syntax_data: {"ast_node_type":"impl","tokens":[{"end":80,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // Ensure that the impl is constrained, otherwise projection may give us
context_before:     if let Some(&impl_item_id) = tcx.impl_item_implementor_ids(impl_def_id).get(&assoc_def_id) {
context_after:         // bad unconstrained infer vars.