re. [-no-undefined issues] Re: [PATCH] Fix build on PE-COFF targets and PR40125

[IainS]

On 28 Nov 2010, at 19:17, Ralf Wildenhues wrote:

> * IainS wrote on Sun, Nov 28, 2010 at 07:24:42PM CET:
>> On 28 Nov 2010, at 18:16, Ralf Wildenhues wrote:
>>>> Libtool has its undefined flag set to something like this.  Why
>>>> would it be necessary to try to override it?  Also, the libtool
>>>> script will eat those arguments not prefixed with -Wl, anyway.  To
>>>> me it seems the darwin special case is not needed at all.
> [...]
>>> If it causes problems on Darwin, then it's probably better to fix
>>> libtool.m4 to adjust.
>>
>> it seems to override libtool's normal choice  
>> (_lt_dar_allow_undefined=)
>
> Where would that setting be?

... the causality is conjecture, the flag (_lt_dar_allow_undefined) is  
present in lib*/configure.
... I'll try and track down where it comes from (that's just what came  
out of grepping configure).

>> this causes a problem for plugins that need -undefined  
>> dynamic_lookup.
>
> Ah.  But *that* is a problem for plugins only, not for libraries like
> libquadmath or libgfortran, right?

yes, that's what I think.

> It seems a bit suboptimal to not see a specific build failure,  
> including
> all details here.  Can you please open a PR with all the information  
> and
> a cut and paste of the build failure, how configure was invoked etc?

The comments here are not in lieu of a proper PR - but it might take a  
while to re-construct what happened.

The fail was of a X from i686-darwin9 to cris-elf  ...

... the lto-plugin failed to build because of an unresolved symbol  
(that needs to come from crt).

[this is not noticed on Darwin native, since we don't use the lto- 
plugin]

it was tracked down to the inclusion of '-no-unresolved' as a flag to  
libtool -- which seemed (conjecture) to override libtool's normally  
correct choice for "-undefined"

The flag does not seem to be present in current trunk - so I'll have  
to look for the patch and cook something up to replicate the issue.

cheers
Iain