Multi-line comments

[froystig]

Currently no support for multi-line comments in source files, only single-line (the // kind). Implement multi-line comments in the frontend. Should be depth-balanced. As Graydon puts it, "the lexer already has a sample bracequote balanced-quote sub-mode, easy to copy for multiline comments."

[mbrubeck]

Here's an implementation of /* */ comments with nesting:
http://github.com/mbrubeck/rust/commit/fdab6b81b7478394d8fd9e10a2f1b005e6b7a16c

[graydon]

Thanks. Taken as 244ea68 .