fix (again) the handling of read errors in the debugger

Actually the read errors were doing what we wanted, but EOF was no
longer popping one debugger level.  The control transfer is a bit
gnarly, so explicitly grab the restart we might want to use and pass
it as an argument to DEBUG-READ.

diff --git a/src/code/debug.lisp b/src/code/debug.lisp
index 150e306..76a87d8 100644 (file)
--- a/src/code/debug.lisp
+++ b/src/code/debug.lisp
@@ -1063,12 +1063,12 @@ and LDB (the low-level debugger).  See also ENABLE-DEBUGGER."
   "When set, avoid calling INVOKE-DEBUGGER recursively when errors occur while
    executing in the debugger.")
 
-(defun debug-read (stream)
+(defun debug-read (stream eof-restart)
   (declare (type stream stream))
   (let* ((eof-marker (cons nil nil))
          (form (read stream nil eof-marker)))
     (if (eq form eof-marker)
-        (abort)
+        (invoke-restart eof-restart)
         form)))
 
 (defun debug-loop-fun ()
@@ -1099,17 +1099,20 @@ and LDB (the low-level debugger).  See also ENABLE-DEBUGGER."
                                            '*flush-debug-errors*)
                                    (/show0 "throwing DEBUG-LOOP-CATCHER")
                                    (throw 'debug-loop-catcher nil)))))
-           ;; We have to bind LEVEL for the restart function created by
-           ;; WITH-SIMPLE-RESTART.
+           ;; We have to bind LEVEL for the restart function created
+           ;; by WITH-SIMPLE-RESTART, and we need the explicit ABORT
+           ;; restart that exists now so that EOF from read can drop
+           ;; one debugger level.
            (let ((level *debug-command-level*)
-                 (restart-commands (make-restart-commands)))
+                 (restart-commands (make-restart-commands))
+                 (abort-restart-for-eof (find-restart 'abort)))
              (flush-standard-output-streams)
              (debug-prompt *debug-io*)
              (force-output *debug-io*)
              (with-simple-restart (abort
                                    "~@<Reduce debugger level (to debug level ~W).~@:>"
                                    level)
-               (let* ((exp (debug-read *debug-io*))
+               (let* ((exp (debug-read *debug-io* abort-restart-for-eof))
                       (cmd-fun (debug-command-p exp restart-commands)))
                  (cond ((not cmd-fun)
                         (debug-eval-print exp))