syntax_data: {"ast_node_type":"other","tokens":[{"end":88,"kind":"keyword","start":0,"text":"ty::ConstKind::Placeholder(placeholder)"}]}
source_snippet:             ty::ConstKind::Placeholder(placeholder) => write!(self, "{placeholder:?}")?,
context_before:             }
context_after:             // FIXME(generic_const_exprs):