ghc7, -rtsopts, and g++

Simon Marlow marlowsd at
Fri May 6 12:38:44 CEST 2011

On 05/05/2011 17:24, Evan Laforge wrote:
> So as everyone probably knows, ghc7 requires -rtsopts to enable +RTS
> parsing.  Apparently this makes it include various header files in
> rts/ when linking, because after upgrading to ghc7 I suddenly got
> syntax errors from headers there.  Some investigation revealed that
> the problems were use of 'new' as a variable name in
> rts/storage/Block.h, and implicit conversion from a bool to an enum
> rtsBool in rts/ClosureMacros.h.  These things are fine in C, but not
> in C++, and I'm linking with -pgmc g++ -pgml g++ so they were a
> problem.  I was able to fix them by simply renaming 'new' and
> replacing the implicit conversion with explicit.
> But it makes me think setting g++ for the "C" compiler was incorrect.
> I'm linking with c++ code via a wrapper that uses 'extern "C" { ... }'
> to ensure the haskell FFI knows how to call it, and if I don't set
> pgmc then the link dies horribly and very verbosely when none of the
> c++ symbols are visible.  So I arrived at that flag by guessing after
> my program wouldn't link without it, not because I saw documentation
> saying this is how to do it.
> Is there a better way to link to c++?

Does it work with just -pgml, or do you need -pgmc too?


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