Func

    pub const Func = struct {
        ret_ty: RetTy,
        /// Points to the block that contains the param instructions for this function.
        /// If this is a `declaration`, it refers to the declaration's value body.
        param_block: Index,
        body_len: u32,

        pub const RetTy = packed struct(u32) {
            /// 0 means `void`.
            /// 1 means the type is a simple `Ref`.
            /// Otherwise, the length of a trailing body.
            body_len: u31,
            /// Whether the return type is generic, i.e. refers to one or more previous parameters.
            is_generic: bool,
        };

        pub const SrcLocs = struct {
            /// Line index in the source file relative to the parent decl.
            lbrace_line: u32,
            /// Line index in the source file relative to the parent decl.
            rbrace_line: u32,
            /// lbrace_column is least significant bits u16
            /// rbrace_column is most significant bits u16
            columns: u32,
        };
    }