infer non-falsy-string in string replace functions

[staabm]

No description provided.

[staabm]

I reproduced the build error locally with

<?php

function foo(float $f) {
	$s = (string) $f;
	\PHPStan\dumpType($s); // line 5
	$price = str_replace(',', '.', $s);
	\PHPStan\dumpType($price); // line 7
	if ($price == '0') {
		$price = 0.000001;
	}
}

which leads to

> php bin/phpstan analyze test.php  --debug

Note: Using configuration file /Users/staabm/workspace/phpstan-src/phpstan.neon.dist.
/Users/staabm/workspace/phpstan-src/test.php
 ------ -------------------------------------------------------------------------------------------
  Line   test.php
 ------ -------------------------------------------------------------------------------------------
  3      Function foo() has no return type specified.
  5      Dumped type: numeric-string
  7      Dumped type: non-falsy-string
  8      If condition is always false.
  8      Loose comparison using == between non-falsy-string and '0' will always evaluate to false.
  8      Loose comparison via "==" is not allowed.
         💡 Use strict comparison via "===" instead.
 ------ -------------------------------------------------------------------------------------------

 [ERROR] Found 6 errors

and reproduces with https://3v4l.org/6emcl

will work on a fix

[ondrejmirtes]

Thank you.