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

[rikki cattermole]

On 19/01/2018 8:08 AM, Jonathan M Davis wrote:
> 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.

It's in built into LLVM. No requirements on having clang (we already 
have it on offer).

> 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
>