debug_check calls are the culprit triggering lookahead

in lazy lists. Changing the semantics of the data argument
so that it can just be the list.

* debug.c (debug): If data is a cons, then replace it with
the first item.

* match.c (match_files): Pass c.data to debug_check, rather
than the value of if2(consp(c.data), car(c.data)) which accesses
car(c.data) whether or not we are debugging.
(match_fun): Likewise.

3 files changed, 18 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index f3da9b17..85ffdb77 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2013-12-02  Kaz Kylheku  <kaz@kylheku.com>
+
+	debug_check calls are the culprit triggering lookahead
+	in lazy lists. Changing the semantics of the data argument
+	so that it can just be the list.
+
+	* debug.c (debug): If data is a cons, then replace it with
+	the first item.
+
+	* match.c (match_files): Pass c.data to debug_check, rather
+	than the value of if2(consp(c.data), car(c.data)) which accesses
+	car(c.data) whether or not we are debugging.
+	(match_fun): Likewise.
+
 2013-12-01  Kaz Kylheku  <kaz@kylheku.com>
 
 	Steps toward fixing an issue: lazy list readahead.
diff --git a/debug.c b/debug.c
index fa7c439e..ec754874 100644
--- a/debug.c
+++ b/debug.c
@@ -92,6 +92,8 @@ val debug(val form, val bindings, val data, val line, val pos, val base)
   val loc = source_loc(form);
   cons_bind (lineno, file, loc);
 
+  data = if2(consp(data), car(data));
+
   if (!step_mode && !memqual(loc, breakpoints) 
       && (debug_depth > next_depth))
   {
diff --git a/match.c b/match.c
index 746a622c..81107598 100644
--- a/match.c
+++ b/match.c
@@ -3700,8 +3700,7 @@ repeat_spec_same_data:
   {
     spec_bind (specline, first_spec, c.spec);
 
-    debug_check(first_spec, c.bindings, if2(consp(c.data), car(c.data)), 
-                c.data_lineno, nil, nil);
+    debug_check(first_spec, c.bindings, c.data, c.data_lineno, nil, nil);
 
     if (consp(first_spec) && !rest(specline)) {
       val sym = first(first_spec);
@@ -3809,8 +3808,7 @@ val match_fun(val name, val args, val input, val files)
 
   debug_enter;
 
-  debug_check(call, c.bindings, if2(consp(c.data), car(c.data)), 
-              c.data_lineno, nil, nil);
+  debug_check(call, c.bindings, c.data, c.data_lineno, nil, nil);
 
   ret = v_fun(&c);