Make input constraints into memoization hash immutable (bug#45376)

	* lisp/emacs-lisp/comp-cstr.el (comp-cstr-union-1)
	(comp-cstr-intersection): Copy input before soting it into the
	memoization hash table.

3 files changed, 20 insertions, 2 deletions

diff --git a/lisp/emacs-lisp/comp-cstr.el b/lisp/emacs-lisp/comp-cstr.el
index aaeb9cf3e9b..480d15616a0 100644
--- a/lisp/emacs-lisp/comp-cstr.el
+++ b/lisp/emacs-lisp/comp-cstr.el
@@ -507,7 +507,7 @@ DST is returned."
                     (comp-cstr-ctxt-union-1-mem-no-range comp-ctxt)))
            (res (or (gethash srcs mem-h)
                     (puthash
-                     srcs
+                     (mapcar #'comp-cstr-copy srcs)
                      (apply #'comp-cstr-union-1-no-mem range srcs)
                      mem-h))))
       (setf (typeset dst) (typeset res)
@@ -676,7 +676,7 @@ DST is returned."
     (let* ((mem-h (comp-cstr-ctxt-intersection-mem comp-ctxt))
            (res (or (gethash srcs mem-h)
                     (puthash
-                     srcs
+                     (mapcar #'comp-cstr-copy srcs)
                      (apply #'comp-cstr-intersection-no-mem srcs)
                      mem-h))))
       (setf (typeset dst) (typeset res)
diff --git a/test/src/comp-test-funcs.el b/test/src/comp-test-funcs.el
index a2663eaf9cf..d6bcfca2d94 100644
--- a/test/src/comp-test-funcs.el
+++ b/test/src/comp-test-funcs.el
@@ -417,6 +417,20 @@
         (setq args (cons (substring arg start pos) args))))
     args))
 
+(defun comp-test-45376-f ()
+  ;; Reduced from `eshell-ls-find-column-lengths'.
+  (let* (res
+         (len 2)
+         (i 0)
+         (j 0))
+    (while (< j len)
+      (if (= i len)
+          (setq i 0))
+      (setq res (cons i res)
+            j (1+ j)
+            i (1+ i)))
+    res))
+
 
 ;;;;;;;;;;;;;;;;;;;;
 ;; Tromey's tests ;;
diff --git a/test/src/comp-tests.el b/test/src/comp-tests.el
index 0594a4e086c..5f2d702fca0 100644
--- a/test/src/comp-tests.el
+++ b/test/src/comp-tests.el
@@ -409,6 +409,10 @@ https://lists.gnu.org/archive/html/bug-gnu-emacs/2020-03/msg00914.html."
   "Broken call args assumptions lead to infinite loop."
   (should (equal (comp-test-assume-in-loop-1-f "cd") '("cd"))))
 
+(comp-deftest bug-45376 ()
+  "<https://lists.gnu.org/archive/html/bug-gnu-emacs/2020-12/msg01883.html>"
+  (should (equal (comp-test-45376-f) '(1 0))))
+
 (defvar comp-test-primitive-advice)
 (comp-deftest primitive-advice ()
   "Test effectiveness of primitive advicing."