[GHC] #14732: -fdefer-type-holes breaks a correct program
#14732: -fdefer-type-holes breaks a correct program -------------------------------------+------------------------------------- Reporter: MitchellSalad | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Here's a bug I discovered in `vector` that Ryan Scott identified as a regression from 7.10.3: https://github.com/haskell/vector/issues/200 Here is Ryan's minimal example: {{{#!hs {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE MultiParamTypeClasses #-} module Bug where import Prelude hiding (zip, zipWith) zipWith :: (a -> b -> c) -> Bundle v a -> Bundle v b -> Bundle v c zipWith = undefined class GVector (v :: * -> *) a instance GVector Vector a data Bundle (v :: * -> *) a data Vector a class Unbox a stream :: GVector v a => v a -> Bundle v a {-# INLINE [1] stream #-} stream = undefined zip :: (Unbox a, Unbox b) => Vector a -> Vector b -> Vector (a, b) {-# INLINE [1] zip #-} zip = undefined {-# RULES "stream/zip [Vector.Unboxed]" forall as bs . stream (zip as bs) = zipWith (,) (stream as) (stream bs) #-}{#!hs }}} Output (8.2.2): {{{ Bug.hs:29:11: error: • Could not deduce (Unbox a) arising from a use of ‘zip’ from the context: GVector Vector (a, b) bound by the RULE "stream/zip [Vector.Unboxed]" at Bug.hs:(28,11)-(30,46) Possible fix: add (Unbox a) to the context of the RULE "stream/zip [Vector.Unboxed]" • In the first argument of ‘stream’, namely ‘(zip as bs)’ In the expression: stream (zip as bs) When checking the transformation rule "stream/zip [Vector.Unboxed]" | 29 | stream (zip as bs) = zipWith (,) (stream as) | ^^^^^^^^^ }}} Similar output in 8.0.1, 8.0.2, 8.2.1 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14732 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14732: -fdefer-type-holes breaks a correct program -------------------------------------+------------------------------------- Reporter: MitchellSalad | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by MitchellSalad: Old description:
Here's a bug I discovered in `vector` that Ryan Scott identified as a regression from 7.10.3:
https://github.com/haskell/vector/issues/200
Here is Ryan's minimal example:
{{{#!hs
{-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE MultiParamTypeClasses #-} module Bug where
import Prelude hiding (zip, zipWith)
zipWith :: (a -> b -> c) -> Bundle v a -> Bundle v b -> Bundle v c zipWith = undefined
class GVector (v :: * -> *) a instance GVector Vector a
data Bundle (v :: * -> *) a data Vector a class Unbox a
stream :: GVector v a => v a -> Bundle v a {-# INLINE [1] stream #-} stream = undefined
zip :: (Unbox a, Unbox b) => Vector a -> Vector b -> Vector (a, b) {-# INLINE [1] zip #-} zip = undefined {-# RULES "stream/zip [Vector.Unboxed]" forall as bs . stream (zip as bs) = zipWith (,) (stream as) (stream bs) #-}{#!hs
}}}
Output (8.2.2):
{{{ Bug.hs:29:11: error: • Could not deduce (Unbox a) arising from a use of ‘zip’ from the context: GVector Vector (a, b) bound by the RULE "stream/zip [Vector.Unboxed]" at Bug.hs:(28,11)-(30,46) Possible fix: add (Unbox a) to the context of the RULE "stream/zip [Vector.Unboxed]" • In the first argument of ‘stream’, namely ‘(zip as bs)’ In the expression: stream (zip as bs) When checking the transformation rule "stream/zip [Vector.Unboxed]" | 29 | stream (zip as bs) = zipWith (,) (stream as) | ^^^^^^^^^ }}}
Similar output in 8.0.1, 8.0.2, 8.2.1
New description: Here's a bug I discovered in `vector` that Ryan Scott identified as a regression from 7.10.3: https://github.com/haskell/vector/issues/200 Here is Ryan's minimal example: {{{#!hs {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE MultiParamTypeClasses #-} module Bug where import Prelude hiding (zip, zipWith) zipWith :: (a -> b -> c) -> Bundle v a -> Bundle v b -> Bundle v c zipWith = undefined class GVector (v :: * -> *) a instance GVector Vector a data Bundle (v :: * -> *) a data Vector a class Unbox a stream :: GVector v a => v a -> Bundle v a {-# INLINE [1] stream #-} stream = undefined zip :: (Unbox a, Unbox b) => Vector a -> Vector b -> Vector (a, b) {-# INLINE [1] zip #-} zip = undefined {-# RULES "stream/zip [Vector.Unboxed]" forall as bs . stream (zip as bs) = zipWith (,) (stream as) (stream bs) #-} }}} Output (8.2.2): {{{ Bug.hs:29:11: error: • Could not deduce (Unbox a) arising from a use of ‘zip’ from the context: GVector Vector (a, b) bound by the RULE "stream/zip [Vector.Unboxed]" at