22.1 Translation
Implementation-Defined Behavior for Translation is covered in section G.3.1 of the ANSI C Standard.
Is each non-empty sequence of white-space characters, other than new line, retained or is it replaced by one space character? (ISO 5.1.1.2)
It is replaced by one space character.
How is a diagnostic message identified? (ISO 5.1.1.3)
Diagnostic messages are identified by prefixing them with the source file name and line number corresponding to the message, separated by colon characters (‘:’).
Are there different classes of message? (ISO 5.1.1.3)
Yes.
If yes, what are they? (ISO 5.1.1.3)
Errors, which inhibit production of an output file, and warnings, which do not inhibit production of an output file.
What is the translator return status code for each class of message? (ISO 5.1.1.3)
The return status code for errors is 1; for warnings it is 0.
Can a level of diagnostic be controlled? (ISO 5.1.1.3)
Yes.
If yes, what form does the control take? (ISO 5.1.1.3)
Compiler command-line options may be used to request or inhibit the generation of warning messages.