#10403: GHC crashes on a partial type signature -------------------------------------+------------------------------------- Reporter: Artyom.Kazak | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Description changed by Artyom.Kazak: Old description:

The following code crashes GHC 7.10.1 as is, but doesn't result in a crash if the signature is specified completely or isn't specified at all (inferred):

{{{#!hs {-# LANGUAGE PartialTypeSignatures #-} module Main where

data I a = I a instance Functor I where fmap f (I a) = I (f a)

newtype B t a = B a instance Functor (B t) where fmap f (B a) = B (f a)

newtype H f = H (f ())

app :: H (B t) app = h (H . I) (B ())

h :: _ --h :: Functor m => (a -> b) -> m a -> H m h f b = (H . fmap (const ())) (fmap f b) }}}

New description: The following code crashes GHC 7.10.1 as is, but doesn't result in a crash if the signature is specified completely or isn't specified at all (inferred): {{{#!hs {-# LANGUAGE PartialTypeSignatures #-} module Main where main :: IO () main = return () data I a = I a instance Functor I where fmap f (I a) = I (f a) newtype B t a = B a instance Functor (B t) where fmap f (B a) = B (f a) newtype H f = H (f ()) app :: H (B t) app = h (H . I) (B ()) h :: _ --h :: Functor m => (a -> b) -> m a -> H m h f b = (H . fmap (const ())) (fmap f b) }}} -- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10403#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

#10403: GHC crashes on a partial type signature -------------------------------------+------------------------------------- Reporter: Artyom.Kazak | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by Artyom.Kazak): Error message (in GHCi 7.10.1): {{{#!hs $ ghci GHCi, version 7.10.1: http://www.haskell.org/ghc/ :? for help Prelude Control.Applicative Control.Monad Data.Ratio> :l Bug.hs [1 of 1] Compiling Main ( Bug.hs, interpreted ) Bug.hs:18:10: Couldn't match type `b' with `H I' `b' is untouchable inside the constraints () bound by the type signature for app :: H (B t) at Bug.hs:17:8-14ghc: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-unknown-linux): No skolem info: b_aFd[sk] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10403#comment:4> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

#10403: GHC crashes on a partial type signature -------------------------------------+------------------------------------- Reporter: Artyom.Kazak | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"a9ccd37add8315e061c02e5bf26c08f05fad9ac9/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="a9ccd37add8315e061c02e5bf26c08f05fad9ac9" Test Trac #10403 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10403#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

#10403: GHC crashes on a partial type signature -------------------------------------+------------------------------------- Reporter: Artyom.Kazak | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: fixed | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by Austin Seipp <austin@…>): In [changeset:"3cf8ecdc70cb295a2b9606080a1c7b5fa8eb16f4/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="3cf8ecdc70cb295a2b9606080a1c7b5fa8eb16f4" Revert multiple commits This reverts multiple commits from Simon: - 04a484eafc9eb9f8774b4bdd41a5dc6c9f640daf Test Trac #10359 - a9ccd37add8315e061c02e5bf26c08f05fad9ac9 Test Trac #10403 - c0aae6f699cbd222d826d0b8d78d6cb3f682079e Test Trac #10248 - eb6ca851f553262efe0824b8dcbe64952de4963d Make the "matchable-given" check happen first - ca173aa30467a0b1023682d573fcd94244d85c50 Add a case to checkValidTyCon - 51cbad15f86fca1d1b0e777199eb1079a1b64d74 Update haddock submodule - 6e1174da5b8e0b296f5bfc8b39904300d04eb5b7 Separate transCloVarSet from fixVarSet - a8493e03b89f3b3bfcdb6005795de050501f5c29 Fix imports in HscMain (stage2) - a154944bf07b2e13175519bafebd5a03926bf105 Two wibbles to fix the build - 5910a1bc8142b4e56a19abea104263d7bb5c5d3f Change in capitalisation of error msg - 130e93aab220bdf14d08028771f83df210da340b Refactor tuple constraints - 8da785d59f5989b9a9df06386d5bd13f65435bc0 Delete commented-out line These break the build by causing Haddock to fail mysteriously when trying to examine GHC.Prim it seems. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10403#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

#10403: GHC crashes on a partial type signature -------------------------------------+------------------------------------- Reporter: Artyom.Kazak | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"f1f265df0742b7214f3b909190f5a171819392b5/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="f1f265df0742b7214f3b909190f5a171819392b5" Test Trac #10403 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10403#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

#10403: GHC crashes on a partial type signature -------------------------------------+------------------------------------- Reporter: Artyom.Kazak | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: fixed | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash | Test Case: partial- Blocked By: | sigs/should_compile/T10403 Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by simonpj): * status: new => closed * testcase: => partial-sigs/should_compile/T10403 * resolution: => fixed Comment: I've elaborate the test to check both `h :: _` and `h :: _ => _`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10403#comment:12> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

#10403: GHC crashes on a partial type signature -------------------------------------+------------------------------------- Reporter: Artyom.Kazak | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash | Test Case: partial- Blocked By: | sigs/should_compile/T10403 Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by int-index): Simon, could you please add the code from the ticket to the test case verbatim? Your new variation does not trigger the bug because you removed the `app` function. Since you want to test both `h1 :: _` and `h2 :: _ => _`, please do not forget to include `add1` and `add2` so they get called. Here's code that triggers the bug: {{{ {-# LANGUAGE PartialTypeSignatures #-} module T10403 where main :: IO () main = return () data I a = I a instance Functor I where fmap f (I a) = I (f a) newtype B t a = B a instance Functor (B t) where fmap f (B a) = B (f a) newtype H f = H (f ()) app1 :: H (B t) app1 = h1 (H . I) (B ()) app2 :: H (B t) app2 = h2 (H . I) (B ()) h1 :: _ => _ --h1 :: Functor m => (a -> b) -> m a -> H m h1 f b = (H . fmap (const ())) (fmap f b) h2 :: _ --h2 :: Functor m => (a -> b) -> m a -> H m h2 f b = (H . fmap (const ())) (fmap f b) }}} The error message I'm getting when loading it in GHCi is: {{{ GHCi, version 7.10.1: http://www.haskell.org/ghc/ :? for help λ> :l Bug.hs [1 of 1] Compiling T10403 ( Bug.hs, interpreted ) Bug.hs:21:12: Couldn't match type ‘b’ with ‘H I’ ‘b’ is untouchable inside the constraints () bound by the type signature for app2 :: H (B t) at Bug.hs:20:9-15ghc: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-unknown-linux): No skolem info: b_ao6[sk] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10403#comment:14> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

#10403: GHC crashes on a partial type signature -------------------------------------+------------------------------------- Reporter: Artyom.Kazak | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash | Test Case: partial- Blocked By: | sigs/should_compile/T10403 Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by simonpj): OK, I've elaborated the test with the extra pieces you suggest. It all works fine in HEAD. It does not work in 7.10; and, as you'll see in #10045, we don't propose to fix in 7.10. I hope you can live without it. Sound OK? Simon -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10403#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

#10403: GHC crashes on a partial type signature -------------------------------------+------------------------------------- Reporter: Artyom.Kazak | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: fixed | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash | Test Case: partial- Blocked By: | sigs/should_compile/T10403 Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by int-index): Yes, it sounds ok. I just wanted to make sure that the bug is known of and reflected in the test suite. Thanks. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10403#comment:18> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler