rustc::lint::builtin::ILLEGAL_STRUCT_OR_ENUM_CONSTANT_PATTERN

pub static ILLEGAL_STRUCT_OR_ENUM_CONSTANT_PATTERN: &'static Lint = &::rustc::lint::Lint{name: "ILLEGAL_STRUCT_OR_ENUM_CONSTANT_PATTERN",
                     default_level: ::rustc::lint::Warn,
                     desc:
                         "constants of struct or enum type can only be used in a pattern if the struct or enum has `#[derive(PartialEq, Eq)]`",}

Unstable (rustc_private)