[GHC] #15111: GHCi leaks the first modules loaded

[GHC]

#15111: GHCi leaks the first modules loaded
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        Reporter:  simonmar          |                Owner:  simonmar
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:  ghci
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4658
       Wiki Page:                    |  Phab:D4659
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Comment (by Simon Marlow <marlowsd@…>):

 In [changeset:"5fe6aaa3756cda654374ebfd883fa8f064ff64a4/ghc" 5fe6aaa/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="5fe6aaa3756cda654374ebfd883fa8f064ff64a4"
 Add -fghci-leak-check to check for space leaks

 Summary:
 Space leaks in GHCi emerge from time to time and tend to come back again
 after they get fixed. This is an attempt to limit regressions by

 * adding a reliable detection for some classes of space leaks in GHCi
 * turning on leak checking for all GHCi tests in the test suite, so that
   we'll notice if the leak appears again.

 The idea for detecting space leaks is quite simple:

 * find some data that we expect to be GC'd later, make a weak pointer to
 it
 * when we expect the data to be dead, do a `performGC` and then check
   the status of the weak pointer.

 It would be nice to apply this trick to lots of things in GHC,
 e.g. ensuring that HsSyn is not retained after the desugarer, or
 ensuring that CoreSyn from the previous simplifier pass is not retained.

 Test Plan: validate

 Reviewers: bgamari, simonpj, erikd, niteria

 Subscribers: thomie, carter

 GHC Trac Issues: #15111

 Differential Revision: https://phabricator.haskell.org/D4658
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15111#comment:4>
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