[GHC] #14127: -fignore-interface-pragmas and -fspecialise do not go well together
#14127: -fignore-interface-pragmas and -fspecialise do not go well together -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): corePrepPgm [True] $s$fSelectorMetaMetaSel_a = "_dconf_dump_annotations"# }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14127 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14127: -fignore-interface-pragmas and -fspecialise do not go well together -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * status: new => infoneeded Comment: Can you post a minimal program which triggers this panic? I'm unable to construct one from the little info on this ticket. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14127#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14127: -fignore-interface-pragmas and -fspecialise do not go well together -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by lspitzner): Sorry, I wrongly assumed this was much easier to reproduce. Now that I try, it appears to be pretty specific, in fact I can't even simplify properly. This still needs a dependency on aeson-1.2.1.0: - A.hs {{{#!hs {-# LANGUAGE DeriveGeneric #-} {-# LANGUAGE DeriveDataTypeable #-} module A where import GHC.Generics data Foo = AltChooserSimpleQuick deriving (Generic) }}} - B.hs {{{#!hs {-# OPTIONS_GHC -fno-pre-inlining #-} {-# OPTIONS_GHC -fspecialise #-} {-# OPTIONS_GHC -fignore-interface-pragmas #-} module B where import A import qualified Data.Aeson.Types as Aeson instance Aeson.FromJSON Foo where parseJSON = Aeson.genericParseJSON Aeson.defaultOptions {-# NOINLINE parseJSON #-} }}} I have made several attempts to reproduce this with a standalone class instead of the one from aeson, but failed to do so. It also appears that the panic disappears when there is no orphan instance in play (i.e. if you merge modules A/B). Also note that simply replacing `data Foo = AltChooseSimpleQuick` with `data Foo = AltChoose` the panic disappears. Further testing suggests that it requires any constructor identifier with at least 21 characters to trigger the panic. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14127#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14127: -fignore-interface-pragmas and -fspecialise do not go well together -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by lspitzner): And now that I noticed this 21 character relevance, perhaps producing a standalone testcase without aeson is possible. But maybe it depends on some other random length of some textual representation or whatever? In that case creating a reliable smaller testcase might be a challenge. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14127#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14127: -fignore-interface-pragmas and -fspecialise do not go well together -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): To make things more interesting, I can reproduce this panic on GHC 8.0.2, but not on 8.2.1. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14127#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14127: -fignore-interface-pragmas and -fspecialise do not go well together -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * status: infoneeded => closed * resolution: => fixed Comment: After reading the source code some more, I believe this was properly fixed in GHC 8.2. Specifically, in commit d49b2bb21691892ca6ac8f2403e31f2a5e53feb3 (Allow top-level string literals in Core (#8472)). That patch made the [http://git.haskell.org/ghc.git/blobdiff/a2a67b77c3048713541d1ed96ec0b95fb254... following change]: {{{#!diff diff --git a/compiler/coreSyn/CorePrep.hs b/compiler/coreSyn/CorePrep.hs index c93a121..fb650f6 100644 (file) --- a/compiler/coreSyn/CorePrep.hs +++ b/compiler/coreSyn/CorePrep.hs @@ -1168,7 +1168,9 @@ deFloatTop (Floats _ floats) = foldrOL get [] floats where get (FloatLet b) bs = occurAnalyseRHSs b : bs - get b _ = pprPanic "corePrepPgm" (ppr b) + get (FloatCase var body _) bs = + occurAnalyseRHSs (NonRec var body) : bs + get b _ = pprPanic "corePrepPgm" (ppr b) -- See Note [Dead code in CorePrep] occurAnalyseRHSs (NonRec x e) = NonRec x (occurAnalyseExpr_NoBinderSwap e) }}} Before, `get` was being called on a `FloatCase`, which is the only constructor that could have given the output `[True] $s$fSelectorMetaMetaSel_a = "_dconf_dump_annotations"#`. But now that this case is covered properly, the issue appears to have gone away. So I'll opt to close this issue, since I can't reproduce the problem on 8.2, and coming up with a minimal regression test doesn't seem feasible. Please feel free to re-open the issue if you come across the same panic on GHC 8.2 or later. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14127#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14127: -fignore-interface-pragmas and -fspecialise do not go well together -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by lspitzner): thanks for looking into this! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14127#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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