id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
4980	Warning about module abbreviation clashes	Lemming		"Please add the option -fwarn-module-rename-collision that makes GHC to do the following: If GHC encounters an import situation like
{{{
module Main where

import qualified Data.A as A
import qualified Control.A as A
}}}
then GHC should emit a warning like
{{{
Main.hs:3:0:
Main.hs:4:0:
    Warning: Both Data.A and Control.A are renamed to A.
             An identifier like A.ident can only be resolved,
             if it is either in Data.A or Control.A.
             Better rename both modules to different names.
}}}

Reason for this warning is, that if 'ident' is from Data.A as of writing Main, and later another variable named 'ident' is added to Control.A, then A.ident can no longer be resolved in Main. That is, by accidental module rename collisions even qualified imports carry the risk of future name collisions.

Related to #4977
"	feature request	new	low	7.6.2	Compiler	7.0.1			ghc@…	Unknown/Multiple	Unknown/Multiple	None/Unknown