mac os x - How to use MacPorts' gcc with CreateLibrary?

Short version: What's the simplest way to use MacPorts' gcc with CreateLibrary?

Long version:

CreateLibrary uses /usr/bin/gcc by default on OS X. I can get it to use clang by using the option "CompilerName" -> "clang++" or "CompilerName" -> "c++" (I'm using C++).

However, I would like to use MacPorts' gcc because it boosts the performance significantly for this particular program I need to compile. It also supports OpenMP; the system compiler doesn't. "CompilerName" -> "g++-mp-5" tells me that

CreateLibrary::instl: The compiler installation directive "CompilerInstallation" -> "/usr/bin" does not indicate a usable installation of "GCC"

So I tried "CompilerInstallation" -> "/opt/local/bin", which is the location of g++-mp-5. This results in the same error:

CreateLibrary::instl: The compiler installation directive "CompilerInstallation" -> "/opt/local/bin" does not indicate a usable installation of "GCC"

Is there a simpler solution than using GenericCCompiler?

Answer

I ended up using the GenericCCompiler driver, as follows:

$CCompiler = {
 "Compiler" -> CCompilerDriver`GenericCCompiler`GenericCCompiler, 
 "CompilerInstallation" -> "/opt/local/bin", 
 "CompilerName" -> "g++-mp-5", 
 "SystemCompileOptions" -> "-O2 -m64 -fPIC -framework Foundation -framework mathlink"
};

The compiler definition should use "SystemCompileOptions" instead of "CompileOptions" so that the user can set their own custom "CompileOptions" when desired.

CreateLibrary[{"mylib.cpp"}, "mylib", 
 "IncludeDirectories" -> "/opt/local/include", 
 "ShellOutputFunction" -> Print, "ShellCommandFunction" -> Print, 
 "Language" -> "C++"]

It is good to note that the "Libraries" and "SystemLibraries" options are not usable on OS X because this driver auto-appends .lib to any library name, which is incorrect on OS X.