diff --git a/ChangeLog b/ChangeLog
index 0c3ff01c..68ac27ff 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2000-11-02  Akim Demaille  <akim@epita.fr>
+
+	* autoconf.sh (task trace) [debug]: Instead of a long pipe, extend
+	trace.m4.
+
+	
 2000-11-02  Akim Demaille  <akim@epita.fr>
 
 	* autoupdate.sh (m4.txt): Use `dumpdef' and m4 to build it.
diff --git a/autoconf.in b/autoconf.in
index 39334577..7017bd7c 100644
--- a/autoconf.in
+++ b/autoconf.in
@@ -635,14 +635,19 @@ EOF
   $run_m4_trace $infile 2>&1 >/dev/null |
     sed -f $tmp/trace2m4.sed |
     # Now we are ready to run m4 to process the trace file.
-    $M4 $tmp/trace.m4 - |
-    # It makes no sense to try to transform __oline__.
-    sed '
-      s/@<:@/[/g
-      s/@:>@/]/g
-      s/@S|@/$/g
-      s/@%:@/#/g
-      ' >&4
+    if $debug; then
+      cat >>$tmp/trace.m4
+      $M4 $tmp/trace.m4
+    else
+      $M4 $tmp/trace.m4 -
+    fi |
+      # It makes no sense to try to transform __oline__.
+      sed '
+	s/@<:@/[/g
+	s/@:>@/]/g
+	s/@S|@/$/g
+	s/@%:@/#/g
+	' >&4
   ;;
 
 
diff --git a/autoconf.sh b/autoconf.sh
index 39334577..7017bd7c 100644
--- a/autoconf.sh
+++ b/autoconf.sh
@@ -635,14 +635,19 @@ EOF
   $run_m4_trace $infile 2>&1 >/dev/null |
     sed -f $tmp/trace2m4.sed |
     # Now we are ready to run m4 to process the trace file.
-    $M4 $tmp/trace.m4 - |
-    # It makes no sense to try to transform __oline__.
-    sed '
-      s/@<:@/[/g
-      s/@:>@/]/g
-      s/@S|@/$/g
-      s/@%:@/#/g
-      ' >&4
+    if $debug; then
+      cat >>$tmp/trace.m4
+      $M4 $tmp/trace.m4
+    else
+      $M4 $tmp/trace.m4 -
+    fi |
+      # It makes no sense to try to transform __oline__.
+      sed '
+	s/@<:@/[/g
+	s/@:>@/]/g
+	s/@S|@/$/g
+	s/@%:@/#/g
+	' >&4
   ;;
 
 
diff --git a/bin/autoconf.in b/bin/autoconf.in
index 39334577..7017bd7c 100644
--- a/bin/autoconf.in
+++ b/bin/autoconf.in
@@ -635,14 +635,19 @@ EOF
   $run_m4_trace $infile 2>&1 >/dev/null |
     sed -f $tmp/trace2m4.sed |
     # Now we are ready to run m4 to process the trace file.
-    $M4 $tmp/trace.m4 - |
-    # It makes no sense to try to transform __oline__.
-    sed '
-      s/@<:@/[/g
-      s/@:>@/]/g
-      s/@S|@/$/g
-      s/@%:@/#/g
-      ' >&4
+    if $debug; then
+      cat >>$tmp/trace.m4
+      $M4 $tmp/trace.m4
+    else
+      $M4 $tmp/trace.m4 -
+    fi |
+      # It makes no sense to try to transform __oline__.
+      sed '
+	s/@<:@/[/g
+	s/@:>@/]/g
+	s/@S|@/$/g
+	s/@%:@/#/g
+	' >&4
   ;;