diff --git a/lisp/emulation/cua-rect.el b/lisp/emulation/cua-rect.el
index ea8b52476f7..d389f6ec0a2 100644
--- a/lisp/emulation/cua-rect.el
+++ b/lisp/emulation/cua-rect.el
@@ -666,6 +666,22 @@ If command is repeated at same position, delete the rectangle."
     	     (setq rect (cons row rect))))))
     (nreverse rect)))
 
+(defun cua--extract-rectangle-bounds ()
+  (let (rect)
+    (if (not (cua--rectangle-virtual-edges))
+        (cua--rectangle-operation nil nil nil nil nil ; do not tabify
+          (lambda (s e _l _r)
+             (setq rect (cons (cons s e) rect))))
+      (cua--rectangle-operation nil 1 nil nil nil ; do not tabify
+        (lambda (s e l r _v)
+           (goto-char s)
+           (move-to-column l)
+           (setq s (point))
+           (move-to-column r)
+           (setq e (point))
+           (setq rect (cons (cons s e) rect)))))
+    (nreverse rect)))
+
 (defun cua--insert-rectangle (rect &optional below paste-column line-count)
   ;; Insert rectangle as insert-rectangle, but don't set mark and exit with
   ;; point at either next to top right or below bottom left corner
@@ -1394,6 +1410,8 @@ With prefix arg, indent to that column."
 
 (add-function :around region-extract-function
               #'cua--rectangle-region-extract)
+(add-function :around region-insert-function
+              #'cua--insert-rectangle)
 (add-function :around redisplay-highlight-region-function
               #'cua--rectangle-highlight-for-redisplay)
 
@@ -1405,8 +1423,12 @@ With prefix arg, indent to that column."
 
 (defun cua--rectangle-region-extract (orig &optional delete)
   (cond
-   ((not cua--rectangle) (funcall orig delete))
-   ((eq delete 'delete-only) (cua--delete-rectangle))
+   ((not cua--rectangle)
+    (funcall orig delete))
+   ((eq delete 'bounds)
+    (cua--extract-rectangle-bounds))
+   ((eq delete 'delete-only)
+    (cua--delete-rectangle))
    (t
     (let* ((strs (cua--extract-rectangle))
            (str (mapconcat #'identity strs "\n")))
diff --git a/lisp/progmodes/elisp-mode.el b/lisp/progmodes/elisp-mode.el
index af2ea56dcee..2c22483e86f 100644
--- a/lisp/progmodes/elisp-mode.el
+++ b/lisp/progmodes/elisp-mode.el
@@ -228,8 +228,7 @@ Blank lines separate paragraphs.  Semicolons start comments.
 
 \\{emacs-lisp-mode-map}"
   :group 'lisp
-  (defvar xref-find-function)
-  (defvar xref-identifier-completion-table-function)
+  (defvar xref-backend-functions)
   (defvar project-library-roots-function)
   (lisp-mode-variables nil nil 'elisp)
   (add-hook 'after-load-functions #'elisp--font-lock-flush-elisp-buffers)
@@ -239,9 +238,7 @@ Blank lines separate paragraphs.  Semicolons start comments.
   (setq imenu-case-fold-search nil)
   (add-function :before-until (local 'eldoc-documentation-function)
                 #'elisp-eldoc-documentation-function)
-  (setq-local xref-find-function #'elisp-xref-find)
-  (setq-local xref-identifier-completion-table-function
-              #'elisp--xref-identifier-completion-table)
+  (add-hook 'xref-backend-functions #'elisp--xref-backend nil t)
   (setq-local project-library-roots-function #'elisp-library-roots)
   (add-hook 'completion-at-point-functions
             #'elisp-completion-at-point nil 'local))
@@ -588,21 +585,7 @@ It can be quoted, or be inside a quoted form."
 (declare-function xref-make "xref" (summary location))
 (declare-function xref-collect-references "xref" (symbol dir))
 
-(defun elisp-xref-find (action id)
-  (require 'find-func)
-  ;; FIXME: use information in source near point to filter results:
-  ;; (dvc-log-edit ...) - exclude 'feature
-  ;; (require 'dvc-log-edit) - only 'feature
-  ;; Semantic may provide additional information
-  (pcase action
-    (`definitions
-      (let ((sym (intern-soft id)))
-        (when sym
-          (elisp--xref-find-definitions sym))))
-    (`references
-     (elisp--xref-find-references id))
-    (`apropos
-     (elisp--xref-find-apropos id))))
+(defun elisp--xref-backend () 'elisp)
 
 ;; WORKAROUND: This is nominally a constant, but the text properties
 ;; are not preserved thru dump if use defconst.  See bug#21237.
@@ -638,7 +621,17 @@ Each function should return a list of xrefs, or nil; the first
 non-nil result supercedes the xrefs produced by
 `elisp--xref-find-definitions'.")
 
-;; FIXME: name should be singular; match xref-find-definition
+(cl-defmethod xref-backend-definitions ((_backend (eql elisp)) identifier)
+  (require 'find-func)
+  ;; FIXME: use information in source near point to filter results:
+  ;; (dvc-log-edit ...) - exclude 'feature
+  ;; (require 'dvc-log-edit) - only 'feature
+  ;; Semantic may provide additional information
+  ;;
+  (let ((sym (intern-soft identifier)))
+    (when sym
+      (elisp--xref-find-definitions sym))))
+
 (defun elisp--xref-find-definitions (symbol)
   ;; The file name is not known when `symbol' is defined via interactive eval.
   (let (xrefs)
@@ -805,7 +798,7 @@ non-nil result supercedes the xrefs produced by
 (declare-function project-roots "project")
 (declare-function project-current "project")
 
-(defun elisp--xref-find-references (symbol)
+(cl-defmethod xref-backend-references ((_backend (eql elisp)) symbol)
   "Find all references to SYMBOL (a string) in the current project."
   (cl-mapcan
    (lambda (dir)
@@ -815,7 +808,7 @@ non-nil result supercedes the xrefs produced by
       (project-roots pr)
       (project-library-roots pr)))))
 
-(defun elisp--xref-find-apropos (regexp)
+(cl-defmethod xref-backend-apropos ((_backend (eql elisp)) regexp)
   (apply #'nconc
          (let (lst)
            (dolist (sym (apropos-internal regexp))
@@ -832,7 +825,7 @@ non-nil result supercedes the xrefs produced by
                          (facep sym)))
                    'strict))
 
-(defun elisp--xref-identifier-completion-table ()
+(cl-defmethod xref-backend-identifier-completion-table ((_backend (eql elisp)))
   elisp--xref-identifier-completion-table)
 
 (cl-defstruct (xref-elisp-location
diff --git a/lisp/progmodes/etags.el b/lisp/progmodes/etags.el
index 38c5cc2bdb6..ae1aa11fbc2 100644
--- a/lisp/progmodes/etags.el
+++ b/lisp/progmodes/etags.el
@@ -2084,17 +2084,12 @@ for \\[find-tag] (which see)."
 
