Merge from origin/emacs-26

a89f0b6f33 maint: shorten https://lists.gnu.org/archive/html/... links
8be3aee281 Merge from Gnulib
265cee553f Work around GCC bug 80776 on Fedora 27 x86
dc7a97fb84 Tweak copy-file, rename-file doc
cfa2a944d4 Change font-lock-extend-region-multiline handling in mhtml...
a8664cc998 Minor cleanup in tramp-gvfs-handle-file-local-copy
55c5b12fa0 Add test for Bug#29423 in Tramp.
3198a1646e Avoid jumbled order in HTML rendered by shr.el
23bfc2d2db Make sure 'dired-filename' property is always put by ls-lisp
f7fdaea4c0 A better solution for bug#29347
86e6ed8521 ; * src/thread.c (acquire_global_lock): Fix thinko in last...
f300852037 Avoid a hang after C-g while sit-for on a Unix TTY
d7fc719ff1 Improve the doc string of 'list-packages'
b4f67ebb92 Improve discoverability of 'defvar' for suppressing warnings
8a2b204e64 Improve discoverability of 'read-buffer-completion-ignore-...
eea4e9194c Improve documentation of self-insert-uses-region-functions
e6e41dac87 Reflect changes in copy-file and rename-file in doc strings
0ec534070f * lisp/progmodes/cc-vars.el (c-offsets-alist): Doc fix.  (...
1d0dbdff6c Reorder type predicates in ELisp manual
b081ec9dd7 Fix backward scrolling in buffers with header-line
8e40429c96 ; Fix some doc typos
ed2c542920 * lisp/bindings.el (buffer-file-coding-system): Add explic...
d82474e452 * src/fns.c (syms_of_fns) <overriding-plist-environment>: ...
292c09ff6d Fix incorrect interaction of drag/drop and double click (b...
d6fadb1d26 * lisp/menu-bar.el (menu-bar-options-save): Add display-li...
daa959efbc * lisp/menu-bar.el (menu-bar-options-save): Add global-dis...
17fc74d1b9 * lisp/follow.el (follow-mode): Restore mode line lighter....
f20c2e2f3d ; Compare process status against 127 exactly
2d203ffb7e Extract the common part of ruby-flymake-simple and ruby-fl...
09944d499a Add Rubocop Flymake backend
c65a0ae7c4 ; Fix a typo
7ab7603125 Update nt/INSTALL.W64 (Bug#28601)
11db253c08 Remove incorrect NEWS item about VC state indicator (Bug#2...
2fdc01c036 * lisp/emacs-lisp/byte-run.el (defsubst): Doc fix.
735c8b516e Make c-defun-name analyze more thoroughly a function type ...
92f0c4cd56 Avoid bogus abbreviated file names if HOME changes
8d450453fa * lisp/emacs-lisp/byte-run.el (inline): Give it a doc.
37a3b4ea40 Fix erc keep-place module with new defaults (Bug#29111)
6c312605bf Add window divider faces to NS (bug#29353)

# Conflicts:
#	etc/NEWS
#	lisp/ruler-mode.el

1 files changed, 34 insertions, 24 deletions

diff --git a/lisp/files.el b/lisp/files.el
index 63dd509eab8..5d78cd07b6e 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -1859,9 +1859,9 @@ home directory is a root directory) and removes automounter prefixes
 
 When this function is first called, it caches the user's home
 directory as a regexp in `abbreviated-home-dir', and reuses it
-afterwards.  Lisp programs that temporarily set the home directory
-to a different value should let-bind `abbreviated-home-dir' for
-the modified home directory to take effect."
+afterwards (so long as the home directory does not change;
+if you want to permanently change your home directory after having
+started Emacs, set `abbreviated-home-dir' to nil so it will be recalculated)."
   ;; Get rid of the prefixes added by the automounter.
   (save-match-data
     (if (and automount-dir-prefix
@@ -1883,29 +1883,37 @@ the modified home directory to take effect."
       ;; give time for directory-abbrev-alist to be set properly.
       ;; We include a slash at the end, to avoid spurious matches
       ;; such as `/usr/foobar' when the home dir is `/usr/foo'.
-      (or abbreviated-home-dir
-	  (setq abbreviated-home-dir
-		(let ((abbreviated-home-dir "$foo"))
-                  (setq abbreviated-home-dir
-                        (concat "\\`"
-                                (abbreviate-file-name (expand-file-name "~"))
-                                "\\(/\\|\\'\\)"))
-                  ;; Depending on whether default-directory does or
-                  ;; doesn't include non-ASCII characters, the value
-                  ;; of abbreviated-home-dir could be multibyte or
-                  ;; unibyte.  In the latter case, we need to decode
-                  ;; it.  Note that this function is called for the
-                  ;; first time (from startup.el) when
-                  ;; locale-coding-system is already set up.
-                  (if (multibyte-string-p abbreviated-home-dir)
-                      abbreviated-home-dir
-                    (decode-coding-string abbreviated-home-dir
-                                          (if (eq system-type 'windows-nt)
-                                              'utf-8
-                                            locale-coding-system))))))
+      (unless abbreviated-home-dir
+        (put 'abbreviated-home-dir 'home (expand-file-name "~"))
+        (setq abbreviated-home-dir
+              (let ((abbreviated-home-dir "$foo"))
+                (setq abbreviated-home-dir
+                      (concat "\\`"
+                              (abbreviate-file-name
+                               (get 'abbreviated-home-dir 'home))
+                              "\\(/\\|\\'\\)"))
+                ;; Depending on whether default-directory does or
+                ;; doesn't include non-ASCII characters, the value
+                ;; of abbreviated-home-dir could be multibyte or
+                ;; unibyte.  In the latter case, we need to decode
+                ;; it.  Note that this function is called for the
+                ;; first time (from startup.el) when
+                ;; locale-coding-system is already set up.
+                (if (multibyte-string-p abbreviated-home-dir)
+                    abbreviated-home-dir
+                  (decode-coding-string abbreviated-home-dir
+                                        (if (eq system-type 'windows-nt)
+                                            'utf-8
+                                          locale-coding-system))))))
 
       ;; If FILENAME starts with the abbreviated homedir,
+      ;; and ~ hasn't changed since abbreviated-home-dir was set,
       ;; make it start with `~' instead.
+      ;; If ~ has changed, we ignore abbreviated-home-dir rather than
+      ;; invalidating it, on the assumption that a change in HOME
+      ;; is likely temporary (eg for testing).
+      ;; FIXME Is it even worth caching abbreviated-home-dir?
+      ;; Ref: https://debbugs.gnu.org/19657#20
       (if (and (string-match abbreviated-home-dir filename)
 	       ;; If the home dir is just /, don't change it.
 	       (not (and (= (match-end 0) 1)
@@ -1914,7 +1922,9 @@ the modified home directory to take effect."
 	       ;; Novell Netware allows drive letters beyond `Z:'.
 	       (not (and (memq system-type '(ms-dos windows-nt cygwin))
 			 (save-match-data
-			   (string-match "^[a-zA-`]:/$" filename)))))
+			   (string-match "^[a-zA-`]:/$" filename))))
+               (equal (get 'abbreviated-home-dir 'home)
+                      (expand-file-name "~")))
 	  (setq filename
 		(concat "~"
 			(match-string 1 filename)