Incorrect variable may not be defined

[1ed]

Summary of a problem or a feature request

"Variable $key might not be defined." reported incorrectly. The $key variable is a scalar bool value (not a reference) and it is assigned only once.

Code snippet that reproduces the problem

https://phpstan.org/r/a8eba03f-946a-426f-90af-7575659a6a9e

Expected output

Do not report this.

[ondrejmirtes]

Hi, this is very analyser-unfriendly code. It wouldn't work in other languages either. I group similar issues here: https://github.com/phpstan/phpstan/milestone/12

The main problem is that the value of $a can change meanwhile. For example if it changes from false to true, you'll get "undefined variable" PHP error. Variable can change in many ways - it can be passed by reference somewhere, or it can be overwritten directly or for example by an extract() call.

I usually solve this with an isset: https://phpstan.org/r/1795fe9c-8125-4a8b-818a-682652ec3b08

[MacGritsch]

If extract() is not used in whole (analyzed) code and the variable is not passed to any other function (and even if it is passed, the analyzer should know if it is by reference) and not modified in code, the false positive error could be suppressed. I think that could cover more than 95%.
Otherwise the "solution" for most projects is to ignore that error completly :-/

[ondrejmirtes]

Implemented: phpstan/phpstan-src@54284c8

[github-actions]

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