http://d.puremagic.com/issues/show_bug.cgi?id=4398

           Summary: dmd always uses Windows name mangling for _d_throw
           Product: D
           Version: D1 & D2
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: johannespfau@gmail.com


--- Comment #0 from Johannes Pfau <johannespfau@gmail.com> 2010-06-27 10:41:17 PDT ---
When calling _d_throw dmd always uses the name _d_throw@4 regardless of the operating system. Dynamic ELF libraries support versioning symbols using the syntax name@version. Therefore when ld encounters _d_throw@4 it reads "symbol _d_throw, version 4" and complains that there is no version 4. As long as this isn't fixed Dynamic D libraries can't be created on operating systems using ELF executables.

See also: http://www.digitalmars.com/pnews/read.php?server=news.digitalmars.com&group=digitalmars.D&artnum=112648 and the links referred in the newspost.

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--- Comment #1 from Johannes Pfau <johannespfau@gmail.com> 2010-06-27 10:46:51 PDT ---
Created an attachment (id=678)
Patch for dmd2

Patch for dmd2.
This patch also fixes the _seh_longjmp_unwind@4 and _cpp_longjmp_unwind@4
symbols. This might not be necessary, it seems those symbols are used on
windows only.

This also requires a patch to druntime, and both must be applied or there will be link errors on linux.

BTW: If I understand windows name mangling correctly, @4 means the arguments have size 4 bytes. As the argument is a pointer hardcoding it to 4 will not work on 64bit.

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--- Comment #2 from Johannes Pfau <johannespfau@gmail.com> 2010-06-27 10:53:23 PDT ---
Created an attachment (id=679)
Patch for druntime

This is the patch required for druntime.

In /src/rt/deh2.d "void _d_throw(Object *h)" must be extern(Windows) for
windows and extern(C) for all other platforms.

In /src/rt/deh.c "void __stdcall _d_throw(Object *h)" must have __stdcall for
windows and "void _d_throw(Object *h)" for all other platforms.

The other 2 symbols modified in the dmd patch are not used in druntime.

This patch places the whole functions in version blocks. Therefore a lot of code is duplicated. I guess this could be done in a better way, but I could get it to work with e.g. alias.

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--- Comment #3 from Johannes Pfau <johannespfau@gmail.com> 2010-06-27 11:04:12 PDT ---
I wanted to say "but I could _not_ get
it to work with e.g. alias".

A different solution to this problem is to use extern(C) everywhere, even for windows. This also solves the 64bit problem. However, I'm not sure why __stdcall was used on windows, maybe it is needed (performance related?).

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--- Comment #4 from Leandro Lucarella <llucax@gmail.com> 2010-06-27 17:00:08 PDT ---
First of all, thanks for tackling this!

I wonder if there is any way to avoid code duplication in druntime, as (unless
I'm missing something) the _d_throw() body seems to be the same for Windows and
Posix, only the function signature changes.

Isn't extern (System) -which, btw, seems to be missing in the docs- exactly for
this case?

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Eldar Insafutdinov <e.insafutdinov@gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |e.insafutdinov@gmail.com


--- Comment #5 from Eldar Insafutdinov <e.insafutdinov@gmail.com> 2010-06-28 03:11:27 PDT ---
To avoid code duplication in case extern(System) won't help you here you can
use string mixins.

P.S. Is it the only issue that prevents dmd from being able to build shared libraries on linux or there are more?

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Jacob Carlborg <doob@me.com> changed:

           What    |Removed                     |Added
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                 CC|                            |doob@me.com


--- Comment #6 from Jacob Carlborg <doob@me.com> 2010-06-28 05:57:47 PDT ---
The runtime needs to be modified of course, then there is always the chance of new bugs showing up.

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--- Comment #7 from Leandro Lucarella <llucax@gmail.com> 2010-06-28 06:40:40 PDT ---
(In reply to comment #5)
> To avoid code duplication in case extern(System) won't help you here

Why? Doesn't extern(System) means extern(Windows) if version is Windows and
extern (C) if version is Posix?

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--- Comment #8 from Eldar Insafutdinov <e.insafutdinov@gmail.com> 2010-06-28 06:46:39 PDT ---
(In reply to comment #7)
> (In reply to comment #5)
> > To avoid code duplication in case extern(System) won't help you here
> 
> Why? Doesn't extern(System) means extern(Windows) if version is Windows and
> extern (C) if version is Posix?

Yes that's entirely correct. I meant that in case you have some other types of linkage or other variations in function signature you can use string mixins. Sorry for confusion.

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--- Comment #9 from Leandro Lucarella <llucax@gmail.com> 2010-06-28 06:50:36 PDT ---
(In reply to comment #8)
> (In reply to comment #7)
> > (In reply to comment #5)
> > > To avoid code duplication in case extern(System) won't help you here
> > 
> > Why? Doesn't extern(System) means extern(Windows) if version is Windows and
> > extern (C) if version is Posix?
> 
> Yes that's entirely correct. I meant that in case you have some other types of linkage or other variations in function signature you can use string mixins. Sorry for confusion.

Woops, my eyes completely ignored the "in case". My mistake =)

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