id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
5038	internal error with rebindable if-then-else	Philonous	simonpj	"Defining ifThenElse in a module with RebindableSyntax enabled and using if-then-else in the same module leads to an internal ghc error. 


ifThenElse.hs:
{{{
{-# LANGUAGE RebindableSyntax #-}

module IfThenElse (ifThenElse) where

import Prelude (Bool(..))

ifThenElse True t f = t
ifThenElse False t f = f

foo = if True then () else ()
}}}

Error message: 

{{{

# ghc IfThenElse.hs
[1 of 1] Compiling IfThenElse       ( IfThenElse.hs, IfThenElse.o )

IfThenElse.hs:10:7:
    GHC internal error: `ifThenElse' is not in scope during type checking, but it passed the renamer
    tcg_type_env of environment: []
    tcl_env of environment: []
    In the expression: if True then () else ()
    In an equation for `foo': foo = if True then () else ()
}}}

Importing ifThenElse from another module (even with RebindableSyntax enabled) will make the error go away."	bug	closed	high	7.2.1	Compiler	7.0.2	fixed		p.balzarek@…	Linux	x86_64 (amd64)	None/Unknown		rebindable/T5038