clang++ 11 broken by MacOS 11.3 update

[haberg-1]

The update to MacOS 11.3 and Xcode 12.5, with Command Line Tools, broke clang++ 11: It can not find system headers such as wchar.h, it seems. Unclear with workarounds. Curiously, g++ 10 works.

Specifically, /opt/local/bin/clang++-mp-11 hello_world.cc -o hello_world produces the errors below, whereas /opt/local/bin/g++-mp-10 hello_world.cc -o hello_world works.

—

% /opt/local/bin/clang++-mp-11 hello_world.cc -o hello_world
In file included from hello_world.cc:2:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/iostream:37:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/ios:214:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/iosfwd:95:
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:137:77: error: use of undeclared identifier 'wcschr'
wchar_t* __libcpp_wcschr(const wchar_t* __s, wchar_t __c) {return (wchar_t*)wcschr(__s, __c);}
                                                                            ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:144:87: error: use of undeclared identifier 'wcspbrk'
wchar_t* __libcpp_wcspbrk(const wchar_t* __s1, const wchar_t* __s2) {return (wchar_t*)wcspbrk(__s1, __s2);}
                                                                                      ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:151:78: error: use of undeclared identifier 'wcsrchr'; did you mean 'wcschr'?
wchar_t* __libcpp_wcsrchr(const wchar_t* __s, wchar_t __c) {return (wchar_t*)wcsrchr(__s, __c);}
                                                                             ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:139:16: note: 'wcschr' declared here
const wchar_t* wcschr(const wchar_t* __s, wchar_t __c) {return __libcpp_wcschr(__s, __c);}
               ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:158:86: error: use of undeclared identifier 'wcsstr'; did you mean 'wcschr'?
wchar_t* __libcpp_wcsstr(const wchar_t* __s1, const wchar_t* __s2) {return (wchar_t*)wcsstr(__s1, __s2);}
                                                                                     ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:141:16: note: 'wcschr' declared here
      wchar_t* wcschr(      wchar_t* __s, wchar_t __c) {return __libcpp_wcschr(__s, __c);}
               ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:158:86: error: no matching function for call to 'wcschr'
wchar_t* __libcpp_wcsstr(const wchar_t* __s1, const wchar_t* __s2) {return (wchar_t*)wcsstr(__s1, __s2);}
                                                                                     ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:141:16: note: candidate disabled: <no message provided>
      wchar_t* wcschr(      wchar_t* __s, wchar_t __c) {return __libcpp_wcschr(__s, __c);}
               ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:158:93: error: cannot initialize a parameter of type 'wchar_t *' with an lvalue of type 'const wchar_t *'
wchar_t* __libcpp_wcsstr(const wchar_t* __s1, const wchar_t* __s2) {return (wchar_t*)wcsstr(__s1, __s2);}
                                                                                            ^~~~
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:141:38: note: passing argument to parameter '__s' here
      wchar_t* wcschr(      wchar_t* __s, wchar_t __c) {return __libcpp_wcschr(__s, __c);}
                                     ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:165:60: error: unknown type name 'size_t'
wchar_t* __libcpp_wmemchr(const wchar_t* __s, wchar_t __c, size_t __n) {return (wchar_t*)wmemchr(__s, __c, __n);}
                                                           ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:167:57: error: unknown type name 'size_t'
const wchar_t* wmemchr(const wchar_t* __s, wchar_t __c, size_t __n) {return __libcpp_wmemchr(__s, __c, __n);}
                                                        ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/wchar.h:169:57: error: unknown type name 'size_t'
      wchar_t* wmemchr(      wchar_t* __s, wchar_t __c, size_t __n) {return __libcpp_wmemchr(__s, __c, __n);}
                                                        ^
In file included from hello_world.cc:2:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/iostream:37:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/ios:214:
/opt/local/libexec/llvm-11/bin/../include/c++/v1/iosfwd:189:14: error: use of undeclared identifier 'mbstate_t'
typedef fpos<mbstate_t>    streampos;
             ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/iosfwd:190:14: error: use of undeclared identifier 'mbstate_t'
typedef fpos<mbstate_t>    wstreampos;
             ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/iosfwd:195:14: error: use of undeclared identifier 'mbstate_t'
typedef fpos<mbstate_t>    u16streampos;
             ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/iosfwd:196:14: error: use of undeclared identifier 'mbstate_t'
typedef fpos<mbstate_t>    u32streampos;
             ^
In file included from hello_world.cc:2:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/iostream:37:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/ios:215:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/__locale:14:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/string:506:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/string_view:175:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/__string:57:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/algorithm:639:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/initializer_list:46:
/opt/local/libexec/llvm-11/bin/../include/c++/v1/cstddef:49:9: error: no member named 'ptrdiff_t' in the global namespace
using ::ptrdiff_t;
      ~~^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/cstddef:50:9: error: no member named 'size_t' in the global namespace
using ::size_t;
      ~~^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/cstddef:53:9: error: no member named 'max_align_t' in the global namespace
using ::max_align_t;
      ~~^
In file included from hello_world.cc:2:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/iostream:37:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/ios:215:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/__locale:14:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/string:506:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/string_view:175:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/__string:57:
In file included from /opt/local/libexec/llvm-11/bin/../include/c++/v1/algorithm:639:
/opt/local/libexec/llvm-11/bin/../include/c++/v1/initializer_list:61:5: error: unknown type name 'size_t'
    size_t    __size_;
    ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/initializer_list:65:38: error: unknown type name 'size_t'
    initializer_list(const _Ep* __b, size_t __s) _NOEXCEPT
                                     ^
/opt/local/libexec/llvm-11/bin/../include/c++/v1/initializer_list:73:13: error: unknown type name 'size_t'
    typedef size_t    size_type;
            ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

—

[haberg-1]

Includes <iostream> and calls std::cout to trigger the issue.