Compiler exit status codes and termination messages

If the compiler detects any warnings or errors during compilation, the compiler writes the messages to stderr. At the end of the messages, a summary message is displayed that gives the total number of each type of message of the form:

filename: n warnings, n errors

where n indicates the number of warnings or errors detected.

The signals SIGINT (caused by a user interrupt, like ^C) and SIGTERM (caused by a UNIX kill command) are trapped by the compiler and cause abnormal termination.

On completion, the compiler returns a value greater than zero if an error is detected. If no error is detected, a value of zero is returned.