On Fri, Nov 12, 2021 at 7:00 AM Nikita Popov <nikita....@gmail.com> wrote:
> > With the introduction of Stringable PHP also started automatically adding > the string result type to __toString(), specifically for compatibility with > the interface. As such, it should be safe to add the string return type > everywhere for PHP >= 8.0. (If you use stubs with legacy arginfo, that > would automatically give you the right behavior: types on PHP 8, no types > on old versions.) > We haven't explored using stubs, but I'll keep that in mind. Andreas has definitely mentioned that in the past and I believe it's on the list of ideas to implement once we revisit typing across the board for the extension (which we plan to do since we finally dropped support for PHP 7.1). I previously added explicit string return types to all of our toString methods (including interfaces), which I understand is a small BC break for any userland classes implementing those interfaces (as rare as that is). Just yesterday, I had an idea to use tentative return type info on the interface toString methods ([mongodb/mongo-php-driver#1283]( https://github.com/mongodb/mongo-php-driver/pull/1283)), which seems to require no changes at all to userland classes. ReturnTypeWillChange attributes are not even required on PHP 8.1+ since the Stringable behavior will automatically add the return type info if it's omitted. For PHP 8.0 and earlier, we map the ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX macro to ZEND_BEGIN_ARG_INFO_EX -- so these methods will continue to have no return types there (also avoiding a BC break). I tested the change (i.e. tentative return type info for interfaces) with PHP's master branch to cover the warning you added in [86379b6]( https://github.com/php/php-src/commit/86379b6710f972e0d4a11c89ce28d5768d9824d3). There seems to be no conflict, which seems reasonable considering that return type is only "tentative" from the context of userland (and only until PHP 9.0, when it becomes enforced). Tentative return types are still considered the actual return type for internal purposes and satisfies the check for Stringable compatibility. Are we likely to run into issues with this approach? If so, I'll consider your last suggestion to define non-tentative return type info for interfaces on PHP 8.0+ (where Stringable will add it to userland classes automatically), and leave return type info absent for PHP 7.x. But if both are viable solutions, I think I prefer the tentative return type info approach. -- jeremy mikola
