[GHC] #10184: Coercible solver incomplete with recursive newtypes
#10184: Coercible solver incomplete with recursive newtypes -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: low | Milestone: ⊥ Component: Compiler | Version: 7.10.1-rc3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The following module fails to compile due to infinite recursion: {{{ import Data.Coerce newtype Bar a = Bar (Either a (Bar a)) newtype Age = MkAge Int x :: Bar Age x = coerce (Bar (Left (5 :: Int))) }}} It tries to coerce `Bar Int` to `Bar Age`. This is clearly doable, via tyconapp decomposition. But we don't find it. Before worrying too much about it, though, we'll wait for a real example. Do speak up if this problem is ruining your day! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10184> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#10184: Coercible solver incomplete with recursive newtypes -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: low | Milestone: ⊥ Component: Compiler | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by goldfire): * version: 7.10.1-rc3 => 7.11 Comment: Oops -- this is about 7.11, not 7.10. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10184#comment:1> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#10184: Coercible solver incomplete with recursive newtypes -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: low | Milestone: ⊥ Component: Compiler | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by Richard Eisenberg <eir@…>): In [changeset:"c1edbdfd9148ad9f74bfe41e76c524f3e775aaaa/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="c1edbdfd9148ad9f74bfe41e76c524f3e775aaaa" Do proper depth checking in the flattener to avoid looping. This implements (roughly) the plan put forward in comment:14:ticket:7788, fixing #7788, #8550, #9554, #10139, and addressing concerns raised in #10079. There are some regressions w.r.t. GHC 7.8, but only with pathological type families (like F a = F a). This also (hopefully -- don't have a test case) fixes #10158. Unsolved problems include #10184 and #10185, which are both known deficiencies of the approach used here. As part of this change, the plumbing around detecting infinite loops has changed. Instead of -fcontext-stack and -ftype-function-depth, we now have one combined -freduction-depth parameter. Setting it to 0 disbales the check, which is now the recommended way to get (terminating) code to typecheck in releases. (The number of reduction steps may well change between minor GHC releases!) This commit also introduces a new IntWithInf type in BasicTypes that represents an integer+infinity. This type is used in a few places throughout the code. Tests in indexed-types/should_fail/T7788 indexed-types/should_fail/T8550 indexed-types/should_fail/T9554 indexed-types/should_compile/T10079 indexed-types/should_compile/T10139 typecheck/should_compile/T10184 (expected broken) typecheck/should_compile/T10185 (expected broken) This commit also changes performance testsuite numbers, for the better. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10184#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#10184: Coercible solver incomplete with recursive newtypes -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: low | Milestone: ⊥ Component: Compiler | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | typecheck/should_compile/T10184 | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by goldfire): * testcase: => typecheck/should_compile/T10184 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10184#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#10184: Coercible solver incomplete with recursive newtypes -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: bug | Status: new Priority: low | Milestone: ⊥ Component: Compiler | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | typecheck/should_compile/T10184 Blocked By: | Blocking: Related Tickets: #14247 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * related: => #14247 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10184#comment:4> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
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