Fix 'expand-file-name' during startup on MS-Windows

* src/w32.c (w32_init_file_name_codepage): New function, resets
file_name_codepage and w32_ansi_code_page to undo the values
recorded during dumping.
(codepage_for_filenames): Fix an embarrassing typo.  Ignore the
cached value of file-name encoding if it is nil, i.e. not
initialized yet.  Actually cache the last used file-name encoding
to avoid calling APIs when not necessary.

* src/w32.h (w32_init_file_name_codepage): Add prototype.

* src/w32term.c (syms_of_w32term): Set the value of
w32_unicode_filenames according to the OS version.  This avoids
resetting it during startup, which then causes temacs to run with
the incorrect value.

* src/emacs.c (main): Call w32_init_file_name_codepage early
during the startup.

* src/fileio.c (Fexpand_file_name) [WINDOWSNT]: Update 'newdir'
after converting $HOME to a UTF-8 string, so that 'newdirlim' is
consistent with it.  (Bug#25038)

* lisp/international/mule-cmds.el (set-locale-environment): Set
'default-file-name-coding-system' to the ANSI codepage even in
non-interactive sessions.

* lisp/files.el (directory-abbrev-alist, abbreviated-home-dir):
Doc fix.
(abbreviate-file-name): Decode 'abbreviated-home-dir' if it is a
unibyte string.

* doc/lispref/files.texi (Directory Names): Index
'directory-abbrev-alist'.

1 files changed, 7 insertions, 5 deletions

diff --git a/lisp/international/mule-cmds.el b/lisp/international/mule-cmds.el
index 5008fd5f27b..1ec7456c9e1 100644
--- a/lisp/international/mule-cmds.el
+++ b/lisp/international/mule-cmds.el
@@ -2704,10 +2704,12 @@ See also `locale-charset-language-names', `locale-language-names',
     ;; terminal-coding-system with the ANSI or console codepage.
     (when (and (eq system-type 'windows-nt)
                (boundp 'w32-ansi-code-page))
-      (let* ((code-page-coding
-              (intern (format "cp%d" (if noninteractive
-                                         (w32-get-console-codepage)
-                                       w32-ansi-code-page))))
+      (let* ((ansi-code-page-coding
+              (intern (format "cp%d" w32-ansi-code-page)))
+             (code-page-coding
+              (if noninteractive
+                  (intern (format "cp%d" (w32-get-console-codepage)))
+                ansi-code-page-coding))
              (output-coding
               (if noninteractive
                   (intern (format "cp%d" (w32-get-console-output-codepage)))
@@ -2717,7 +2719,7 @@ See also `locale-charset-language-names', `locale-language-names',
 	  (unless frame (setq locale-coding-system code-page-coding))
 	  (set-keyboard-coding-system code-page-coding frame)
 	  (set-terminal-coding-system output-coding frame)
-	  (setq default-file-name-coding-system code-page-coding))))
+	  (setq default-file-name-coding-system ansi-code-page-coding))))
 
     (when (eq system-type 'darwin)
       ;; On Darwin, file names are always encoded in utf-8, no matter