Non regression test

Author: VincentLanglet

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php

@@ -1100,6 +1100,12 @@ public function testBug10394(): void
 		$this->analyse([__DIR__ . '/data/bug-10394.php'], []);
 	}
 
+	public function testBug12930(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-12930.php'], []);
+	}
+
 	public function testBug13628(): void
 	{
 		$this->treatPhpDocTypesAsCertain = true;

tests/PHPStan/Rules/Comparison/data/bug-12930.php

@@ -0,0 +1,13 @@
+<?php declare(strict_types = 1);
+
+namespace Bug12930;
+
+/** @return mixed */
+function getMixed() {return \stdClass::class;}
+
+$val = getMixed();
+if (is_string($val) && !is_a($val, \stdClass::class, true)) {
+	throw new \Exception();
+}
+
+echo is_string($val) ? 'string' : 'something else';

tests/PHPStan/Type/TypeCombinatorTest.php

@@ -2136,7 +2136,7 @@ public static function dataUnion(): iterable
 			[
 				[
 					new ArrayType(new MixedType(), new StringType()),
-					new MixedType(false, new ArrayType(new MixedType(), new MixedType())),
+					new MixedType(subtractedType: new ArrayType(new MixedType(), new MixedType())),
 				],
 				MixedType::class,
 				'mixed=implicit',