Fix BackedEnum::tryFrom not being nullable

Author: schlndh

src/Type/Php/BackedEnumFromMethodDynamicReturnTypeExtension.php

@@ -54,21 +54,31 @@ public function getTypeFromStaticMethodCall(MethodReflection $methodReflection,
 		}
 
 		$resultEnumCases = [];
+		$addNull = false;
+		foreach ($valueType->getConstantScalarValues() as $value) {
+			$hasMatching = false;
 			foreach ($enumCases as $enumCase) {
 				if ($enumCase->getBackingValueType() === null) {
 					continue;
 				}
+
 				$enumCaseValues = $enumCase->getBackingValueType()->getConstantScalarValues();
 				if (count($enumCaseValues) !== 1) {
 					continue;
 				}
 
-			foreach ($valueType->getConstantScalarValues() as $value) {
 				if ($value === $enumCaseValues[0]) {
 					$resultEnumCases[] = new EnumCaseObjectType($enumCase->getDeclaringEnum()->getName(), $enumCase->getName(), $enumCase->getDeclaringEnum());
+					$hasMatching = true;
 					break;
 				}
 			}
+
+			if ($hasMatching) {
+				continue;
+			}
+
+			$addNull = true;
 		}
 
 		if (count($resultEnumCases) === 0) {
@@ -79,7 +89,12 @@ public function getTypeFromStaticMethodCall(MethodReflection $methodReflection,
 			return null;
 		}
 
-		return TypeCombinator::union(...$resultEnumCases);
+		$result = TypeCombinator::union(...$resultEnumCases);
+		if ($addNull && $methodReflection->getName() === 'tryFrom') {
+			return TypeCombinator::addNull($result);
+		}
+
+		return $result;
 	}
 
 }

tests/PHPStan/Analyser/data/enum-from.php

@@ -1,4 +1,4 @@
-<?php // lint >= 8.1
+<?php declare(strict_types=1); // lint >= 8.1
 
 namespace EnumFrom;
 
@@ -12,6 +12,13 @@ enum FooIntegerEnum: int
 
 }
 
+enum FooIntegerEnumSubset: int
+{
+
+	case BAR = 1;
+
+}
+
 enum FooStringEnum: string
 {
 
@@ -20,6 +27,13 @@ enum FooStringEnum: string
 
 }
 
+enum FooNumericStringEnum: string
+{
+
+	case ONE = '1';
+
+}
+
 class Foo
 {
 
@@ -49,6 +63,24 @@ public function doFoo(): void
 		assertType('EnumFrom\FooStringEnum::BAZ', FooStringEnum::tryFrom('baz'));
 		assertType('EnumFrom\FooStringEnum::BAZ', FooStringEnum::tryFrom(FooStringEnum::BAZ->value));
 		assertType('EnumFrom\FooStringEnum::BAZ', FooStringEnum::from(FooStringEnum::BAZ->value));
+
+		assertType('null', FooIntegerEnum::tryFrom('1'));
+		assertType('null', FooIntegerEnum::tryFrom(1.0));
+		assertType('null', FooIntegerEnum::tryFrom(1.0001));
+		assertType('null', FooIntegerEnum::tryFrom(true));
+		assertType('null', FooNumericStringEnum::tryFrom(1));
+	}
+
+	public function supersetToSubset(FooIntegerEnum $foo): void
+	{
+		assertType('EnumFrom\FooIntegerEnumSubset::BAR|null', FooIntegerEnumSubset::tryFrom($foo->value));
+		assertType('EnumFrom\FooIntegerEnumSubset::BAR', FooIntegerEnumSubset::from($foo->value));
+	}
+
+	public function subsetToSuperset(FooIntegerEnumSubset $foo): void
+	{
+		assertType('EnumFrom\FooIntegerEnum::BAR', FooIntegerEnum::tryFrom($foo->value));
+		assertType('EnumFrom\FooIntegerEnum::BAR', FooIntegerEnum::from($foo->value));
 	}
 
 }