It's a common practice to use intptr_t-typed negative values. It would be handy to have a suffix for such literals in order to not confuse anyone with implicit sign-extending integer conversions and not use a cast at the same time.
Comment #1 by bugzilla — 2012-01-23T23:02:36Z
You can create a template to do custom literals, like for octal:
octal!1234