call to __toString may return Exception

[orklah]

Hi,

I'm not sure it will be worth fixing but I'll report it anyway.

While working on phpDocumentor/phpDocumentor#2263

I noticed Psalm suggested to delete a cast to string that seemed not useful: https://github.com/phpDocumentor/phpDocumentor/pull/2263/files#diff-5844ff81b5eb5ff658aabe38d06279fdL70

I reproduced something similar in psalm.dev:
https://psalm.dev/r/d50c69dac0

We have an exception that could be thrown in __toString (note that this is valid from PHP 7.4 only).

The cast to (string) on a class that implements __toString can actually be valid code that may throw and that could be catched and handled.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/d50c69dac0

<?php
  
class maybe_stringable{
 /** @throws Exception */
  public function __toString(){
     if(rand(0,1)){
      	throw new exception(); 
     }
     return "";
  }
}

$a = new maybe_stringable();
try{
  (string) $a;
}
catch(Exception $e){
  //this class is not stringable
}

Psalm output (using commit b486bd4):

No issues!

[muglug]

I'm not sure it will be worth fixing but I'll report it anyway.

Anything that deletes working code is a bug that's worth fixing!