improve EnumCaseObjectType subtracting

Author: schlndh

phpstan-baseline.neon

@@ -1692,12 +1692,6 @@ parameters:
 			count: 5
 			path: src/Type/TypeCombinator.php
 
-		-
-			message: '#^Doing instanceof PHPStan\\Type\\Enum\\EnumCaseObjectType is error\-prone and deprecated\. Use Type\:\:getEnumCases\(\) instead\.$#'
-			identifier: phpstanApi.instanceofType
-			count: 2
-			path: src/Type/TypeCombinator.php
-
 		-
 			message: '#^Doing instanceof PHPStan\\Type\\FloatType is error\-prone and deprecated\. Use Type\:\:isFloat\(\) instead\.$#'
 			identifier: phpstanApi.instanceofType

src/Type/Enum/EnumCaseObjectType.php

@@ -18,6 +18,7 @@
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\GeneralizePrecision;
 use PHPStan\Type\IsSuperTypeOfResult;
+use PHPStan\Type\NeverType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\SubtractableType;
 use PHPStan\Type\Type;
@@ -94,7 +95,7 @@ public function isSuperTypeOf(Type $type): IsSuperTypeOfResult
 
 	public function subtract(Type $type): Type
 	{
-		return $this;
+		return $this->changeSubtractedType($type);
 	}
 
 	public function getTypeWithoutSubtractedType(): Type
@@ -104,7 +105,11 @@ public function getTypeWithoutSubtractedType(): Type
 
 	public function changeSubtractedType(?Type $subtractedType): Type
 	{
-		return $this;
+		if ($subtractedType === null || ! $this->equals($subtractedType)) {
+			return $this;
+		}
+
+		return new NeverType();
 	}
 
 	public function getSubtractedType(): ?Type

src/Type/TypeCombinator.php

@@ -18,7 +18,6 @@
 use PHPStan\Type\Constant\ConstantFloatType;
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Constant\ConstantStringType;
-use PHPStan\Type\Enum\EnumCaseObjectType;
 use PHPStan\Type\Generic\GenericClassStringType;
 use PHPStan\Type\Generic\TemplateArrayType;
 use PHPStan\Type\Generic\TemplateBenevolentUnionType;
@@ -540,7 +539,7 @@ private static function unionWithSubtractedType(
 			return $type;
 		}
 
-		if ($type instanceof SubtractableType && ! $type instanceof EnumCaseObjectType) {
+		if ($type instanceof SubtractableType) {
 			$subtractedType = $type->getSubtractedType() === null
 				? $subtractedType
 				: self::union($type->getSubtractedType(), $subtractedType);
@@ -596,17 +595,31 @@ private static function intersectWithSubtractedType(
 			}
 
 			$subtractedType = self::union(...$subtractedTypes);
-		} elseif ($b instanceof SubtractableType && ! $b instanceof EnumCaseObjectType) {
-			$subtractedType = $b->getSubtractedType();
-			if ($subtractedType === null) {
-				return $a->getTypeWithoutSubtractedType();
-			}
 		} else {
-			$subtractedTypeTmp = self::intersect($a->getTypeWithoutSubtractedType(), $a->getSubtractedType());
-			if ($b->isSuperTypeOf($subtractedTypeTmp)->yes()) {
-				return $a->getTypeWithoutSubtractedType();
+			$isBAlreadySubtracted = $a->getSubtractedType()->isSuperTypeOf($b);
+
+			if ($isBAlreadySubtracted->no()) {
+				return $a;
+			} elseif ($isBAlreadySubtracted->yes()) {
+				$subtractedType = self::remove($a->getSubtractedType(), $b);
+
+				if ($subtractedType instanceof NeverType) {
+					$subtractedType = null;
+				}
+
+				return $a->changeSubtractedType($subtractedType);
+			} elseif ($b instanceof SubtractableType) {
+				$subtractedType = $b->getSubtractedType();
+				if ($subtractedType === null) {
+					return $a->getTypeWithoutSubtractedType();
+				}
+			} else {
+				$subtractedTypeTmp = self::intersect($a->getTypeWithoutSubtractedType(), $a->getSubtractedType());
+				if ($b->isSuperTypeOf($subtractedTypeTmp)->yes()) {
+					return $a->getTypeWithoutSubtractedType();
+				}
+				$subtractedType = new MixedType(false, $b);
 			}
-			$subtractedType = new MixedType(false, $b);
 		}
 
 		$subtractedType = self::intersect(

tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php

@@ -8105,11 +8105,11 @@ public function dataArrayKeysInBranches(): array
 				'$array',
 			],
 			[
-				'non-empty-array&hasOffsetValue(\'key\', mixed)',
+				'non-empty-array&hasOffsetValue(\'key\', mixed~null)',
 				'$generalArray',
 			],
 			[
-				'mixed',
+				'mixed~null',
 				'$generalArray[\'key\']',
 			],
 			[

tests/PHPStan/Type/TypeCombinatorTest.php

@@ -1069,7 +1069,7 @@ public function dataUnion(): iterable
 					new ObjectWithoutClassType(new ObjectType('A')),
 				],
 				MixedType::class,
-				'mixed=implicit',
+				'mixed~int=implicit',
 			],
 			[
 				[
@@ -1125,7 +1125,7 @@ public function dataUnion(): iterable
 					new ObjectType('InvalidArgumentException'),
 				],
 				MixedType::class,
-				'mixed=implicit', // should be MixedType~Exception+InvalidArgumentException
+				'mixed~Exception~InvalidArgumentException=implicit',
 			],
 			[
 				[