syntax_data: {"ast_node_type":"other","tokens":[{"end":46,"kind":"keyword","start":0,"text":"ty::Str"}]}
source_snippet:                 ty::Str => PatKind::Constant {
context_before:                 // optimization for now.
context_after:                     value: mir::Const::Ty(ty, ty::Const::new_value(tcx, cv, ty)),