[GHC] #9010: TemplateHaskell leads to an "unknown symbol" error

[GHC]

#9010: TemplateHaskell leads to an "unknown symbol" error
-------------------------------------+-------------------------------------
        Reporter:  Feuerbach         |                Owner:
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by basvandijk):

 * status:  closed => new
 * cc: vandijk.roel@… (added)
 * version:  7.6.3 => 7.10.2
 * resolution:  fixed =>
 * priority:  normal => high


Comment:

 At LumiGuide we're hitting this issue on GHC-7.10.2.

 We're developing a binding to `opencv-3.0.0` which is a C++ library. The
 Haskell package is called `thea` and `thea.cabal` specifies the following
 `cc-options: -O2 -std=c++11`. We also need to build the package using the
 following cabal flags:
 `--with-gcc=g++ --with-ld=g++`. Maybe irrelevant but `thea` uses
 [http://hackage.haskell.org/package/inline-c inline-c] for the FFI.

 We have another Haskell package called `vision-playground` that depends on
 `thea`. This all works great. However I need to use some !TemplateHaskell
 in `TM.Types` (one of the modules of `vision-playground`) and get the
 following error when doing a `cabal build`:


 {{{
 [1 of 3] Compiling TM.Types         ( src/TM/Types.hs, dist/build/vision-
 playground/vision-playground-tmp/TM/Types.o )
 ghc: /nix/store/1wyif1adq0pb9h08jqr0v5lrykfhdhah-
 opencv-3.0.0/lib/libopencv_hal.a: unknown symbol
 `_ZGVZN2cv9v_invsqrtERKNS_11v_float32x4EE4_0_5'
 ghc: unable to load package `thea-0.0.0'
 }}}

 I tried the hacks suggested by @rwbarton but they did not work for me.

 I hope there's a work-around since this is a high priority issue for us at
 LumiGuide.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9010#comment:4>
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