HP aC++/HP C Programmer's Guide (B3901-90036; A.06.26; September 2011)

-w
The -w option disables all warnings except those that are explicitly enabled with a
+Wwargs option or a subsequent +w-prefix option. By default, the compiler reports all
errors and warnings.
HP recommends against using the -w option. In addition to disabling messages currently
output by the compiler, it will also disable any new messages added to the compiler in
the future that could identify problem areas in user code. HP recommends using the
+Wargs option to disable a message. Although it can often take a long list of +Warg
options to disable all desired warnings, this list can be included in an options file and
referenced using the +opts option to avoid listing them all directly on the command
line.
Example:
The following command compiles file.C and reports errors but does not report any
warnings.
aCC -w file.C
+w
The +w option warns you about all questionable constructs and gives pedantic warnings.
+w enables all checks except for the +wsecurity, +wendian, +wperfadvice,
and+wlock warnings. Those need to be enabled explicitly if needed. The default is to
warn only about constructs that are almost certainly problems.
For example, this option warns you when calls to inline functions cannot be expanded
inline.
The following command compiles file.C and warns about both questionable and
problematic constructs:
aCC +w file.C
NOTE: This option is equivalent to the +w1 option of legacy HP C.
+wn
The +wn option specifies the level of the warnings messages.
+w{1|2|3}
The value of n can be one of the following:
1 All warnings are issued. This includes low level warnings that may not indicate
anything wrong with the program.
2 Only warnings indicating that code generation might be affected are issued. This is
equivalent to the compiler default without the -w options.
3 No warnings are issued. This is equivalent to the -w option. This option is the same
as -W c and-wn.
44 Command-Line Options