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,
    };
}