Commit 8b9fffbf authored by Simon Peyton Jones's avatar Simon Peyton Jones
Browse files

Test Trac #5287

parent 3cd7b401
{-# LANGUAGE MultiParamTypeClasses, UndecidableInstances #-}
module Bug where
class A a oops
data D d = D d
instance A a oops => Read (D a)
data E e = E (D e) deriving Read
ghc-stage2.exe: panic! (the 'impossible' happened)
(GHC version 7.3.20110721 for i386-unknown-mingw32):
solveDerivEqns: probable loop
(T5287.hs:6:29-32 main:Bug.$fReadE{v rhW} [e{tv aaR} [tv]] base:GHC.Read.Read{tc 2d} [main:Bug.E{tc raM}
e{tv aaR} [tv]] = [base:GHC.Read.Read{tc 2d}
(main:Bug.D{tc raO}
e{tv aaR} [tv])])
[[main:Bug.A{tc raQ} e{tv aaR} [tv] oops{tv alO} [tcs]]]
Please report this as a GHC bug:
......@@ -32,4 +32,5 @@ test('drvfail-foldable-traversable1', normal, compile_fail,
test('T3833', normal, compile_fail, [''])
test('T3834', normal, compile_fail, [''])
test('T4528', normal, compile_fail, [''])
test('T5287', normal, compile_fail, [''])
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