#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 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler