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Date: Fri, 19 May 2023 05:52:08 +0200 (CEST)
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Subject: Re: [PHP-DEV] PHP 8 Backward Incompatible Change Notifications
From: mails@thomasbley.de (Thomas Bley)

Hi Alan,

regarding "String to Number Comparison", you can cast the value to int to get the old behaviour:

php -r "var_dump(0 == (int) '0');"
php -r "var_dump(0 == (int) '0.0');"
php -r "var_dump(0 == (int) 'foo');"
php -r "var_dump(0 == (int) '');"
php -r "var_dump(42 == (int) ' 42');"
php -r "var_dump(42 == (int) '42foo');"

gives:
bool(true)
bool(true)
bool(true)
bool(true)
bool(true)
bool(true)

Best Regards
Thomas

> Alan Smithee <alan.smithee@fivecolorteam.com> hat am 18.05.2023 23:34 CEST geschrieben:
> 
>  
> Hi Internals!
> 
> Looking for counsel from the PHP maintainers here regarding the upgrade 
> path from PHP v7 to v8.
> 
> There is a subset of backward incompatible language changes that are 
> remarkably tricky to track back into a codebase through manual code 
> inspection, automated testing, or static analysis (...I'd love to be 
> proven wrong here). The behavior change in these cases are triggered by 
> data passed into functions or operators at runtime, such as "String to 
> Number Comparison" [1].
> 
> Using this example, in a large-enough (and legacy-enough) codebase for a 
> data-driven application where there is a cost to every change, I am 
> struggling to find an effective mechanism for targeting the set of all 
> equality comparisons in the codebase that could potentially operate on a 
> pair of number/string operands.
> 
> I've found that the most effective mechanism that has helped me to 
> quickly and comprehensively identify areas of code at highest risk for 
> the upgrade has been deprecation and warning notifications provided by 
> the PHP language regarding backward incompatible changes.
> 
> To this end, I'm considering patching the current version of the 
> language I use, i.e. v7.4.24, for my own benefit and introducing more 
> notifications for the handful of highest-risk, backward incompatible 
> changes not currently reported by PHP.
> 
> I see Nikita Popov has already done something along these lines [2] for 
> the "String to Number Comparison" change mentioned above.
> 
> My questions for the group:
> 
>    1. Are there any particular reason(s) why some PHP 8 backward 
> incompatible changes, like "String to Number Comparison", weren't 
> instrumented as deprecation or warning notifications in PHP 7?
>    2. Are there simpler or more effective strategies to account for the 
> set of backward incompatible changes I've called out given the 
> constraint of a large, legacy codebase?
> 
> [1] 
> https://www.php.net/manual/en/migration80.incompatible.php#migration80.incompatible.core.string-number-comparision
> [2] https://github.com/php/php-src/pull/3917
> 
> Thanks in advance for any insight or advice anyone may be able to offer!
> 
> -- 
> ALAN SMITHEE
> Software Engineer | Five Color Team
> 
> -- 
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