bug#44807: 28.0.50; pcase macroexpander for rx is not autoloaded

[Basil L. Contovounesios]

Severity: wishlist

0. emacs -Q
1. (pcase "a" ((rx "a")))
2. C-x C-s /tmp/a.el RET
3. M-x compile RET
4. C-a C-k emacs -Q -batch -f batch-byte-compile a.el RET

This fails with:

  In toplevel form:
  a.el:4:1: Error: Unknown rx pattern: (rx "a")

This can be solved by adding (require 'rx) to the file.  Given that all
other rx.el entry points are autoloaded, however, I was wondering
whether the same could be done for its pcase macroexpander.

Would adding an autoload cookie before (pcase-defmacro rx ...) work?

Thanks,

-- 
Basil

In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo version 
1.16.0, Xaw3d scroll bars)
 of 2020-11-22 built on thunk
Repository revision: 9490f12c4dc4deb16f4e900646319f6de033982c
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description: Debian GNU/Linux bullseye/sid

Configured using:
 'configure 'CC=ccache gcc' 'CFLAGS=-O2 -march=native' --config-cache
 --prefix=/home/blc/.local --with-x-toolkit=lucid
 --with-file-notification=yes --with-x'

Configured features:
XAW3D XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND GPM DBUS GSETTINGS GLIB
NOTIFY INOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT
LIBOTF ZLIB TOOLKIT_SCROLL_BARS LUCID X11 XDBE XIM MODULES THREADS
LIBSYSTEMD JSON PDUMPER LCMS2

Important settings:
  value of $LANG: en_IE.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix