panic! Simplifier ticks exhausted
Compiling the following with -O2 causes a panic.
module GHCPanic where
data IValue = IDefault
| IInt Int
| IBlob String
(?) :: Applicative m => (IValue -> m a) -> IValue -> m (Maybe a)
(?) _ IDefault = pure Nothing
(?) p x = Just <$> p x
getInt :: IValue -> Either () Int
getInt (IInt i) = Right i
getInt v = Left ()
getString :: IValue -> Either () String
getString (IBlob b) = Right $ b
getString v = Left ()
(<+>) :: Applicative m => (m (a -> b), [IValue]) -> (IValue -> m a) -> (m b, [IValue])
(<+>) (f, (v:vs)) p = (f <*> (p v), vs)
data TestStructure = TestStructure
{ _param1 :: Int
, _param2 :: Maybe String
, _param3 :: Maybe Int
, _param4 :: Maybe String
, _param5 :: Maybe Int
, _param6 :: Maybe Int
, _param7 :: Maybe String
, _param8 :: Maybe String
, _param9 :: Maybe Int
, _param10 :: Maybe Int
, _param11 :: Maybe String
, _param12 :: Maybe String
, _param13 :: Maybe Int
, _param14 :: Maybe Int
, _param15 :: Maybe String
}
getMenuItem :: [IValue] -> Either () TestStructure
getMenuItem vs = fst $ (pure TestStructure, vs)
<+> getInt
<+> (getString ?)
<+> (getInt ?)
<+> (getString ?)
<+> (getInt ?)
<+> (getInt ?)
<+> (getString ?)
<+> (getString ?)
<+> (getInt ?)
<+> (getInt ?)
<+> (getString ?)
<+> (getString ?)
<+> (getInt ?)
<+> (getInt ?)
<+> (getString ?)
ghc.exe: panic! (the 'impossible' happened)
(GHC version 8.2.2 for x86_64-unknown-mingw32):
Simplifier ticks exhausted
When trying UnfoldingDone $j_s1y9
To increase the limit, use -fsimpl-tick-factor=N (default 100)
If you need to do this, let GHC HQ know, and what factor you needed
To see detailed counts use -ddump-simpl-stats
Total ticks: 71323
Call stack:
CallStack (from HasCallStack):
prettyCurrentCallStack, called at compiler\utils\Outputable.hs:1133:58 in ghc:Outputable
callStackDoc, called at compiler\utils\Outputable.hs:1137:37 in ghc:Outputable
pprPanic, called at compiler\simplCore\SimplMonad.hs:199:31 in ghc:SimplMonad
This seems similar to #8319 which was marked as being fixed.
It compiles (albeit very very slowly!) if I remove the last parameter and the last application of (<+>).
Trac metadata
Trac field | Value |
---|---|
Version | 8.2.2 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |