Fix byte-opt lists of pure functions etc.

This fixes a bug where a byte-compiler running on 64-bit Emacs
optimized (lsh -1 -1) to #x1fffffffffffffff, an optimization
that is incorrect for .elc files intended for either 32- or
64-bit Emacs.  While I was in the neighborhood, I noticed other
glitches in the lists of pure and side-effect-free functions, and
fixed the errors that I found.
* lisp/emacs-lisp/byte-opt.el (side-effect-free-fns):
Move some functions here from side-effect-and-error-free-fns,
since they can now signal errors.  The affected functions are
current-time-string, current-time-zone,
line-beginning-position, line-end-position.  Rename langinfo
to locale-info.  Add logcount.  Remove string-to-int.
(side-effect-and-error-free-fns): Remove minibuffer-window, a
function that can signal errors, and that is already in
side-effect-free-fns.
(pure-fns): Remove ash, lsh, and logb, since they are
platform-dependent and .elc files should be
platform-independent.  Add %, logand, logcount.  Sort.
Clarify what is meant by “pure”.

1 files changed, 23 insertions, 14 deletions

diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index a316364761d..55343e1e3af 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -1186,6 +1186,7 @@
          char-equal char-to-string char-width compare-strings
          compare-window-configurations concat coordinates-in-window-p
          copy-alist copy-sequence copy-marker cos count-lines
+         current-time-string current-time-zone
          decode-char
          decode-time default-boundp default-value documentation downcase
          elt encode-char exp expt encode-time error-message-string
@@ -1199,8 +1200,9 @@
          hash-table-count
          int-to-string intern-soft
          keymap-parent
-         length local-variable-if-set-p local-variable-p log log10 logand
-         logb logior lognot logxor lsh langinfo
+         length line-beginning-position line-end-position
+         local-variable-if-set-p local-variable-p locale-info
+         log log10 logand logb logcount logior lognot logxor lsh
          make-list make-string make-symbol marker-buffer max member memq min
          minibuffer-selected-window minibuffer-window
          mod multibyte-char-to-unibyte next-window nth nthcdr number-to-string
@@ -1210,7 +1212,7 @@
          radians-to-degrees rassq rassoc read-from-string regexp-quote
          region-beginning region-end reverse round
          sin sqrt string string< string= string-equal string-lessp string-to-char
-         string-to-int string-to-number substring
+         string-to-number substring
          sxhash sxhash-equal sxhash-eq sxhash-eql
          symbol-function symbol-name symbol-plist symbol-value string-make-unibyte
          string-make-multibyte string-as-multibyte string-as-unibyte
@@ -1240,7 +1242,6 @@
          charsetp commandp cons consp
          current-buffer current-global-map current-indentation
          current-local-map current-minor-mode-maps current-time
-         current-time-string current-time-zone
          eobp eolp eq equal eventp
          floatp following-char framep
          get-largest-window get-lru-window
@@ -1248,9 +1249,9 @@
          identity ignore integerp integer-or-marker-p interactive-p
          invocation-directory invocation-name
          keymapp keywordp
-         line-beginning-position line-end-position list listp
+         list listp
          make-marker mark mark-marker markerp max-char
-         memory-limit minibuffer-window
+         memory-limit
          mouse-movement-p
          natnump nlistp not null number-or-marker-p numberp
          one-window-p overlayp
@@ -1275,16 +1276,24 @@
   nil)
 
 
-;; pure functions are side-effect free functions whose values depend
-;; only on their arguments. For these functions, calls with constant
-;; arguments can be evaluated at compile time. This may shift run time
-;; errors to compile time.
+;; Pure functions are side-effect free functions whose values depend
+;; only on their arguments, not on the platform.  For these functions,
+;; calls with constant arguments can be evaluated at compile time.
+;; This may shift runtime errors to compile time.  For example, logand
+;; is pure since its results are machine-independent, whereas ash is
+;; not pure because (ash 1 29)'s value depends on machine word size.
+;;
+;; When deciding whether a function is pure, do not worry about
+;; mutable strings or markers, as they are so unlikely in real code
+;; that they are not worth worrying about.  Thus string-to-char is
+;; pure even though it might return different values if a string is
+;; changed, and logand is pure even though it might return different
+;; values if a marker is moved.
 
 (let ((pure-fns
-       '(concat symbol-name regexp-opt regexp-quote string-to-syntax
-         string-to-char
-         ash lsh logb lognot logior logxor
-         ceiling floor)))
+       '(% concat logand logcount logior lognot logxor
+         regexp-opt regexp-quote
+         string-to-char string-to-syntax symbol-name)))
   (while pure-fns
     (put (car pure-fns) 'pure t)
     (setq pure-fns (cdr pure-fns)))