Re: AC_CHECK_LIB(m, main, LIBM="-lm") broken with C++ [PATCH]

How about this patch?
The math library is not actually used by anything but the
test suite in Libtool, so as long as the C standard and
common practice put "cos" in -lm it's all good.

ChangeLog entry:

2003-02-05  Robert Boehne  <rboehne@xxxxxxx>

        * libtool.m4 (AC_CHECK_LIBM): Search for a real symbol in
        the math library rather than 'main', it causes problems for
        C++ compilers with certain Auto* tools.
        (AC_LIBLTDL_INSTALLABLE): ditto.

Index: libtool.m4
===================================================================
RCS file: /cvsroot/libtool/libtool/libtool.m4,v
retrieving revision 1.297
diff -u -r1.297 libtool.m4
--- libtool.m4  5 Feb 2003 07:03:55 -0000       1.297
+++ libtool.m4  6 Feb 2003 02:50:39 -0000
@@ -2246,10 +2246,10 @@
   ;;
 *-ncr-sysv4.3*)
   AC_CHECK_LIB(mw, _mwvalidcheckl, LIBM="-lmw")
-  AC_CHECK_LIB(m, main, LIBM="$LIBM -lm")
+  AC_CHECK_LIB(m, cos, LIBM="$LIBM -lm")
   ;;
 *)
-  AC_CHECK_LIB(m, main, LIBM="-lm")
+  AC_CHECK_LIB(m, cos, LIBM="-lm")
   ;;
 esac
 ])# AC_CHECK_LIBM
@@ -2294,7 +2294,7 @@
 # In the future, this macro may have to be called after
AC_PROG_LIBTOOL.
 AC_DEFUN([AC_LIBLTDL_INSTALLABLE],
 [AC_BEFORE([$0],[AC_LIBTOOL_SETUP])dnl
-  AC_CHECK_LIB(ltdl, main,
+  AC_CHECK_LIB(ltdl, lt_dlinit,
   [test x"$enable_ltdl_install" != xyes && enable_ltdl_install=no],
   [if test x"$enable_ltdl_install" = xno; then
      AC_MSG_WARN([libltdl not installed, but installation disabled])


Albert Chin wrote:
> 
> On Wed, Feb 05, 2003 at 03:00:39PM -0600, Bob Friesenhahn wrote:
> > I posted a detailed message to bugs-libtool@xxxxxxx and
> > bugs-autoconf@xxxxxxx but there has been no response at all so I will
> > post again.
> >
> > CVS libtool.m4 contains lines like
> >
> >   AC_CHECK_LIB(m, main, LIBM="-lm")
> >
> >     and
> >
> >   AC_CHECK_LIB(ltdl, main, ... blah
> 
> Gross!
> 
> > What is the best path forward?
> 
> Replace main with a *real* function in one of the libraries.
> 
> --
> albert chin (china@xxxxxxxxxxxxxxxxxx)
> 
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