Panic in GHCi when using :print

When using names generated by :print, GHCi panics sometimes. According to #ghc, this is reproducible on x86_64-apple-darwin as well, but is not an issue in 7.6.3 x86_64 linux.

> let a = [1]

> :print a
a = (_t1::Num t => [t])

> :t _t1
ghc: panic! (the 'impossible' happened)
  (GHC version 7.8.2 for x86_64-unknown-linux):
	tcTyVarDetails t{tv avD} [tv]

> _t1
<same panic>

From playing around with it a bit, this seems to have something to do with polymorphic values.

-- No panic
> let a = [1 :: Int]
> let a = 1 :: Int
> let a = "hello"

-- Panic
> let a = [1]
> let a = 1
> let a = "hello" -- With -XOverloadedStrings

Trac metadata

Trac field	Value
Version	7.8.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
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CC	hvr
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