在安装vcpkg时遇到如下报错

6/75] Building CXX object CMakeFiles/vcpkglib.dir/src/vcpkg/archives.cpp.o
FAILED: CMakeFiles/vcpkglib.dir/src/vcpkg/archives.cpp.o
/usr/local/bin/g++-9  -DVCPKG_DISABLE_METRICS=0 -DVCPKG_USE_STD_FILESYSTEM=1 -I../include -O3 -DNDEBUG -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk   -std=c++17 -MD -MT CMakeFiles/vcpkglib.dir/src/vcpkg/archives.cpp.o -MF CMakeFiles/vcpkglib.dir/src/vcpkg/archives.cpp.o.d -o CMakeFiles/vcpkglib.dir/src/vcpkg/archives.cpp.o -c ../src/vcpkg/archives.cpp
In file included from /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/wchar.h:90,
                 from /usr/local/Cellar/gcc/9.1.0/include/c++/9.1.0/cwchar:44,
                 from /usr/local/Cellar/gcc/9.1.0/include/c++/9.1.0/bits/postypes.h:40,
                 from /usr/local/Cellar/gcc/9.1.0/include/c++/9.1.0/bits/char_traits.h:40,
                 from /usr/local/Cellar/gcc/9.1.0/include/c++/9.1.0/string:40,
                 from /usr/local/Cellar/gcc/9.1.0/include/c++/9.1.0/stdexcept:39,
                 from /usr/local/Cellar/gcc/9.1.0/include/c++/9.1.0/array:39,
                 from /usr/local/Cellar/gcc/9.1.0/include/c++/9.1.0/tuple:39,
                 from /usr/local/Cellar/gcc/9.1.0/include/c++/9.1.0/functional:54,
                 from /usr/local/Cellar/gcc/9.1.0/include/c++/9.1.0/pstl/glue_algorithm_defs.h:13,
                 from /usr/local/Cellar/gcc/9.1.0/include/c++/9.1.0/algorithm:71,
                 from ../include/pch.h:22,
                 from ../src/vcpkg/archives.cpp:1:
/usr/local/Cellar/gcc/9.1.0/lib/gcc/9/gcc/x86_64-apple-darwin18/9.1.0/include-fixed/stdio.h:222:7: error: conflicting declaration of 'char* ctermid(char*)' with 'C' linkage
  222 | char *ctermid(char *);
      |       ^~~~~~~
In file included from /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/unistd.h:525,
                 from ../include/pch.h:19,
                 from ../src/vcpkg/archives.cpp:1:
/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_ctermid.h:26:10: note: previous declaration with 'C++' linkage
   26 | char    *ctermid(char *);
      |          ^~~~~~~
ninja: build stopped: subcommand failed.

解决方法

./bootstrap-vcpkg.sh --allowAppleClang