Rollup merge of #138929 - oli-obk:assoc-ctxt-of-trait, r=compiler-errors

Visitors track whether an assoc item is in a trait impl or an inherent impl

`AssocCtxt::Impl` now contains an `of_trait` field. This allows ast lowering and nameres to not have to track whether we're in a trait impl or an inherent impl.

Author: matthiaskrgr

src/visitor.rs

@@ -624,7 +624,8 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
         // TODO(calebcartwright): Not sure the skip spans are correct
         let (ai, skip_span, assoc_ctxt) = match visitor_kind {
             AssocTraitItem(ai) => (*ai, ai.span(), visit::AssocCtxt::Trait),
-            AssocImplItem(ai) => (*ai, ai.span, visit::AssocCtxt::Impl),
+            // There is no difference between trait and inherent assoc item formatting
+            AssocImplItem(ai) => (*ai, ai.span, visit::AssocCtxt::Impl { of_trait: false }),
             _ => unreachable!(),
         };
         skip_out_of_file_lines_range_visitor!(self, ai.span);