Method parse_meta

zeroize_derive/src/lib.rs:233–317

Parse `#[zeroize(...)]` attribute metadata (e.g. `drop`)

(&mut self, meta: &Meta, variant: Option<&Variant>, binding: Option<&Field>)

    /// Parse `#[zeroize(...)]` attribute metadata (e.g. `drop`)
    fn parse_meta(&mut self, meta: &Meta, variant: Option<&Variant>, binding: Option<&Field>) {
        if meta.path().is_ident("drop") {
            assert!(!self.drop, "duplicate #[zeroize] drop flags");

            match (variant, binding) {
                (_variant, Some(_binding)) => {
                    // structs don't have a variant prefix, and only structs have bindings outside of a variant
                    let item_kind = match variant {
                        Some(_) => "enum",
                        None => "struct",
                    };
                    panic!(
                        concat!(
                            "The #[zeroize(drop)] attribute is not allowed on {} fields. ",
                            "Use it on the containing {} instead.",
                        ),
                        item_kind, item_kind,
                    )
                }
                (Some(_variant), None) => panic!(concat!(
                    "The #[zeroize(drop)] attribute is not allowed on enum variants. ",
                    "Use it on the containing enum instead.",
                )),
                (None, None) => (),
            };

            self.drop = true;
        } else if meta.path().is_ident("bound") {
            assert!(self.bound.is_none(), "duplicate #[zeroize] bound flags");

            match (variant, binding) {
                (_variant, Some(_binding)) => {
                    // structs don't have a variant prefix, and only structs have bindings outside of a variant
                    let item_kind = match variant {
                        Some(_) => "enum",
                        None => "struct",
                    };
                    panic!(
                        concat!(
                            "The #[zeroize(bound)] attribute is not allowed on {} fields. ",
                            "Use it on the containing {} instead.",
                        ),
                        item_kind, item_kind,
                    )
                }
                (Some(_variant), None) => panic!(concat!(
                    "The #[zeroize(bound)] attribute is not allowed on enum variants. ",
                    "Use it on the containing enum instead.",
                )),
                (None, None) => {
                    if let Meta::NameValue(meta_name_value) = meta {
                        if let Expr::Lit(ExprLit {
                            lit: Lit::Str(lit), ..
                        }) = &meta_name_value.value
                        {
                            if lit.value().is_empty() {
                                self.bound = Some(Bounds(Punctuated::new()));
                            } else {