[GHC] #14675: GHC 8.4.1 regression: segfault when loading doctest on a module with ANNs on Ubuntu 16.04 or later

[GHC]

#14675: GHC 8.4.1 regression: segfault when loading doctest on a module with ANNs
on Ubuntu 16.04 or later
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.4.1
       Component:  GHC API           |              Version:  8.4.1-alpha1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Runtime crash     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #14603            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by alpmestan):

 I started taking a look at this. First, I haven't been able to reproduce
 the issue on NixOS.

 So I started toying around in an Ubuntu 16.04 virtual machine, on which I
 installed ghc 8.2.2 and 8.4.1, both from hvr's PPA. And I can indeed
 reproduce the segmentation fault, only with 8.4.1 just like you. However,
 I started thinking that it might be nice to be able to use gdb to see
 exactly what code is being executed when the segfault happens. Then I
 built both the same commit from which hvr's ghc-8.4.1 was built as well as
 the tip of the 8.4.1 alpha1 branch, both with the quick flavour, the
 --enable-dwarf-unwind configure option and -g3 for the libs and the RTS.
 Now, for the fun part: I have _not_ been able to reproduce the bug with
 those builds of GHC.

 I'll start looking into the Debian build recipes used by hvr's PPA, with
 the hope of being able to build a gdb-friendly clone of hvr's 8.4.1 build
 that does have the bug but also allows me to look around right before it
 happens.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14675#comment:4>
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