[PATCH 1/2] ltmain.in: ensure old libraries are not archived

Previously, adding a static archive library, aka. old library, as a
dependency of a new libtool library compiled as a static archive (be it
a convenience library or an installed static library) resulted in the
dependency archive being added into the target archive as-is.

However, linkers are usually not able to use nested archive as-is. It
results in errors like these on Linux and Darwin at least:

    /usr/bin/ld: ./.libs/libfoo.a: member ./.libs/libfoo.a(libbar.a) in
    archive is not an object

or

    /usr/bin/nm: libbar.a: file format not recognized

With libfoo.a being the static libtool target and libbar.a being the
nested/linked static library.

Libtool has a quite close behaviour with convenience libraries, where
the content (objects) of the convenience library are extracted and added
back into the new target, but that´s mostly a libtool creation.

The static dependencies should not be "linked" into other static
libraries as there should not be linking involved, and we don´t want to
potentially duplicate symbols like done for the convenience libraries.

Instead, keep them in the dependency_libs of the new libtool archive
created and forward them until we link a shared library or an
executable.
---
 build-aux/ltmain.in | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/build-aux/ltmain.in b/build-aux/ltmain.in
index 96b37003..d172deae 100644
--- a/build-aux/ltmain.in
+++ b/build-aux/ltmain.in
@@ -5508,7 +5508,6 @@ func_mode_link ()
       *.$libext)
 	# An archive.
 	func_append deplibs " $arg"
-	func_append old_deplibs " $arg"
 	continue
 	;;
 
@@ -5867,6 +5866,8 @@ func_mode_link ()
 	  if test conv = "$pass"; then
 	    deplibs="$deplib $deplibs"
 	    continue
+	  else
+	    func_append old_deplibs " $deplib"
 	  fi
 	  case $linkmode in
 	  lib)
@@ -6817,7 +6818,6 @@ func_mode_link ()
       # Now set the variables for building old libraries.
       build_libtool_libs=no
       oldlibs=$output
-      func_append objs "$old_deplibs"
       ;;
 
     lib)
@@ -8697,7 +8697,11 @@ EOF
 	  build_libtool_libs=no
           ;;
 	*)
-	  oldobjs="$old_deplibs $non_pic_objects"
+	  oldobjs="$non_pic_objects"
+	  # This is not correct to add old_deplibs creating an archive
+	  # so append them only when creating an executable or a shared
+	  # library.
+	  test yes != "$build_old_libs" && oldobjs="$oldobjs $old_deplibs"
 	  $preload && test -f "$symfileobj" \
 	    && func_append oldobjs " $symfileobj"
 	  addlibs=$old_convenience
@@ -8958,6 +8962,7 @@ EOF
 	    done
 	    dlprefiles=$newdlprefiles
 	  fi
+	  func_append dependency_libs " $old_deplibs"
 	  $RM $output
 	  # place dlname in correct position for cygwin
 	  # In fact, it would be nice if we could use this code for all target
-- 
2.31.1