Re: syntax-ppss bug?

[Stefan Monnier]

> I tracked down the problem below to an infloop in
> python-beginning-of-statement which occurs because syntax-ppss returns -1
> as the depth.  I think that is the wrong value.  Would you
> please investigate?

Actually, parse-partial-sexp returns the same -1.  And if you close more
parens, you can get to -2, -3, ... it seems it's done on purpose.

> I suspect this Python program was garbled by introduction of
> incorrect line breaks, and that it is actually invalid.  Do you know?

I believe so as well.  I think the problem is that only the first of the two
lines below is commented, so the second line's closing parens confuse the
paren-counter.

   # tablename -> [ ["query templates for subqueries", 
   ['columnkey1','columnkey2'...] ]  , ... ]

> I was editing some pyton and hit the tab button.  Then emacs
> started processing and 'froze up'.  C-g brought it out.

> It happended when I hit tab at the start of the line
> that has [ ["App", "SELECT a.appi ...

Does the patch below fix it for you?


        Stefan


--- orig/lisp/progmodes/python.el
+++ mod/lisp/progmodes/python.el
@@ -292,9 +292,9 @@
 comments and strings, or that the bracket/paren nesting depth is nonzero."
   (or (and (eq ?\\ (char-before (line-end-position 0)))
           (not (syntax-ppss-context (syntax-ppss))))
-      (/= 0 (syntax-ppss-depth
-            (save-excursion      ; syntax-ppss with arg changes point
-              (syntax-ppss (line-beginning-position)))))))
+      (< 0 (syntax-ppss-depth
+            (save-excursion      ; syntax-ppss with arg changes point
+              (syntax-ppss (line-beginning-position)))))))
 
 (defun python-comment-line-p ()
   "Return non-nil iff current line has only a comment."
@@ -719,7 +719,10 @@
        (python-beginning-of-string)
        ;; Skip forward out of nested brackets.
        (condition-case ()              ; beware invalid syntax
-           (progn (backward-up-list (syntax-ppss-depth (syntax-ppss))) t)
+           (let ((depth (syntax-ppss-depth (syntax-ppss))))
+              ;; Beware negative depths.
+              (if (> depth 0) (backward-up-list depth))
+              t)
          (error (throw 'foo nil))))))
   (back-to-indentation))