[Emacs-diffs] master c63e7f1: Remove no-longer-needed integer overflow code

[Paul Eggert]

branch: master
commit c63e7f1bf6151d4bb5fde01890c69cdd515e2df3
Author: Paul Eggert <address@hidden>
Commit: Paul Eggert <address@hidden>

    Remove no-longer-needed integer overflow code
    
    * lisp/calculator.el (calculator-number-to-string):
    Use truncate, not calculator-truncate, since integer
    overflow cannot occur here.
    * lisp/calendar/cal-persia.el (calendar-persian-year-from-absolute):
    * lisp/gnus/gnus-agent.el (gnus-agent-read-article-number):
    * lisp/gnus/nnmaildir.el (nnmaildir--group-maxnum)
    (nnmaildir--new-number):
    * lisp/scroll-bar.el (scroll-bar-scale):
    * lisp/simple.el (beginning-of-buffer, end-of-buffer):
    Simplify, now that integer overflow cannot occur.
---
 lisp/calculator.el          |  2 +-
 lisp/calendar/cal-persia.el |  8 +-------
 lisp/files.el               |  4 ++--
 lisp/gnus/gnus-agent.el     | 15 +--------------
 lisp/gnus/nnmaildir.el      |  6 +-----
 lisp/scroll-bar.el          |  4 +---
 lisp/simple.el              | 14 +++-----------
 7 files changed, 10 insertions(+), 43 deletions(-)

diff --git a/lisp/calculator.el b/lisp/calculator.el
index eec7aff..281151c 100644
--- a/lisp/calculator.el
+++ b/lisp/calculator.el
@@ -1054,7 +1054,7 @@ the `left' or `right' when one of the standard modes is 
used."
      ;; print with radix -- for binary, convert the octal number
      (let* ((fmt (if (eq calculator-output-radix 'hex) "%x" "%o"))
             (str (if calculator-2s-complement num (abs num)))
-            (str (format fmt (calculator-truncate str)))
+           (str (format fmt (truncate str)))
             (bins '((?0 "000") (?1 "001") (?2 "010") (?3 "011")
                     (?4 "100") (?5 "101") (?6 "110") (?7 "111")))
             (str (if (not (eq calculator-output-radix 'bin)) str
diff --git a/lisp/calendar/cal-persia.el b/lisp/calendar/cal-persia.el
index 897208f..59fe52a 100644
--- a/lisp/calendar/cal-persia.el
+++ b/lisp/calendar/cal-persia.el
@@ -100,13 +100,7 @@ Gregorian date Sunday, December 31, 1 BC."
          (d2                         ; prior days not in n2820 or n768
           (mod d1 280506))
          (n1        ; years not in n2820 or n768
-          ;; Want:
-          ;; (floor (+ (* 2820 d2) (* 2820 366)) 1029983))
-          ;; but that causes overflow, so use the following.
-          ;; Use 366 as the divisor because (2820*366 mod 1029983) is small.
-          (let ((a (floor d2 366))
-                (b (mod d2 366)))
-            (+ 1 a (floor (+ (* 2137 a) (* 2820 b) 2137) 1029983))))
+         (floor (* 2820 (+ d2 366)) 1029983))
          (year (+ (* 2820 n2820)        ; complete 2820 year cycles
                   (* 768 n768)          ; complete 768 year cycles
                   ;; Remaining years.
diff --git a/lisp/files.el b/lisp/files.el
index 70865eb..81ca948 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -4959,8 +4959,8 @@ Uses `backup-directory-alist' in the same way as
              (list (make-backup-file-name fn))
            (cons (format "%s.~%d~" basic-name (1+ high-water-mark))
                  (if (and (> number-to-delete 0)
-                          ;; Delete nothing if there is overflow
-                          ;; in the number of versions to keep.
+                          ;; Delete nothing if kept-new-versions and
+                          ;; kept-old-versions combine to an outlandish value.
                           (>= (+ kept-new-versions kept-old-versions -1) 0))
                      (mapcar (lambda (n)
                                (format "%s.~%d~" basic-name n))
diff --git a/lisp/gnus/gnus-agent.el b/lisp/gnus/gnus-agent.el
index a09b436..40d0d24 100644
--- a/lisp/gnus/gnus-agent.el
+++ b/lisp/gnus/gnus-agent.el
@@ -1909,21 +1909,8 @@ article numbers will be returned."
 (defsubst gnus-agent-read-article-number ()
   "Reads the article number at point.  Returns nil when a valid article number 
can not be read."
 
