Suppress debug stepping into auto-loaded library code.

* debug.c (debug_set_state, debug_restore_state): New functions.

* debug.h (debug_state_t): New type.
(debug_set_state, debug_restore_state): Declared, and defined
as dummy macros in non-debug-support build.

* lisplib.c (opt_dbg_autoload): New global variable.
(lisplib_try_load): Disable or enable debugging around
library loading based on opt_dbg_autoload option.

* lisplib.h (opt_dbg_autoload): Declared.

* txr.c (help): List --debug-autoload option.
(no_dbg_support): New static function to avoid repeated code.
(txr_main): Add debugger option. Change duplicate no debug support
error messages into calls to no_dbg_support.

* txr.1: Document --debug-autoload

7 files changed, 86 insertions, 8 deletions

diff --git a/ChangeLog b/ChangeLog
index 8caefa5b..6c2d36f6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,28 @@
 2015-08-06  Kaz Kylheku  <kaz@kylheku.com>
 
+	Suppress debug stepping into auto-loaded library code.
+
+	* debug.c (debug_set_state, debug_restore_state): New functions.
+
+	* debug.h (debug_state_t): New type.
+	(debug_set_state, debug_restore_state): Declared, and defined
+	as dummy macros in non-debug-support build.
+
+	* lisplib.c (opt_dbg_autoload): New global variable.
+	(lisplib_try_load): Disable or enable debugging around
+	library loading based on opt_dbg_autoload option.
+
+	* lisplib.h (opt_dbg_autoload): Declared.
+
+	* txr.c (help): List --debug-autoload option.
+	(no_dbg_support): New static function to avoid repeated code.
+	(txr_main): Add debugger-autoload option. Change duplicate no debug
+	support error messages into calls to no_dbg_support.
+
+	* txr.1: Document --debug-autoload
+
+2015-08-06  Kaz Kylheku  <kaz@kylheku.com>
+
 	* txr.c (txr_main): Bugfix: debugger long option nonfunctional.
 
 2015-08-06  Kaz Kylheku  <kaz@kylheku.com>
diff --git a/debug.c b/debug.c
index 00117558..0fb426b2 100644
--- a/debug.c
+++ b/debug.c
@@ -241,6 +241,20 @@ val debug(val form, val bindings, val data, val line, val pos, val base)
   }
 }
 
+debug_state_t debug_set_state(int depth, int step)
+{
+  debug_state_t old = { next_depth, step_mode };
+  next_depth = depth;
+  step_mode = step;
+  return old;
+}
+
+void debug_restore_state(debug_state_t state)
+{
+  next_depth = state.next_depth;
+  step_mode = state.step_mode;
+}
+
 void debug_init(void)
 {
   step_mode = 1;
diff --git a/debug.h b/debug.h
index c14a304c..3ae18cab 100644
--- a/debug.h
+++ b/debug.h
@@ -31,6 +31,11 @@ val debug(val form, val bindings, val data, val line, val pos, val base);
 
 #if CONFIG_DEBUG_SUPPORT
 
+typedef struct {
+  int next_depth;
+  int step_mode;
+} debug_state_t;
+
 #define debug_enter                             \
   {                                             \
     int debug_depth_save = debug_depth++;       \
@@ -55,6 +60,8 @@ INLINE val debug_check(val form, val bindings, val data, val line,
   return (opt_debugger) ? debug(form, bindings, data, line, pos, base) : nil;
 }
 
+debug_state_t debug_set_state(int depth, int step);
+void debug_restore_state(debug_state_t);
 void debug_init(void);
 
 #define debug_frame(FUNC, ARGS, UBP,    \
@@ -77,6 +84,8 @@ void debug_init(void);
 
 #else
 
+typedef int debug_state_t;
+
 #define debug_enter {
 
 #define debug_leave }
@@ -98,6 +107,9 @@ INLINE val debug_check(val form, val bindings, val data, val line,
 #define debug_end                       \
   } while (0)
 
