[GHC] #15607: RebindableSyntax warns `return` is not in scope when trying to call `pure`, but does not desugar between the two

[GHC]

#15607: RebindableSyntax warns `return` is not in scope when trying to call `pure`,
but does not desugar between the two
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        Reporter:  isovector         |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.6.1-beta1
      Resolution:                    |             Keywords:
                                     |  RebindableSyntax
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"4bde71df9a32bf6f5ee7d44fbbf79523da4b0a9e/ghc"
 4bde71df/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="4bde71df9a32bf6f5ee7d44fbbf79523da4b0a9e"
 Don't look up unnecessary return in LastStmt

 This fixes Trac #15607. The general pattern is well
 established (e.g. see the guard_op binding in rnStmt
 of BodyStme), but we weren't using it for LastStmt.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15607#comment:2>
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