Fix 'treesit-max-buffer-size' and its use

* lisp/treesit.el (treesit-max-buffer-size): Avoid overflow in
computing buffer-size limit.  Account for 32-but systems built
"--with-wide-int".  Extend doc string.
(treesit-ready-p): Compare the limit with the size of the buffer
in bytes, not in characters.

* src/treesit.c (treesit_check_buffer_size): Measure buffer size
in bytes.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/treesit.c b/src/treesit.c
index 835b07c9312..4a7c4019561 100644
--- a/src/treesit.c
+++ b/src/treesit.c
@@ -840,11 +840,11 @@ treesit_ensure_position_synced (Lisp_Object parser)
 static void
 treesit_check_buffer_size (struct buffer *buffer)
 {
-  ptrdiff_t buffer_size = (BUF_Z (buffer) - BUF_BEG (buffer));
-  if (buffer_size > UINT32_MAX)
+  ptrdiff_t buffer_size_bytes = (BUF_Z_BYTE (buffer) - BUF_BEG_BYTE (buffer));
+  if (buffer_size_bytes > UINT32_MAX)
     xsignal2 (Qtreesit_buffer_too_large,
               build_pure_c_string ("Buffer size cannot be larger than 4GB"),
-              make_fixnum (buffer_size));
+              make_fixnum (buffer_size_bytes));
 }
 
 static Lisp_Object treesit_make_ranges (const TSRange *, uint32_t, struct buffer *);