Fix infinite loop when opening file containing "comment" (#651)

Closes #586

CHANGELOG.md

@@ -6,6 +6,10 @@
 
 * Font-lock Lein's `defproject` as a keyword.
 
+### Bugs fixed
+
+* [#586](https://github.com/clojure-emacs/clojure-mode/issues/586): Fix infinite loop when opening file containing `comment` with `clojure-toplevel-inside-comment-form` set to `t`.
+
 ## 5.16.0 (2022-12-14)
 
 ### Changes

clojure-mode.el

@@ -2264,8 +2264,11 @@ position before the current position."
           (while (< (point) position)
             (clojure-forward-logical-sexp 1)
             (clojure-backward-logical-sexp 1)
-            (push (point) sexp-positions)
-            (clojure-forward-logical-sexp 1))
+            ;; Needed to prevent infinite recursion when there's only 1 form in buffer.
+            (if (eq (point) (car sexp-positions))
+                (goto-char position)
+              (push (point) sexp-positions)
+              (clojure-forward-logical-sexp 1)))
         (scan-error nil))
       sexp-positions)))
 

test/clojure-mode-sexp-test.el

@@ -169,6 +169,24 @@
             (goto-char (point-max))
             (expect (clojure-find-ns) :to-equal expected)))))))
 
+(describe "clojure-sexp-starts-until-position"
+  (it "should return starting points for forms after POINT until POSITION"
+    (with-clojure-buffer "(run 1) (def b 2) (slurp \"file\")\n"
+        (goto-char (point-min))
+        (expect (not (cl-set-difference '(19 9 1)
+                                        (clojure-sexp-starts-until-position (point-max)))))))
+
+  (it "should return starting point for a single form in buffer after POINT"
+    (with-clojure-buffer "comment\n"
+        (goto-char (point-min))
+        (expect (not (cl-set-difference '(1)
+                                        (clojure-sexp-starts-until-position (point-max)))))))
+
+  (it "should return nil if POSITION is behind POINT"
+    (with-clojure-buffer "(run 1) (def b 2)\n"
+        (goto-char (point-max))
+        (expect (not (clojure-sexp-starts-until-position (- (point-max) 1)))))))
+
 (provide 'clojure-mode-sexp-test)
 
 ;;; clojure-mode-sexp-test.el ends here