 (defvar etags-xref-find-definitions-tag-order '(tag-exact-match-p
                                                 tag-implicit-name-match-p)
-  "Tag order used in `etags-xref-find' to look for definitions.")
+  "Tag order used in `xref-backend-definitions' to look for definitions.")
 
-;;;###autoload
-(defun etags-xref-find (action id)
-  (pcase action
-    (`definitions (etags--xref-find-definitions id))
-    (`references  (etags--xref-find-references id))
-    (`apropos (etags--xref-find-definitions id t))))
+(cl-defmethod xref-backend-identifier-completion-table ((_backend (eql etags)))
+  (tags-lazy-completion-table))
 
-(defun etags--xref-find-references (symbol)
-  ;; TODO: Merge together with the Elisp impl.
+(cl-defmethod xref-backend-references ((_backend (eql etags)) symbol)
   (cl-mapcan
    (lambda (dir)
      (xref-collect-references symbol dir))
@@ -2103,6 +2098,12 @@ for \\[find-tag] (which see)."
       (project-roots pr)
       (project-library-roots pr)))))
 
+(cl-defmethod xref-backend-definitions ((_backend (eql etags)) symbol)
+  (etags--xref-find-definitions symbol))
+
+(cl-defmethod xref-backend-apropos ((_backend (eql etags)) symbol)
+  (etags--xref-find-definitions symbol t))
+
 (defun etags--xref-find-definitions (pattern &optional regexp?)
   ;; This emulates the behaviour of `find-tag-in-order' but instead of
   ;; returning one match at a time all matches are returned as list.
diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
index 89a06046ca2..6a3b42ff646 100644
--- a/lisp/progmodes/xref.el
+++ b/lisp/progmodes/xref.el
@@ -23,14 +23,21 @@
 ;; referencing commands, in particular "find-definition".
 ;;
 ;; Some part of the functionality must be implemented in a language
-;; dependent way and that's done by defining `xref-find-function',
-;; `xref-identifier-at-point-function' and
-;; `xref-identifier-completion-table-function', which see.
+;; dependent way and that's done by defining an xref backend.
 ;;
-;; A major mode should make these variables buffer-local first.
+;; That consists of a constructor function, which should return a
+;; backend value, and a set of implementations for the generic
+;; functions:
 ;;
-;; `xref-find-function' can be called in several ways, see its
-;; description.  It has to operate with "xref" and "location" values.
+;; `xref-backend-identifier-at-point',
+;; `xref-backend-identifier-completion-table',
+;; `xref-backend-definitions', `xref-backend-references',
+;; `xref-backend-apropos', which see.
+;;
+;; A major mode would normally use `add-hook' to add the backend
+;; constructor to `xref-backend-functions'.
+;;
+;; The last three methods operate with "xref" and "location" values.
 ;;
 ;; One would usually call `make-xref' and `xref-make-file-location',
 ;; `xref-make-buffer-location' or `xref-make-bogus-location' to create
@@ -38,15 +45,19 @@
 ;; class inheriting from `xref-location' and implementing
 ;; `xref-location-group' and `xref-location-marker'.
 ;;
+;; There's a special kind of xrefs we call "match xrefs", which
+;; correspond to search results.  For these values,
+;; `xref-match-length' must be defined, and `xref-location-marker'
+;; must return the beginning of the match.
+;;
 ;; Each identifier must be represented as a string.  Implementers can
 ;; use string properties to store additional information about the
 ;; identifier, but they should keep in mind that values returned from
-;; `xref-identifier-completion-table-function' should still be
+;; `xref-backend-identifier-completion-table' should still be
 ;; distinct, because the user can't see the properties when making the
 ;; choice.
 ;;
-;; See the functions `etags-xref-find' and `elisp-xref-find' for full
-;; examples.
+;; See the etags and elisp-mode implementations for full examples.
 
 ;;; Code:
 
@@ -79,8 +90,8 @@ This is typically the filename.")
   "Return the line number corresponding to the location."
   nil)
 
-(cl-defgeneric xref-match-bounds (_item)
-  "Return a cons with columns of the beginning and end of the match."
+(cl-defgeneric xref-match-length (_item)
+  "Return the length of the match."
   nil)
 
 ;;;; Commonly needed location classes are defined here:
@@ -109,7 +120,7 @@ Line numbers start from 1 and columns from 0.")
         (save-excursion
           (goto-char (point-min))
           (beginning-of-line line)
-          (move-to-column column)
+          (forward-char column)
           (point-marker))))))
 
 (cl-defmethod xref-location-group ((l xref-file-location))
@@ -176,55 +187,60 @@ LOCATION is an `xref-location'."
    (location :initarg :location
              :type xref-file-location
              :reader xref-item-location)
-   (end-column :initarg :end-column))
-  :comment "An xref item describes a reference to a location
-somewhere.")
+   (length :initarg :length :reader xref-match-length))
+  :comment "A match xref item describes a search result.")
 
-(cl-defmethod xref-match-bounds ((i xref-match-item))
-  (with-slots (end-column location) i
-    (cons (xref-file-location-column location)
-          end-column)))
-
-(defun xref-make-match (summary end-column location)
+(defun xref-make-match (summary location length)
   "Create and return a new `xref-match-item'.
 SUMMARY is a short string to describe the xref.
-END-COLUMN is the match end column number inside SUMMARY.
-LOCATION is an `xref-location'."
-  (make-instance 'xref-match-item :summary summary :location location
-                 :end-column end-column))
+LOCATION is an `xref-location'.
+LENGTH is the match length, in characters."
+  (make-instance 'xref-match-item :summary summary
+                 :location location :length length))
 
 
 ;;; API
 
-(declare-function etags-xref-find "etags" (action id))
-(declare-function tags-lazy-completion-table "etags" ())
+;; We make the etags backend the default for now, until something
+;; better comes along.
+(defvar xref-backend-functions (list #'xref--etags-backend)
+  "Special hook to find the xref backend for the current context.
+Each functions on this hook is called in turn with no arguments
+and should return either nil to mean that it is not applicable,
+or an xref backend, which is a value to be used to dispatch the
+generic functions.")
 
