，您应该指向clang另一个“sysroot”，例如：

clang -isysroot `xcrun --show-sdk-path` hello.c

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