How a diagnostic is identified (3.10, 5.1.1.3).
Error and warning messages have the following format:
filename, line number: message
Where filename is the name of the file that contains the error or warning,
line number is the number of the line on which the error or warning is found, and message is the diagnostic message.
Whether each non-empty sequence of white-space characters other than new-line is retained or replaced by one space character in translation phase 3 (5.1.1.2).
A sequence of non-empty characters consisting of a tab (\t), form-feed (\f), or vertical-feed (\v) are replaced by a single space character.