-;; For now, make the etags backend the default.
-(defvar xref-find-function #'etags-xref-find
-  "Function to look for cross-references.
-It can be called in several ways:
+(defun xref-find-backend ()
+  (run-hook-with-args-until-success 'xref-backend-functions))
 
- (definitions IDENTIFIER): Find definitions of IDENTIFIER.  The
-result must be a list of xref objects.  If IDENTIFIER contains
-sufficient information to determine a unique definition, returns
-only that definition. If there are multiple possible definitions,
-return all of them.  If no definitions can be found, return nil.
+(defun xref--etags-backend () 'etags)
 
- (references IDENTIFIER): Find references of IDENTIFIER.  The
-result must be a list of xref objects.  If no references can be
-found, return nil.
+(cl-defgeneric xref-backend-definitions (backend identifier)
+  "Find definitions of IDENTIFIER.
 
- (apropos PATTERN): Find all symbols that match PATTERN.  PATTERN
-is a regexp.
+The result must be a list of xref objects.  If IDENTIFIER
+contains sufficient information to determine a unique definition,
+return only that definition. If there are multiple possible
+definitions, return all of them.  If no definitions can be found,
+return nil.
 
 IDENTIFIER can be any string returned by
-`xref-identifier-at-point-function', or from the table returned
-by `xref-identifier-completion-table-function'.
+`xref-backend-identifier-at-point', or from the table returned by
+`xref-backend-identifier-completion-table'.
 
 To create an xref object, call `xref-make'.")
 
-(defvar xref-identifier-at-point-function #'xref-default-identifier-at-point
-  "Function to get the relevant identifier at point.
+(cl-defgeneric xref-backend-references (backend identifier)
+  "Find references of IDENTIFIER.
+The result must be a list of xref objects.  If no references can
+be found, return nil.")
+
+(cl-defgeneric xref-backend-apropos (backend pattern)
+  "Find all symbols that match PATTERN.
+PATTERN is a regexp")
+
+(cl-defgeneric xref-backend-identifier-at-point (_backend)
+  "Return the relevant identifier at point.
 
 The return value must be a string or nil.  nil means no
 identifier at point found.
@@ -232,16 +248,14 @@ identifier at point found.
 If it's hard to determine the identifier precisely (e.g., because
 it's a method call on unknown type), the implementation can
 return a simple string (such as symbol at point) marked with a
-special text property which `xref-find-function' would recognize
-and then delegate the work to an external process.")
-
-(defvar xref-identifier-completion-table-function #'tags-lazy-completion-table
-  "Function that returns the completion table for identifiers.")
-
-(defun xref-default-identifier-at-point ()
+special text property which e.g. `xref-backend-definitions' would
+recognize and then delegate the work to an external process."
   (let ((thing (thing-at-point 'symbol)))
     (and thing (substring-no-properties thing))))
 
+(cl-defgeneric xref-backend-identifier-completion-table (backend)
+  "Returns the completion table for identifiers.")
+
 
 ;;; misc utilities
 (defun xref--alistify (list key test)
@@ -345,22 +359,14 @@ elements is negated."
   (pcase-let ((`(,beg . ,end)
                (save-excursion
                  (or
-                  (xref--match-buffer-bounds xref--current-item)
+                  (let ((length (xref-match-length xref--current-item)))
+                    (and length (cons (point) (+ (point) length))))
                   (back-to-indentation)
                   (if (eolp)
                       (cons (line-beginning-position) (1+ (point)))
                     (cons (point) (line-end-position)))))))
     (pulse-momentary-highlight-region beg end 'next-error)))
 
-(defun xref--match-buffer-bounds (item)
-  (save-excursion
-    (let ((bounds (xref-match-bounds item)))
-      (when bounds
-        (cons (progn (move-to-column (car bounds))
-                     (point))
-              (progn (move-to-column (cdr bounds))
-                     (point)))))))
-
 ;; etags.el needs this
 (defun xref-clear-marker-stack ()
   "Discard all markers from the marker stack."
@@ -487,50 +493,54 @@ WINDOW controls how the buffer is displayed:
         (progn
           (save-excursion
             (goto-char (point-min))
-            ;; TODO: Check that none of the matches are out of date;
-            ;; offer to re-scan otherwise.  Note that saving the last
-            ;; modification tick won't work, as long as not all of the
-            ;; buffers are kept open.
             (while (setq item (xref--search-property 'xref-item))
-              (when (xref-match-bounds item)
+              (when (xref-match-length item)
                 (save-excursion
-                  ;; FIXME: Get rid of xref--goto-location, by making
-                  ;; xref-match-bounds return markers already.
-                  (xref--goto-location (xref-item-location item))
-                  (let ((bounds (xref--match-buffer-bounds item))
-                        (beg (make-marker))
-                        (end (make-marker)))
-                    (move-marker beg (car bounds))
-                    (move-marker end (cdr bounds))
-                    (push (cons beg end) pairs)))))
+                  (let* ((loc (xref-item-location item))
+                         (beg (xref-location-marker loc))
+                         (len (xref-match-length item)))
+                    ;; Perform sanity check first.
+                    (xref--goto-location loc)
+                    ;; FIXME: The check should probably be a generic
+                    ;; function, instead of the assumption that all
+                    ;; matches contain the full line as summary.
+                    ;; TODO: Offer to re-scan otherwise.
+                    (unless (equal (buffer-substring-no-properties
+                                    (line-beginning-position)
+                                    (line-end-position))
+                                   (xref-item-summary item))
+                      (user-error "Search results out of date"))
+                    (push (cons beg len) pairs)))))
             (setq pairs (nreverse pairs)))
           (unless pairs (user-error "No suitable matches here"))
           (xref--query-replace-1 from to pairs))
       (dolist (pair pairs)
-        (move-marker (car pair) nil)
-        (move-marker (cdr pair) nil)))))
+        (move-marker (car pair) nil)))))
 
