Re: [GHC] #11155: Trivial thunk gives "undefined reference to stg_ap_0_upd_info"

4 Dec 2015

      #11155: Trivial thunk gives "undefined reference to stg_ap_0_upd_info"
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        Reporter:  simonpj           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:
       Component:  Compiler          |              Version:  7.10.2
      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:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"1c9fd3f1c5522372fcaf250c805b959e8090a62c/ghc"
 1c9fd3f1/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="1c9fd3f1c5522372fcaf250c805b959e8090a62c"
 Case-of-empty-alts is trivial (Trac #11155)

 As you'll see from Trac #11155, the code generator was confused
 by a binding let x = y in ....   Why did that happen? Because of
 a (case y of {}) expression on the RHS.

 The right thing is just to expand what a "trivial" expression is.

 See Note [Empty case is trivial] in CoreUtils.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11155#comment:4>
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