+#define debug_set_state(D, S) (0)
+#define debug_restore_state(S) ((void) 0)
+
 INLINE void debug_init(void)
 {
 }
diff --git a/lisplib.c b/lisplib.c
index 699d076e..8a98a23e 100644
--- a/lisplib.c
+++ b/lisplib.c
@@ -35,10 +35,12 @@
 #include "stream.h"
 #include "hash.h"
 #include "gc.h"
+#include "debug.h"
 #include "txr.h"
 #include "lisplib.h"
 
 val dl_table;
+int opt_dbg_autoload;
 
 void set_dlt_entries(val dlt, val *name, val fun)
 {
@@ -186,5 +188,9 @@ void lisplib_init(void)
 val lisplib_try_load(val sym)
 {
   val fun = gethash(dl_table, sym);
-  return if3(fun, (funcall(fun), t), nil);
+  debug_state_t ds;
+  return if3(fun, (ds = debug_set_state(opt_dbg_autoload ? 0 : -1,
+                                        opt_dbg_autoload),
+                   funcall(fun),
+                   debug_restore_state(ds), t), nil);
 }
diff --git a/lisplib.h b/lisplib.h
index 1e5ce485..e12d4641 100644
--- a/lisplib.h
+++ b/lisplib.h
@@ -25,7 +25,7 @@
  */
 
 extern val dl_table;
-
+extern int opt_dbg_autoload;
 void lisplib_init(void);
 val lisplib_try_load(val sym);
 void set_dlt_entries(val dlt, val *name, val fun);
diff --git a/txr.1 b/txr.1
index e30f47a7..bf5a553f 100644
--- a/txr.1
+++ b/txr.1
@@ -671,6 +671,13 @@ See the
 .code gc-set-delta
 function for a description.
 
+.meIP --debug-autoload
+This option turns on debugging, like
+.code --debugger
+but also arranges for stepping into the auto-load processing of
+\*(TL library code.  Normally, debugging through the evaluations
+triggered by auto-loading is suppressed.
+
 .coIP --help
 Prints usage summary on standard output, and terminates successfully.
 
diff --git a/txr.c b/txr.c
index e784c224..b9a65f80 100644
--- a/txr.c
+++ b/txr.c
@@ -52,6 +52,7 @@
 #include "eval.h"
 #include "regex.h"
 #include "arith.h"
+#include "lisplib.h"
 #include "txr.h"
 
 const wchli_t *version = wli(TXR_VER);
@@ -144,6 +145,7 @@ static void help(void)
 "--compat=N             Synonym for -C N\n"
 "--gc-delta=N           Invoke garbage collection when malloc activity\n"
 "                       increments by N megabytes since last collection.\n"
+"--debug-autoload       Allow debugger to step through library auto-loading.\n"
 "\n"
 "Options that take no argument can be combined. The -q and -v options\n"
 "are mutually exclusive; the right-most one dominates.\n"
@@ -366,6 +368,15 @@ static int gc_delta(val optval)
   return 1;
 }
 
+#ifndef CONFIG_DEBUG_SUPPORT
+static void no_dbg_support(val arg)
+{
+  format(std_error,
+         lit("~a: option ~a requires debug support compiled in\n"),
+         prog_string, arg, nao);
+}
+#endif
+
 int txr_main(int argc, char **argv)
 {
   val specstring = nil;
@@ -500,9 +511,16 @@ int txr_main(int argc, char **argv)
         opt_debugger = 1;
         continue;
 #else
-        format(std_error,
-               lit("~a: option ~a requires debug support compiled in\n"),
-               prog_string, arg, nao);
+        no_dbg_support(arg);
+        return EXIT_FAILURE;
+#endif
+      } else if (equal(opt, lit("debug-autoload"))) {
+#if CONFIG_DEBUG_SUPPORT
+        opt_debugger = 1;
+        opt_dbg_autoload = 1;
+        continue;
+#else
+        no_dbg_support(opt);
         return EXIT_FAILURE;
 #endif
       } else if (equal(opt, lit("noninteractive"))) {
@@ -591,9 +609,7 @@ int txr_main(int argc, char **argv)
 #if CONFIG_DEBUG_SUPPORT
           opt_debugger = 1;
 #else
-          format(std_error,
-                 lit("~a: option ~a requires debug support compiled in\n"),
-                 prog_string, opch, nao);
+          no_dbg_support(opch);
           return EXIT_FAILURE;
 #endif
           break;