+;; FIXME: Write a nicer UI.
 (defun xref--query-replace-1 (from to pairs)
   (let* ((query-replace-lazy-highlight nil)
-         current-pair current-buf
+         current-beg current-len current-buf
          ;; Counteract the "do the next match now" hack in
          ;; `perform-replace'.  And still, it'll report that those
          ;; matches were "filtered out" at the end.
          (isearch-filter-predicate
           (lambda (beg end)
-            (and current-pair
+            (and current-beg
                  (eq (current-buffer) current-buf)
-                 (>= beg (car current-pair))
-                 (<= end (cdr current-pair)))))
+                 (>= beg current-beg)
+                 (<= end (+ current-beg current-len)))))
          (replace-re-search-function
           (lambda (from &optional _bound noerror)
-            (let (found)
+            (let (found pair)
               (while (and (not found) pairs)
-                (setq current-pair (pop pairs)
-                      current-buf  (marker-buffer (car current-pair)))
+                (setq pair (pop pairs)
+                      current-beg (car pair)
+                      current-len (cdr pair)
+                      current-buf (marker-buffer current-beg))
                 (pop-to-buffer current-buf)
-                (goto-char (car current-pair))
-                (when (re-search-forward from (cdr current-pair) noerror)
+                (goto-char current-beg)
+                (when (re-search-forward from (+ current-beg current-len) noerror)
                   (setq found t)))
               found))))
     ;; FIXME: Despite this being a multi-buffer replacement, `N'
@@ -695,7 +705,8 @@ Return an alist of the form ((FILENAME . (XREF ...)) ...)."
 
 (defun xref--read-identifier (prompt)
   "Return the identifier at point or read it from the minibuffer."
-  (let ((id (funcall xref-identifier-at-point-function)))
+  (let* ((backend (xref-find-backend))
+         (id (xref-backend-identifier-at-point backend)))
     (cond ((or current-prefix-arg
                (not id)
                (xref--prompt-p this-command))
@@ -705,7 +716,7 @@ Return an alist of the form ((FILENAME . (XREF ...)) ...)."
                                                              "[ :]+\\'" prompt))
                                         id)
                               prompt)
-                            (funcall xref-identifier-completion-table-function)
+                            (xref-backend-identifier-completion-table backend)
                             nil nil nil
                             'xref--read-identifier-history id))
           (t id))))
@@ -714,7 +725,9 @@ Return an alist of the form ((FILENAME . (XREF ...)) ...)."
 ;;; Commands
 
 (defun xref--find-xrefs (input kind arg window)
-  (let ((xrefs (funcall xref-find-function kind arg)))
+  (let ((xrefs (funcall (intern (format "xref-backend-%s" kind))
+                        (xref-find-backend)
+                        arg)))
     (unless xrefs
       (user-error "No %s found for: %s" (symbol-name kind) input))
     (xref--show-xrefs xrefs window)))
@@ -799,14 +812,9 @@ and just use etags."
   :lighter ""
   (if xref-etags-mode
       (progn
-        (setq xref-etags-mode--saved
-              (cons xref-find-function
-                    xref-identifier-completion-table-function))
-        (kill-local-variable 'xref-find-function)
-        (kill-local-variable 'xref-identifier-completion-table-function))
-    (setq-local xref-find-function (car xref-etags-mode--saved))
-    (setq-local xref-identifier-completion-table-function
-                (cdr xref-etags-mode--saved))))
+        (setq xref-etags-mode--saved xref-backend-functions)
+        (kill-local-variable 'xref-backend-functions))
+    (setq-local xref-backend-functions xref-etags-mode--saved)))
 
 (declare-function semantic-symref-find-references-by-name "semantic/symref")
 (declare-function semantic-find-file-noselect "semantic/fw")
@@ -826,10 +834,11 @@ tools are used, and when."
          (hits (and res (oref res hit-lines)))
          (orig-buffers (buffer-list)))
     (unwind-protect
-        (delq nil
-              (mapcar (lambda (hit) (xref--collect-match
-                                hit (format "\\_<%s\\_>" (regexp-quote symbol))))
-                      hits))
+        (cl-mapcan (lambda (hit) (xref--collect-matches
+                             hit (format "\\_<%s\\_>" (regexp-quote symbol))))
+                   hits)
+      ;; TODO: Implement "lightweight" buffer visiting, so that we
+      ;; don't have to kill them.
       (mapc #'kill-buffer
             (cl-set-difference (buffer-list) orig-buffers)))))
 
@@ -860,9 +869,9 @@ IGNORES is a list of glob patterns."
                     (match-string 1))
               hits)))
     (unwind-protect
-        (delq nil
-              (mapcar (lambda (hit) (xref--collect-match hit regexp))
-                      (nreverse hits)))
+        (cl-mapcan (lambda (hit) (xref--collect-matches hit regexp))
+                   (nreverse hits))
+      ;; TODO: Same as above.
       (mapc #'kill-buffer
             (cl-set-difference (buffer-list) orig-buffers)))))
 
@@ -918,7 +927,7 @@ IGNORES is a list of glob patterns."
                (match-string 1 str)))))
    str t t))
 
-(defun xref--collect-match (hit regexp)
+(defun xref--collect-matches (hit regexp)
   (pcase-let* ((`(,line . ,file) hit)
                (buf (or (find-buffer-visiting file)
                         (semantic-find-file-noselect file))))
@@ -926,18 +935,22 @@ IGNORES is a list of glob patterns."
       (save-excursion
         (goto-char (point-min))
         (forward-line (1- line))
-        (syntax-propertize (line-end-position))
-        ;; TODO: Handle multiple matches per line.
-        (when (re-search-forward regexp (line-end-position) t)
-          (goto-char (match-beginning 0))
-          (let ((loc (xref-make-file-location file line
-                                              (current-column))))
-            (goto-char (match-end 0))
-            (xref-make-match (buffer-substring
-                              (line-beginning-position)
-                              (line-end-position))
-                             (current-column)
-                             loc)))))))
+        (let ((line-end (line-end-position))
+              (line-beg (line-beginning-position))
+              matches)
+          (syntax-propertize line-end)
+          ;; FIXME: This results in several lines with the same
+          ;; summary. Solve with composite pattern?
+          (while (re-search-forward regexp line-end t)
+            (let* ((beg-column (- (match-beginning 0) line-beg))
+                   (end-column (- (match-end 0) line-beg))
+                   (loc (xref-make-file-location file line beg-column))
+                   (summary (buffer-substring line-beg line-end)))
+              (add-face-text-property beg-column end-column 'highlight
+                                      t summary)
+              (push (xref-make-match summary loc (- end-column beg-column))
+                    matches)))
+          (nreverse matches))))))
 
