id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
5246	Duplicate type error messages with implicit parameters	NickSmallbone		"The following ill-typed program generates two identical type errors at the same source location:

{{{
{-# LANGUAGE ImplicitParams #-}

foo :: (?x :: Int) => a
foo = undefined

bar =
    let ?x = ""hello""
    in foo
}}}

The error messages are:

{{{
Test.hs:8:8:
    Couldn't match type `Int' with `[Char]'
    In the expression: foo
    In the expression: let ?x = ""hello"" in foo
    In an equation for `bar': bar = let ?x = ""hello"" in foo

Test.hs:8:8:
    Couldn't match type `Int' with `[Char]'
    In the expression: foo
    In the expression: let ?x = ""hello"" in foo
    In an equation for `bar': bar = let ?x = ""hello"" in foo
}}}

Obviously, it should only print this error once. I encountered this in a larger program where it meant I got ''eight'' identical type errors at the same source position!"	bug	closed	normal		Compiler (Type checker)	7.0.3	fixed		dimitris@…	Unknown/Multiple	Unknown/Multiple	None/Unknown		typecheck/should_fail/T5246