emit FutureWarning for negative start/end indices

anilbey · anilbey · commit b3fe8ee211ce · 2023-07-23T11:46:34.000+02:00
diff --git a/Modules/_sre/sre.c b/Modules/_sre/sre.c
@@ -453,13 +453,22 @@ state_init(SRE_STATE* state, PatternObject* pattern, PyObject* string,
     }
 
     /* adjust boundaries */
-    if (start < 0)
+    if (start < 0) {
+        PyErr_WarnEx(PyExc_FutureWarning,
+                     "Negative start index will not be truncated to zero in the future",
+                     1);
         start = 0;
+    }
     else if (start > length)
         start = length;
 
-    if (end < 0)
+
+    if (end < 0) {
+        PyErr_WarnEx(PyExc_FutureWarning,
+                     "Negative end index will not be truncated to zero in the future",
+                     1);
         end = 0;
+    }
     else if (end > length)
         end = length;
 
