id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
3085	warn about language extensions that are not used	PVerswyvelen		"When I put

`{-# OPTIONS_GHC -Wall -Werror #-}`

in my source file, I don't get compiler warnings about redundant language extensions that I enabled in that file.

For example if I write

`{-# LANGUAGE GeneralizedNewtypeDeriving #-}`

in the file, but I never do newtype deriving, the compiler could give me a warning.

It would be nice if the compiler gave warnings about this, since after refactoring, some language extensions might not be needed anymore, and hence should be removed since fewer language extensions mean more stable and portable code no?

"	feature request	new	normal	7.6.2	Compiler	6.10.1		warnings extensions language	ndmitchell@… deduktionstheorem@… conal@… id@… haskell@… chevalier@… vogt.adam@… merehap@… mmitar@… shahn hackage.haskell.org@… pho@…	Unknown/Multiple	Unknown/Multiple	None/Unknown	Unknown