syntax_data: {"ast_node_type":"variable","tokens":[{"end":67,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                                             let source_projection =
context_before:                                         .enter_forall(hr_target_projection, |target_projection| {
context_after:                                                 self.infcx.instantiate_binder_with_fresh_vars(