1 files changed, 4 insertions, 2 deletions
diff --git a/src/buffer.h b/src/buffer.h
index dc1d62beb00..a13351b5ea6 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -309,8 +309,10 @@ while (0)
 /* Maximum number of bytes in a buffer.
   A buffer cannot contain more bytes than a 1-origin fixnum can represent,
-   nor can it be so large that C pointer arithmetic stops working.  */
+   nor can it be so large that C pointer arithmetic stops working.
-#define BUF_BYTES_MAX min (MOST_POSITIVE_FIXNUM - 1, min (SIZE_MAX, PTRDIFF_MAX))
+   The ptrdiff_t cast ensures that this is signed, not unsigned.  */
+#define BUF_BYTES_MAX \
+  (ptrdiff_t) min (MOST_POSITIVE_FIXNUM - 1, min (SIZE_MAX, PTRDIFF_MAX))
 /* Return the address of byte position N in current buffer.  */

diff --git a/src/buffer.h b/src/buffer.h index dc1d62beb00..a13351b5ea6 100644 --- a/src/buffer.h +++ b/src/buffer.h
@@ -309,8 +309,10 @@ while (0)
309		309
310	/* Maximum number of bytes in a buffer.	310	/* Maximum number of bytes in a buffer.
311	A buffer cannot contain more bytes than a 1-origin fixnum can represent,	311	A buffer cannot contain more bytes than a 1-origin fixnum can represent,
312	nor can it be so large that C pointer arithmetic stops working. */	312	nor can it be so large that C pointer arithmetic stops working.
313	#define BUF_BYTES_MAX min (MOST_POSITIVE_FIXNUM - 1, min (SIZE_MAX, PTRDIFF_MAX))	313	The ptrdiff_t cast ensures that this is signed, not unsigned. */
		314	#define BUF_BYTES_MAX \
		315	(ptrdiff_t) min (MOST_POSITIVE_FIXNUM - 1, min (SIZE_MAX, PTRDIFF_MAX))
314		316
315	/* Return the address of byte position N in current buffer. */	317	/* Return the address of byte position N in current buffer. */
316		318