* lisp/vc/ediff-init.el (ediff-H-glyph):
* lisp/vc/ediff-util.el (ediff-inferior-compare-regions)
(ediff-setup-keymap):
* lisp/vc/ediff-wind.el (ediff-control-frame-parameters)
(ediff-prefer-iconified-control-frame)
(ediff-setup-control-frame, ediff-xemacs-select-frame-hook): Remove
XEmacs compat code and declare compatibility functions obsolete.

* lisp/vc/ediff-init.el (ediff-temp-file-prefix): Redefine as
obsolete variable alias for 'temporary-file-directory'.
* lisp/vc/ediff-util.el (ediff-make-temp-file): Don't use obsolete
variable name.

* lisp/emacs-lisp/edebug.el (edebug--display-1): Remove comment
regarding an XEmacs exclusive variable.

These are not used for anything these days and can therefore be
removed.  Package developers should check the Emacs version instead.
Ref: https://lists.gnu.org/r/emacs-devel/2020-03/msg00080.html

* lisp/calendar/icalendar.el (icalendar-version):
* lisp/dframe.el (dframe-version):
* lisp/emacs-lisp/checkdoc.el (checkdoc-version):
* lisp/emulation/edt.el (edt-version):
* lisp/international/mule.el (mule-version)
(mule-version-date):
* lisp/linum.el (linum-version):
* lisp/play/bubbles.el (bubbles-version):
* lisp/speedbar.el (speedbar-version):
* lisp/textmodes/remember.el (remember-version):
* lisp/url/url-vars.el (url-version):
* lisp/woman.el (woman-version): Declare obsolete.

* lisp/emacs-lisp/checkdoc.el (checkdoc-start-section):
* lisp/speedbar.el (speedbar-mode):
* lisp/url/url-about.el (url-about-protocols):
* lisp/url/url-http.el (url-http--user-agent-default-string):
* lisp/url/url-news.el (url-news-fetch-message-id):
* lisp/woman.el (woman-menu, woman-mode): Stop using variables
declared obsolete above.

These version numbers are historical accidents and not relevant today.
Ref: https://lists.gnu.org/r/emacs-devel/2020-03/msg00080.html

* lisp/calendar/icalendar.el:
* lisp/emacs-lisp/checkdoc.el:
* lisp/hippie-exp.el:
* lisp/linum.el:
* lisp/master.el:
* lisp/progmodes/cwarn.el:
* lisp/repeat.el:
* lisp/ruler-mode.el:
* lisp/textmodes/remember.el:
* lisp/wdired.el:
* lisp/woman.el: Change "Version" header to "Old-Version".

* lisp/gnus/message.el (message-draft-headers): The Date header should
reflect when the message is sent, not when it was saved or delayed.

* lisp/image/exif.el (exif--direct-ascii-value): New function
(bug#40127).
(exif--parse-directory): Use it to get the correct values for
in-directory (i.e., shorter than 4 octets) strings.

* src/xdisp.c (reset_box_start_end_flags): New function.
(handle_face_prop): Only set the start_of_box_run_p flag, don't
reset it.
(pop_it): Set the face_box_p flag, if the popped face requires
that, when continuing iteration over buffer text.
(get_next_display_element, next_element_from_display_vector): Only
set the end_of_box_run_p flag, never reset it here.
(set_iterator_to_next): Don't reset the start_of_box_run_p and
end_of_box_run_p flags here.  They are now reset as side effect of
PRODUCE_GLYPHS.
(append_space_for_newline): Restore the end_of_box_run_p flag
after PRODUCE_GLYPHS where we previously didn't reset it.
* src/dispextern.h (PRODUCE_GLYPHS): Call
reset_box_start_end_flags after producing glyphs.
(Bug#40124)

* src/timefns.c (frac_to_double): Remove unnecessary runtime check,
since the denominator is always positive.

* src/timefns.c (frac_to_double): Omit optimization that is
invalid on machines with excess precision (e.g., gcc x86 with 387
FPU), because it double-rounds.  Found via ‘gcc -m32’ on x86-64.