Re: -no-undefined vs gcc 4.6.0

[Vincent Torri]

On Sat, 19 Mar 2011, LRN wrote:

> On 19.03.2011 0:17, Vincent Torri wrote:
> > On Sat, 19 Mar 2011, LRN wrote:
> >
> > > On 18.03.2011 23:51, Vincent Torri wrote:
> > > > On Fri, 18 Mar 2011, LRN wrote:
> > > >
> > > > > Since gcc 4.6.0 it is no longer possible to use LDFLAGS=-no-undefined
> > > > > gcc now says something like this:
> > > > > gcc.exe: error: unrecognized option '-no-undefined'
> > > > > Before 4.6.0 it was possible to do that, and gcc said only this:
> > > > > gcc.exe: unrecognized option '-no-undefined'
> > > > > That is, unrecognized option was not considered a show-stopper, and 
> > > > > everything worked just fine - the option, being part of LDFLAGS, 
> > > > > eventually reached libtool, and libtool were taking the clue to disallow 
> > > > > undefined symbols. Not anymore. Now i have to pass 
> > > > > LDFLAGS=-Wl,-no-undefined. Which is ok from gcc' point of view, but 
> > > > > libtool is unable to recognize this argument in such form and simply 
> > > > > refuses to build shared libraries outright.
> > > > > Not sure if it's a bug or a feature, and how to work through that 
> > > > > without making groundbreaking changes in software packages that use 
> > > > > libtool.
> > > >
> > > > I think that you have to pass -no-undefined to the ***_LDFLAGS variable 
> > > > of your library:
> > > >
> > > > lib_LTLIBRARIES = libproject.la
> > > > libproject_la_LDFLAGS = -no-undefined
> > > >
> > > > or, globally:
> > > >
> > > > AM_LDFLAGS = -no-undefined
> > > >
> > > > it has always worked for me, without gcc warning.
> > > It's not my library. I'm compiling mpc-0.8.2
> >
> > ok. Anyway you have to pass -Wl,-no-undefined. It's an option for the 
> > linker [1], not for gcc [2]
> >
> > Vincent Torri
> >
> > [1] http://unixhelp.ed.ac.uk/CGI/man-cgi?ld
> > [2] http://gcc.gnu.org/onlinedocs/gcc/Link-Options.html#Link-Options
> I *know* that it's a linker option. And i know that i have to pass it with 
> -Wl because of that. What i do not know is how to make libtool see it when it 
> is passed like that.
>
> Finally got it to work with `make libmpc_la_LDFLAGS="-version-info 2:0:0 
> -no-undefined"', because mpc does not use AM_LDFLAGS in the link command that

i'm wondering if you ever read my first answer...

Vincent


> is used to build libmpc (mpc devs are probably the ones to blame, but right 
> now i just want to make it work). Although i've found no way to pass such an 
> option with spaces to `make' from a variable expansion (i.e. `make $opts'), 
> so i've had to hard-code it into make invocation instead.
>
> I expect to find a lot of libtool-using projects that will require such hacks 
> or workarounds, because `unrecognized option  '-no-undefined'' is very 
> common.
>
> _______________________________________________
> http://lists.gnu.org/mailman/listinfo/libtool