strpos/stripos should assert non-empty-string like str_contains

[kkmuffme]

https://psalm.dev/r/2f458027ac

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/2f458027ac

<?php

/**
 * @var string $a
 * @var string $b
 */

if ( str_contains( $a, 'foo' ) ) {
 	/** @psalm-trace $a */;   
}

if ( strpos( $b, 'foo' ) !== false ) {
 	/** @psalm-trace $b */;   
}

if ( stripos( $b, 'foo' ) !== false ) {
 	/** @psalm-trace $b */;   
}

Psalm output (using commit 0ea2a6a):

INFO: Trace - 9:25 - $a: non-empty-string

INFO: Trace - 13:25 - $b: string

INFO: Trace - 17:25 - $b: string

[orklah]

seems easy to implement:

psalm/stubs/CoreGenericFunctions.phpstub

Line 1085 in 1a1d9c9

* @psalm-assert-if-true =(T is '' ? string : non-empty-string) $haystack

[robchett]

I'm not sure this is a simple fix as the return type of str(i)pos is false|int, there would need to be an assert-if-int annotation?

[orklah]

Some tests would be needed but it could still work with assert-if-true because Psalm does not check for true but check if you will enter the condition or not, so it's more a assert-if-truthy

[robchett]

int is not truthy because of 0 and 0 is a valid return when the haystack starts with the needle.

Is it currently possible to do input type narrowing in a ReturnTypeProvider?

[orklah]

0 is not truthy, but for things like

if(strpos(...)){ }
or
if(strpos(...) !== false){ }
it should still work as intended, but yeah, it's a dirty hack.

It could probably be possible to narrow the type from a ReturnTypeProvider but it may be hard. You do have the context so you know the type of each variable in the caller context and you can change them

[kkmuffme]

Why not just do it the other way round? assert-if-false -> if it's false, we cannot infer anything, but in the opposite case we know it's non-empty?

[robchett]

assert-if-false would require changing the type to non-empty-string in the default case then widening when false which would require multiple annotations if it worked at all

/** 
 * @psalm-assert non-empty-string $haystack
 * @psalm-assert-if-false string $haystack
 */

Orklah's "hack" did indeed work he said it would so I've opened #9788

[orklah]

That was fixed :)