clarify comment

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@6674

diff --git a/include/pub_tool_tooliface.h b/include/pub_tool_tooliface.h
index 77e6761e3e34d0f19fbc592c61c7eaf86406f9e1..065b637c58039ed32b55062d3b7d71ddc952a54a 100644 (file)
--- a/include/pub_tool_tooliface.h
+++ b/include/pub_tool_tooliface.h
@@ -368,7 +368,9 @@ extern void VG_(needs_superblock_discards) (
 /* Tool defines its own command line options? */
 extern void VG_(needs_command_line_options) (
    // Return True if option was recognised.  Presumably sets some state to
-   // record the option as well.
+   // record the option as well.  Nb: tools can assume that the argv will
+   // never disappear.  So they can, for example, store a pointer to a string
+   // within an option, rather than having to make a copy.
    Bool (*process_cmd_line_option)(Char* argv),
 
    // Print out command line usage for options for normal tool operation.