[devel] Q: --no-copy-dt-needed-entries

[Alexey Tourbin]

On Mon, Mar 22, 2010 at 05:41:07PM +0200, Kirill A. Shutemov wrote:
> > Do they?  https://fedoraproject.org/wiki/GoldLinking -
> > "may make it default linker in the future", with no schedule.
> Do you think they rebuild packages with gold just for fun? ;)

This does not look solid:
https://fedoraproject.org/wiki/Features/ChangeInImplicitDSOLinking
"Dangerous default behaviour", blah-blah-blah.
I hope they have fun, though. :-)

> > By the way, I'm not sure if gold(1) can do the --as-needed thing.
> > Probably we need to implement it, too.
> 
> Yes, it can. It's default behavior. And it's not necessary to specify
> libraries you want to link with at the end of command line.

Can you please refer to a piece of source code where --as-needed logic
is implemented?  And is there an option like --no-as-needed then?

You see, generally there can be two ld modes.

1) Dumb mode: just do what you see on the command line.
You're just a special cat(1) for object files.
Resolving symbols is none of your business.

2) Smart mode: try to do the right thing.  Find implicit dependencies
and remove unused libraries, based on how symbols are resolved.

So the hallmark is whether a link editor should involve into resolving
symbols (at all).  The problem is that any implementation which supports
symbol versioning _has_ to resolve symbols (to make versioned references).
And since support for symbols is already there, it is hard to resist the
temptation to implement "smart options"...

I believe that "--as-need" + "--copy-dt-needed-entries" makes sense -
it's a smart mode, and it does the right thing, most of the time.
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