-  ;; It is unfortunate but the read function quietly overflows
-  ;; integer.  As a result, I have to use string operations to test
-  ;; for overflow BEFORE calling read.
   (when (looking-at "[0-9]+\t")
-    (let ((len (- (match-end 0) (match-beginning 0))))
-      (cond ((< len 9)
-            (read (current-buffer)))
-           ((= len 9)
-            ;; Many 9 digit base-10 numbers can be represented in a 27-bit int
-            ;; Back convert from int to string to ensure that this is one of 
them.
-            (let* ((str1 (buffer-substring (match-beginning 0) (1- (match-end 
0))))
-                   (num (read (current-buffer)))
-                   (str2 (int-to-string num)))
-              (when (equal str1 str2)
-                num)))))))
+    (read (current-buffer))))
 
 (defsubst gnus-agent-copy-nov-line (article)
   "Copy the indicated ARTICLE from the overview buffer to the nntp server 
buffer."
diff --git a/lisp/gnus/nnmaildir.el b/lisp/gnus/nnmaildir.el
index 3becee3..246f52c 100644
--- a/lisp/gnus/nnmaildir.el
+++ b/lisp/gnus/nnmaildir.el
@@ -322,8 +322,6 @@ This variable is set by `nnmaildir-request-article'.")
        (setq ino-opened (file-attribute-inode-number attr)
              nlink (file-attribute-link-number attr)
              number-linked (+ number-opened nlink))
-       (if (or (< nlink 1) (< number-linked nlink))
-           (signal 'error '("Arithmetic overflow")))
        (setq attr (file-attributes
                    (concat dir (number-to-string number-linked))))
        (or attr (throw 'return (1- number-linked)))
@@ -395,9 +393,7 @@ This variable is set by `nnmaildir-request-article'.")
        (let* ((attr (file-attributes path-open))
               (nlink (file-attribute-link-number attr)))
          (setq ino-open (file-attribute-inode-number attr)
-               number-link (+ number-open nlink))
-         (if (or (< nlink 1) (< number-link nlink))
-             (signal 'error '("Arithmetic overflow"))))
+               number-link (+ number-open nlink)))
        (if (= number-link previous-number-link)
            ;; We've already tried this number, in the previous loop iteration,
            ;; and failed.
diff --git a/lisp/scroll-bar.el b/lisp/scroll-bar.el
index dc0df7a..61fa754 100644
--- a/lisp/scroll-bar.el
+++ b/lisp/scroll-bar.el
@@ -49,9 +49,7 @@ from a scroll bar event, then (scroll-bar-scale SCROLL-BAR-POS
 \(buffer-size)) is the position in the current buffer corresponding to
 that scroll bar position."
   ;; We multiply before we divide to maintain precision.
-  ;; We use floating point because the product of a large buffer size
-  ;; with a large scroll bar portion can easily overflow a lisp int.
-  (truncate (/ (* (float (car num-denom)) whole) (cdr num-denom))))
+  (truncate (* (car num-denom) whole) (cdr num-denom)))
 
 (defun scroll-bar-columns (side)
   "Return the width, measured in columns, of the vertical scrollbar on SIDE.
diff --git a/lisp/simple.el b/lisp/simple.el
index 00265ec..e33709e 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -1037,12 +1037,8 @@ is supplied, or Transient Mark mode is enabled and the 
mark is active."
       (push-mark))
   (let ((size (- (point-max) (point-min))))
     (goto-char (if (and arg (not (consp arg)))
-                  (+ (point-min)
-                     (if (> size 10000)
-                         ;; Avoid overflow for large buffer sizes!
-                         (* (prefix-numeric-value arg)
-                            (/ size 10))
-                       (/ (+ 10 (* size (prefix-numeric-value arg))) 10)))
+                  (+ (point-min) 1
+                     (/ (* size (prefix-numeric-value arg)) 10))
                 (point-min))))
   (if (and arg (not (consp arg))) (forward-line 1)))
 
@@ -1060,11 +1056,7 @@ is supplied, or Transient Mark mode is enabled and the 
mark is active."
   (let ((size (- (point-max) (point-min))))
     (goto-char (if (and arg (not (consp arg)))
                   (- (point-max)
-                     (if (> size 10000)
-                         ;; Avoid overflow for large buffer sizes!
-                         (* (prefix-numeric-value arg)
-                            (/ size 10))
-                       (/ (* size (prefix-numeric-value arg)) 10)))
+                     (/ (* size (prefix-numeric-value arg)) 10))
                 (point-max))))
   ;; If we went to a place in the middle of the buffer,
   ;; adjust it to the beginning of a line.