don't force CXX and F77 to be configured in

[Alexandre Oliva]

Currently, at least in the 1.5 branch, a configure.ac as simple as:

configure.ac
Description: Binary data

causes libtool to be configured for CXX and F77, in addition to the
implicitly requested CC tag.

That's caused by an undesirable interaction between _LT_AC_TAGCONFIG
and the code that detects whether AC_PROG_{CXX,F77} were used:
_LT_AC_TAGCONFIG expands unconditionally macros that AC_REQUIRE
AC_PROG_CXX and AC_PROG_F77, such that the test whether they are
provided always results positive.

This patch avoids expanding the AC_REQUIREing macros if they haven't
been explicitly brought in before, using the same logic as the
existing test, thereby fixing the problem.  Ok to install?


Incidentally, I noticed that, even after the fix, adding AC_PROG_CXX
or AC_PROG_F77 after AC_PROG_LIBTOOL doesn't trigger the autoconf
AC_BEFORE error I expected; it instead now causes a configure-time
error because the CXX and F77 sections of _LT_AC_TAGCONFIG are
missing.  I wish we could do better than this, but I couldn't quite
figure out how.


(Ralf, thanks for picking up the patch I posted a couple of weeks ago,
and sorry for not completing the work before noticing you'd already
done it :-)

Index: ChangeLog
from  Alexandre Oliva  <address@hidden>

        * libtool.m4 (_LT_AC_TAGCONFIG): Don't bring in CXX and F77 unless
        the corresponding AC_PROG_ macro was provided.

Index: libtool.m4
===================================================================
RCS file: /cvsroot/libtool/libtool/Attic/libtool.m4,v
retrieving revision 1.314.2.81
diff -u -p -r1.314.2.81 libtool.m4
--- libtool.m4 15 Apr 2005 14:40:09 -0000 1.314.2.81
+++ libtool.m4 17 Apr 2005 04:49:36 -0000
@@ -1701,6 +1701,7 @@ if test -f "$ltmain" && test -n "$tagnam
       echo appending configuration tag \"$tagname\" to $ofile
 
       case $tagname in
+AC_PROVIDE_IFELSE([AC_PROG_CXX],[
       CXX)
        if test -n "$CXX" && ( test "X$CXX" != "Xno" &&
            ( (test "X$CXX" = "Xg++" && `g++ -v >/dev/null 2>&1` ) ||
@@ -1711,6 +1712,8 @@ if test -f "$ltmain" && test -n "$tagnam
        fi
        ;;
 
+])dnl
+AC_PROVIDE_IFELSE([AC_PROG_F77],[
       F77)
        if test -n "$F77" && test "X$F77" != "Xno"; then
          AC_LIBTOOL_LANG_F77_CONFIG
@@ -1719,6 +1722,7 @@ if test -f "$ltmain" && test -n "$tagnam
        fi
        ;;
 
+])dnl
       GCJ)
        if test -n "$GCJ" && test "X$GCJ" != "Xno"; then
          AC_LIBTOOL_LANG_GCJ_CONFIG

-- 
Alexandre Oliva             http://www.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer   address@hidden, gcc.gnu.org}
Free Software Evangelist  address@hidden, gnu.org}