# HG changeset patch
# Parent  89821243621b2ebf7aa38143e813c2cc76739fff
Issue #1621: Abort on integer overflows with GCC; avoid some trivial overflows

diff -r 89821243621b Modules/_elementtree.c
--- a/Modules/_elementtree.c	Thu Jul 14 07:45:24 2016 +0300
+++ b/Modules/_elementtree.c	Fri Jul 15 02:52:10 2016 +0000
@@ -1725,11 +1725,13 @@
             if (!list)
                 return NULL;
 
-            for (cur = start, i = 0; i < slicelen;
-                 cur += step, i++) {
+            for (cur = start, i = 0; i < slicelen; i++) {
                 PyObject* item = self->extra->children[cur];
                 Py_INCREF(item);
                 PyList_SET_ITEM(list, i, item);
+                if (i + 1 < slicelen) {
+                    cur += step;
+                }
             }
 
             return list;
@@ -1880,9 +1882,12 @@
                 Py_DECREF(seq);
                 return -1;
             }
-            for (cur = start, i = 0; i < slicelen;
-                 cur += step, i++)
+            for (cur = start, i = 0; i < slicelen; i++) {
                 PyList_SET_ITEM(recycle, i, self->extra->children[cur]);
+                if (i + 1 < slicelen) {
+                    cur += step;
+                }
+            }
         }
 
         if (newlen < slicelen) {
@@ -1896,11 +1901,13 @@
         }
 
         /* replace the slice */
-        for (cur = start, i = 0; i < newlen;
-             cur += step, i++) {
+        for (cur = start, i = 0; i < newlen; i++) {
             PyObject* element = PySequence_Fast_GET_ITEM(seq, i);
             Py_INCREF(element);
             self->extra->children[cur] = element;
+            if (i + 1 < newlen) {
+                cur += step;
+            }
         }
 
         self->extra->length += newlen - slicelen;
diff -r 89821243621b Modules/audioop.c
--- a/Modules/audioop.c	Thu Jul 14 07:45:24 2016 +0300
+++ b/Modules/audioop.c	Fri Jul 15 02:52:10 2016 +0000
@@ -446,7 +446,9 @@
         return NULL;
     for (i = 0; i < fragment->len; i += width) {
         int val = GETRAWSAMPLE(width, fragment->buf, i);
-        if (val < 0) absval = (-val);
+        /* Cast to unsigned before negating. Unsigned overflow is well-
+        defined, but signed overflow is not. */
+        if (val < 0) absval = -(unsigned int)val;
         else absval = val;
         if (absval > max) max = absval;
     }
diff -r 89821243621b configure
--- a/configure	Thu Jul 14 07:45:24 2016 +0300
+++ b/configure	Fri Jul 15 02:52:10 2016 +0000
@@ -6763,7 +6763,7 @@
         if test "$CC" != 'g++' ; then
 	    STRICT_PROTO="-Wstrict-prototypes"
 	fi
-        # For gcc 4.x we need to use -fwrapv so lets check if its supported
+        # For GCC >= 4.x we need to use -fwrapv, so check if it's supported
         if "$CC" -v --help 2>/dev/null |grep -- -fwrapv > /dev/null; then
            WRAP="-fwrapv"
         fi
@@ -6779,8 +6779,12 @@
 	    if test "$Py_DEBUG" = 'true' ; then
 		# Optimization messes up debuggers, so turn it off for
 		# debug builds.
+                if "$CC" -v --help 2>/dev/null |grep -- -ftrapv > /dev/null
+                then
+                    TRAPV="-ftrapv"
+                fi
                 if "$CC" -v --help 2>/dev/null |grep -- -Og > /dev/null; then
-                    OPT="-g -Og -Wall $STRICT_PROTO"
+                    OPT="-g $TRAPV -Og -Wall $STRICT_PROTO"
                 else
                     OPT="-g -O0 -Wall $STRICT_PROTO"
                 fi
diff -r 89821243621b configure.ac
--- a/configure.ac	Thu Jul 14 07:45:24 2016 +0300
+++ b/configure.ac	Fri Jul 15 02:52:10 2016 +0000
@@ -1367,7 +1367,7 @@
         if test "$CC" != 'g++' ; then
 	    STRICT_PROTO="-Wstrict-prototypes"
 	fi
-        # For gcc 4.x we need to use -fwrapv so lets check if its supported
+        # For GCC >= 4.x we need to use -fwrapv, so check if it's supported
         if "$CC" -v --help 2>/dev/null |grep -- -fwrapv > /dev/null; then
            WRAP="-fwrapv"
         fi
@@ -1383,8 +1383,12 @@
 	    if test "$Py_DEBUG" = 'true' ; then
 		# Optimization messes up debuggers, so turn it off for
 		# debug builds.
+                if "$CC" -v --help 2>/dev/null |grep -- -ftrapv > /dev/null
+                then
+                    TRAPV="-ftrapv"
+                fi
                 if "$CC" -v --help 2>/dev/null |grep -- -Og > /dev/null; then
-                    OPT="-g -Og -Wall $STRICT_PROTO"
+                    OPT="-g $TRAPV -Og -Wall $STRICT_PROTO"
                 else
                     OPT="-g -O0 -Wall $STRICT_PROTO"
                 fi