Remove no-op calls to decode-char with 'ucs' arg

* lisp/gnus/mm-util.el (mm-ucs-to-char):
* lisp/language/hanja-util.el (hangul-to-hanja-char):
* lisp/leim/quail/hangul.el (hangul3-input-method-internal)
(hangul390-input-method-internal):
* lisp/nxml/rng-cmpct.el (rng-c-process-escapes):
* lisp/nxml/xsd-regexp.el (xsdre-compile-single-char)
(xsdre-range-list-to-char-alternative):
* lisp/xml.el (xml-parse-string, xml--entity-replacement-text)
(xml-substitute-special): Remove calls to decode-char where first
argument is 'ucs'; that is now a no-op.  Discussed in Bug#52263.

* lisp/nxml/xmltok.el (xmltok-unicode-to-char): Make into obsolete
function alias for 'identity'.  Update single caller.

lisp/gnus/mm-util.el

@@ -31,7 +31,7 @@
 
 (defun mm-ucs-to-char (codepoint)
   "Convert Unicode codepoint to character."
-  (or (decode-char 'ucs codepoint) ?#))
+  (or codepoint ?#))
 
 (defvar mm-coding-system-list nil)
 (defun mm-get-coding-system-list ()

lisp/language/hanja-util.el

@@ -6573,8 +6573,8 @@ The value is a hanja character that is selected interactively."
            (hanja-filter (lambda (x) (car x))
                          (mapcar (lambda (c)
                                    (if (listp c)
-                                       (cons (decode-char 'ucs (car c)) (cdr c))
-				     (list (decode-char 'ucs c))))
+                                       (cons (car c) (cdr c))
+                                     (list c)))
                                  (aref hanja-table char)))))
     (unwind-protect
 	(when (aref hanja-conversions 2)

lisp/leim/quail/hangul.el

@@ -429,7 +429,7 @@ When a Korean input method is off, convert the following hangul character."
            (hangul3-input-method-jong char))
           (t
            (setq hangul-queue (make-vector 6 0))
-           (insert (decode-char 'ucs char))
+           (insert char)
            (move-overlay quail-overlay (point) (point))))))
 
 (defun hangul3-input-method (key)
@@ -476,7 +476,7 @@ When a Korean input method is off, convert the following hangul character."
            (hangul3-input-method-jong char))
           (t
            (setq hangul-queue (make-vector 6 0))
-           (insert (decode-char 'ucs char))
+           (insert char)
            (move-overlay quail-overlay (point) (point))))))
 
 (defun hangul390-input-method (key)

lisp/nxml/rng-cmpct.el

@@ -369,7 +369,7 @@ OVERRIDE is either nil, require or t."
     (while (re-search-forward "\\\\x+{\\([[:xdigit:]]+\\)}"
 			      (point-max)
 			      t)
-      (let* ((ch (decode-char 'ucs (string-to-number (match-string 1) 16))))
+      (let* ((ch (string-to-number (match-string 1) 16)))
 	(if (and ch (> ch 0))
 	    (let ((begin (match-beginning 0))
 		  (end (match-end 0)))

lisp/nxml/xmltok.el

@@ -943,7 +943,6 @@ and VALUE-END, otherwise a STRING giving the value."
 	(let ((n (string-to-number (buffer-substring-no-properties start end)
 				base)))
 	  (cond ((and (integerp n) (xmltok-valid-char-p n))
-		 (setq n (xmltok-unicode-to-char n))
 		 (and n (string n)))
 		(t
 		 (xmltok-add-error "Invalid character code" start end)
@@ -971,11 +970,6 @@ and VALUE-END, otherwise a STRING giving the value."
 	(t (and (> n #xFFFF)
 		(< n #x110000)))))
 
-(defun xmltok-unicode-to-char (n)
-  "Return the character corresponding to Unicode scalar value N.
-Return nil if unsupported in Emacs."
-  (decode-char 'ucs n))
-
 ;;; Prolog parsing
 
 (defvar xmltok-contains-doctype nil)
@@ -1766,6 +1760,10 @@ and `xmltok-namespace-attributes'."
 		 xmltok-type))
     (message "Scanned end of file")))
 
+;;; Obsolete
+
+(define-obsolete-function-alias 'xmltok-unicode-to-char #'identity "29.1")
+
 (provide 'xmltok)
 
 ;;; xmltok.el ends here

lisp/nxml/xsd-regexp.el

@@ -287,7 +287,7 @@ and whose tail is ACCUM."
 (defun xsdre-compile-single-char (ch)
   (if (memq ch '(?. ?* ?+ ?? ?\[ ?\] ?^ ?$ ?\\))
       (string ?\\ ch)
-    (string (decode-char 'ucs ch))))
+    (string ch)))
 
 (defun xsdre-char-class-to-range-list (cc)
   "Return a range-list for a symbolic char-class CC."
@@ -404,10 +404,6 @@ consisting of a single char alternative delimited with []."
 		    (cons last chars)
 		  (cons last (cons ?- chars))))))
       (setq range-list (cdr range-list)))
-    (setq chars
-	  (mapcar (lambda (c)
-		    (decode-char 'ucs c))
-		  chars))
     (when caret
       (setq chars (cons ?^ chars)))
     (when hyphen

lisp/xml.el

@@ -612,8 +612,8 @@ references."
 	(if (setq ref (match-string 2))
 	    (progn  ; Numeric char reference
 	      (setq val (save-match-data
-			  (decode-char 'ucs (string-to-number
-					     ref (if (match-string 1) 16)))))
+                          (string-to-number
+                           ref (if (match-string 1) 16))))
 	      (and (null val)
 		   xml-validating-parser
 		   (error "XML: (Validity) Invalid character reference `%s'"
@@ -898,11 +898,11 @@ references and parameter-entity references."
 	    ref val)
 	(cond ((setq ref (match-string 1 string))
 	       ;; Decimal character reference
-	       (setq val (decode-char 'ucs (string-to-number ref)))
+               (setq val (string-to-number ref))
 	       (if val (push (string val) children)))
 	      ;; Hexadecimal character reference
 	      ((setq ref (match-string 2 string))
-	       (setq val (decode-char 'ucs (string-to-number ref 16)))
+               (setq val (string-to-number ref 16))
 	       (if val (push (string val) children)))
 	      ;; Parameter entity reference
 	      ((setq ref (match-string 3 string))
@@ -962,7 +962,7 @@ STRING is assumed to occur in an XML attribute value."
 	(if ref
 	    ;; [4.6] Character references are included as
 	    ;; character data.
-	    (let ((val (decode-char 'ucs (string-to-number ref (if is-hex 16)))))
+            (let ((val (string-to-number ref (if is-hex 16))))
 	      (push (cond (val (string val))
 			  (xml-validating-parser
 			   (error "XML: (Validity) Undefined character `x%s'" ref))