passing -no-undefined to libtool with autoconf/automake

passing -no-undefined to libtool with autoconf/automake

[marco atzeri]

Hi All,

As latest gcc's are not ignoring anymore "-no-undefined"
and the configure halt with error if LDFLAGS="-no-undefined"
is defined in advance

--------------------------------------------
*** Startup tests
checking build system type... i686-pc-cygwin
checking host system type... i686-pc-cygwin
checking target system type... i686-pc-cygwin
checking for gcc... gcc
checking whether the C compiler works... no
configure: error: in `/pub/devel/openmpi/openmpi-1.7.2-1/build':
configure: error: C compiler cannot create executables
See `config.log' for more details
---------------------------------------------

I am currently building packages adding almost at the
end of configure.ac

----------------------------------------------
AC_MSG_CHECKING([if libtool needs -no-undefined flag to build shared 
libraries])
case "`uname`" in
   CYGWIN*|MINGW*|AIX*)
     ## Add in the -no-undefined flag to LDFLAGS for libtool.
     AC_MSG_RESULT([yes])
     LDFLAGS="$LDFLAGS -no-undefined"
     ;;
   *)
     ## Don't add in anything.
     AC_MSG_RESULT([no])
     ;;
esac
----------------------------------------------

just before  AC_CONFIG_FILES.

There is any better/practical way ?

Regards
Marco


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Re: passing -no-undefined to libtool with autoconf/automake

[LRN]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 21.07.2013 12:43, marco atzeri wrote:
> Hi All,
> 
> As latest gcc's are not ignoring anymore "-no-undefined"
> and the configure halt with error if LDFLAGS="-no-undefined"
> is defined in advance
I usually patch packages and add -no-undefined to
libblahblahblah_la_LDFLAGS where necessary.

That is more-or-less the same thing you do, but more precise.

The better way is to tell upstream that they need -no-undefined or a way
to put it there.
Some packages already add -no-undefined, or they add to libraries'
LDFLAGS from a variable that configure may (by its own accord or by
user's command) set to -no-undefined, if the platform requires that.


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Re: passing -no-undefined to libtool with autoconf/automake

[Yaakov (Cygwin/X)]

On 2013-07-21 03:43, marco atzeri wrote:
> As latest gcc's are not ignoring anymore "-no-undefined"
> and the configure halt with error if LDFLAGS="-no-undefined"
> is defined in advance

Right, as gcc no longer ignores arguments it doesn't accept.

> I am currently building packages adding almost at the
> end of configure.ac
[snip]
> just before  AC_CONFIG_FILES.
>
> There is any better/practical way ?

The "correct" way is to add -no-undefined to lib*_la_LDFLAGS variables 
for each library, which is portable and can be sent upstream (despite 
popular misconception, this flag is harmless on non-PE targets).  If 
that's too difficult (e.g. a package won't autoreconf cleanly), then if 
LDFLAGS is otherwise empty, then pass LDFLAGS=-no-undefined to cygmake 
(or MAKEOPTS).


Yaakov


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