Infer non-empty-array after array_key_first/last()

[staabm]

closes phpstan/phpstan#13546

[phpstan-bot]

This pull request has been marked as ready for review.

[VincentLanglet]

I thought you forgot null !== array_key_first($a) but seems like it works looking at the test.
I'm not familiar with this code to know why at first sight.

[staabm]

we are in resolveNormalizedIdentical, which is invoked in both directions here:

phpstan-src/src/Analyser/TypeSpecifier.php

Lines 2258 to 2269 in eb4e247

	// Normalize to: fn() === expr
	if ($rightExpr instanceof FuncCall && !$leftExpr instanceof FuncCall) {
	$specifiedTypes = $this->resolveNormalizedIdentical(new Expr\BinaryOp\Identical(
	$rightExpr,
	$leftExpr,
	), $scope, $context);
	} else {
	$specifiedTypes = $this->resolveNormalizedIdentical(new Expr\BinaryOp\Identical(
	$leftExpr,
	$rightExpr,
	), $scope, $context);
	}

[VincentLanglet]

You're getting escaped mutant here, but if I understand correctly, it should be supported by

if (array_key_first($array) !== $nullOrInt) {
		assertType('list<string>', $array);
	}

[staabm]

agree. I tested it locally and the test starts failling when I manually mutate the code.