[GHC] #16257: -fexternal-interpreter with external C shared library leads to undefined symbol during template haskell phase

30 Jan 2019

      #16257: -fexternal-interpreter with external C shared library leads to undefined
symbol during template haskell phase
-------------------------------------+-------------------------------------
           Reporter:  guibou         |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.6.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 I'm building the following `Foo.hs` program using the `hmatrix-gsl`
 library:

 {{{#!haskell
 {-# LANGUAGE TemplateHaskell #-}

 import Numeric.GSL.Integration

 main = do
   print $([| 10 |])
   print $ integrateQNG 1 (\x -> x) 0 1
 }}}

 I observes undefined symbols during the template haskell phase when using
 `-fexternal-interpreter`:

 Without `-fexternal-interpreter`:

 {{{
 $ ghc -package hmatrix-gsl Foo.hs
 [1 of 1] Compiling Main             ( Foo.hs, Foo.o )
 Linking Foo ...

 [nix-shell:~/bug_report_external]$ ./Foo
 10
 (0.5,5.551115123125783e-15)
 }}}

 But with `-fexternal-interpreter`:

 {{{
 $ ghc -fexternal-interpreter -package hmatrix-gsl Foo.hs
 [1 of 1] Compiling Main             ( Foo.hs, Foo.o )
 <command line>: can't load .so/.DLL for: /nix/store
 /6dhcmmfgy5fa0p3d235yaz4qfx8jhpar-gsl-2.5/lib/libgsl.so (/nix/store
 /6dhcmmfgy5fa0p3d235yaz4qfx8jhpar-gsl-2.5/lib/libgsl.so: undefined symbol:
 cblas_ctrmv)
 }}}

 I suspect that it happen during the template haskell phase because I
 cannot observe this issue without template haskell.

 I can observe this issue with a few other libraries, I used `hmatrix-gsl`
 in this example because it is on hackage. Actually, you can even reduce
 the file to:

 {{{#!haskell
 {-# LANGUAGE TemplateHaskell #-}

 main = do
   print $([| 10 |])
 }}}

 and get the same error as long as you have `-package hmatrix-gsl` in your
 command line.

 I generate the build environment with this nix file:

 {{{#!nix
 with import (fetchTarball {
    # 25/01/2019
    url = https://github.com/nixos/nixpkgs/archive/11cf7d6e1ff.tar.gz;
    sha256 = "0zcg4mgfdk3ryiqj1j5iv5bljjvsgi6q6j9z1vkq383c4g4clc72";
    }) {};
 mkShell {
   buildInputs = [(haskellPackages.ghcWithPackages(p: [p.hmatrix-gsl]))];
 }
 }}}

 It setups `ghc-8.6.3` with `hmatrix-gsl-0.19.0.1` (the latest on hackage).

 Note that `hmatrix-gsl` depends on library `gsl` which have a weird symbol
 setup. The main library file `libgsl` does not contain the `cbal_ctrmv`
 symbol which is contained in another library `libgslcbal` which is not a
 dependency of the shared object `libgsl.so`.

 library `gslcblas` is listed in `extra-libraries` of the `hmatrix-gsl`
 package:

 {{{
 ghc-pkg field hmatrix-gsl extra-libraries
 extra-libraries:
     gsl gslcblas m
 }}}

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16257
GHC http://www.haskell.org/ghc/
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