* lisp/files.el (dir-locals-file): Allow wildcardsscratch/dir-local-wildcard

(dir-locals-find-file, dir-locals-collect-variables)
(dir-locals-read-from-file): Update accordingly.
(hack-dir-local-variables): Rename a local variable.

3 files changed, 123 insertions, 88 deletions

diff --git a/lisp/files-x.el b/lisp/files-x.el
index a130ffcf928..dcd495db15a 100644
--- a/lisp/files-x.el
+++ b/lisp/files-x.el
@@ -429,18 +429,23 @@ from the MODE alist ignoring the input argument VALUE."
   (catch 'exit
     (unless enable-local-variables
       (throw 'exit (message "Directory-local variables are disabled")))
-    (let ((variables-file (or (and (buffer-file-name)
-				   (not (file-remote-p (buffer-file-name)))
-				   (dir-locals-find-file (buffer-file-name)))
-			      dir-locals-file))
+    (let ((variables-file (and (buffer-file-name)
+                               (not (file-remote-p (buffer-file-name)))
+                               (dir-locals-find-file (buffer-file-name))))
 	  variables)
-      (if (consp variables-file)	; result from cache
-	  ;; If cache element has an mtime, assume it came from a file.
-	  ;; Otherwise, assume it was set directly.
-	  (setq variables-file (if (nth 2 variables-file)
-				   (expand-file-name dir-locals-file
-						     (car variables-file))
-				 (cadr variables-file))))
+      (setq variables-file
+            ;; If there are several .dir-locals, the user probably
+            ;; wants to edit the last one (the highest priority).
+            (cond ((stringp variables-file)
+                   (car (last (file-expand-wildcards variables-file))))
+                  ((consp variables-file)	; result from cache
+                   ;; If cache element has an mtime, assume it came from a file.
+                   ;; Otherwise, assume it was set directly.
+                   (if (nth 2 variables-file)
+                       (let ((default-directory (car variables-file)))
+                         (car (last (file-expand-wildcards dir-locals-file 'full))))
+                     (cadr variables-file)))
+                  (t dir-locals-file)))
       ;; I can't be bothered to handle this case right now.
       ;; Dir locals were set directly from a class.  You need to
       ;; directly modify the class in dir-locals-class-alist.
diff --git a/lisp/files.el b/lisp/files.el
index 9de9ac09f48..3d6495f30d2 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -28,6 +28,8 @@
 
 ;;; Code:
 
+(require 'map)
+(require 'seq)
 (defvar font-lock-keywords)
 
 (defgroup backup nil
@@ -3648,7 +3650,7 @@ Return the new variables list."
       (error
        ;; The file's content might be invalid (e.g. have a merge conflict), but
        ;; that shouldn't prevent the user from opening the file.
-       (message ".dir-locals error: %s" (error-message-string err))
+       (message "%s error: %s" dir-locals-file (error-message-string err))
        nil))))
 
 (defun dir-locals-set-directory-class (directory class &optional mtime)
@@ -3698,7 +3700,7 @@ VARIABLES list of the class.  The list is processed in order.
   applied by recursively following these rules."
   (setf (alist-get class dir-locals-class-alist) variables))
 
