L'ab' is an error

[tydeman]

#include <wchar.h>
int main(void){
  if(1){
    static wchar_t wc = L'ab';
  }
  return 0;
}

Fails to compile with this error:
test190.c:5:25: error: wide character literals may not contain multiple characters

C23 says in 6.4.4.5, paragraph 15 that this is implementation defined.

Since I cannot find the implementation documentation, I do not know if this is a
valid error or a bug.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Fred Tydeman (tydeman)

#include <wchar.h> int main(void){ if(1){ static wchar_t wc = L'ab'; } return 0; }

Fails to compile with this error:
test190.c:5:25: error: wide character literals may not contain multiple characters

C23 says in 6.4.4.5, paragraph 15 that this is implementation defined.

Since I cannot find the implementation documentation, I do not know if this is a
valid error or a bug.

[cor3ntin]

This is intended - L'ab' used to be either equivalent to L'a' or L'b' depending on implementation which is both super confusing and not very useful (unlike 'ab' which has some historical motivation).
It can also cause subtle bugs in the presence of combining characters.
C++ moved to make that ill-formed in the standard. Given that the C behavior was implementation-defined, we made it ill-formed too.

[frederick-vs-ja]

Possibly a duplicate of #156269.