Re: Why are dwarf2 symbols getting assigned hidden visibility?

[Andrew Haley <aph at redhat dot com>]

Hi,

On 01/17/2011 07:37 PM, MFL Commissioner wrote:
> On 1/17/2011 8:29 PM, Andrew Haley wrote:
> > libgcc_s is supposed to be backwards compatible in all cases, so this
> > really shouldn't be a problem. Having said that, there may be
> > incompatibilities in your version.
> As I understand it, the problem is that the system libgcc (v4.1)
> isn't forwards compatible with the newly build compiler (v4.6). The
> addition of Unwind_GetIPInfo came about 4 years ago, I guess version
> 4.1 is older than that. As long as the object files from the new
> compiler get linked with the new libgcc_s, there's no problem, but
> if they get linked with an older libgcc_s, then some symbols might
> not be known.

Sure, so you need to put a recent libgcc at the front of your library
path.  As long as it really is backwards compatible, all your programs
will still work.

> > > /usr/lib/libgcc_s.so (NetBSD 5.1)
> > > /usr/pkg/lib/libgcc_s.so (pkgsrc version)
> > >
> > > Dealing with multiple versions of libgcc_s seems painful....
> >
> > No more so than any other shared library, I would have thought.
>
> Well, in additional to the library that comes with the operating
> system which can't be removed, there could be multiple versions of
> gcc on the same system for any number of reasons. Each may want to
> build it's own libgcc_s and perhaps place in the same directory.

So, as long as you have the most recent at the head of your path
you'll be fine.

Andrew.