re: cairo symbol check

[matthew green <mrg%eterna.com.au@localhost>]

Thomas Klausner writes:
> On Tue, Jun 20, 2017 at 01:23:42PM +0200, Thomas Klausner wrote:
> > On Tue, Jun 20, 2017 at 01:17:00PM +0200, Martin Husemann wrote:
> > > On Tue, Jun 20, 2017 at 01:13:38PM +0200, Thomas Klausner wrote:
> > > > The symbol extraction part looks like this (from src/check-def.sh):
> > > > 
> > > > if [ "`uname -s`" = "Linux" ]; then
> > > >         get_cairo_syms='( objdump -t "$so" | grep "^[^ ]* [^l.*]*[.]"; objdump -t "$so" | grep "[.]hidden.*\\<cairo"; ) | sed "s/.* //"'
> > > 
> > > We should use that branch too, it may be better to test for ELF object
> > > format than uname -s.
> > 
> > I changed it to
> > 
> > if [ "`uname -s`" = "Linux" -o "`uname -s`" = "NetBSD" ]; then
> > 
> > and now the upper branch is executed, but it fails the same way.
> > 
> > Checking that .libs/libcairo.so has the same symbol list as cairo.def
> > 1a2,3
> > > __udivti3
> > > __umodti3
> 
> In further discussions we found out that this is caused by the NetBSD
> spec file for gcc:
> 
> # gcc -dumpspecs
> ...
> *libgcc:
> %{static|static-libgcc:-lgcc -lgcc_eh}%{!static:%{!static-libgcc:%{!shared-libgcc:-lgcc --as-needed -lgcc_s --no-as-needed}%{shared-libgcc:--as-needed -lgcc_
> s --no-as-needed -lgcc}}}
> ...
> 
> In particular, the !shared-libgcc case where -lgcc is before -lgcc_s.
> 
> On NetBSD, both are needed, but libgcc_s must be before libgcc (which
> is needed for the millicode).
> 
> Linking cairo with "gcc .. -shared-libgcc ..." reverses the order of
> gcc_s and gcc and fixes the problem.
> 
> Linux has the same spec file (in this regard, except for as-needed
> stuff) so we're not sure why the problem (probably) doesn't happen
> there.
> 
> I'm not sure how to continue here, so I posted this for more comments/action.

i don't understand what the symbol check is trying to do.  both
these symbols are in both libgcc and libgcc_s, and in one case
you'll get them linked statically into the binary and in the other
case you'll get them dynamically linked.

what is the output of the original nm case without the cut -- ie,
what's the full output of these two lines -- what sort of symbol
are they?


.mrg.