-(defconst dir-locals-file ".dir-locals.el"
+(defconst dir-locals-file ".dir-locals*.el"
   "File that contains directory-local variables.
 It has to be constant to enforce uniform values
 across different environments and users.")
@@ -3719,17 +3721,23 @@ If not, the cache entry is cleared so that the file will be re-read.
 This function returns either nil (no directory local variables found),
 or the matching entry from `dir-locals-directory-cache' (a list),
 or the full path to the `dir-locals-file' (a string) in the case
-of no valid cache entry."
-  (setq file (expand-file-name file))
-  (let* ((dir-locals-file-name
-	  (if (eq system-type 'ms-dos)
-	      (dosified-file-name dir-locals-file)
-	    dir-locals-file))
-	 (locals-file (locate-dominating-file file dir-locals-file-name))
-	 (dir-elt nil))
+of no valid cache entry.  If `dir-locals-file' contains
+wildcards, then the return value is not a proper filename, it is
+an absolute version of `dir-locals-file' which is guaranteed to
+expand to at least one file."
+  (setq file (file-name-directory (expand-file-name file)))
+  (let* ((dir-locals-file-name (if (eq system-type 'ms-dos)
+                                   (dosified-file-name dir-locals-file)
+                                 dir-locals-file))
+         (locals-dir (locate-dominating-file
+                      file (lambda (dir)
+                             (let ((default-directory dir))
+                               (file-expand-wildcards dir-locals-file-name 'full)))))
+         locals-file dir-elt)
     ;; `locate-dominating-file' may have abbreviated the name.
-    (and locals-file
-	 (setq locals-file (expand-file-name dir-locals-file-name locals-file)))
+    (when locals-dir
+      (setq locals-dir (expand-file-name locals-dir))
+      (setq locals-file (expand-file-name dir-locals-file-name locals-dir)))
 	 ;; Let dir-locals-read-from-file inform us via demoted-errors
 	 ;; about unreadable files, etc.
 	 ;; Maybe we'd want to keep searching though - that is
@@ -3740,54 +3748,69 @@ of no valid cache entry."
     ;; Find the best cached value in `dir-locals-directory-cache'.
     (dolist (elt dir-locals-directory-cache)
       (when (and (string-prefix-p (car elt) file
-				  (memq system-type
-					'(windows-nt cygwin ms-dos)))
-		 (> (length (car elt)) (length (car dir-elt))))
-	(setq dir-elt elt)))
+                                  (memq system-type
+                                        '(windows-nt cygwin ms-dos)))
+                 (> (length (car elt)) (length (car dir-elt))))
+        (setq dir-elt elt)))
     (if (and dir-elt
-	     (or (null locals-file)
-		 (<= (length (file-name-directory locals-file))
-		     (length (car dir-elt)))))
-	;; Found a potential cache entry.  Check validity.
-	;; A cache entry with no MTIME is assumed to always be valid
-	;; (ie, set directly, not from a dir-locals file).
-	;; Note, we don't bother to check that there is a matching class
-	;; element in dir-locals-class-alist, since that's done by
-	;; dir-locals-set-directory-class.
-	(if (or (null (nth 2 dir-elt))
-		(let ((cached-file (expand-file-name dir-locals-file-name
-						     (car dir-elt))))
-		  (and (file-readable-p cached-file)
-		       (equal (nth 2 dir-elt)
-			      (nth 5 (file-attributes cached-file))))))
-	    ;; This cache entry is OK.
-	    dir-elt
-	  ;; This cache entry is invalid; clear it.
-	  (setq dir-locals-directory-cache
-		(delq dir-elt dir-locals-directory-cache))
-	  ;; Return the first existing dir-locals file.  Might be the same
-	  ;; as dir-elt's, might not (eg latter might have been deleted).
-	  locals-file)
+             (or (null locals-dir)
+                 (<= (length locals-dir)
+                     (length (car dir-elt)))))
+        ;; Found a potential cache entry.  Check validity.
+        ;; A cache entry with no MTIME is assumed to always be valid
+        ;; (ie, set directly, not from a dir-locals file).
+        ;; Note, we don't bother to check that there is a matching class
+        ;; element in dir-locals-class-alist, since that's done by
+        ;; dir-locals-set-directory-class.
+        (if (or (null (nth 2 dir-elt))
+                (let* ((default-directory (car dir-elt))
+                       (cached-files (seq-filter #'file-readable-p
+                                                 (file-expand-wildcards dir-locals-file))))
+                  ;; The entry MTIME should match the most recent
+                  ;; MTIME among matching files.
+                  (and cached-files
+                       (= (time-to-seconds (nth 2 dir-elt))
+                          (apply #'max (mapcar (lambda (f) (time-to-seconds (nth 5 (file-attributes f))))
+                                               cached-files))))))
+            ;; This cache entry is OK.
+            dir-elt
+          ;; This cache entry is invalid; clear it.
+          (setq dir-locals-directory-cache
+                (delq dir-elt dir-locals-directory-cache))
+          ;; Return the first existing dir-locals file.  Might be the same
+          ;; as dir-elt's, might not (eg latter might have been deleted).
+          locals-file)
       ;; No cache entry.
       locals-file)))
 
