The recently added weak attribute shows a small difference in behavior compared to c:

------------------------
#include <stdio.h>
__attribute__((weak)) int test();
int main()
{
    printf("%p %d\n", &test, (int)&test);
    return 0;
}
------------------------
(nil) 0
------------------------
import core.stdc.stdio, gcc.attribute;
@attribute("weak") void test();
int main()
{
    printf("%p %d\n", &test, cast(int)&test);
    return 0;
}
------------------------
=> unresolved symbol test

The problem is that we mark the function decl as TREE_STATIC. The C compiler marks it as DECL_EXTERNAL instead. Interestingly for variables things work as 'expected':

---------------------------------------------
__gshared @attribute("weak") extern int test; => address (nil) / 0
__gshared @attribute("weak") int test; => real address
---------------------------------------------


So:
1) Can we mark int test(); as DECL_EXTERNAL or am I missing something?
2) Is this change correct or is there a better way:

@@ -1717,7 +1717,7 @@ setup_symbol_storage (Dsymbol *dsym, tree decl,
bool public_p) }

       VarDeclaration *vd = rd ? rd->isVarDeclaration() : NULL;
-      if (!local_p || (vd && vd->storage_class & STCextern))
+      if (!local_p || (vd && vd->storage_class & STCextern) || (rd &&
rd->isFuncDeclaration() && !rd->isFuncDeclaration()->fbody)) {
 	  DECL_EXTERNAL (decl) = 1;
 	  TREE_STATIC (decl) = 0;

On Tuesday, 7 April 2015 at 19:31:25 UTC, Johannes Pfau wrote:
> The recently added weak attribute shows a small difference in behavior compared to c {snip}
>
> __attribute__((weak)) int test();
>
> (nil) 0
> ------------------------
> @attribute("weak") void test();
>
> => unresolved symbol test
>
> The problem is that we mark the function decl as TREE_STATIC. The C compiler marks it as DECL_EXTERNAL instead. Interestingly for variables things work as 'expected' {snip}

I'm still hoping for a solution to this. Should I file a bug-report ?

Am Tue, 21 Apr 2015 11:42:40 +0000
schrieb "Jens Bauer" <doctor@who.no>:

> On Tuesday, 7 April 2015 at 19:31:25 UTC, Johannes Pfau wrote:
> > The recently added weak attribute shows a small difference in behavior compared to c {snip}
> >
> > __attribute__((weak)) int test();
> >
> > (nil) 0
> > ------------------------
> > @attribute("weak") void test();
> >
> > => unresolved symbol test
> >
> > The problem is that we mark the function decl as TREE_STATIC. The C compiler marks it as DECL_EXTERNAL instead. Interestingly for variables things work as 'expected' {snip}
> 
> I'm still hoping for a solution to this. Should I file a bug-report ?

Didn't this[1] commit fix the problem?

[1] https://github.com/D-Programming-GDC/GDC/commit/85c65ea7304700c69fcffd51db9589d2cbc1fe03

On Tuesday, 21 April 2015 at 14:10:36 UTC, Johannes Pfau wrote:
> Am Tue, 21 Apr 2015 11:42:40 +0000 schrieb "Jens Bauer" <doctor@who.no>:
>> 
>> I'm still hoping for a solution to this. Should I file a bug-report ?
>
> Didn't this[1] commit fix the problem?

My mistake. I had my git repository stuck on a 2 week old version, so running my update script didn't do anything useful.
I'm building GDC now and will test tomorrow; sorry for the noise.

On Tuesday, 21 April 2015 at 14:10:36 UTC, Johannes Pfau wrote:
> Am Tue, 21 Apr 2015 11:42:40 +0000
> schrieb "Jens Bauer" <doctor@who.no>:
>
>> I'm still hoping for a solution to this. Should I file a bug-report ?
>
> Didn't this[1] commit fix the problem?

I can confirm that the problem is fixed.
-And the code generation is quite impressive.

In C I had ...

if(LowLevelInit) LowLevelInit();  /* generates a lot of redundant code: load register, compare, branch, branch+link */

In D, I only need:

LowLevelInit;

This generates a nop.w instruction if the LowLevelInit does not exist (this is definitely the desired behaviour, if the BL instruction can not be removed completely; but I believe we're speaking about code that's already generated, thus the optimizer is doing quite well).

I can now conclude my startup.d; which will be a "production ready" startup file, that can replace both startup.s and startup.c completely.
Thank you for making this possible!