0.8.16.2: TYPE-ERROR for ERROR

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

diff --git a/src/code/pprint.lisp b/src/code/pprint.lisp
index 57024e6..5032ecb 100644 (file)
--- a/src/code/pprint.lisp
+++ b/src/code/pprint.lisp
@@ -364,21 +364,23 @@
 ;;;; tab support
 
 (defun compute-tab-size (tab section-start column)
-  (let ((origin (if (tab-sectionp tab) section-start 0))
-       (colnum (tab-colnum tab))
-       (colinc (tab-colinc tab)))
+  (let* ((origin (if (tab-sectionp tab) section-start 0))
+         (colnum (tab-colnum tab))
+         (colinc (tab-colinc tab))
+         (position (- column origin)))
     (cond ((tab-relativep tab)
           (unless (<= colinc 1)
-            (let ((newposn (+ column colnum)))
+            (let ((newposn (+ position colnum)))
               (let ((rem (rem newposn colinc)))
                 (unless (zerop rem)
                   (incf colnum (- colinc rem))))))
           colnum)
-         ((<= column (+ colnum origin))
-          (- (+ colnum origin) column))
-         (t
+         ((< position colnum)
+           (- colnum position))
+         ((zerop colinc) 0)
+          (t
           (- colinc
-             (rem (- column origin) colinc))))))
+             (rem (- position colnum) colinc))))))
 
 (defun index-column (index stream)
   (let ((column (pretty-stream-buffer-start-column stream))