C++11 raw string literals with embedded escapes are mislexed

[edaskel@…]

Raw string literals are partly intended to make it easier to write strings that would otherwise require extensive escaping - e.g., regular expressions. Unfortunately Wave seems to get confused when backslashes appear in C++11 raw string literals. For example:

R"(A\+)"

is parsed by compilers as a string of three characters: A, backslash, and +. Wave lexes this as an unterminated raw string literal followed by six individual character tokens. By contrast:

R"(A+)"

is correctly parsed as a two-character raw string literal.

[edaskel@…]

A minimal example of the problem