 (provide 'xref)
 
diff --git a/lisp/rect.el b/lisp/rect.el
index acd3a48f2da..46ebbf259cf 100644
--- a/lisp/rect.el
+++ b/lisp/rect.el
@@ -257,6 +257,19 @@ Return it as a list of strings, one for each line of the rectangle."
     (apply-on-rectangle 'extract-rectangle-line start end lines)
     (nreverse (cdr lines))))
 
+(defun extract-rectangle-bounds (start end)
+  "Return the bounds of the rectangle with corners at START and END.
+Return it as a list of (START . END) positions, one for each line of
+the rectangle."
+  (let (bounds)
+    (apply-on-rectangle
+     (lambda (startcol endcol)
+       (move-to-column startcol)
+       (push (cons (prog1 (point) (move-to-column endcol)) (point))
+	     bounds))
+     start end)
+    (nreverse bounds)))
+
 (defvar killed-rectangle nil
   "Rectangle for `yank-rectangle' to insert.")
 
@@ -563,6 +576,8 @@ with a prefix argument, prompt for START-AT and FORMAT."
               #'rectangle--unhighlight-for-redisplay)
 (add-function :around region-extract-function
               #'rectangle--extract-region)
+(add-function :around region-insert-function
+              #'rectangle--insert-region)
 
 (defvar rectangle-mark-mode-map
   (let ((map (make-sparse-keymap)))
@@ -681,8 +696,12 @@ Ignores `line-move-visual'."
 
 
 (defun rectangle--extract-region (orig &optional delete)
-  (if (not rectangle-mark-mode)
-      (funcall orig delete)
+  (cond
+   ((not rectangle-mark-mode)
+    (funcall orig delete))
+   ((eq delete 'bounds)
+    (extract-rectangle-bounds (region-beginning) (region-end)))
+   (t
     (let* ((strs (funcall (if delete
                               #'delete-extract-rectangle
                             #'extract-rectangle)
@@ -696,7 +715,14 @@ Ignores `line-move-visual'."
         (put-text-property 0 (length str) 'yank-handler
                            `(rectangle--insert-for-yank ,strs t)
                            str)
-        str))))
+        str)))))
+
+(defun rectangle--insert-region (orig strings)
+  (cond
+   ((not rectangle-mark-mode)
+    (funcall orig strings))
+   (t
+    (funcall #'insert-rectangle strings))))
 
 (defun rectangle--insert-for-yank (strs)
   (push (point) buffer-undo-list)
diff --git a/lisp/replace.el b/lisp/replace.el
index d6590c5516a..b6802aeaf57 100644
--- a/lisp/replace.el
+++ b/lisp/replace.el
@@ -284,7 +284,7 @@ the original string if not."
 	  (and current-prefix-arg (not (eq current-prefix-arg '-)))
 	  (and current-prefix-arg (eq current-prefix-arg '-)))))
 
-(defun query-replace (from-string to-string &optional delimited start end backward)
+(defun query-replace (from-string to-string &optional delimited start end backward region-noncontiguous-p)
   "Replace some occurrences of FROM-STRING with TO-STRING.
 As each match is found, the user must type a character saying
 what to do with it.  For directions, type \\[help-command] at that time.
@@ -328,22 +328,21 @@ To customize possible responses, change the bindings in `query-replace-map'."
 		   (if current-prefix-arg
 		       (if (eq current-prefix-arg '-) " backward" " word")
 		     "")
-		   (if (and transient-mark-mode mark-active) " in region" ""))
+		   (if (use-region-p) " in region" ""))
 	   nil)))
      (list (nth 0 common) (nth 1 common) (nth 2 common)
 	   ;; These are done separately here
 	   ;; so that command-history will record these expressions
 	   ;; rather than the values they had this time.
-	   (if (and transient-mark-mode mark-active)
-	       (region-beginning))
-	   (if (and transient-mark-mode mark-active)
-	       (region-end))
-	   (nth 3 common))))
-  (perform-replace from-string to-string t nil delimited nil nil start end backward))
+	   (if (use-region-p) (region-beginning))
+	   (if (use-region-p) (region-end))
+	   (nth 3 common)
+	   (if (use-region-p) (region-noncontiguous-p)))))
+  (perform-replace from-string to-string t nil delimited nil nil start end backward region-noncontiguous-p))
 
 (define-key esc-map "%" 'query-replace)
 
-(defun query-replace-regexp (regexp to-string &optional delimited start end backward)
+(defun query-replace-regexp (regexp to-string &optional delimited start end backward region-noncontiguous-p)
   "Replace some things after point matching REGEXP with TO-STRING.
 As each match is found, the user must type a character saying
 what to do with it.  For directions, type \\[help-command] at that time.
@@ -408,18 +407,17 @@ Use \\[repeat-complex-command] after this command for details."
 		       (if (eq current-prefix-arg '-) " backward" " word")
 		     "")
 		   " regexp"
-		   (if (and transient-mark-mode mark-active) " in region" ""))
+		   (if (use-region-p) " in region" ""))
 	   t)))
      (list (nth 0 common) (nth 1 common) (nth 2 common)
 	   ;; These are done separately here
 	   ;; so that command-history will record these expressions
 	   ;; rather than the values they had this time.
-	   (if (and transient-mark-mode mark-active)
-	       (region-beginning))
-	   (if (and transient-mark-mode mark-active)
-	       (region-end))
-	   (nth 3 common))))
-  (perform-replace regexp to-string t t delimited nil nil start end backward))
+	   (if (use-region-p) (region-beginning))
+	   (if (use-region-p) (region-end))
+	   (nth 3 common)
+	   (if (use-region-p) (region-noncontiguous-p)))))
+  (perform-replace regexp to-string t t delimited nil nil start end backward region-noncontiguous-p))
 
