0.8.13.31:

[sbcl.git] / src / code / debug.lisp

diff --git a/src/code/debug.lisp b/src/code/debug.lisp
index 632ddc4..b7c1306 100644 (file)
--- a/src/code/debug.lisp
+++ b/src/code/debug.lisp
@@ -703,6 +703,25 @@ Other commands:
           (*package* original-package)
           (*print-pretty* original-print-pretty)
           (*print-readably* nil)
+          ;; Clear the circularity machinery to try to to reduce the
+          ;; pain from sharing the circularity table across all
+          ;; streams; if these are not rebound here, then setting
+          ;; *PRINT-CIRCLE* within the debugger when debugging in a
+          ;; state where something circular was being printed (e.g.,
+          ;; because the debugger was entered on an error in a
+          ;; PRINT-OBJECT method) makes a hopeless mess. Binding them
+          ;; here does seem somewhat ugly because it makes it more
+          ;; difficult to debug the printing-of-circularities code
+          ;; itself; however, as far as I (WHN, 2004-05-29) can see,
+          ;; that's almost entirely academic as long as there's one
+          ;; shared *C-H-T* for all streams (i.e., it's already
+          ;; unreasonably difficult to debug print-circle machinery
+          ;; given the buggy crosstalk between the debugger streams
+          ;; and the stream you're trying to watch), and any fix for
+          ;; that buggy arrangement will likely let this hack go away
+          ;; naturally.
+          (sb!impl::*circularity-hash-table* . nil)
+          (sb!impl::*circularity-counter* . nil)
           ;; These rebindings are now (as of early 2004) deprecated,
           ;; with the new *PRINT-VAR-ALIST* mechanism preferred.
           (*print-length* *debug-print-length*)
@@ -710,11 +729,12 @@ Other commands:
           (*readtable* *debug-readtable*))
        (progv
           ;; (Why NREVERSE? PROGV makes the later entries have
-          ;; precedence over the earlier entries. *PRINT-VAR-ALIST*
-          ;; is called an alist, so it's expected that its earlier
-          ;; entries have precedence. And the earlier-has-precedence
-          ;; behavior is mostly more convenient, so that programmers
-          ;; can use PUSH or LIST* to customize *PRINT-VAR-ALIST*.)
+          ;; precedence over the earlier entries.
+          ;; *DEBUG-PRINT-VARIABLE-ALIST* is called an alist, so it's
+          ;; expected that its earlier entries have precedence. And
+          ;; the earlier-has-precedence behavior is mostly more
+          ;; convenient, so that programmers can use PUSH or LIST* to
+          ;; customize *DEBUG-PRINT-VARIABLE-ALIST*.)
           (nreverse (mapcar #'car *debug-print-variable-alist*))
           (nreverse (mapcar #'cdr *debug-print-variable-alist*))
         (apply fun rest))))))