Fix supertype checks between int range and constant int union

src/Type/UnionType.php

@@ -17,6 +17,7 @@
 use PHPStan\ShouldNotHappenException;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Constant\ConstantBooleanType;
+use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Generic\GenericClassStringType;
 use PHPStan\Type\Generic\TemplateMixedType;
 use PHPStan\Type\Generic\TemplateType;
@@ -137,6 +138,10 @@ public function isSuperTypeOf(Type $otherType): TrinaryLogic
 			return $otherType->isSubTypeOf($this);
 		}
 
+		if ($otherType instanceof IntegerRangeType && $otherType->getMin() !== null && $otherType->getMax() !== null) {
+			return $this->isSuperTypeOfIntegerRange($otherType);
+		}
+
 		$result = TrinaryLogic::createNo()->lazyOr($this->getTypes(), static fn (Type $innerType) => $innerType->isSuperTypeOf($otherType));
 		if ($result->yes()) {
 			return $result;
@@ -149,6 +154,41 @@ public function isSuperTypeOf(Type $otherType): TrinaryLogic
 		return $result;
 	}
 
+	private function isSuperTypeOfIntegerRange(IntegerRangeType $otherType): TrinaryLogic
+	{
+		$min = $otherType->getMin();
+		$max = $otherType->getMax();
+		if ($min === null || $max === null) {
+			throw new ShouldNotHappenException();
+		}
+
+		$matchingConstantIntegers = 0;
+		$results = [];
+
+		foreach ($this->types as $innerType) {
+			if ($innerType instanceof ConstantIntegerType) {
+				if ($innerType->getValue() >= $min && $innerType->getValue() <= $max) {
+					$matchingConstantIntegers++;
+					continue;
+				}
+				return TrinaryLogic::createNo();
+			}
+
+			$result = $innerType->isSuperTypeOf($otherType);
+			if ($result->yes()) {
+				return $result;
+			}
+
+			$results[] = $result;
+		}
+
+		if ($matchingConstantIntegers === ($max - $min + 1)) {
+			return TrinaryLogic::createYes();
+		}
+
+		return TrinaryLogic::createNo()->or(...$results);
+	}
+
 	public function isSubTypeOf(Type $otherType): TrinaryLogic
 	{
 		return TrinaryLogic::lazyExtremeIdentity($this->getTypes(), static fn (Type $innerType) => $otherType->isSuperTypeOf($innerType));

tests/PHPStan/Rules/Properties/TypesAssignedToPropertiesRuleTest.php

@@ -445,4 +445,10 @@ public function testBug4680(): void
 		$this->analyse([__DIR__ . '/data/bug-4680.php'], []);
 	}
 
+	public function testBug3383(): void
+	{
+		$this->checkExplicitMixed = true;
+		$this->analyse([__DIR__ . '/data/bug-3383.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Properties/data/bug-3383.php

@@ -0,0 +1,13 @@
+<?php declare(strict_types = 1);
+
+namespace Bug3383;
+
+class HelloWorld
+{
+	/** @var 0|1|2|3 */
+	public $classification = 0;
+
+	public function test(): void {
+		$this->classification = random_int(0, 3);
+	}
+}