On Wed, Jul 29, 2020 at 2:21 AM tyson andre <tysonandre...@hotmail.com> wrote:
> Hi internals, > > For #[, my main objection is the various ways this can change the lexing > in a way that is impractical to (efficiently) backfill, > and that the proposed patch doesn't address the fact that the syntax may > change the syntax of php 7 code in unexpected ways. > > This syntax would help phpcs with easy examples **in the short term**, > when attributes are on a single line, > but would make more complicated refactorings buggy and error-prone unless > phpcbf was run in the same major version. > When attributes span multiple lines, the lexing is completely different > for `#[]`. > For example, the below syntax would yield false in php 7, but a generator > in php 8. > (There's precedent at least - the lexing of heredocs changed in php 7.3 or > 7.4) > That's an interesting point. Emulating #[] lexing on older versions will definitely be a challenge for PHP-Parser. I don't think we should make concerns of external tooling hold us back too much, but the phpcs argument really doesn't hold water. Regards, Nikita > ``` > // Aside: This code snippet seems to have an assert failure in the lexer > with the patch in the RFC > // Zend/zend_compile.c:1794: zendlex: Assertion > `!(executor_globals.exception) || ret == T_ERROR' failed. > function generator() { > yield #[MyCustomAttribute(' > false; > // ']function() {}; > } > ``` > > And another example which would cause problems for phpcs in php 7 - the > comment syntax can cause code to be treated as inline html instead of php > tokens. > > ``` > <?php > // This example echoes the rest of the source code in php 7 > // and echoes "Test" in php 8. > #[DeprecationReason('reason: <https://some-website/reason?>')] > function main() {} > const APP_SECRET = 'app-secret'; > echo "Test\n"; > ``` > > I'd posted another example in https://externals.io/message/111101#111133 > > One way I'd thought of to avoid this ambiguity would be to assert in PHP > 8.0 with an E_COMPILE_ERROR (or E_COMPILE_WARNING) that: > 1. All tokens of the #[...] annotation are on the same line > 2. No non-whitespace token follows the ] on the same line. > It may be permissible to allow other `//` comments or multiple > attributes after it on the same line, though. > 3. No `?>` substrings within the rest of the line after #[, maybe > > Although I'm not sure if others are actually concerned about this > ambiguity and these are really artificial examples for code. > > As for `<<`, I'm assuming people may have meant `yield <<JIT>> function() > {};`, > but `yield` already has a precedence and didn't have issues - otherwise > `yield+2;` could be adding 2 to the result of a yield. > (It's unambiguously `yield(+2);` right now). > I forget how it'd be parsed, but it wouldn't be ambiguous. > > As for `@@`, all of its known issues seem to have been resolved, > and there is still the potential for future issues, but I still prefer it > over the `#[` implementation in that patch. > > P.S. I'd like to note that > 1. A lot more discussion has occurred since the initial vote. > 2. Since `@@` was obviously passing at the time, fewer voters would put > much thought into detailed tradeoffs of `#[` > 3. I haven't seen those specific drawbacks to `#[` of potentially > significantly changing lexing (not just losing tokens) mentioned, > but the shorter attributes syntax RFC did seem to mention params were > commented out. > > One idea I'd have on voting would be to have the exact same 3-way vote, > again, and pick the attribute syntax with the same ranked choice procedure. > I assume proponents of `#[` would have similar objections if an RFC with a > two-way vote for `<<>>` and `@@` was started first. > > Regards, > - Tyson > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: https://www.php.net/unsub.php > >