 (defun dir-locals-read-from-file (file)
   "Load a variables FILE and register a new class and instance.
-FILE is the name of the file holding the variables to apply.
+FILE is the absolute name of the file holding the variables to
+apply.  It may contain wildcards.
 The new class name is the same as the directory in which FILE
 is found.  Returns the new class name."
-  (with-temp-buffer
+  (let* ((dir-name (file-name-directory file))
+         (class-name (intern dir-name))
+         (files (sort (file-expand-wildcards "/home/artur/Git/emacs/.dir-locals*.el") #'string<))
+         (read-circle nil)
+         (variables))
     (with-demoted-errors "Error reading dir-locals: %S"
-      (insert-file-contents file)
-      (unless (zerop (buffer-size))
-        (let* ((dir-name (file-name-directory file))
-               (class-name (intern dir-name))
-               (variables (let ((read-circle nil))
-                            (read (current-buffer)))))
-          (dir-locals-set-class-variables class-name variables)
-          (dir-locals-set-directory-class dir-name class-name
-                                          (nth 5 (file-attributes file)))
-          class-name)))))
+      (dolist (file files)
+        (with-temp-buffer
+          (insert-file-contents file)
+          (condition-case-unless-debug nil
+              (setq variables
+                    (map-merge-with 'list (lambda (a b) (map-merge 'list a b))
+                                    variables
+                                    (read (current-buffer))))
+            (end-of-file nil)))))
+    (dir-locals-set-class-variables class-name variables)
+    (dir-locals-set-directory-class
+     dir-name class-name
+     (seconds-to-time (apply #'max (mapcar (lambda (file)
+                                             (time-to-seconds (nth 5 (file-attributes file))))
+                                           files))))
+    class-name))
 
 (defcustom enable-remote-dir-locals nil
   "Non-nil means dir-local variables will be applied to remote files."
@@ -3810,17 +3833,17 @@ This does nothing if either `enable-local-variables' or
 		 (not (file-remote-p (or (buffer-file-name)
 					 default-directory)))))
     ;; Find the variables file.
-    (let ((variables-file (dir-locals-find-file
-                           (or (buffer-file-name) default-directory)))
+    (let ((file-pattern-or-cache (dir-locals-find-file
+                                  (or (buffer-file-name) default-directory)))
 	  (class nil)
 	  (dir-name nil))
       (cond
-       ((stringp variables-file)
-	(setq dir-name (file-name-directory variables-file)
-	      class (dir-locals-read-from-file variables-file)))
-       ((consp variables-file)
-	(setq dir-name (nth 0 variables-file))
-	(setq class (nth 1 variables-file))))
+       ((stringp file-pattern-or-cache)
+	(setq dir-name (file-name-directory file-pattern-or-cache)
+	      class (dir-locals-read-from-file file-pattern-or-cache)))
+       ((consp file-pattern-or-cache)
+	(setq dir-name (nth 0 file-pattern-or-cache))
+	(setq class (nth 1 file-pattern-or-cache))))
       (when class
 	(let ((variables
 	       (dir-locals-collect-variables
diff --git a/lisp/help-fns.el b/lisp/help-fns.el
index 958a0754946..4e0bfee5bf7 100644
--- a/lisp/help-fns.el
+++ b/lisp/help-fns.el
@@ -907,29 +907,36 @@ if it is given a local binding.\n"))))
                                             (buffer-file-name buffer)))
                                       (dir-locals-find-file
                                        (buffer-file-name buffer))))
-                          (dir-file t))
+                          (is-directory nil))
 		      (princ (substitute-command-keys
 			      "  This variable's value is directory-local"))
-		      (if (null file)
-			  (princ ".\n")
-			(princ ", set ")
-                        (if (consp file) ; result from cache
-                            ;; If the cache element has an mtime, we
-                            ;; assume it came from a file.
-                            (if (nth 2 file)
-                                (setq file (expand-file-name
-                                            dir-locals-file (car file)))
-                              ;; Otherwise, assume it was set directly.
-                              (setq file (car file)
-                                    dir-file nil)))
-			(princ (substitute-command-keys
-                                (if dir-file
-                                    "by the file\n  `"
-                                  "for the directory\n  `")))
+                      (when (consp file) ; result from cache
+                        ;; If the cache element has an mtime, we
+                        ;; assume it came from a file.
+                        (if (nth 2 file)
+                            (setq file (expand-file-name
+                                        dir-locals-file (car file)))
+                          ;; Otherwise, assume it was set directly.
+                          (setq file (car file)
+                                is-directory t)))
+                      (if (null file)
+                          (princ ".\n")
+                        (princ ", set ")
+                        (let ((files (file-expand-wildcards file)))
+                          (princ (substitute-command-keys
+                                  (cond
+                                   (is-directory "for the directory\n  `")
+                                   ;; Many files matched.
+                                   ((cdr files)
+                                    (setq file (file-name-directory (car files)))
+                                    (format "by a file\n  matching `%s' in the directory\n  `"
+                                            dir-locals-file))
+                                   (t (setq file (car files))
+                                      "by the file\n  `"))))
 			(with-current-buffer standard-output
 			  (insert-text-button
 			   file 'type 'help-dir-local-var-def
-			   'help-args (list variable file)))
+                             'help-args (list variable file))))
 			(princ (substitute-command-keys "'.\n"))))
 		  (princ (substitute-command-keys
 			  "  This variable's value is file-local.\n"))))