formal parameter number has different type when promoted
The type of the specified parameter is not compatible through default promotions with the type found in a previous declaration.
For functions are compatible only if the types of each parameter are compatible after the application of default argument promotions.
This is an error in ANSI C (/Za) and a warning when the Microsoft extension (/Ze) is used.
The following example causes this error:
void func();
void func(char); // error, char promotes to int