(set_text_properties_1): Clearly mark that the interval should not be empty.

diff --git a/src/textprop.c b/src/textprop.c
index a473bebeab6995a69e402e7a8a22fd24b8444a27..cd07484204bf128a4aed23f0105435016ce83fbd 100644 (file)
--- a/src/textprop.c
+++ b/src/textprop.c
@@ -1303,7 +1303,8 @@ set_text_properties (start, end, properties, object, signal_after_change_p)
    properties PROPERTIES.  BUFFER is the buffer containing
    the text.  This does not obey any hooks.
    You can provide the interval that START is located in as I,
-   or pass NULL for I and this function will find it.  */
+   or pass NULL for I and this function will find it.
+   This function assumes that START < END.  */
 
 void
 set_text_properties_1 (start, end, properties, buffer, i)
@@ -1316,6 +1317,7 @@ set_text_properties_1 (start, end, properties, buffer, i)
 
   s = XINT (start);
   len = XINT (end) - s;
+  eassert (len > 0);
   if (i == 0)
     i = find_interval (BUF_INTERVALS (XBUFFER (buffer)), s);