#11230: No run-time exception for deferred type errors when error is in a phantom role position -------------------------------------+------------------------------------- Reporter: darchon | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.11 Resolution: | Keywords: deferred, | roles Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by darchon: Old description:

The following code:

{{{#!hs {-# LANGUAGE RoleAnnotations #-} {-# OPTIONS_GHC -fdefer-type-errors #-}

import Control.Exception

newtype Representational a = Representational () type role Representational representational

newtype Phantom a = Phantom () type role Phantom phantom

testRepresentational :: Representational Char -> Representational Bool testRepresentational = id {-# NOINLINE testRepresentational #-}

testPhantom :: Phantom Char -> Phantom Bool testPhantom = id {-# NOINLINE testPhantom #-}

throwsException :: String -> a -> IO () throwsException c v = do result <- try (evaluate v) case result of Right _ -> error (c ++ " (Failure): No exception!") -- #if MIN_VERSION_base(4,9,0) Left (TypeError msg) -> putStrLn (c ++ "(Succes): exception found") -- #else -- Left (ErrorCall _) -> putStrLn "Succes: exception found" -- #endif

main = do throwsException "representational" testRepresentational throwsException "phantom" testPhantom }}}

Produces the following result in HEAD:

{{{ representational(Succes): exception found *** Exception: phantom (Failure): No exception! CallStack (from ImplicitParams): error, called at Main.hs:24:16 in main:Main }}}

In 7.10.2 (after commenting the `TypeError` line, and uncommenting the `ErrorCall` line), we get the following output:

{{{ Succes: exception found Succes: exception found }}}

I think the HEAD result is wrong: deferred type errors should always result in a run-time exception when their associated value is evaluated, regardless of whether the error occurred in a phantom role position or not.

Looking at the core (`ghc -O0 -ddump-simpl`) in HEAD is see:

{{{ -- RHS size: {terms: 3, types: 15, coercions: 0} testRepresentational_rqP :: Representational Char -> Representational Bool [GblId, Str=DmdType b] testRepresentational_rqP = case typeError @ 'Unlifted @ (Char ~# Bool) "Main.hs:13:24: error:\n\ \ \\226\\128\\162 Couldn't match type \\226\\128\\152Char\\226\\128\\153 with \\226\\128\\152Bool\\226\\128\\153\n\ \ Expected type: Representational Char -> Representational Bool\n\ \ Actual type: Representational Bool -> Representational Bool\n\ \ \\226\\128\\162 In the expression: id\n\ \ In an equation for \\226\\128\\152testRepresentational\\226\\128\\153:\n\ \ testRepresentational = id\n\ \(deferred type error)"# of wild0_00 { }

-- RHS size: {terms: 1, types: 2, coercions: 10} testPhantom_rqQ :: Phantom Char -> Phantom Bool [GblId, Str=DmdType] testPhantom_rqQ = (id @ (Phantom Bool)) `cast` ((Phantom _P{<*>_N})_R -> <Phantom Bool>_R :: (Phantom Bool -> Phantom Bool) ~R# (Phantom Char -> Phantom Bool)) }}}

while in 7.10.2 I see:

{{{ testRepresentational_rnc :: Representational Char -> Representational Bool [GblId, Str=DmdType b] testRepresentational_rnc = case Control.Exception.Base.runtimeError @ (Char ~ Bool) "Main.hs:13:24:\n\ \ Couldn't match type \\226\\128\\152Char\\226\\128\\153 with \\226\\128\\152Bool\\226\\128\\153\n\ \ Expected type: Representational Char -> Representational Bool\n\ \ Actual type: Representational Bool -> Representational Bool\n\ \ In the expression: id\n\ \ In an equation for \\226\\128\\152testRepresentational\\226\\128\\153:\n\ \ testRepresentational = id\n\ \(deferred type error)"# of wild_00 { }

testPhantom_rnd :: Phantom Char -> Phantom Bool [GblId, Str=DmdType b] testPhantom_rnd = case Control.Exception.Base.runtimeError @ (Char ~ Bool) "Main.hs:17:15:\n\ \ Couldn't match type \\226\\128\\152Char\\226\\128\\153 with \\226\\128\\152Bool\\226\\128\\153\n\ \ Expected type: Phantom Char -> Phantom Bool\n\ \ Actual type: Phantom Bool -> Phantom Bool\n\ \ In the expression: id\n\ \ In an equation for \\226\\128\\152testPhantom\\226\\128\\153: testPhantom = id\n\ \(deferred type error)"# of wild_00 { } }}}

