[GHC] #11303: Pattern matching against sets of strings sharing a prefix blows up pattern checker

[GHC]

#11303: Pattern matching against sets of strings sharing a prefix blows up pattern
checker
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        Reporter:  bgamari           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.11
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:  T11303
      Blocked By:                    |             Blocking:
 Related Tickets:  #11302            |  Differential Rev(s):  Phab:D1716,
       Wiki Page:                    |  Phab:D1719
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Comment (by RyanGlScott):

 Another reason it's probably #11276 instead is because the same workaround
 can be applied to `text-icu`:

 {{{#!diff
 index 38765d4..c31f4b6 100644
 --- a/Data/Text/ICU/Regex/Internal.hsc
 +++ b/Data/Text/ICU/Regex/Internal.hsc
 @@ -174,6 +174,7 @@ toURegexpOpts = foldl go (0,-1,-1)
    where
      go (!flag,work,stack) opt = (flag+flag',work',stack')
       where
 +      flag' :: URegexpFlag
        flag' = case opt of
                  CaseInsensitive       -> #const UREGEX_CASE_INSENSITIVE
                  Comments              -> #const UREGEX_COMMENTS
 }}}

 Adding a type signature makes the rest of `text-icu` compile.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11303#comment:12>
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