Normalize decimal-int-string intersection with lowercase-string/uppercase-string

Author: ondrejmirtes

src/Type/Accessory/AccessoryDecimalIntegerStringType.php

@@ -124,7 +124,14 @@ public function isSubTypeOf(Type $otherType): IsSuperTypeOfResult
 			return $otherType->isSuperTypeOf($this);
 		}
 
-		if ($otherType instanceof AccessoryNumericStringType && !$this->inverse) {
+		if (
+			(
+				$otherType instanceof AccessoryNumericStringType
+				|| $otherType instanceof AccessoryLowercaseStringType
+				|| $otherType instanceof AccessoryUppercaseStringType
+			)
+			&& !$this->inverse
+		) {
 			return IsSuperTypeOfResult::createYes();
 		}
 
@@ -357,12 +364,12 @@ public function isLiteralString(): TrinaryLogic
 
 	public function isLowercaseString(): TrinaryLogic
 	{
-		return TrinaryLogic::createMaybe();
+		return $this->inverse ? TrinaryLogic::createMaybe() : TrinaryLogic::createYes();
 	}
 
 	public function isUppercaseString(): TrinaryLogic
 	{
-		return TrinaryLogic::createMaybe();
+		return $this->inverse ? TrinaryLogic::createMaybe() : TrinaryLogic::createYes();
 	}
 
 	public function isClassString(): TrinaryLogic

tests/PHPStan/Type/TypeCombinatorTest.php

@@ -2874,6 +2874,24 @@ public static function dataUnion(): iterable
 			StringType::class,
 			'string',
 		];
+
+		yield [
+			[
+				$decimalIntString,
+				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			],
+			IntersectionType::class,
+			'lowercase-string',
+		];
+
+		yield [
+			[
+				$nonDecimalIntString,
+				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			],
+			StringType::class,
+			'string',
+		];
 	}
 
 	/**
@@ -5024,6 +5042,29 @@ public static function dataIntersect(): iterable
 			NeverType::class,
 			'*NEVER*=implicit',
 		];
+
+		yield [
+			[
+				$decimalIntString,
+				new IntersectionType([
+					new StringType(),
+					new AccessoryLowercaseStringType(),
+				]),
+			],
+			IntersectionType::class,
+			'decimal-int-string',
+		];
+		yield [
+			[
+				$nonDecimalIntString,
+				new IntersectionType([
+					new StringType(),
+					new AccessoryLowercaseStringType(),
+				]),
+			],
+			IntersectionType::class,
+			'lowercase-string&non-decimal-int-string',
+		];
 	}
 
 	/**