New description: The following code: {{{#!hs {-# LANGUAGE RoleAnnotations #-} {-# OPTIONS_GHC -fdefer-type-errors #-} import Control.Exception newtype Representational a = Representational () type role Representational representational newtype Phantom a = Phantom () type role Phantom phantom testRepresentational :: Representational Char -> Representational Bool testRepresentational = id {-# NOINLINE testRepresentational #-} testPhantom :: Phantom Char -> Phantom Bool testPhantom = id {-# NOINLINE testPhantom #-} throwsException :: String -> a -> IO () throwsException c v = do result <- try (evaluate v) case result of Right _ -> error (c ++ " (Failure): No exception!") -- #if MIN_VERSION_base(4,9,0) Left (TypeError _) -> putStrLn (c ++ "(Succes): exception found") -- #else -- Left (ErrorCall _) -> putStrLn (c ++ " (Succes): exception found") -- #endif main = do throwsException "representational" testRepresentational throwsException "phantom" testPhantom }}} Produces the following result in HEAD: {{{ representational(Succes): exception found *** Exception: phantom (Failure): No exception! CallStack (from ImplicitParams): error, called at Main.hs:24:16 in main:Main }}} In 7.10.2 (after commenting the `TypeError` line, and uncommenting the `ErrorCall` line), we get the following output: {{{ representational (Succes): exception found phantom (Succes): exception found }}} I think the HEAD result is wrong: deferred type errors should always result in a run-time exception when their associated value is evaluated, regardless of whether the error occurred in a phantom role position or not. Looking at the core (`ghc -O0 -ddump-simpl`) in HEAD is see: {{{ -- RHS size: {terms: 3, types: 15, coercions: 0} testRepresentational_rqP :: Representational Char -> Representational Bool [GblId, Str=DmdType b] testRepresentational_rqP = case typeError @ 'Unlifted @ (Char ~# Bool) "Main.hs:13:24: error:\n\ \ \\226\\128\\162 Couldn't match type \\226\\128\\152Char\\226\\128\\153 with \\226\\128\\152Bool\\226\\128\\153\n\ \ Expected type: Representational Char -> Representational Bool\n\ \ Actual type: Representational Bool -> Representational Bool\n\ \ \\226\\128\\162 In the expression: id\n\ \ In an equation for \\226\\128\\152testRepresentational\\226\\128\\153:\n\ \ testRepresentational = id\n\ \(deferred type error)"# of wild0_00 { } -- RHS size: {terms: 1, types: 2, coercions: 10} testPhantom_rqQ :: Phantom Char -> Phantom Bool [GblId, Str=DmdType] testPhantom_rqQ = (id @ (Phantom Bool)) `cast` ((Phantom _P{<*>_N})_R -> <Phantom Bool>_R :: (Phantom Bool -> Phantom Bool) ~R# (Phantom Char -> Phantom Bool)) }}} while in 7.10.2 I see: {{{ testRepresentational_rnc :: Representational Char -> Representational Bool [GblId, Str=DmdType b] testRepresentational_rnc = case Control.Exception.Base.runtimeError @ (Char ~ Bool) "Main.hs:13:24:\n\ \ Couldn't match type \\226\\128\\152Char\\226\\128\\153 with \\226\\128\\152Bool\\226\\128\\153\n\ \ Expected type: Representational Char -> Representational Bool\n\ \ Actual type: Representational Bool -> Representational Bool\n\ \ In the expression: id\n\ \ In an equation for \\226\\128\\152testRepresentational\\226\\128\\153:\n\ \ testRepresentational = id\n\ \(deferred type error)"# of wild_00 { } testPhantom_rnd :: Phantom Char -> Phantom Bool [GblId, Str=DmdType b] testPhantom_rnd = case Control.Exception.Base.runtimeError @ (Char ~ Bool) "Main.hs:17:15:\n\ \ Couldn't match type \\226\\128\\152Char\\226\\128\\153 with \\226\\128\\152Bool\\226\\128\\153\n\ \ Expected type: Phantom Char -> Phantom Bool\n\ \ Actual type: Phantom Bool -> Phantom Bool\n\ \ In the expression: id\n\ \ In an equation for \\226\\128\\152testPhantom\\226\\128\\153: testPhantom = id\n\ \(deferred type error)"# of wild_00 { } }}} -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11230#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11230: No run-time exception for deferred type errors when error is in a phantom role position -------------------------------------+------------------------------------- Reporter: darchon | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.11 Resolution: | Keywords: deferred, | roles Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): Yes -- I'm pretty sure I know exactly what's going on here. Will fix. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11230#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11230: No run-time exception for deferred type errors when error is in a phantom role position -------------------------------------+------------------------------------- Reporter: darchon | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.11 Resolution: | Keywords: deferred, | roles Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1641 Wiki Page: | -------------------------------------+------------------------------------- Changes (by goldfire): * differential: => Phab:D1641 Comment: This one is fixed. Just validating on Phab. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11230#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11230: No run-time exception for deferred type errors when error is in a phantom role position -------------------------------------+------------------------------------- Reporter: darchon | Owner: Type: bug | Status: closed Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.11 Resolution: fixed | Keywords: deferred, | roles Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Incorrect result | Test Case: at runtime | typecheck/should_run/T11230 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1641 Wiki Page: | -------------------------------------+------------------------------------- Changes (by goldfire): * status: new => closed * testcase: => typecheck/should_run/T11230 * resolution: => fixed -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11230#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler