This pragma sets the diagnostic messages that have the specified tags to Warning severity. Diagnostic messages are messages whose message numbers are postfixed by -D, for example, #550-D.
#pragma diag_warning behaves analogously to #pragma diag_errors, except that the compiler sets the diagnostic messages having the specified tags to Warning severity rather than Error severity.
Syntax
#pragma diag_warning tag[,tag,...]
Where:
tag[,tag,...]
is a comma-separated list of diagnostic message numbers specifying the messages whose severities are to be changed.