[GHC] #14963: ghci -fdefer-type-errors can't run IO action from another module

[GHC]

#14963: ghci -fdefer-type-errors can't run IO action from another module
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        Reporter:  elaforge          |                Owner:  tdammers
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.4.2
       Component:  GHCi              |              Version:  8.4.1
      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 elaforge):

 Surely those people's workflows are already broken by the fact that you
 can't evaluate much of anything without causing a panic.

 If they are just loading the modules to check types and not actually
 running them, then they don't need `-fdefer-type-errors` in the first
 place.  So if someone's tool is thrown by an extra warning msg, they can
 probably just remove the flag.  I also think it's reasonable to expect
 tools to be robust against unexpected messages at startup before the
 prompt comes.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14963#comment:20>
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