#16346: Lint error on master: Occurrence is GlobalId, but binding is LocalId -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 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): Yes I think so. But the real issue is this in `SimplEnv.refineFromInScope`: {{{ refineFromInScope :: InScopeSet -> Var -> Var refineFromInScope in_scope v | isLocalId v = case lookupInScope in_scope v of Just v' -> v' Nothing -> WARN( True, ppr v ) v -- This is an error! | otherwise = v }}} Notice that we don't look `GlobalId`s up in the in-scope set. Yet that is the mechanism that ensures that in a situation like {{{ let f_2dr[LclId] = blah in ...M.f_2df[GblId]... }}} (which has a local binding for a `GlobalId`), we transform to {{{ let f_2dr[LclId] = blah in ...f_2df[LclId]... }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16346#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#16346: Lint error on master: Occurrence is GlobalId, but binding is LocalId -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 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): Here's why the second crash happens. We start with {{{ case M.f_2dr[GblId] of f' { W# y -> let f_2dr[LclId] = f' in case M.f_2dr[GblId] of { W# z -> blah }}} (All this is in the body of `$s$fGBinaryGetTYPE:+:1_sfOT` in `Distribution.Types.ComponentRequestedSpec`.) Then * It turns out that `M.f_2dr` is a HNF so the first case can vanish. We extend the substitution with `f' :-> M.f_2dr[GblId]`. * We simplify the RHS of the `let` to get `M.f_2dr[GblId]` * We simplify the let-binder. It's not in scope, so we don't mess with its unique, and we extend the in-scope set with `M.f_2dr[LclId]`. * Now post-inline-unconditionally fires, so we extend the substitution with `f_2dr :-> M.f_2dr[GblId]` * Now at the occurrence of `M.f_2dr[GblId]` we find it in the substitution, mapping to, well, `M.f_2dr[GblId]`. * Then we look that up in the in-scope set, and get `M.f_2dr[LclId]` * And that is not in scope. What a mess. My conclusion: it's a total disaster to have a local binding for a `LocalId` that shares a unique with a `GlobalId`. We have multiple hacks to avoid trouble, and they don't even work. Let's stop doing it. See #16296. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16346#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#16346: Lint error on master: Occurrence is GlobalId, but binding is LocalId -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #16296 | Differential Rev(s): Wiki Page: | https://gitlab.haskell.org/ghc/ghc/merge_requests/416 -------------------------------------+------------------------------------- Changes (by RyanGlScott): * differential: => https://gitlab.haskell.org/ghc/ghc/merge_requests/416 * related: => #16296 Comment: simonpj, what is the status of this ticket post-[https://gitlab.haskell.org/ghc/ghc/commit/0eb7cf03da3783ca887d5de44d312cf6f3... 0eb7cf03da3783ca887d5de44d312cf6f3a4113c]? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16346#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#16346: Lint error on master: Occurrence is GlobalId, but binding is LocalId -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #16296 | Differential Rev(s): Wiki Page: | https://gitlab.haskell.org/ghc/ghc/merge_requests/416 -------------------------------------+------------------------------------- Changes (by monoidal): * status: new => closed * resolution: => fixed Comment: CI was fixed in {{{ commit 44ad7215a11cb49651233646c30ced9eb72eaad2 Author: Matthew Pickering Date: Wed Feb 20 20:42:13 2019 +0000 Use validate flavour rather than devel2 for DEBUG CI job This also builds stage2 with optimisations and -dcore-lint }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16346#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#16346: Lint error on master: Occurrence is GlobalId, but binding is LocalId -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: 8.10.1 Component: Compiler | Version: 8.6.3 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #16296 | Differential Rev(s): Wiki Page: | https://gitlab.haskell.org/ghc/ghc/merge_requests/416 -------------------------------------+------------------------------------- Comment (by Matthew Pickering ): In [changeset:"0eb7cf03da3783ca887d5de44d312cf6f3a4113c/ghc" 0eb7cf03/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="0eb7cf03da3783ca887d5de44d312cf6f3a4113c" Don't do binder-swap for GlobalIds This patch disables the binder-swap transformation in the (relatively rare) case when the scrutinee is a GlobalId. Reason: we are getting Lint errors so that GHC doesn't even validate. Trac #16346. This is NOT the final solution -- it's just a stop-gap to get us running again. The final solution is in Trac #16296 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16346#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler