How does one suppress specific warnings from source code on g++ 4.5 or later?

The first comment on a feature request for g++ says, "Starting with 4.5 you can disable a class of warnings in the source."

I looked through the 4.5.0 manual, but I can't find the syntax.

What is the 开发者_JS百科syntax in g++ 4.5 and later to suppress individual warning classes in the source?

http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html

http://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html#Diagnostic-Pragmas