int implicit:1;

[Pietrobon Marcello]

While compiling condvar2.c and condvar2_1.c with the Intel compiler, I
get the warning:

../implement.h(134): remark #108: implicitly-signed bit field of length
1
    int implicit:1;

What does it mean
int implicit:1;
?

I never saw something like that in any C or C++ manual.

Regards,
Marcello