使用Clang编译项目时出现__time64_t未定义错误求助

我用GCC编译项目完全正常，但切换到任意基于Clang的编译器时，会触发以下错误：

[build] /usr/bin/clang++ -I/mnt/40ab93ed-5db8-4e22-a055-9775c3e5b937/ISC-parser/include -I/mnt/40ab93ed-5db8-4e22-a055-9775c3e5b937/ISC-parser/stdlibs -I/media/ura/Data/include -g -std=c++17 -MD -MT CMakeFiles/parser.dir/src/CLL/function/function.cpp.o -MF CMakeFiles/parser.dir/src/CLL/function/function.cpp.o.d -o CMakeFiles/parser.dir/src/CLL/function/function.cpp.o -c /mnt/40ab93ed-5db8-4e22-a055-9775c3e5b937/ISC-parser/src/CLL/function/function.cpp
[build] In file included from /mnt/40ab93ed-5db8-4e22-a055-9775c3e5b937/ISC-parser/src/CLL/function/function.cpp:4:
[build] In file included from /mnt/40ab93ed-5db8-4e22-a055-9775c3e5b937/ISC-parser/include/parser.h:8:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/iostream:41:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/ostream:40:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/ios:44:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/bits/ios_base.h:39:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/ext/atomicity.h:35:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/gthr.h:157:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/gthr-default.h:35:
[build] In file included from /include/pthread.h:22:
[build] In file included from /include/sched.h:31:
[build] /usr/include/x86_64-linux-gnu/bits/types/time_t.h:8:9: error: unknown type name '__time64_t'
[build]     8 | typedef __time64_t time_t;
[build]       |         ^
[build] In file included from /mnt/40ab93ed-5db8-4e22-a055-9775c3e5b937/ISC-parser/src/CLL/function/function.cpp:4:
[build] In file included from /mnt/40ab93ed-5db8-4e22-a055-9775c3e5b937/ISC-parser/include/parser.h:8:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/iostream:41:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/ostream:40:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/ios:44:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/bits/ios_base.h:39:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/ext/atomicity.h:35:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/gthr.h:157:
[build] In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14/bits/gthr-default.h:35:
[build] In file included from /include/pthread.h:22:
[build] In file included from /include/sched.h:32:
[build] /usr/include/x86_64-linux-gnu/bits/types/struct_timespec.h:14:3: error: unknown type name '__time64_t'
[build]    14 |   __time64_t tv_sec;            /* Seconds.  */
[build]       |   ^

以下是针对性的解决步骤：

• 修正Clang的系统头文件路径
  错误日志显示编译时引用了异常路径/include/pthread.h（正常应为/usr/include/pthread.h），说明Clang未正确识别系统标准头文件路径。可在CMake中添加：

  include_directories(SYSTEM /usr/include)
  

  或直接在编译参数中加入-isystem /usr/include，强制Clang使用正确的系统头文件目录。

• 切换Clang的C++标准库
  Clang默认可能 fallback 到GCC的libstdc++，存在版本兼容性问题。可强制使用LLVM的libc++，编译时添加参数：

  -stdlib=libc++ -lc++abi
  

  若系统未安装libc++，先执行：

  sudo apt install libc++-dev libc++abi-dev
  

• 调整编译宏定义顺序
  -D_TIME_BITS=64和-D_FILE_OFFSET_BITS=64必须在所有头文件包含前定义才生效。在CMake中优先添加：

  add_compile_definitions(_TIME_BITS=64 _FILE_OFFSET_BITS=64)
  

  或在编译命令中将宏定义放在最左侧：

  clang++ -D_TIME_BITS=64 -D_FILE_OFFSET_BITS=64 [其他编译参数]
  

• 修复系统头文件
  检查/usr/include/x86_64-linux-gnu/bits/types/time_t.h是否存在且定义正常，若文件损坏，重新安装系统头文件包：

  sudo apt reinstall libc6-dev
  

内容的提问来源于stack exchange，提问作者Sinfolke