 (define-key esc-map [?\C-%] 'query-replace-regexp)
 
@@ -485,10 +483,8 @@ for Lisp calls." "22.1"))
        ;; and the user might enter a single token.
        (replace-match-string-symbols to)
        (list from (car to) current-prefix-arg
-	     (if (and transient-mark-mode mark-active)
-		 (region-beginning))
-	     (if (and transient-mark-mode mark-active)
-		 (region-end))))))
+	     (if (use-region-p) (region-beginning))
+	     (if (use-region-p) (region-end))))))
   (perform-replace regexp (cons 'replace-eval-replacement to-expr)
 		   t 'literal delimited nil nil start end))
 
@@ -523,10 +519,8 @@ Fourth and fifth arg START and END specify the region to operate on."
      (list from to
 	   (and current-prefix-arg
 		(prefix-numeric-value current-prefix-arg))
-	   (if (and transient-mark-mode mark-active)
-	       (region-beginning))
-	   (if (and transient-mark-mode mark-active)
-	       (region-end)))))
+	   (if (use-region-p) (region-beginning))
+	   (if (use-region-p) (region-end)))))
   (let (replacements)
     (if (listp to-strings)
 	(setq replacements to-strings)
@@ -587,13 +581,11 @@ and TO-STRING is also null.)"
 		       (if (eq current-prefix-arg '-) " backward" " word")
 		     "")
 		   " string"
-		   (if (and transient-mark-mode mark-active) " in region" ""))
+		   (if (use-region-p) " in region" ""))
 	   nil)))
      (list (nth 0 common) (nth 1 common) (nth 2 common)
-	   (if (and transient-mark-mode mark-active)
-	       (region-beginning))
-	   (if (and transient-mark-mode mark-active)
-	       (region-end))
+	   (if (use-region-p) (region-beginning))
+	   (if (use-region-p) (region-end))
 	   (nth 3 common))))
   (perform-replace from-string to-string nil nil delimited nil nil start end backward))
 
@@ -661,13 +653,11 @@ which will run faster and will not set the mark or print anything."
 		       (if (eq current-prefix-arg '-) " backward" " word")
 		     "")
 		   " regexp"
-		   (if (and transient-mark-mode mark-active) " in region" ""))
+		   (if (use-region-p) " in region" ""))
 	   t)))
      (list (nth 0 common) (nth 1 common) (nth 2 common)
-	   (if (and transient-mark-mode mark-active)
-	       (region-beginning))
-	   (if (and transient-mark-mode mark-active)
-	       (region-end))
+	   (if (use-region-p) (region-beginning))
+	   (if (use-region-p) (region-end))
 	   (nth 3 common))))
   (perform-replace regexp to-string nil t delimited nil nil start end backward))
 
@@ -832,7 +822,7 @@ a previously found match."
 		  (unless (or (bolp) (eobp))
 		    (forward-line 0))
 		  (point-marker)))))
-    (if (and interactive transient-mark-mode mark-active)
+    (if (and interactive (use-region-p))
 	(setq rstart (region-beginning)
 	      rend (progn
 		     (goto-char (region-end))
@@ -901,7 +891,7 @@ starting on the same line at which another match ended is ignored."
       (progn
 	(goto-char (min rstart rend))
 	(setq rend (copy-marker (max rstart rend))))
-    (if (and interactive transient-mark-mode mark-active)
+    (if (and interactive (use-region-p))
 	(setq rstart (region-beginning)
 	      rend (copy-marker (region-end)))
       (setq rstart (point)
@@ -951,7 +941,7 @@ a previously found match."
               (setq rend (max rstart rend)))
           (goto-char rstart)
           (setq rend (point-max)))
-      (if (and interactive transient-mark-mode mark-active)
+      (if (and interactive (use-region-p))
 	  (setq rstart (region-beginning)
 		rend (region-end))
 	(setq rstart (point)
@@ -2068,7 +2058,7 @@ It is called with three arguments, as if it were
 
 (defun perform-replace (from-string replacements
 		        query-flag regexp-flag delimited-flag
-			&optional repeat-count map start end backward)
+			&optional repeat-count map start end backward region-noncontiguous-p)
   "Subroutine of `query-replace'.  Its complexity handles interactive queries.
 Don't use this in your own program unless you want to query and set the mark
 just as `query-replace' does.  Instead, write a simple loop like this:
@@ -2115,6 +2105,9 @@ It must return a string."
 
          ;; If non-nil, it is marker saying where in the buffer to stop.
          (limit nil)
+         ;; Use local binding in add-function below.
+         (isearch-filter-predicate isearch-filter-predicate)
+         (region-bounds nil)
 
          ;; Data for the next match.  If a cons, it has the same format as
          ;; (match-data); otherwise it is t if a match is possible at point.
@@ -2127,6 +2120,24 @@ It must return a string."
                       "Query replacing %s with %s: (\\<query-replace-map>\\[help] for help) ")
                      minibuffer-prompt-properties))))
 
+    ;; Unless a single contiguous chunk is selected, operate on multiple chunks.
+    (when region-noncontiguous-p
+      (setq region-bounds
+            (mapcar (lambda (position)
+                      (cons (copy-marker (car position))
+                            (copy-marker (cdr position))))
+                    (funcall region-extract-function 'bounds)))
+      (add-function :after-while isearch-filter-predicate
+                    (lambda (start end)
+                      (delq nil (mapcar
+                                 (lambda (bounds)
+                                   (and
+                                    (>= start (car bounds))
+                                    (<= start (cdr bounds))
+                                    (>= end   (car bounds))
+                                    (<= end   (cdr bounds))))
+                                 region-bounds)))))
+
     ;; If region is active, in Transient Mark mode, operate on region.
     (if backward
 	(when end
diff --git a/lisp/simple.el b/lisp/simple.el
index b115a2a0cbb..deb5c888c92 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -970,15 +970,34 @@ instead of deleted."
 (defvar region-extract-function
   (lambda (delete)
     (when (region-beginning)
-      (if (eq delete 'delete-only)
-          (delete-region (region-beginning) (region-end))
-        (filter-buffer-substring (region-beginning) (region-end) delete))))
+      (cond
+       ((eq delete 'bounds)
+        (list (cons (region-beginning) (region-end))))
+       ((eq delete 'delete-only)
+        (delete-region (region-beginning) (region-end)))
+       (t
+        (filter-buffer-substring (region-beginning) (region-end) delete)))))
   "Function to get the region's content.
 Called with one argument DELETE.
 If DELETE is `delete-only', then only delete the region and the return value
 is undefined.  If DELETE is nil, just return the content as a string.
+If DELETE is `bounds', then don't delete, but just return the
+boundaries of the region as a list of (START . END) positions.
 If anything else, delete the region and return its content as a string.")
 
