Using templates to declare function prototypes

[Heinz]

Hello D community!!!

I'm porting the NVIDIA CUDA headers to D. The CUDA platform runs on multiple
OS, so functions prototypes (in the D way) are declared as "extern(Windows)
..." for MS Windows and "extern(C) ..." for other OS'es.

The thing is that there's no "alias extern(X) myextern;" in D to be used like
this:

version(Windows)
    alias extern(Windows) myextern;
else
    alias extern(C) myextern;

...
myextern void cudaFunct1();
myextern uint cudaFunct2(byte*);

...The C way to accomplish this is:

#ifdef _WIN32
#define CUDAAPI __stdcall
#else
#define CUDAAPI
#endif
...
CUresult CUDAAPI cuInit(unsigned int Flags);

It is a bit redundant and dirty to declare all the functions twice. So i made
a template to declare functions prototypes with the corresponding naming
convention, here's what i got:

template CUDAAPI(R, P ...)
{
	version(Windows)
		alias extern(Windows) R function(P) CUDAAPI;
	else
		alias extern(C) R function(P) CUDAAPI;
}
...
CUDAAPI!(CUresult, uint) cuInit;

This code actually compiles since its syntax is correct but when linking i
relize that the linker is still looking for the "extern(D)" symbol and by any
means, no matter where i place the extern(X), the compiler is generating the D
mangled symbol (_D5cudad4cuda6cuInitPWkZE5cudad4cuda8CUresult, at least the
template is inserted in the context).
I've tried with DMD 1.030 and the latest 1.069, both with the same result.

I also did a mixin flavored template that also compiles but is even worse
because the linker is still stuck with a templated/D mangled symbol, take a look:

template CUDAAPI(string N, R, P ...)
{
	version(Windows)
		mixin("extern(Windows) R " ~ N ~ "(P);");
}
...
mixin CUDAAPI!("cuInit", CUresult, uint);

The generated symbol for this code is:
__D5cudad4cuda55__T7CUDAAPIVG6aa6_6375496e6974TE5cud
ad4cuda8CUresultTkZ6cuInitWkZE5cudad4cuda8CUresult at 4. As you can see, the
symbol is still recognized as a template so i discard this code.

I found templates to be a very interesting case of study, templates give
languages the fun or the exciting part of programming by presenting challenges
in code complexity but still i can not get some parts of my code to work.

Any aproach or ideas on how to accomplish this template or multi extern
declaration?

Thank you so much for reading.