--- tex-buf.el
+++ tex-buf.el	2019-06-21 13:02:03.572805297 +0000
@@ -555,7 +555,6 @@ without further expansion."
 	pos ;;FIXME: Should this be dynamically scoped?
 	entry TeX-command-text TeX-command-pos
 	(orig-file file)
-	(file #'TeX--master-or-region-file-with-extra-quotes)
         expansion-res case-fold-search string expansion arguments)
     (setq list (cons
 		(list "%%" (lambda nil
@@ -563,6 +562,17 @@ without further expansion."
 			     "%"))
 		(or list (TeX-expand-list)))
 	  pat (regexp-opt (mapcar #'car list)))
+    ;; `TeX-command-expand' is called with `file' argument being one
+    ;; of `TeX-master-file', `TeX-region-file' and
+    ;; `TeX-active-master'.  The return value of these functions
+    ;; sometimes needs suitable "decorations" for an argument for
+    ;; underlying shell or latex executable, or both, when the
+    ;; relavant file name involves some special characters such as
+    ;; space and multibyte characters.  Hence embed that function in a
+    ;; template prepared for that purpose.
+    (setq file (apply-partially
+		#'TeX--master-or-region-file-with-extra-quotes
+		file))
     (while (setq pos (string-match pat command pos))
       (setq string (match-string 0 command)
 	    entry (assoc string list)
@@ -594,24 +604,29 @@ without further expansion."
   command)
 
 (defun TeX--master-or-region-file-with-extra-quotes
-    (&optional extension nondirectory ask extra)
+    (file-fn &optional extension nondirectory ask extra)
   "Return file name with quote for shell.
-Wrapper for `TeX-master-file' or `TeX-region-file' to be used in
-`TeX-command-expand'.
-It is assumed that `orig-file' has dynamic binding of the value of
-`TeX-master-file' or `TeX-region-file'.  Pass EXTENSION, NONDIRECTORY
-and ASK to that function as-is, and arrange the returned file name for
-use with command shell.
-Enclose the file name with space within quotes `\"' first when
-\" \\input\" is supplemented (indicated by dynamically binded
-variable `TeX-command-text' having string value.)
-Enclose the file name within \\detokenize{} when the following three
+Helper function of `TeX-command-expand'.
+
+This is a kind of template.  How to use:
+Fix, by `apply-partially', the first argument FILE-FN as one of
+the three functions `TeX-master-file', `TeX-region-file' or
+`TeX-active-master'.  Then the result is just a wrapper for that
+function suitable in `TeX-command-expand'.
+
+As a wrapper described above, it passes EXTENSION, NONDIRECTORY
+and ASK to the \"bare\" function as-is, and arranges the returned
+file name for use with command shell.  I.e. it encloses the file
+name with space within quotes `\"' first when \" \\input\" is
+supplemented (indicated by dynamically binded variable
+`TeX-command-text' having string value.)  It also encloses the
+file name within \\detokenize{} when the following three
 conditions are met:
 1. compiling with standard (pdf)LaTeX or upLaTeX
 2. \" \\input\" is supplemented
 3. EXTRA is non-nil. (default when expanding \"%T\")"
   (shell-quote-argument
-   (let* ((raw (funcall orig-file extension nondirectory ask))
+   (let* ((raw (funcall file-fn extension nondirectory ask))
 	  ;; String `TeX-command-text' means that the file name is
 	  ;; given through \input command.
 	  (quote-for-space (if (and (stringp TeX-command-text)
@@ -2031,14 +2046,22 @@ command."
        (with-current-buffer TeX-command-buffer
 	 (TeX-process-buffer (TeX-active-master)))))
 
-(defun TeX-active-master (&optional extension nondirectory)
+(defun TeX-active-master (&optional extension nondirectory _ignore)
   "The master file currently being compiled.
 
 If optional argument EXTENSION is non-nil, add that file extension to
 the name.  Special value t means use `TeX-default-extension'.
 
 If optional second argument NONDIRECTORY is non-nil, do not include
-the directory."
+the directory.
+
+The compatibility argument IGNORE is ignored."
+  ;; The third argument `_ignore' is kept for symmetry with
+  ;; `TeX-master-file's third argument `ask'.  For example, it's used
+  ;; in `TeX--master-or-region-file-with-extra-quotes', where we don't
+  ;; know which function has to be called.  Keep this in mind should
+  ;; you want to use another argument here.
+  ;; See also the similar comment in `TeX-region-file'.
   (if TeX-current-process-region-p
       (TeX-region-file extension nondirectory)
     (TeX-master-file extension nondirectory)))
--- tex.el
+++ tex.el	2019-06-21 12:58:20.442057420 +0000
@@ -545,7 +545,11 @@ string."
 		  (setq pos (+ pos (length TeX-command-text) 9))
 		  (concat TeX-command-text " \"\\input\""))
 	      "")))
-    ("%T" TeX--master-or-region-file-with-extra-quotes t t nil t)
+    ;; The fourth argument of t is actually for wrapper function
+    ;; provided by `TeX--master-or-region-file-with-extra-quotes'.
+    ;; See its doc string as well as the comments in
+    ;; `TeX-command-expand'.
+    ("%T" file t t nil t)
     ("%n" TeX-current-line)
     ("%d" file "dvi" t)
     ("%f" file "ps" t)