Each message description includes a Type and an Options field as follows:
Warning messages, in which warning: appears after the file name and line number, provide useful information without interrupting compilation. They may diagnose a programming error, or a violation of C syntax or semantics, for which the compiler will nevertheless generate valid object code.
Error messages, in which error: appears after the file name and line number, will cause the cc command to fail. Errors occur when the compiler has diagnosed a serious problem that makes it unable to understand the program or to continue to generate correct object code. It will attempt to examine the rest of the program for other errors, however. The cc command will not link the program if the compiler diagnoses errors.
Fatal errors cause the compiler to stop
immediately and return an error indication
to the cc command.
A fatal error message is prefixed with
Such messages typically apply to start-up conditions,
such as being unable to find a source file.