Re: libtool bug

[Charles Wilson <cygwin at cwilson dot fastmail dot fm>]

Charles Wilson wrote:

> Whether to set the $PATH and produce wrapper scripts is clearly a 
> distinct issue from "should stuff be relinked on install" -- although on 
> platforms which encode -rpaths into sharedlibs and executables one issue 
> will affect the other.
>
> Not true on cygwin.
>
> These two questions (need wrappers to set PATH/LD_LIBRARY_PATH/etc, vs. 
> need to relink on install) should be disentangled.  On cygwin, we need 
> wrappers, but not relink.  On most OTHER platforms, you probably need 
> relink (but no wrappers?) IF using rpath; you need wrappers (and 
> relink?) if you are NOT using rpath.  Confusing, no?

The culprit is this little stanza in ltmain.m4sh:

***********************************
      if test "$need_relink" = no || test "$build_libtool_libs" != yes; 
then
        # Replace the output file specification.
        compile_command=`$ECHO "X$compile_command" | $Xsed -e 
's%@OUTPUT@%'"$output"'%g'`
        link_command="$compile_command$compile_rpath"

        # We have no uninstalled library dependencies, so finalize 
right now.
        $show "$link_command"
        $run eval "$link_command"
        status=$?

        # Delete the generated files.
        if test -f "$output_objdir/${outputname}S.${objext}"; then
          $show "$RM $output_objdir/${outputname}S.${objext}"
          $run $RM "$output_objdir/${outputname}S.${objext}"
        fi

        exit $status
      fi
***********************************

We finalize and bail out before creating the wrappers (and put the 
result into $output) simply because need_relink is no.  But on cygwin, 
at least, we still need the wrappers!  By manually removing this stanza 
from a prebuilt libtool (but leaving need_relink=no) the -make and -exec 
checks will pass.

e.g. something like the following will "fix it":  wrap the whole stanza 
inside a case statement:

  case $host in
  *cygwin* | *mingw* )
    ;; # don't bail out early on cygwin or mingw
  *)
    <put offending stanza here>
    ;;
  esac

but that just seems wrong somehow.  It's like we need another variable, 
whose meaning is something like "yeah, we don't need to relink, but we 
still need wrappers" -- but we may already have that variable, and just 
need to add it to the 'if' statement in the offending stanza.

Worse, the above change breaks the -inst.test, because with the change 
above we are now creating a wrapper script and wrapper executable for 
hell_static, which we certainly don't need to do.  And the wrapper 
script thus created -- for a STATIC executable -- has an empty 
$notinst_deplibs, which is as it should be, because it's static and 
doesn't care where the deplib came from; the exe "has it" built in.

But libtool checks to make sure that after sourcing the wrapper script, 
$notinst_deplib is non-empty, because the only reason to HAVE a wrapper 
script is if $notinst_deplib would have something in it.

Sheesh.

The attached patch (against libtool cvs branch 2.0) ain't pretty, but it 
works on cygwin and shouldn't break other platforms.

--
Chuck

2004-10-09  Charles Wilson  <spam.protected>

	* config/ltmain.m4sh (func_mode_link): don't relink
	on cygwin/mingw; no need.  But do ensure that wrappers
	are created unless doing a purely static build.

Index: ltmain.m4sh
===================================================================
RCS file: /cvsroot/libtool/libtool/config/ltmain.m4sh,v
retrieving revision 1.1.2.4
diff -u -r1.1.2.4 ltmain.m4sh
--- ltmain.m4sh	8 Oct 2004 16:17:40 -0000	1.1.2.4
+++ ltmain.m4sh	10 Oct 2004 02:10:40 -0000
@@ -3539,10 +3539,19 @@
 	link_static=no # Whether the deplib will be linked statically
 	if test -n "$library_names" &&
 	   { test "$prefer_static_libs" = no || test -z "$old_library"; }; then
-	  if test "$installed" = no; then
-	    notinst_deplibs="$notinst_deplibs $lib"
-	    need_relink=yes
-	  fi
+	  case $host in
+	  *cygwin* | *mingw*)
+	      # No point in relinking DLLs because paths are not encoded
+	      notinst_deplibs="$notinst_deplibs $lib"
+	      need_relink=no
+	    ;;
+	  *)
+	    if test "$installed" = no; then
+	      notinst_deplibs="$notinst_deplibs $lib"
+	      need_relink=yes
+	    fi
+	    ;;
+	  esac
 	  # This is a shared library
 
 	  # Warn about portability, can't link against -module's on some
@@ -5427,7 +5436,21 @@
 
       func_generate_dlsyms "$outputname" "@PROGRAM@" "no"
 
-      if test "$need_relink" = no || test "$build_libtool_libs" != yes; then
+
+      wrappers_required=yes
+      case $host in
+      *cygwin* | *mingw* )
+        if test "$build_libtool_libs" != yes; then
+          wrappers_required=no
+        fi
+        ;;
+      *)
+        if test "$need_relink" = no || test "$build_libtool_libs" != yes; then
+          wrappers_required=no
+        fi
+        ;;
+      esac
+      if test "$wrappers_required" = no; then
 	# Replace the output file specification.
 	compile_command=`$ECHO "X$compile_command" | $Xsed -e 's%@OUTPUT@%'"$output"'%g'`
 	link_command="$compile_command$compile_rpath"

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