[GHC] #10058: Panic: Loading temp shared object failed

[GHC]

#10058: Panic: Loading temp shared object failed
-----------------------------------------+---------------------------------
              Reporter:  goldfire        |             Owner:
                  Type:  bug             |            Status:  new
              Priority:  normal          |         Milestone:  7.10.1
             Component:  Compiler        |           Version:  7.10.1-rc2
              Keywords:                  |  Operating System:  MacOS X
          Architecture:  x86_64 (amd64)  |   Type of failure:  None/Unknown
             Test Case:                  |        Blocked By:
              Blocking:                  |   Related Tickets:
Differential Revisions:                  |
-----------------------------------------+---------------------------------
 I ran into a panic when updating `singletons` for 7.10. I'm clueless as to
 what's going on here, so sorry for not minimizing the test case. A little
 testing has me convinced it's Template Haskell in some way.

 To reproduce:

 {{{
 > git clone http://github.com/goldfirere/singletons.git
 > cd singletons
 > git checkout ghc-loading-panic-test-case
 > cabal update
 > cabal install --only-dependencies
 > cabal configure
 > cabal build
 > cat dist/build/autogen/cabal_macros.h
 # copy the value for CURRENT_PACKAGE_KEY from the end of cabal_macros.h
 > cd tests/compile-and-dump
 > ghc -c -this-package-key <package key from cabal_macros.h>
 -i../../dist/build -XTemplateHaskell Singletons/Maybe.hs
 }}}

 You will see something like

 {{{
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.10.0.20150123 for x86_64-apple-darwin):
         Loading temp shared object failed:
 dlopen(/var/folders/ps/s45r2x1s6r15ws78py_zypl00000gn/T/ghc45837_0/libghc45837_1.dylib,
 5): Symbol not found:
 _mtlzuJNaGzzEkFfL43R3LZZNRlPRm_ControlziMonadziReaderziClass_DZCMonadReader_con_info
   Referenced from:
 /var/folders/ps/s45r2x1s6r15ws78py_zypl00000gn/T/ghc45837_0/libghc45837_1.dylib
   Expected in: flat namespace
  in
 /var/folders/ps/s45r2x1s6r15ws78py_zypl00000gn/T/ghc45837_0/libghc45837_1.dylib

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

 I've observed this on a Mac, but Travis has the same problem, so it's not
 strictly Mac-specific. You can see representative Travis output [https
 ://travis-ci.org/goldfirere/singletons/jobs/49103793 here].

 Why am I doing such a crazy thing? It's part of the `singletons` test
 suite, where it's important to test the output of a run of ghc with
 `-ddump-splices`. Getting the test cases to compile against the built-but-
 not-yet-installed `singletons` object files should work with `-this-
 package-key`. I'm sure there's a better way to structure a testsuite, but
 this general technique works (with `-package-name` instead of `-this-
 package-key`) with 7.8.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10058>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler