So what is the state of cross-compilation in D?

[Jonathan M Davis]

On Friday, January 19, 2018 06:53:16 Rel via Digitalmars-d wrote:
> On Wednesday, 17 January 2018 at 12:31:35 UTC, Kagamin wrote:
> > https://wiki.dlang.org/Build_D_for_Android
> > https://wiki.dlang.org/Building_LDC_runtime_libraries
> > https://github.com/ldc-developers/ldc/pull/2142#issuecomment-304472412
>
> As far as I understand I will need a C toolchain that
> allows cross-compilation to target OS in order to build
> runtime libraries, is it correct? Why is D's runtime library
> is written in C? I thought that D is pretty much capable to
> have runtime libraries written in D, especially after the
> introduction of -betterC flag.

D's runtime is not written in C. It's written in D. However, the C linker is
used to link, and by default, it's used by calling the C/C++ compiler (at
least, that's what dmd does). ldc would be using LLVM's linker and possibly
using it through clang.

However, D's runtime does _call_ into various C functions, because they're
part of the OS' API, and that means that D is ultimately using the C runtime
in addition to its own. So, C is also used in that way even though none of
D's runtime is written in C.

- Jonathan M Davis