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我正在尝试设置我的 neovim C++ 开发环境，并想ccls用作我的 coc 语言服务器。

当我使用 安装时ccls，Homebrew它会安装libffi并llvm作为依赖项。似乎ccls安装成功了，但似乎我需要配置PATH变量，LDFLAGS并且CPPFLAGS.

但我不知道libffiandllvm是干什么用的，他们提出了不同的LDFLAGSand CPPFLAGS，这令人困惑。

可以不导出任何变量来使用ccls吗？或者，我应该在我的 ? 中导出哪个版本~/.zshrc？

下面是我的控制台输出brew install ccls。

❯ brew install ccls
==> Downloading https://homebrew.bintray.com/bottles/libffi-3.3.big_sur.bottle.tar.gz
######################################################################## 100.0%
==> Downloading https://homebrew.bintray.com/bottles/llvm-11.0.0_1.big_sur.bottle.tar.gz
==> Downloading from https://d29vzk4ow07wi7.cloudfront.net/c8e30903a9a4f695780e1eeeaa2cf4d5a95141a1cac98ab1bbc811817cde39ca?response-content-disposition=attachment%3Bfilename%3D
######################################################################## 100.0%
==> Downloading https://homebrew.bintray.com/bottles/ccls-0.20201219.big_sur.bottle.tar.gz
==> Downloading from https://d29vzk4ow07wi7.cloudfront.net/934fb8fd594d6e7adbfa14b5608f1de14309db34f2cf61a0cb572bdc772b2aa3?response-content-disposition=attachment%3Bfilename%3D
######################################################################## 100.0%
==> Installing dependencies for ccls: libffi and llvm
==> Installing ccls dependency: libffi
==> Pouring libffi-3.3.big_sur.bottle.tar.gz
==> Caveats
libffi is keg-only, which means it was not symlinked into /usr/local,
because macOS already provides this software and installing another version in
parallel can cause all kinds of trouble.

For compilers to find libffi you may need to set:
  export LDFLAGS="-L/usr/local/opt/libffi/lib"
  export CPPFLAGS="-I/usr/local/opt/libffi/include"

==> Summary
  /usr/local/Cellar/libffi/3.3: 17 files, 540.2KB
==> Installing ccls dependency: llvm
==> Pouring llvm-11.0.0_1.big_sur.bottle.tar.gz
==> Caveats
To use the bundled libc++ please add the following LDFLAGS:
  LDFLAGS="-L/usr/local/opt/llvm/lib -Wl,-rpath,/usr/local/opt/llvm/lib"

llvm is keg-only, which means it was not symlinked into /usr/local,
because macOS already provides this software and installing another version in
parallel can cause all kinds of trouble.

If you need to have llvm first in your PATH run:
  echo 'export PATH="/usr/local/opt/llvm/bin:$PATH"' >> ~/.zshrc

For compilers to find llvm you may need to set:
  export LDFLAGS="-L/usr/local/opt/llvm/lib"
  export CPPFLAGS="-I/usr/local/opt/llvm/include"

==> Summary
  /usr/local/Cellar/llvm/11.0.0_1: 8,922 files, 1.4GB
==> Installing ccls
==> Pouring ccls-0.20201219.big_sur.bottle.tar.gz
  /usr/local/Cellar/ccls/0.20201219: 5 files, 1.5MB
==> Caveats
==> libffi
libffi is keg-only, which means it was not symlinked into /usr/local,
because macOS already provides this software and installing another version in
parallel can cause all kinds of trouble.

For compilers to find libffi you may need to set:
  export LDFLAGS="-L/usr/local/opt/libffi/lib"
  export CPPFLAGS="-I/usr/local/opt/libffi/include"

==> llvm
To use the bundled libc++ please add the following LDFLAGS:
  LDFLAGS="-L/usr/local/opt/llvm/lib -Wl,-rpath,/usr/local/opt/llvm/lib"

llvm is keg-only, which means it was not symlinked into /usr/local,
because macOS already provides this software and installing another version in
parallel can cause all kinds of trouble.

If you need to have llvm first in your PATH run:
  echo 'export PATH="/usr/local/opt/llvm/bin:$PATH"' >> ~/.zshrc

For compilers to find llvm you may need to set:
  export LDFLAGS="-L/usr/local/opt/llvm/lib"
  export CPPFLAGS="-I/usr/local/opt/llvm/include"
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1 回答 1

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libffi只是一个图书馆。并且llvm是编译器基础设施。并且libc++是LLVM 项目的 C++ 标准库。您可以使用LLVM库或 GNU ( libstdc++) 之一。这取决于您的软件项目（或您的个人喜好）您使用的库。

由于 macOS 已经提供了llvm安装，您可以选择切换到通过brew作为依赖项安装的安装——这不是必需的。

LDFLAGS环境变量确实包含由编译器（gcc/g++或）传递给链接器的附加标志clang/clang++，即添加链接器可以找到库对象文件的路径，然后，如果需要/使用，链接到您的二进制文件。

并且CPPFLAGS做同样的事情，但这次标志直接针对编译器，即为库的头文件添加额外的搜索路径。

在您的情况下，您不必从 , 中导出任何（附加）变量.zshrc，ccls无需定义这些变量即可正常工作。

于 2021-01-06T14:52:50.790 回答