Beware to say "Treat warning as an error" in new GCC

Are you building your something using Gcc(>=4.6) ?
If yes, then you used be more careful to use "treat warning as an error".
Recently I tried to build zbase over Ubuntu 12.04 2 which uses Gcc (4.6.2) and I faced lots of problem.
And then I moved to Gcc(4.2), everything was too smooth. No error or warnings.

Then I looked into Gcc release details and came across with few important points:

• -Wunused-but-set-variable and -Wunused-but-set-parameter warnings were added. Also the -Wunused-but-set-variable warning is enabled by default by -Wall flag and -Wunused-but-set-parameter by -Wall -Wextra flags.
• Also you may face few linkers problem. I faced a one with jemalloc.

For more about changes have a look here :)

In drizzle , I have to include "config.h" in each file to get rid of this type of error.