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Re: Option to use and create "unique" library names

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Craig A. Berry
November 28, 2013 17:56
Re: Option to use and create "unique" library names
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On Tue, Nov 26, 2013 at 6:20 PM, Leon Timmermans <> wrote:
> On Wed, Nov 20, 2013 at 4:04 PM, Craig A. Berry <>
> wrote:
>> We've done this since forever on VMS; the actual shareable image
>> (dynamic library) names come out as PL_HASH__UTIL.EXE and
>> PL_LIST__UTIL.EXE.  There is a function called DynaLoader::mod2fname
>> that gets called from XSLoader::load.  Here's what it does:
>> $ perl -MDynaLoader -e "@a=('Module','SubModule','SubSubModule');
>> print DynaLoader::mod2fname(\@a);"
>> PL_Module__SubModule__SubSubModule
>> So I think you can get what you want by simply implementing a
>> mod2fname function (ours is in vms/vms.c, but dl_xxx.xs might be a
>> better place for a new one).  And I think there's a good chance you
>> wouldn't need any MakeMaker modifications as mod2fname, if it exists,
>> is already called from MM_Unix::init_main().
>> Plus it seems less than optimal to introduce an entirely new mechanism
>> to do something for which there is already an existing mechanism.
> Actually, it seems ExtUtils::CBuilder is currently not doing this correctly
> (it only passes the basename to mod2fname). Module::Build contains a
> workaround that does do the right thing, which is why no one noticed this
> before.

Ouch.  You're right. ExtUtils::CBuilder::Platform::VMS::lib_file() is
definitely wrong.  I don't really see how to fix it as that interface
assumes you can create the correct loadable library name from the name
of a single object file, but you can't.

It looks like ExtUtils::CBuilder::Platform::os2::_do_link may do
things right with regard to mod2fname as it only uses the output of
lib_file() as a fallback.  But I don't think any of this should be in
platform-specific overrides.  The definedness of DynaLoader::mod2fname
is what determines whether it's used at run time, so the same thing
should determine whether it's used at build time.

> I *really* hate how just about any feature in ExtUtils::CBuilder that isn't
> used by Module::Build can be assumed to be broken or unusable on some
> non-Linux-like platform (unless someone fixed it in the past couple of
> years), if not all of them.
> Leon

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