Revert "cl-loop: Calculate the array length just once"

It fails when using 'and' (parallel bindings) for arrays (Bug#40727).
* lisp/emacs-lisp/cl-macs.el (cl--parse-loop-clause): Revert to
recomputing array length.
* test/lisp/emacs-lisp/cl-macs-tests.el (cl-macs-loop-and-arrays): New
test.

2 files changed, 10 insertions, 10 deletions

diff --git a/lisp/emacs-lisp/cl-macs.el b/lisp/emacs-lisp/cl-macs.el
index 4408bb58464..fef8786b599 100644
--- a/lisp/emacs-lisp/cl-macs.el
+++ b/lisp/emacs-lisp/cl-macs.el
@@ -1317,13 +1317,11 @@ For more details, see Info node `(cl)Loop Facility'.
 
                ((memq word '(across across-ref))
                 (let ((temp-vec (make-symbol "--cl-vec--"))
-                      (temp-len (make-symbol "--cl-len--"))
                       (temp-idx (make-symbol "--cl-idx--")))
                   (push (list temp-vec (pop cl--loop-args)) loop-for-bindings)
-                  (push (list temp-len `(length ,temp-vec)) loop-for-bindings)
                   (push (list temp-idx -1) loop-for-bindings)
                   (cl--push-clause-loop-body
-                   `(< (setq ,temp-idx (1+ ,temp-idx)) ,temp-len))
+                   `(< (setq ,temp-idx (1+ ,temp-idx)) (length ,temp-vec)))
                   (if (eq word 'across-ref)
                       (push (list var `(aref ,temp-vec ,temp-idx))
                             cl--loop-symbol-macs)
@@ -1337,7 +1335,6 @@ For more details, see Info node `(cl)Loop Facility'.
                                     (error "Expected `of'"))))
                       (seq (cl--pop2 cl--loop-args))
                       (temp-seq (make-symbol "--cl-seq--"))
-                      (temp-len (make-symbol "--cl-len--"))
                       (temp-idx
                        (if (eq (car cl--loop-args) 'using)
                            (if (and (= (length (cadr cl--loop-args)) 2)
@@ -1348,19 +1345,16 @@ For more details, see Info node `(cl)Loop Facility'.
                   (push (list temp-seq seq) loop-for-bindings)
                   (push (list temp-idx 0) loop-for-bindings)
                   (if ref
-                      (progn
+                      (let ((temp-len (make-symbol "--cl-len--")))
                         (push (list temp-len `(length ,temp-seq))
                               loop-for-bindings)
                         (push (list var `(elt ,temp-seq ,temp-idx))
                               cl--loop-symbol-macs)
-                        (cl--push-clause-loop-body `(< ,temp-idx ,temp-len)))
-                    ;; Evaluate seq length just if needed, that is, when seq is not a cons.
-                    (push (list temp-len (or (consp seq) `(length ,temp-seq)))
-                          loop-for-bindings)
+                        (cl--push-clause-loop-body `(< ,temp-idx ,temp-len)))
                     (push (list var nil) loop-for-bindings)
                     (cl--push-clause-loop-body `(and ,temp-seq
                                                      (or (consp ,temp-seq)
-                                                         (< ,temp-idx ,temp-len))))
+                                                         (< ,temp-idx (length ,temp-seq)))))
                     (push (list var `(if (consp ,temp-seq)
                                          (pop ,temp-seq)
                                        (aref ,temp-seq ,temp-idx)))
diff --git a/test/lisp/emacs-lisp/cl-macs-tests.el b/test/lisp/emacs-lisp/cl-macs-tests.el
index 9ca84f156a0..77609a42a99 100644
--- a/test/lisp/emacs-lisp/cl-macs-tests.el
+++ b/test/lisp/emacs-lisp/cl-macs-tests.el
@@ -39,6 +39,12 @@
                           collect (list c b a))
                  '((4.0 2 1) (8.3 6 5) (10.4 9 8)))))
 
+(ert-deftest cl-macs-loop-and-arrays ()
+  "Bug#40727"
+  (should (equal (cl-loop for y = (- (or x 0)) and x across [1 2]
+                          collect (cons x y))
+                 '((1 . 0) (2 . -1)))))
+
 (ert-deftest cl-macs-loop-destructure ()
   (should (equal (cl-loop for (a b c) in '((1 2 4.0) (5 6 8.3) (8 9 10.4))
                           collect (list c b a))