syntax_data: {"ast_node_type":"other","tokens":[{"end":46,"kind":"keyword","start":0,"text":"self.tcx.def_span(uv.def),"}]}
source_snippet:                     self.tcx.def_span(uv.def),
context_before:                 err.span_label(
context_after:                     crate::fluent_generated::mir_build_const_defined_here,