[mirekrusin]

Exactly, and use 'if ((a = b)) ...' in those rare cases when it's appropriate.

[efaref]

Even then I would prefer an explicit comparison:

    if ((a = b) != NULL) ...

I think Rust has a happy medium, where assignment evaluates to (), not the variable (important as this means you don't have an implicit borrow), but the idiom expressed here is usually replaced by:

    if let Some(thing) = fn_that_returns_option_thing() ...