Simplify Span::source_callee impl

[WaffleLapkin]

Imo the iterator impl is easier to grasp.

[rustbot]

r? @cjgillot

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[cjgillot]

Good catch. A while loop would be even better.

[WaffleLapkin]

@cjgillot I don't see how this can be cleanly written with a while loop. Note that we need two recent versions (because we need the value before the root), which ends up being worse, imo:

    pub fn source_callee(self) -> Option<ExpnData> {
        let mut expn_data = None;
        let mut next_expn_data = self.ctxt().outer_expn_data();

        while !next_expn_data.is_root() {
            expn_data = Some(next_expn_data);
            next_expn_data = next_expn_data.call_site.ctxt().outer_expn_data();
        }

        expn_data
    }

[cjgillot]

Fair enough.
@bors r+ rollup

[bors]

📌 Commit fe4aec1 has been approved by cjgillot

It is now in the queue for this repository.