Avoid crashes when casifying noncontiguous regions

This is a followon fix for Bug#37477.
* lisp/simple.el (region-extract-function):
Use setq here, since the var is now defined in C code.
* src/casefiddle.c (casify_pnc_region): New function.
(Fupcase_region, Fdowncase_region, Fcapitalize_region)
(Fupcase_initials_region): Use it.
(Fupcase_initials_region): Add region-noncontiguous-p flag
for consistency with the others.  All uses changed.
(syms_of_casefiddle): Define Qbounds, Vregion_extract_function.
* src/insdel.c (prepare_to_modify_buffer_1):
* src/keyboard.c (command_loop_1):
Use Vregion_extraction_function.
* src/insdel.c (syms_of_insdel): No need to define
Qregion_extract_function.
* test/src/casefiddle-tests.el (casefiddle-oldfunc): New var.
(casefiddle-loopfunc, casefiddle-badfunc): New functions.
(casefiddle-invalid-region-extract-function): New test.

1 files changed, 2 insertions, 14 deletions

diff --git a/lisp/simple.el b/lisp/simple.el
index 31e3b2bbaba..ecd7eb797e8 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -1087,7 +1087,7 @@ instead of deleted."
   :group 'killing
   :version "24.1")
 
-(defvar region-extract-function
+(setq region-extract-function
   (lambda (method)
     (when (region-beginning)
       (cond
@@ -1096,19 +1096,7 @@ instead of deleted."
        ((eq method 'delete-only)
         (delete-region (region-beginning) (region-end)))
        (t
-        (filter-buffer-substring (region-beginning) (region-end) method)))))
-  "Function to get the region's content.
-Called with one argument METHOD which can be:
-- nil: return the content as a string (list of strings for
-  non-contiguous regions).
-- `delete-only': delete the region; the return value is undefined.
-- `bounds': return the boundaries of the region as a list of one
-  or more cons cells of the form (START . END).
-- anything else: delete the region and return its content
-  as a string (or list of strings for non-contiguous regions),
-  after filtering it with `filter-buffer-substring', which
-  is called, for each contiguous sub-region, with METHOD as its
-  3rd argument.")
+        (filter-buffer-substring (region-beginning) (region-end) method))))))
 
 (defvar region-insert-function
   (lambda (lines)