non-empty-array might be empty after array_keys() with filter

Author: staabm

src/Type/Accessory/NonEmptyArrayType.php

@@ -161,7 +161,7 @@ public function unsetOffset(Type $offsetType): Type
 
 	public function getKeysArrayFiltered(Type $filterValueType, TrinaryLogic $strict): Type
 	{
-		return $this->getKeysArray();
+		return new ErrorType();
 	}
 
 	public function getKeysArray(): Type

tests/PHPStan/Analyser/nsrt/bug-13377.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace Bug13377;
+
+use function PHPStan\Testing\assertType;
+
+function doFoo() {
+	$array = random_array();
+
+	// removing this line prevents the unexpected behavior
+	if(empty($array)){
+		return;
+	}
+
+	// this should not assume result is not empty
+	// same result when $strict is set to true
+	$possiblyEmptyInvalid = array_keys($array, 'yes');
+	assertType('list<(int|string)>', $possiblyEmptyInvalid);
+
+	$possiblyEmptyInvalid = array_keys($array, 'yes', true);
+	assertType('list<(int|string)>', $possiblyEmptyInvalid);
+
+	$possiblyEmptyValid = array_keys(array_filter($array, fn($val) => $val == 'yes'));
+	assertType('list<(int|string)>', $possiblyEmptyValid);
+}
+
+
+
+/**
+ * @return array<string>
+ */
+function random_array(): array
+{
+	$return = [];
+	for($i = 0; $i < 10; $i++){
+		if(random_int(0, 1) === 1){
+			$return[] = 'yes';
+		}else{
+			$return[] = 'no';
+		}
+	}
+
+	return $return;
+}