[GHC] #13531: GHC fails with "Dynamic linker not initialised" when -j is on and trying to load nonexistent .so file

[GHC]

#13531: GHC fails with "Dynamic linker not initialised" when -j is on and trying to
load nonexistent .so file
-------------------------------------+-------------------------------------
           Reporter:  nh2            |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Compile-time
  Unknown/Multiple                   |  crash or panic
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:  #13137, #9868,
                                     |  #10355
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 For ghc 8.0.2 (on Linux, in nixpkgs `0c041520c3` for exact
 reproducibility), when TH is used in a `ghc --make -j1` invocation, and
 thus ghc does the whole

 {{{
 cc -fno-stack-protector -DTABLES_NEXT_TO_CODE '-std=c++14' -Wno-
 deprecated-declarations --print-file-name liblibglog.so
 Loading object (dynamic) glog ... done
 }}}

 business, and the `.so` file in question does not exist, then usually GHC
 prints

 {{{
     <command line>: user specified .o/.so/.DLL could not be loaded
 (libglog.so: cannot open shared object file: No such file or directory)
 }}}

 However, I found that when parallel compilation is enabled, (e.g. `ghc
 -j4`), I can get this instead:

 {{{
 [ 23 of 130] Compiling Mymodule  ( Mymodule.hs, dist/build/Mymodule.o )

 <no location info>: error:
     ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.2 for x86_64-unknown-linux):
   Dynamic linker not initialised

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13531>
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