(ASET): Check bounds.

2 files changed, 9 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index afc6603da5e..b3ffe08f3ba 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2008-02-10  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * lisp.h (ASET): Check bounds.
+
 2008-02-10  Glenn Morris  <rgm@gnu.org>
 
         * buffer.c (mode-name): Doc fix.
diff --git a/src/lisp.h b/src/lisp.h
index 5156386551a..daa45d3aad8 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -589,8 +589,12 @@ extern size_t pure_size;
 /* Convenience macros for dealing with Lisp arrays.  */
 
 #define AREF(ARRAY, IDX)        XVECTOR ((ARRAY))->contents[IDX]
-#define ASET(ARRAY, IDX, VAL)   (AREF ((ARRAY), (IDX)) = (VAL))
 #define ASIZE(ARRAY)            XVECTOR ((ARRAY))->size
+/* The IDX==IDX tries to detect when the macro argument is side-effecting.  */
+#define ASET(ARRAY, IDX, VAL)   \
+  (eassert ((IDX) == (IDX)),                            \
+   eassert ((IDX) >= 0 && (IDX) < ASIZE (ARRAY)),       \
+   ASLOT ((ARRAY), (IDX)) = (VAL))
 
 /* Convenience macros for dealing with Lisp strings.  */