map_collect_result_unit does not recognize for loop

What it does

This is a suggestion for the map_collect_result_unit lint.
I just refactored this piece of code:

fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
    for (uuid, err) in self.0.iter() {
        writeln!(f, "{}: {}", uuid, err)?;
    }
    Ok(())
}

into this:

fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
    self.0.iter().map(|(uuid, err)| writeln!(f, "{}: {}", uuid, err)).collect()
}

And then the lint told me that I can do

fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
    self.0.iter().try_for_each(|(uuid, err)| writeln!(f, "{}: {}", uuid, err))
}

But maybe it is possible that the lint also tells me that my first version can be written better?

I don't know whether this is possible, but it would be nice to catch the for-loop-version as well here.

Categories (optional)

• Kind: clippy::style

Start by locating the map_collect_result_unit lint implementation and its existing tests. Compare how the lint recognizes iterator-based collection with how it analyzes for loops, then determine whether the example should produce the same try_for_each suggestion. Done means the supported loop form is handled and regression coverage verifies the suggested rewrite.