syntax_data: {"ast_node_type":"variable","tokens":[{"end":64,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                     let field_layout = layout_of(cx, field_ty)?;
context_before:                     let field_ty = ty_field(cx, (ty, layout), idx);
context_after:                     let field = Self::from_ty(field_ty, cx)?;