syntax_data: {"ast_node_type":"other","tokens":[{"end":43,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:     if impl_source.has_non_region_infer() {
context_before:     let impl_source = tcx.erase_regions(impl_source);
context_after:         // Unused generic types or consts on an impl get replaced with inference vars,