+(defvar region-insert-function
+  (lambda (lines)
+    (let ((first t))
+      (while lines
+        (or first
+            (insert ?\n))
+        (insert-for-yank (car lines))
+        (setq lines (cdr lines)
+              first nil))))
+  "Function to insert the region's content.
+Called with one argument LINES.
+Insert the region as a list of lines.")
+
 (defun delete-backward-char (n &optional killflag)
   "Delete the previous N characters (following if N is negative).
 If Transient Mark mode is enabled, the mark is active, and N is 1,
@@ -3419,7 +3438,8 @@ and only used if a buffer is displayed."
 
 (defun shell-command-on-region (start end command
 				      &optional output-buffer replace
-				      error-buffer display-error-buffer)
+				      error-buffer display-error-buffer
+				      region-noncontiguous-p)
   "Execute string COMMAND in inferior shell with region as input.
 Normally display output (if any) in temp buffer `*Shell Command Output*';
 Prefix arg means replace the region with it.  Return the exit code of
@@ -3482,7 +3502,8 @@ interactively, this is t."
 		       current-prefix-arg
 		       current-prefix-arg
 		       shell-command-default-error-buffer
-		       t)))
+		       t
+		       (region-noncontiguous-p))))
   (let ((error-file
 	 (if error-buffer
 	     (make-temp-file
@@ -3491,96 +3512,109 @@ interactively, this is t."
 				    temporary-file-directory)))
 	   nil))
 	exit-status)
-    (if (or replace
-	    (and output-buffer
-		 (not (or (bufferp output-buffer) (stringp output-buffer)))))
-	;; Replace specified region with output from command.
-	(let ((swap (and replace (< start end))))
-	  ;; Don't muck with mark unless REPLACE says we should.
-	  (goto-char start)
-	  (and replace (push-mark (point) 'nomsg))
-	  (setq exit-status
-		(call-process-region start end shell-file-name replace
-				     (if error-file
-					 (list t error-file)
-				       t)
-				     nil shell-command-switch command))
-	  ;; It is rude to delete a buffer which the command is not using.
-	  ;; (let ((shell-buffer (get-buffer "*Shell Command Output*")))
-	  ;;   (and shell-buffer (not (eq shell-buffer (current-buffer)))
-	  ;; 	 (kill-buffer shell-buffer)))
-	  ;; Don't muck with mark unless REPLACE says we should.
-	  (and replace swap (exchange-point-and-mark)))
-      ;; No prefix argument: put the output in a temp buffer,
-      ;; replacing its entire contents.
-      (let ((buffer (get-buffer-create
-		     (or output-buffer "*Shell Command Output*"))))
-	(unwind-protect
-	    (if (eq buffer (current-buffer))
-		;; If the input is the same buffer as the output,
-		;; delete everything but the specified region,
-		;; then replace that region with the output.
-		(progn (setq buffer-read-only nil)
-		       (delete-region (max start end) (point-max))
-		       (delete-region (point-min) (min start end))
-		       (setq exit-status
-			     (call-process-region (point-min) (point-max)
-						  shell-file-name t
-						  (if error-file
-						      (list t error-file)
-						    t)
-						  nil shell-command-switch
-						  command)))
-	      ;; Clear the output buffer, then run the command with
-	      ;; output there.
-	      (let ((directory default-directory))
-		(with-current-buffer buffer
-		  (setq buffer-read-only nil)
-		  (if (not output-buffer)
-		      (setq default-directory directory))
-		  (erase-buffer)))
-	      (setq exit-status
-		    (call-process-region start end shell-file-name nil
-					 (if error-file
-					     (list buffer error-file)
-					   buffer)
-					 nil shell-command-switch command)))
-	  ;; Report the output.
-	  (with-current-buffer buffer
-	    (setq mode-line-process
-		  (cond ((null exit-status)
-			 " - Error")
-			((stringp exit-status)
-			 (format " - Signal [%s]" exit-status))
-			((not (equal 0 exit-status))
-			 (format " - Exit [%d]" exit-status)))))
-	  (if (with-current-buffer buffer (> (point-max) (point-min)))
-	      ;; There's some output, display it
-	      (display-message-or-buffer buffer)
-	    ;; No output; error?
-	    (let ((output
-		   (if (and error-file
-			    (< 0 (nth 7 (file-attributes error-file))))
-		       (format "some error output%s"
-			       (if shell-command-default-error-buffer
-				   (format " to the \"%s\" buffer"
-					   shell-command-default-error-buffer)
-				 ""))
-		     "no output")))
-	      (cond ((null exit-status)
-		     (message "(Shell command failed with error)"))
-		    ((equal 0 exit-status)
-		     (message "(Shell command succeeded with %s)"
-			      output))
-		    ((stringp exit-status)
-		     (message "(Shell command killed by signal %s)"
-			      exit-status))
-		    (t
-		     (message "(Shell command failed with code %d and %s)"
-			      exit-status output))))
-	    ;; Don't kill: there might be useful info in the undo-log.
-	    ;; (kill-buffer buffer)
-	    ))))
+    ;; Unless a single contiguous chunk is selected, operate on multiple chunks.
+    (if region-noncontiguous-p
+        (let ((input (concat (funcall region-extract-function 'delete) "\n"))
+              output)
+          (with-temp-buffer
+            (insert input)
+            (call-process-region (point-min) (point-max)
+                                 shell-file-name t t
+                                 nil shell-command-switch
+                                 command)
+            (setq output (split-string (buffer-string) "\n")))
+          (goto-char start)
+          (funcall region-insert-function output))
+      (if (or replace
+              (and output-buffer
+                   (not (or (bufferp output-buffer) (stringp output-buffer)))))
+          ;; Replace specified region with output from command.
+          (let ((swap (and replace (< start end))))
+            ;; Don't muck with mark unless REPLACE says we should.
+            (goto-char start)
+            (and replace (push-mark (point) 'nomsg))
+            (setq exit-status
+                  (call-process-region start end shell-file-name replace
+                                       (if error-file
+                                           (list t error-file)
+                                         t)
+                                       nil shell-command-switch command))
+            ;; It is rude to delete a buffer which the command is not using.
+            ;; (let ((shell-buffer (get-buffer "*Shell Command Output*")))
+            ;;   (and shell-buffer (not (eq shell-buffer (current-buffer)))
+            ;; 	 (kill-buffer shell-buffer)))
+            ;; Don't muck with mark unless REPLACE says we should.
+            (and replace swap (exchange-point-and-mark)))
+        ;; No prefix argument: put the output in a temp buffer,
+        ;; replacing its entire contents.
+        (let ((buffer (get-buffer-create
+                       (or output-buffer "*Shell Command Output*"))))
+          (unwind-protect
+              (if (eq buffer (current-buffer))
+                  ;; If the input is the same buffer as the output,
+                  ;; delete everything but the specified region,
+                  ;; then replace that region with the output.
+                  (progn (setq buffer-read-only nil)
+                         (delete-region (max start end) (point-max))
+                         (delete-region (point-min) (min start end))
+                         (setq exit-status
+                               (call-process-region (point-min) (point-max)
+                                                    shell-file-name t
+                                                    (if error-file
+                                                        (list t error-file)
+                                                      t)
+                                                    nil shell-command-switch
+                                                    command)))
+                ;; Clear the output buffer, then run the command with
+                ;; output there.
+                (let ((directory default-directory))
+                  (with-current-buffer buffer
+                    (setq buffer-read-only nil)
+                    (if (not output-buffer)
+                        (setq default-directory directory))
+                    (erase-buffer)))
+                (setq exit-status
+                      (call-process-region start end shell-file-name nil
+                                           (if error-file
+                                               (list buffer error-file)
+                                             buffer)
+                                           nil shell-command-switch command)))
+            ;; Report the output.
+            (with-current-buffer buffer
+              (setq mode-line-process
+                    (cond ((null exit-status)
+                           " - Error")
+                          ((stringp exit-status)
+                           (format " - Signal [%s]" exit-status))
+                          ((not (equal 0 exit-status))
+                           (format " - Exit [%d]" exit-status)))))
+            (if (with-current-buffer buffer (> (point-max) (point-min)))
+                ;; There's some output, display it
+                (display-message-or-buffer buffer)
+              ;; No output; error?
+              (let ((output
+                     (if (and error-file
+                              (< 0 (nth 7 (file-attributes error-file))))
+                         (format "some error output%s"
+                                 (if shell-command-default-error-buffer
+                                     (format " to the \"%s\" buffer"
+                                             shell-command-default-error-buffer)
+                                   ""))
+                       "no output")))
+                (cond ((null exit-status)
+                       (message "(Shell command failed with error)"))
+                      ((equal 0 exit-status)
+                       (message "(Shell command succeeded with %s)"
+                                output))
+                      ((stringp exit-status)
+                       (message "(Shell command killed by signal %s)"
+                                exit-status))
+                      (t
+                       (message "(Shell command failed with code %d and %s)"
+                                exit-status output))))
+              ;; Don't kill: there might be useful info in the undo-log.
+              ;; (kill-buffer buffer)
+              )))))
 
