2 files changed, 9 insertions, 3 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 54fff9356f3..06682f4637e 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,11 @@
+2012-08-26  Paul Eggert  <eggert@cs.ucla.edu>
+
+        * lisp.h (ASET): Remove attempt to detect side effects.
+        It was meant to be temporary and it often doesn't work,
+        because when IDX has side effects the behavior of IDX==IDX
+        is undefined.  See Stefan Monnier in
+        <http://lists.gnu.org/archive/html/emacs-devel/2012-08/msg00762.html>.
+
 2012-08-26  Barry OReilly  <gundaetiapo@gmail.com>  (tiny change)
 
         * lisp.h (functionp): New function (extracted from Ffunctionp).
diff --git a/src/lisp.h b/src/lisp.h
index c44ba7be347..4437fa44b6d 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -606,10 +606,8 @@ clip_to_bounds (ptrdiff_t lower, EMACS_INT num, ptrdiff_t upper)
 
 #define AREF(ARRAY, IDX)        XVECTOR ((ARRAY))->contents[IDX]
 #define ASIZE(ARRAY)            XVECTOR ((ARRAY))->header.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)),       \
+  (eassert (0 <= (IDX) && (IDX) < ASIZE (ARRAY)),       \
    XVECTOR (ARRAY)->contents[IDX] = (VAL))
 
 /* Convenience macros for dealing with Lisp strings.  */