libtool: mitigate the $sed_quote_subst slowdown

When it is reasonably possible, use shell implementation for
quoting.

References:
http://lists.gnu.org/archive/html/libtool/2015-03/msg00005.html
http://lists.gnu.org/archive/html/libtool/2015-02/msg00000.html
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=20006

* gl/build-aux/funclib.sh (func_quote): New function that can be
used as substitution for '$SED $sed_quote_subst' call.
* build-aux/ltmain.in (func_emit_wrapper): Use func_quote instead
of '$SED $sed_quote_subst'.
(func_mode_link): Likewise.
* NEWS: Document.
* bootstrap: Sync with funclib.sh.

1 files changed, 54 insertions, 7 deletions

diff --git a/bootstrap b/bootstrap
index c179f51d..fe9e9cac 100755
--- a/bootstrap
+++ b/bootstrap
@@ -230,7 +230,7 @@ vc_ignore=
 
 # Source required external libraries:
 # Set a version string for this script.
-scriptversion=2015-01-20.17; # UTC
+scriptversion=2015-10-04.22; # UTC
 
 # General shell script boiler plate, and helper functions.
 # Written by Gary V. Vaughan, 2004
@@ -1257,6 +1257,57 @@ func_relative_path ()
 }
 
 
+# func_quote ARG
+# --------------
+# Aesthetically quote one ARG, store the result into $func_quote_result.  Note
+# that we keep attention to performance here (so far O(N) complexity as long as
+# func_append is O(1)).
+func_quote ()
+{
+    $debug_cmd
+
+    func_quote_result=$1
+
+    case $func_quote_result in
+      *[\\\`\"\$]*)
+        case $func_quote_result in
+          *'*'*|*'['*)
+            func_quote_result=`$ECHO "$func_quote_result" | $SED "$sed_quote_subst"`
+            return 0
+            ;;
+        esac
+
+        func_quote_old_IFS=$IFS
+        for _G_char in '\' '`' '"' '$'
+        do
+          # STATE($1) PREV($2) SEPARATOR($3)
+          set start "" ""
+          func_quote_result=dummy"$_G_char$func_quote_result$_G_char"dummy
+          IFS=$_G_char
+          for _G_part in $func_quote_result
+          do
+            case $1 in
+            quote)
+              func_append func_quote_result "$3$2"
+              set quote "$_G_part" "\\$_G_char"
+              ;;
+            start)
+              set first "" ""
+              func_quote_result=
+              ;;
+            first)
+              set quote "$_G_part" ""
+              ;;
+            esac
+          done
+          IFS=$func_quote_old_IFS
+        done
+        ;;
+      *) ;;
+    esac
+}
+
+
 # func_quote_for_eval ARG...
 # --------------------------
 # Aesthetically quote ARGs to be evaled later.
@@ -1273,12 +1324,8 @@ func_quote_for_eval ()
     func_quote_for_eval_unquoted_result=
     func_quote_for_eval_result=
     while test 0 -lt $#; do
-      case $1 in
-        *[\\\`\"\$]*)
-	  _G_unquoted_arg=`printf '%s\n' "$1" |$SED "$sed_quote_subst"` ;;
-        *)
-          _G_unquoted_arg=$1 ;;
-      esac
+      func_quote "$1"
+      _G_unquoted_arg=$func_quote_result
       if test -n "$func_quote_for_eval_unquoted_result"; then
 	func_append func_quote_for_eval_unquoted_result " $_G_unquoted_arg"
       else