rust-lang/rfcs — pull request #463 by huonw (2014-11-13 01:40:11+00:00)
Title: RFC to restrict placing an identifier after a literal.

Include identifiers immediately after literals in the literal token to allow future expansion, e.g. "foo"bar and a 1baz are considered whole (but semantically invalid) tokens, rather than two separate tokens "foo", bar and 1, baz respectively. This allows future expansion of handling literals without risking breaking (macro) code.