     (when (and error-file (file-exists-p error-file))
       (if (< 0 (nth 7 (file-attributes error-file)))
@@ -5175,6 +5209,11 @@ also checks the value of `use-empty-active-region'."
        ;; region is active when there's no mark.
        (progn (cl-assert (mark)) t)))
 
+(defun region-noncontiguous-p ()
+  "Return non-nil if the region contains several pieces.
+An example is a rectangular region handled as a list of
+separate contiguous regions for each line."
+  (> (length (funcall region-extract-function 'bounds)) 1))
 
 (defvar redisplay-unhighlight-region-function
   (lambda (rol) (when (overlayp rol) (delete-overlay rol))))
diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
index 464e3754eb9..f4d7fe7d9aa 100644
--- a/lisp/vc/diff-mode.el
+++ b/lisp/vc/diff-mode.el
@@ -1821,7 +1821,7 @@ With a prefix argument, try to REVERSE the hunk."
   "Kill all hunks that have already been applied starting at point."
   (interactive)
   (while (not (eobp))
-    (pcase-let ((`(,buf ,line-offset ,pos ,src ,_dst ,switched)
+    (pcase-let ((`(,_buf ,line-offset ,_pos ,_src ,_dst ,switched)
                  (diff-find-source-location nil nil)))
       (if (and line-offset switched)
           (diff-hunk-kill)
diff --git a/src/casefiddle.c b/src/casefiddle.c
index b94ea8e212e..6a2983ef018 100644
--- a/src/casefiddle.c
+++ b/src/casefiddle.c
@@ -306,14 +306,30 @@ See also `capitalize-region'.  */)
   return Qnil;
 }
 
-DEFUN ("downcase-region", Fdowncase_region, Sdowncase_region, 2, 2, "r",
+DEFUN ("downcase-region", Fdowncase_region, Sdowncase_region, 2, 3,
+       "(list (region-beginning) (region-end) (region-noncontiguous-p))",
        doc: /* Convert the region to lower case.  In programs, wants two arguments.
 These arguments specify the starting and ending character numbers of
 the region to operate on.  When used as a command, the text between
 point and the mark is operated on.  */)
-  (Lisp_Object beg, Lisp_Object end)
+  (Lisp_Object beg, Lisp_Object end, Lisp_Object region_noncontiguous_p)
 {
-  casify_region (CASE_DOWN, beg, end);
+  Lisp_Object bounds = Qnil;
+
+  if (!NILP (region_noncontiguous_p))
+    {
+      bounds = call1 (Fsymbol_value (intern ("region-extract-function")),
+		      intern ("bounds"));
+
+      while (CONSP (bounds))
+	{
+	  casify_region (CASE_DOWN, XCAR (XCAR (bounds)), XCDR (XCAR (bounds)));
+	  bounds = XCDR (bounds);
+	}
+    }
+  else
+    casify_region (CASE_DOWN, beg, end);
+
   return Qnil;
 }