Can weak references refer to a variable (instead of a function)?

[Erik Leunissen]

On 27/06/12 07:35, Ian Lance Taylor wrote:
>
> There are a few different versions of weak symbols, and I'm not sure
> which one you mean.  Are you talking about __attribute__ ((weak,
> alias("name"))), or just __attribute__ ((weak)), or __attribute__
> ((weakref("name")))?
>

I meant __attribute__ ((weakref("name"))) indeed. So all your answers
are very to-the point. Thanks very much.

There's one thing though that I do not yet understand, probably due to
me underspecifying the case (I'll retry below):

> ...
>>  c. does it matter whether the link is resolved by the link editor or
>>  dynamically, at runtime, by the loader?
>
> No.  __attribute__ ((weakref("name"))) only works with static symbols,
> so it is basicall just renaming the symbol in the compiler.  No
> significant linker action is involved.

What I meant is the following:

When specifying a weak reference using __attribute__
((weakref("name"))), an attempt to resolve the symbol "name" will be
done at some time, possibly when linking together program files before
the code is run, possibly at run-time using the loader.

OK?

So, all other things being equal, does it matter for the success of
symbol resolution whether it is performed by the link-editor (ld), or by
the loader (ld.so)? In other words: is __attribute__ ((weakref("name")))
a useful construct for both linking scenario's?

Erik.


>
> Ian
>