DMD as cross-compiler

[Elronnd]

On Thursday, 12 November 2020 at 06:42:00 UTC, Jacob Carlborg 
wrote:
> Unfortunately it won't be that simple for D. D took the easy 
> way out and relies both on the C standard library and other 
> platform specific libraries implemented in C. While it's easy 
> to cross-compile and object file, linking will not be as easy.

FWIW I started working on some stubs for a pure-d libc a while 
back - https://github.com/moon-chilled/dlibc/.  If it were 
completed and integrated into druntime--or, at least, if enough 
of it were completed to support druntime+phobos--then it would 
make for a much nicer cross-compiling experience.


> Also, on macOS they're cheating. Because they cannot ship the 
> SDK, they solve the linking problem by allowing undefined 
> symbols. I don't know if Go does the same.

Perhaps a better solution would be to link to a stub dylib of 
libc?  (Assuming macos libc has a stable ABI.)


> There's LLD, which works on Windows and Linux, but it doesn't 
> work for macOS.

As of about a year and a half ago, its status was

> LLD for Mach-O has bitrotted significantly and isn't really 
> functional anymore (beyond the most basic programs). I'd 
> recommend sticking with ld64 as the linker.

(From 
http://lists.llvm.org/pipermail/cfe-dev/2019-March/061666.html)

so the situation may have improved in the mean time; looking at 
the logs 
(https://github.com/llvm/llvm-project/commits/master/lld/MachO) I 
see a fair amount of activity.  (In particular, commit 2e8e1bd 
adds support for stub dylibs, relevant to my above proposal.)