Clang 18.1.5 和 std::println 的支持

Question

我最近通过brew包管理器将我的M1 Mini Mac上的Clang编译器从Clang 17.0.6升级到Clang 18.1.5。我有几个测试程序具有与 Clang 17.0.6 配合良好的

std::println

。现在使用 Clang 18.1.5 我收到以下错误消息：

Undefined symbols for architecture arm64:
  "std::__1::__is_posix_terminal(__sFILE*)", referenced from:
      std::__1::__print::__is_terminal[abi:ne180100](__sFILE*) in main.cpp.o
ld: symbol(s) not found for architecture arm64
clang++: error: linker command failed with exit code 1 (use -v to see invocation)`

我不确定 Clang 18.1.6 是否删除了对

std::println

或

<print>

头库的支持？我尝试搜索发行说明，但没有找到与此主题相关的任何内容。顺便说一句，我在我的

CMakeLists.txt

中将 C++ 标准指定为 23

Answer 1

这是正确的 libc++ 的链接器问题。我不确定brew更新发生了什么，它改变了安装位置而没有符号链接。我已经通过brew重新安装了llvm并收到以下消息：

To use the bundled libc++ please add the following LDFLAGS:
  LDFLAGS="-L/opt/homebrew/opt/llvm/lib/c++ -Wl,-rpath,/opt/homebrew/opt/llvm/lib/c++"
llvm is keg-only, which means it was not symlinked into /opt/homebrew,
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="/opt/homebrew/opt/llvm/bin:$PATH"' >> ~/.zshrc

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

因此，我已将以下行添加到我的 CMakeLists.txt 中，然后一切都按预期工作

std::println

set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -L/opt/homebrew/opt/llvm/lib/c++ -Wl,-rpath,/opt/homebrew/opt/llvm/lib/c++")