Bug.hs:(28,11)-(30,46) Possible fix: add (Unbox a) to the context of the RULE "stream/zip [Vector.Unboxed]" • In the first argument of ‘stream’, namely ‘(zip as bs)’ In the expression: stream (zip as bs) When checking the transformation rule "stream/zip [Vector.Unboxed]" | 29 | stream (zip as bs) = zipWith (,) (stream as) | ^^^^^^^^^ }}} Similar output in 8.0.1, 8.0.2, 8.2.1 -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14732#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14732: -fdefer-typed-holes breaks a correct program -------------------------------------+------------------------------------- Reporter: MitchellSalad | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14732#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14732: -fdefer-typed-holes breaks a correct program -------------------------------------+------------------------------------- Reporter: MitchellSalad | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): What exactly is the bug here, and how can I reproduce it? What has it got to do with `-fdefer-type-errors`? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14732#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14732: -fdefer-typed-holes breaks a correct program -------------------------------------+------------------------------------- Reporter: MitchellSalad | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): You need to compile the program with `-fdefer-typed-holes` to trigger the error: {{{ $ /opt/ghc/8.2.2/bin/ghc -fdefer-typed-holes Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) Bug.hs:29:11: error: • Could not deduce (Unbox a) arising from a use of ‘zip’ from the context: GVector Vector (a, b) bound by the RULE "stream/zip [Vector.Unboxed]" at Bug.hs:(28,11)-(30,46) Possible fix: add (Unbox a) to the context of the RULE "stream/zip [Vector.Unboxed]" • In the first argument of ‘stream’, namely ‘(zip as bs)’ In the expression: stream (zip as bs) When checking the transformation rule "stream/zip [Vector.Unboxed]" | 29 | stream (zip as bs) = zipWith (,) (stream as) | ^^^^^^^^^ }}} This regression was introduced in 6746549772c5cc0ac66c0fce562f297f4d4b80a2 (`Add kind equalities to GHC.`). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14732#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14732: -fdefer-typed-holes breaks a correct program
-------------------------------------+-------------------------------------
Reporter: MitchellSalad | Owner: (none)
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 8.2.2
Resolution: | Keywords:
Operating System: Unknown/Multiple | Architecture:
| Unknown/Multiple
Type of failure: None/Unknown | Test Case:
Blocked By: | Blocking:
Related Tickets: | Differential Rev(s):
Wiki Page: |
-------------------------------------+-------------------------------------
Comment (by Simon Peyton Jones
#14732: -fdefer-typed-holes breaks a correct program -------------------------------------+------------------------------------- Reporter: MitchellSalad | Owner: (none) Type: bug | Status: merge Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | typecheck/should_compile/T14732 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonpj): * testcase: => typecheck/should_compile/T14732 * status: new => merge -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14732#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14732: -fdefer-typed-holes breaks a correct program -------------------------------------+------------------------------------- Reporter: MitchellSalad | Owner: (none) Type: bug | Status: merge Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | typecheck/should_compile/T14732 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * milestone: => 8.4.1 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14732#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14732: -fdefer-typed-holes breaks a correct program -------------------------------------+------------------------------------- Reporter: MitchellSalad | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.2.2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | typecheck/should_compile/T14732 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: merge => closed * resolution: => fixed Comment: Merged with d3573e4ae63d6ae1ac0cd4bf5692a9bcd39ba733. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14732#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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