Adjust some pure and side-effect-free function declarations

* lisp/emacs-lisp/byte-opt.el (side-effect-free-fns):
Add `format-message` and `substring-no-properties`.
* lisp/subr.el (number-sequence, copy-tree, looking-at-p)
(string-match-p, string-trim-right, string-lines):
Declare side-effect-free.
(syntax-class, version-list-<, version-list-=, version-list-<=)
(version-list-not-zero): Declare pure and side-effect-free.
(ensure-list): Declare side-effect-free and error-free.
(string-equal-ignore-case): Remove `pure` declaration.
We may want it to be pure but right now it's not.

lisp/emacs-lisp/byte-opt.el

@@ -1664,8 +1664,8 @@ See Info node `(elisp) Integer Basics'."
 	 file-directory-p file-exists-p file-locked-p file-name-absolute-p
          file-name-concat
 	 file-newer-than-file-p file-readable-p file-symlink-p file-writable-p
-	 float float-time floor format format-time-string frame-first-window
-	 frame-root-window frame-selected-window
+	 float float-time floor format format-message format-time-string
+         frame-first-window frame-root-window frame-selected-window
 	 frame-visible-p fround ftruncate
 	 get gethash get-buffer get-buffer-window get-file-buffer
 	 hash-table-count
@@ -1685,7 +1685,7 @@ See Info node `(elisp) Integer Basics'."
          regexp-quote region-beginning region-end reverse round
 	 sin sqrt string string-equal string-lessp
          string-search string-to-char
-	 string-to-number string-to-syntax substring
+	 string-to-number string-to-syntax substring substring-no-properties
 	 sxhash-equal sxhash-eq sxhash-eql
 	 symbol-function symbol-name symbol-plist symbol-value
          string-make-unibyte

lisp/subr.el

@@ -806,6 +806,7 @@ TO as (+ FROM (* N INC)) or use a variable whose value was
 computed with this exact expression.  Alternatively, you can,
 of course, also replace TO with a slightly larger value
 \(or a slightly more negative value if INC is negative)."
+  (declare (side-effect-free t))
   (if (or (not to) (= from to))
       (list from)
     (or inc (setq inc 1))
@@ -827,6 +828,7 @@ of course, also replace TO with a slightly larger value
 If TREE is a cons cell, this recursively copies both its car and its cdr.
 Contrast to `copy-sequence', which copies only along the cdrs.  With second
 argument VECP, this copies vectors as well as conses."
+  (declare (side-effect-free t))
   (if (consp tree)
       (let (result)
 	(while (consp tree)
@@ -5241,11 +5243,13 @@ wherever possible, since it is slow."
 (defsubst looking-at-p (regexp)
   "\
 Same as `looking-at' except this function does not change the match data."
+  (declare (side-effect-free t))
   (looking-at regexp t))
 
 (defsubst string-match-p (regexp string &optional start)
   "\
 Same as `string-match' except this function does not change the match data."
+  (declare (side-effect-free t))
   (string-match regexp string start t))
 
 (defun subregexp-context-p (regexp pos &optional start)
@@ -5516,7 +5520,7 @@ Upper-case and lower-case letters are treated as equal.
 Unibyte strings are converted to multibyte for comparison.
 
 See also `string-equal'."
-  (declare (pure t) (side-effect-free t))
+  (declare (side-effect-free t))
   (eq t (compare-strings string1 0 nil string2 0 nil t)))
 
 (defun string-prefix-p (prefix string &optional ignore-case)
@@ -5843,6 +5847,7 @@ integer that encodes the corresponding syntax class.  See Info
 node `(elisp)Syntax Table Internals' for a list of codes.
 
 If SYNTAX is nil, return nil."
+  (declare (pure t) (side-effect-free t))
   (and syntax (logand (car syntax) 65535)))
 
 ;; Utility motion commands
@@ -6693,6 +6698,7 @@ Note that a version specified by the list (1) is equal to (1 0),
 \(1 0 0), (1 0 0 0), etc.  That is, the trailing zeros are insignificant.
 Also, a version given by the list (1) is higher than (1 -1), which in
 turn is higher than (1 -2), which is higher than (1 -3)."
+  (declare (pure t) (side-effect-free t))
   (while (and l1 l2 (= (car l1) (car l2)))
     (setq l1 (cdr l1)
 	  l2 (cdr l2)))
@@ -6714,6 +6720,7 @@ Note that a version specified by the list (1) is equal to (1 0),
 \(1 0 0), (1 0 0 0), etc.  That is, the trailing zeros are insignificant.
 Also, a version given by the list (1) is higher than (1 -1), which in
 turn is higher than (1 -2), which is higher than (1 -3)."
+  (declare (pure t) (side-effect-free t))
   (while (and l1 l2 (= (car l1) (car l2)))
     (setq l1 (cdr l1)
 	  l2 (cdr l2)))
@@ -6735,6 +6742,7 @@ Note that integer list (1) is equal to (1 0), (1 0 0), (1 0 0 0),
 etc.  That is, the trailing zeroes are insignificant.  Also, integer
 list (1) is greater than (1 -1) which is greater than (1 -2)
 which is greater than (1 -3)."
+  (declare (pure t) (side-effect-free t))
   (while (and l1 l2 (= (car l1) (car l2)))
     (setq l1 (cdr l1)
 	  l2 (cdr l2)))
@@ -6752,6 +6760,7 @@ which is greater than (1 -3)."
   "Return the first non-zero element of LST, which is a list of integers.
 
 If all LST elements are zeros or LST is nil, return zero."
+  (declare (pure t) (side-effect-free t))
   (while (and lst (zerop (car lst)))
     (setq lst (cdr lst)))
   (if lst
@@ -6918,6 +6927,7 @@ REGEXP defaults to \"[ \\t\\n\\r]+\"."
   "Trim STRING of trailing string matching REGEXP.
 
 REGEXP defaults to  \"[ \\t\\n\\r]+\"."
+  (declare (side-effect-free t))
   (let ((i (string-match-p (concat "\\(?:" (or regexp "[ \t\n\r]+") "\\)\\'")
                            string)))
     (if i (substring string 0 i) string)))
@@ -6989,6 +6999,7 @@ sentence (see Info node `(elisp) Documentation Tips')."
   "Return OBJECT as a list.
 If OBJECT is already a list, return OBJECT itself.  If it's
 not a list, return a one-element list containing OBJECT."
+  (declare (side-effect-free error-free))
   (if (listp object)
       object
     (list object)))
@@ -7064,6 +7075,7 @@ is inserted before adjusting the number of empty lines."
 If OMIT-NULLS, empty lines will be removed from the results.
 If KEEP-NEWLINES, don't strip trailing newlines from the result
 lines."
+  (declare (side-effect-free t))
   (if (equal string "")
       (if omit-nulls
           nil