-Wformat-signedness silently ignored if no -Wformat

[Jonny Grant <jg@xxxxxxxx>]

Hello

Noticed that a lot of warning options are silently ignored if not also 
coupled with -Wformat

https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html

Could gcc also give a build message when these warnings are actually not 
active? eg

"warning: -Wformat-signedness is ignored because -Wformat option was not 
specified"

Jonny