Understanding compiler warning options

[Edward Diener]

I am trying to understand how the compiler decides which warnings are 
issued when compiling a translation unit.

What is the default warnings that are issued if no compiler warning 
options is set on the command line ?

If I set a general option, such as -w, -Wall, or -Wextra, do these get 
overridden by more specific compiler options no matter where in the 
command line they are encountered, or does the order of the compiler 
warnings on the command line matter in such a case ? As a specific 
practical example if the command line has "-Wno-unused-local-typedef 
-Wall ..." does the "-Wno-unused-local-typedef" override the "-Wall" 
option ?