Merge from origin/emacs-26

0589de5 (origin/emacs-26) Fix markup of fake keys in the ELisp manual
82d4b98 Avoid errors in Auto Revert mode
a3b1935 Mention empty strings in file name expansion, emacs lisp refe...
a38da0d cc-mode.texi: Work around makeinfo alignment bug.  Fix proble...
464ee80 Warn against recursive invocations of 'buffer-list-update-hoo...
60b5c10 Provide more details in doc-string of 'delete-windows-on' (Bu...
f0be0f1 Improve documentation of 'delete-windows-on'
f1bddc7 * lisp/frame.el (make-frame-command): Doc fix.  (Bug#34715)
2848623 Avoid undefined behavior in gdb-mi.el
dbf1837 * lisp/window.el (fit-frame-to-buffer): Make doc-string more ...
099ef44 Minor spelling and grammar fixes (bug#34756)
52fd400 Minor improvement of documentation of '(when CONDITION . SPEC)'
f872b65 Improve documentation of 'auto-coding-functions'
04cad5e Fix visiting XML files with non-Unix EOL format
a89fabe Update example major mode code in Elisp manual

# Conflicts:
#	lisp/autorevert.el
#	lisp/window.el

1 files changed, 12 insertions, 1 deletions

diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index 5c99ea2781c..0e57cf9666f 100644
--- a/doc/lispref/files.texi
+++ b/doc/lispref/files.texi
@@ -16,7 +16,7 @@ described in @ref{Backups and Auto-Saving}.
 names.  A file name is a string.  Most of these functions expand file
 name arguments using the function @code{expand-file-name}, so that
 @file{~} is handled correctly, as are relative file names (including
-@file{../}).  @xref{File Name Expansion}.
+@file{../} and the empty string).  @xref{File Name Expansion}.
 
   In addition, certain @dfn{magic} file names are handled specially.
 For example, when a remote file name is specified, Emacs accesses the
@@ -2402,6 +2402,17 @@ This is for the sake of filesystems that have the concept of a
 superroot above the root directory @file{/}.  On other filesystems,
 @file{/../} is interpreted exactly the same as @file{/}.
 
+Expanding @file{.} or the empty string returns the default directory:
+
+@example
+@group
+(expand-file-name "." "/usr/spool/")
+     @result{} "/usr/spool"
+(expand-file-name "" "/usr/spool/")
+     @result{} "/usr/spool"
+@end group
+@end example
+
 Note that @code{expand-file-name} does @emph{not} expand environment
 variables; only @code{substitute-in-file-name} does that: