Rule A1-4-3 (advisory, implementation, automated)
All code should compile free of compiler warnings.
Rationale
Compiler warnings provide the earliest tool-supported indication of potential problems in source code. Developers should not ignore compiler warnings. Note: Compiler warnings should be turned on to a level matching (as far as possible) the rules in this document, in particular A1-1-1. A possible enforcement of this rule is to turn compiler warnings into errors.
See also
A1-1-1 in section 6.1.1