Emacs mode has issues with single quotes

[haxney]

The latest version of rust-mode for Emacs (20130928.1740) has issues with
single-quoted characters, especially when that character is a " (double
quote). The following program executes correctly in Rust 0.8, but is font-locked
improperly in Emacs:

fn main() {
    println!("{}", '"');
}

It treats the double quote as the beginning of a string which runs to the end of
the file. If the double quote character is escaped like so:

fn main() {
    println!("{}", '\"');
}

Then there is not a problem with an unterminated string, but the characters
inside the single quotes are not fontified at all.

Note: Both programs compile and execute successfully under Rust 0.8.

This is related to #8793

[haxney]

A related problem is in the following program:

fn main() {
    println!("{}", '(');
}

The paren in the quotations is matched with the paren closing the println!,
and so the final close brace is shown as being an invalid match with the opening
paren of println!. Strangely enough, the paren in the single quote is shown as
having font-lock-string-face.

[dcrewi]

Fixing this issue is a single-line patch, but that still leaves the problem of font-locking lifetimes. They use unbalanced single quotes.

[steveklabnik]

Moved to rust-lang/rust-mode#5