proposal: heredoc comments to allow `+/` in comments, eg from urls or documented unittests

[timotheecour]

On Monday, 12 February 2018 at 01:27:19 UTC, Walter Bright wrote:
> Know what is a heavyweight problem worth our while? Having dmd 
> be able to directly read C .h files, so the poor user does not 
> have to manually translate them.

read directly C++ header files instead of C .h files is what we 
should aim for. https://github.com/Syniurge/Calypso/ is actually 
already doing just that and already works in many situations (eg 
opencv).

> Replace the preprocessor in dmc++ with Warp, slice off the back 
> end, and make it a module that dmd can import.
>
> Wouldn't it be nice to support:
>
>     import stdio.h;    // Look, Ma! C headers!
>
> There are some intractable issues, and it may be impossible to 
> get 100% to "it just works", but looking past that it might be 
> a huge win for us.

llvm+clang is a much better approach, guaranteeing compatibility 
with not just C but also and especially C++ (including current 
and future C++ standards). Calypso already understands C++ 
templates, C++ exceptions, can return C++ classes by value (not 
just by reference), without the restrictions imposed on 
extern(C++) classes/structs.

```
modmap (C++) "opencv2.hpp";
import (C++) cv.Mat;
// can now use C++ templates, functions, macros etc in D code.
```

There are of course a number of issues left to be ironed out, but 
it's a much more promising direction than restricting ourselves 
to C (as done with `cgo` for go). That's where we should focus 
our efforts as far as interop is concerned.