#11549: Add -fshow-runtime-rep -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 8.1 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonpj): * keywords: => TypeInType -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11549#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11549: Add -fshow-runtime-rep -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: patch Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 8.1 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1961 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: new => patch * differential: => Phab:D1961 Comment: I gave this a shot in Phab:D1961. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11549#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11549: Add -fshow-runtime-rep -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: patch Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 8.1 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1961 Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): But #11660 seems orthogonal to this -- the general idea that is described in this ticket and the implementation in Phab:D1961 would still need to exist even after #11660. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11549#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11549: Add -fshow-runtime-rep -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: patch Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 8.1 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1961 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ben Gamari ): In [changeset:"371608f1cdaf20c49eb6c5ec165b9eb08b745a89/ghc" 371608f/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="371608f1cdaf20c49eb6c5ec165b9eb08b745a89" Default RuntimeRep variables unless -fprint-explicit-runtime-reps Summary: Addresses #11549 by defaulting `RuntimeRep` variables to `PtrRepLifted` and adding a new compiler flag `-fprint-explicit-runtime-reps` to disable this behavior. This is just a guess at the right way to go about this. If it's wrong-beyond-any-hope just say so. Test Plan: Working on a testcase Reviewers: goldfire, austin Subscribers: simonpj, thomie Differential Revision: https://phabricator.haskell.org/D1961 GHC Trac Issues: #11549 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11549#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11549: Add -fshow-runtime-rep -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: closed Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 8.1 Resolution: fixed | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1961 Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): Do you think it's worth special-casing this kind of behavior with `-XTypeApplications` as well? Currently, it's quite easy to leak `RuntimeRep`: {{{ $ /opt/ghc/8.0.1/bin/ghci GHCi, version 8.0.0.20160324: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/ryanglscott/.ghci λ> :t undefined undefined :: GHC.Stack.Types.HasCallStack => a λ> :set -XTypeApplications λ> :t undefined @Int <interactive>:1:12: error: • Expected kind ‘GHC.Types.RuntimeRep’, but ‘Int’ has kind ‘*’ • In the type ‘Int’ In the expression: undefined @Int }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11549#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11549: Add -fshow-runtime-rep -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 8.1 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1961 Wiki Page: | -------------------------------------+------------------------------------- Changes (by thoughtpolice): * status: closed => new * priority: highest => normal * resolution: fixed => * owner: goldfire => -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11549#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11549: Add -fshow-runtime-rep -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.2 Component: Compiler | Version: 8.0.1-rc2 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1961 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * milestone: 8.0.1 => 8.0.2 Comment: Unfortunately I don't see an easy way to make comment:11 happen. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11549#comment:14 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11549: Add -fshow-runtime-rep -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 8.0.1-rc2 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1961 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * milestone: 8.0.2 => 8.2.1 Comment: This won't be happening for 8.0.2. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11549#comment:16 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11549: Add -fshow-runtime-rep -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.0.1-rc2 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1961 Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): While comment:10 is indeed an odd interaction, these sorts of problems become inevitable. I'm reminded of a scene in the movie Interstellar where a robot describes that his "honesty setting" is at 90%, because that just works out better than being 100% honest. As GHC's type system has become more complicated, users have been requesting it to lower its honesty setting, hiding bits and pieces that look scary. We now have `-fprint- explicit-kinds`, `-fprint-explicit-coercions`, `-fprint-explicit-foralls`, `-fprint-equality-relations`, and `-fprint-explicit-runtime-reps`. Each of these flags are off by default, and each one is essentially an honesty setting. Perhaps with the exception of `-fprint-explicit-coercions`, the fact that GHC lies about these aspects of a program means that programmers may make mistakes -- it's the old "garbage in, garbage out", but in reverse! (with the humans getting and producing the garbage) I don't know how to really solve this, short of #8809, which would lead to Idris-like interactivity in error messages. We could try to figure out when a user has produced garbage in response to a lie that GHC has told and then tell the user to tell GHC not to lie (as we do when we suggest `-fprint-explicit-kinds` in error messages), but I think we'll always be playing catch-up. Instead, we should give the user the direct option (via #8809) to know when GHC is lying and to request the truth. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11549#comment:18 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#11549: Add -fshow-runtime-rep -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: 8.8.1 Component: Compiler | Version: 8.0.1-rc2 Resolution: fixed | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1961 Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * status: new => closed * resolution: => fixed Comment: Indeed, I think my suggestion in comment:10 is far too ambitious to be realistic (at least, at the moment). Moreover, `-fprint-explicit-runtime- reps` is now fully implemented and does the job that it advertises in the users' guide (namely, it prints `RuntimeRep`-polymorphic type variables in full detail), so I think this can be closed. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11549#comment:22 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler