syntax_data: {"ast_node_type":"impl","tokens":[{"end":73,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // logic sometimes passing identity-substituted impl headers.
context_before:             // We may still encounter projections here due to the printing
context_after:             ty::Alias(ty::Projection, ty::AliasTy { def_id, args, .. }) => {