gcc -v:

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/Volumes/FORKUB/Safety/bin/../libexec/gcc/x86_64-apple-darwin19/9.2.0/lto-wrapper
Target: x86_64-apple-darwin19
Configured with: ...
Thread model: posix
gcc version 9.2.0 (GCC) 

OS: macOS(darwin)
用不了 homebrew，只有命令行，#include <iostream> 时报错

In file included from ~/include/c++/9.2.0/bits/postypes.h:40,
                 from ~/include/c++/9.2.0/iosfwd:40,
                 from ~/include/c++/9.2.0/ios:38,
                 from ~/include/c++/9.2.0/ostream:38,
                 from ~/include/c++/9.2.0/iostream:39,
                 from test.cpp:1:
~/include/c++/9.2.0/cwchar:44:10: fatal error: wchar.h: No such file or directory
   44 | #include <wchar.h>
      |          ^~~~~~~~~

求问如何解决orz