Duplicate symbol definition linker error

[thomasjm]

I have a Windows project that's organized using the standard template generated by stack new nowadays, with

1) a library section with the majority of the dependencies and source files 2) a short executable which depends on the library, and 3) a test suite which depends on the library.

In the library section, I have a module which uses inline-c to do a simple Windows system call.

The main executable builds successfully if I run stack build. But, when I try to run stack test I get a linker error:

...
[41 of 41] Compiling AppMain          ( app\AppMain.hs, .stack-work\dist\5c8418a7\build\AppMain.o )
Preprocessing test suite 'hite-test' for hite-0.1.0.0..
Building test suite 'hite-test' for hite-0.1.0.0..
[ 1 of 45] Compiling Paths_hite       ( .stack-work\dist\5c8418a7\build\hite-test\autogen\Paths_hite.hs, .stack-work\dist\5c8418a7\build\hite-test\hite-test-tmp\Paths_hite.o )
[ 2 of 45] Compiling Test.CollaborationTests.CursoringTests ( test\Test\CollaborationTests\CursoringTests.hs, .stack-work\dist\5c8418a7\build\hite-test\hite-test-tmp\Test\CollaborationTests\CursoringTests.o )
GHC runtime linker: fatal error: I found a duplicate definition for symbol
   inline_c_OSCompat_Interrupt_0
whilst processing object file
   C:\Users\tom\hite\hite\.stack-work\dist\5c8418a7\build\HShite-0.1.0.0-IDiA7VshXkO53Edvdb5QZc.o
The symbol was previously defined in
   C:\Users\tom\hite\hite\.stack-work\install\2d3db291\lib\x86_64-windows-ghc-8.2.2\hite-0.1.0.0-HQALbSItfMOFfZeOJxQ9T2\HShite-0.1.0.0-HQALbSItfMOFfZeOJxQ9T2.o
This could be caused by:
   * Loading two different object files which export the same symbol
   * Specifying the same object file twice on the GHCi command line
   * An incorrect `package.conf' entry, causing some object to be
     loaded twice.
ghc.EXE: panic! (the 'impossible' happened)
  (GHC version 8.2.2 for x86_64-unknown-mingw32):
        loadObj "C:\\Users\\tom\\hite\\hite\\.stack-work\\dist\\5c8418a7\\build\\HShite-0.1.0.0-IDiA7VshXkO53Edvdb5QZc.o": failed

I'm guessing that somehow the C file is getting generated/linked twice, once for the main library/executable and once for the test suite. I've tried a NOINLINE pragma but it didn't help. I'm not sure if it's significant that one symbol is in .stack-work\install and one is in .stack-work\dist.

This is also slightly hard to reproduce -- for a little while it disappeared and the test suite ran fine, then it started happening again. I tried to make a minimal repro project but have so far failed to reproduce in a simpler setting. I've tried some combinations of stack clean and re-building but no luck.

Any chance you can shed any light on this? Thanks!

[tolysz]

Which lts are you using?

if impl(ghc < 8.2)
      c-sources:       src/Network/Mosquitto.c

i.e do not include c-sources for the newer c-inline and ghc-8.2+

[thomasjm]

I'm using lts-10.0, and have not specified any c-sources.