Add binding for item to ensure it is evaluated before place

s-expressionists · Jun 4, 2024 · 74b5c6f · 74b5c6f
1 parent 5b0c32d
commit 74b5c6f
Showing 1 changed file with 7 additions and 5 deletions.
diff --git a/Code/pushnew.lisp b/Code/pushnew.lisp
@@ -9,11 +9,13 @@
   (if (and test-supplied-p test-not-supplied-p)
       (progn (warn 'warn-both-test-and-test-not-given)
              `(error 'both-test-and-test-not-given))
-      (multiple-value-bind (vars vals store-vars writer-form reader-form)
-          (get-setf-expansion place environment)
-        `(let (,@(mapcar #'list vars vals))
-           (let ((,(car store-vars)
-                   (adjoin ,item ,reader-form ,@rest)))
+      (let ((item-var (gensym)))
+        (multiple-value-bind (vars vals store-vars writer-form reader-form)
+            (get-setf-expansion place environment)
+          `(let* ((,item-var ,item)
+                  ,@(mapcar #'list vars vals)
+                  (,(car store-vars)
+                    (adjoin ,item-var ,reader-form ,@rest)))
              ,writer-form)))))
 
 (setf (documentation 'pushnew 'function)