Fix: (org-ql--define-query-preamble-fn) Pcase pattern for Emacs 30

Now all tests and lints pass on Emacs versions 27.1-29.4, and the
current 30.0.50-ish snapshot build.

Note: This change was originally applied on master, but it seems
reasonable to apply it to this stable bugfix release now.

Fixes #433.

Reported-by: Akira Komamura <akira.komamura@gmail.com>
Co-developed-by: Stefan Monnier <monnier@iro.umontreal.ca>

README.org

@@ -560,6 +560,9 @@ Simple links may also be written manually in either sexp or non-sexp form, like:
 + Predicate ~level~'s preamble optimizer allows expressions in place of the numeric argument.  (See [[https://github.com/alphapapa/org-ql/issues/460][#460]].  Thanks to [[https://github.com/Stewmath][Stewmath]] for reporting.)
 + Reading of view settings from Org links in upcoming Emacs version.  ([[https://github.com/alphapapa/org-ql/issues/461][#461]].  Thanks to [[https://github.com/snogge][Ola Nilsson]] for help debugging, and for maintaining [[https://github.com/jorgenschaefer/emacs-buttercup][Buttercup]].)
 
+*Compatibility*
++ Fix compilation error on Emacs 30.  ([[https://github.com/alphapapa/org-ql/issues/433][#433]].  Thanks to [[https://github.com/akirak][Akira Komamura]] and [[https://github.com/monnier][Stefan Monnier]].)
+
 ** 0.8.8
 
 *Fixes*

org-ql.el

@@ -1118,7 +1118,10 @@ defined in `org-ql-predicates' by calling `org-ql-defpred'."
                                         ;; Only one preamble is allowed
                                         element)
                                       (pcase element
-                                        (`(or _) element)
+                                        (`(or ,element)
+                                         ;; A predicate with a single name: unwrap the OR.  (Pcase doesn't like
+                                         ;; "one-armed ORs", giving a "Please avoid it" compilation error.)
+                                         element)
 
                                         ,@preamble-patterns
 

org-ql.info

@@ -1099,6 +1099,12 @@ File: README.info,  Node: 089-pre,  Next: 088,  Up: Changelog
      maintaining Buttercup
      (https://github.com/jorgenschaefer/emacs-buttercup).)
 
+   *Compatibility*
+   • Fix compilation error on Emacs 30.  (#433
+     (https://github.com/alphapapa/org-ql/issues/433).  Thanks to Akira
+     Komamura (https://github.com/akirak) and Stefan Monnier
+     (https://github.com/monnier).)
+
 
 File: README.info,  Node: 088,  Next: 087,  Prev: 089-pre,  Up: Changelog
 
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