Show or suppress warning messages.
This option shows or suppresses most warning messages. However, if one option overrides all or part of an option earlier on the command line, you do get a warning.
-w0 shows just error messages. This is equivalent to -w. -w1 shows errors and warnings. This is the default without -w.-w2 shows errors, warnings, and cautions.-w3 shows errors, warnings, cautions, and notes.-w4 shows errors, warnings, cautions, notes, and comments.