if x { true } else { false }

[kmcallister]

Not a Rust-specific problem but I've seen it a lot in code from people who are new to programming in general.

Could generalize to find other forms that are better expressed by logical operators.

[llogiq]

I think that one should be simple enough to detect, and it's also easy to create a good warning. I'd catch all instances of if { Lit:bool } else { Lit:bool } and suggest a suitable replacement based on the literals.

I'll take a stab at it when I find some free time.

[Manishearth]

Yep, it's pretty simple. Go ahead! :)

[kmcallister]

I'd catch all instances of if { Lit:bool } else { Lit:bool } and suggest a suitable replacement based on the literals.

It'd be great to have a general, declarative way to express rules like that. Maybe something similar to Coccinelle.

[Manishearth]

Technically it's just a single huge match statement (assuming syntax::ptr::P doesn't get in the way) ;)

[kmcallister]

It would be cool to do this with quotation:

fn check_expr(&mut self, cx: &Context, expr: &Expr) {
    match *expr {
        q!(if $e:expr { $a:lit } else { $b:lit }) => ...

I think this is actually achievable now, if you replace the whole match by an invocation of a procedural macro, similar to html5ever's match_token!.

[llogiq]

A macro should be able to generate code to deal with ptr::P, as irritating as it sometimes is. But until we have this macro, I'm going to write the lint the traditional way.

[llogiq]

Done. The warnings could give more specific directions (they are a bit abstract for a newbie), but it works, and it's late now; I guess, I'll revisit them later.