Ehem, ARM

[Rainer Schuetze]

On 02.12.2013 10:36, Joakim wrote:
> On Monday, 2 December 2013 at 08:25:39 UTC, Rainer Schuetze wrote:
>>
>>
>> On 01.12.2013 14:30, Joakim wrote:
>>> //test.d
>>> import core.stdc.stdio;
>>>
>>> extern (C) int main() { fputs("doing this for real?", stderr); return
>>> 0;}
>>>
>>> It doesn't link on Win32, Win64, or Android.  It works on linux and
>>> FreeBSD.  Here's the output on platforms where it doesn't work:
>>
>> The reason this does not work on Win32/Win64 comes from declaring main
>> as "extern(C)", which declares "main" for the C runtime. This prevents
>> adding an implicite include directive to add the phobos library to the
>> link. This happens only for D's main.
> I just tested this: you're right, removing the "extern (C)" linkage for
> main fixes the linking problem on Win32/Win64.  That makes sense that
> druntime/phobos wasn't added to the link, as the symbols _were_ added by
> the above stdio.d for Android.
>
> Where is this "implicit include directive?"  It's confusing because "dmd
> -v" shows the exact same linker command being run whether that "extern
> (C)" is there before main or not.

The compiler embeds it into the object file if code for "D main" is 
generated. The respective code is around line 742, glue.c.

>
>> So, you should either drop the "extern(C)" or add phobos.lib to the
>> command line.
> Yes, both do fix the problem.
>
>> If including the library is not an option, you'll have to repeat the
>> respective declarations in your source. Just adding core.stdc.stdio to
>> the command line might also work.
> I was reusing the existing Makefiles as much as possible and archiving
> the ported core.stdc druntime object files for Android into a
> libphobos2.a, as that library name is hardcoded into dmd. Perhaps that
> was a mistake, I'll look further into why it doesn't link.

IIRC it is not possible to embed a linker directive into an ELF object 
file, so it must always be specified on the command line. Maybe the 
linker is looking for libphobos2.a in the wrong directories?

You can change the name of the runtime library with -defaultlib.