GHCI doesn't work with dtrace on OS X

On OS X, user-defined dtrace probes are implemented as special symbols of the form ___dtrace_probe$... which are magically resolved by the linker. In the attached package, we have this dtrace script:

provider haskell {
  probe demo__trace(char*);
};

and this C file:

void demo_trace( char *s )
{
  HASKELL_DEMO_TRACE(s);
}

When we compile it, we get:

newbie:dtrace-demo rl$ nm demo-trace.o
         U ___dtrace_probe$haskell$demo__trace$v1$63686172202a
         U ___dtrace_stability$haskell$v1$1_1_0_1_1_0_1_1_0_1_1_0_1_1_0
         U ___dtrace_typedefs$haskell$v1
00000000 T _demo_trace

When linked as a dynamic library, the undefined symbols disappear:

newbie:dtrace-demo rl$ ld -dylib -o demo-trace.dylib demo-trace.o 
newbie:dtrace-demo rl$ nm demo-trace.dylib 
00000000 t __mh_dylib_header
000008b0 T _demo_trace

But GHCI's linker can't resolve the symbols which means that GHCI will fail if it tries to load demo-trace.o or a package file that contains demo-trace.o. For the attached package, ghci -package dtrace-demo produces this error:

unknown symbol `___dtrace_probe$haskell$demo__trace$v1$63686172202a'
Loading package dtrace-demo-1.0 ... linking ... ghc: unable to load package `dtrace-demo-1.0'

Unless I'm mistaken, the only solution is to use dlopen instead of a hand-written linker as the dtrace symbols are actually resolved by the kernel.

The problem came up while implementing dtrace-based profiling for DPH. DPH uses Template Haskell so GHC tries to load a package which uses dtrace and dies.

Trac metadata

Trac field	Value
Version	6.10.4
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
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