[GHC] #14350: Infinite loop when typechecking incorrect implementation (GHC HEAD only)

[GHC]

#14350: Infinite loop when typechecking incorrect implementation (GHC HEAD only)
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  high              |            Milestone:  8.4.1
       Component:  Compiler (Type    |              Version:  8.3
  checker)                           |
      Resolution:  fixed             |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
                                     |  typecheck/should_fail/T14350
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by simonpj):

 * status:  new => closed
 * testcase:   => typecheck/should_fail/T14350
 * resolution:   => fixed


Comment:

 Fixed by
 {{{
 In 74cd1be0/ghc:

 Don't deeply expand insolubles

 Trac #13450 went bananas if we expand insoluble constraints.
 Better just to leave them un-expanded.

 I'm not sure in detail about why it goes so badly wrong; but
 regardless, the less we mess around with insoluble contraints
 the better the error messages will be.
 }}}
 Sorry I mis-typed the trac ticket in the commit.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14350#comment:3>
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