Remove unused lowering field and method #51034
                
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r? @nikomatsakis
So while trying to understand lowering better, I found out that there's something related to creating definitions. Analyzing that further, I realized that it is entirely dead code.
The
parent_deffield was only ever used for setting and resetting the field itself. The field was never read anywhere else and thus its value was entirely unused.Maybe the
unused_fieldlint should detect when the only use of a field is the field being read without using the read value other than writing back to the field?The diff is best viewed without whitespace changes getting in the way: https://github.com/rust-lang/rust/pull/51034/files?w=1