Support narrowing down via in_array with enum cases

Author: herndlm

src/Type/Php/InArrayFunctionTypeSpecifyingExtension.php

@@ -46,6 +46,7 @@ public function specifyTypes(FunctionReflection $functionReflection, FuncCall $n
 if (
 $context->truthy()
 || count(TypeUtils::getConstantScalars($arrayValueType)) > 0
+|| count(TypeUtils::getEnumCaseObjects($arrayValueType)) > 0
 ) {
 return $this->typeSpecifier->create(
 $node->getArgs()[0]->value,

src/Type/TypeUtils.php

@@ -7,6 +7,7 @@
 use PHPStan\Type\Constant\ConstantArrayType;
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Constant\ConstantStringType;
+use PHPStan\Type\Enum\EnumCaseObjectType;
 use PHPStan\Type\Generic\TemplateType;
 use function array_merge;
 
@@ -173,6 +174,14 @@ public static function getConstantScalars(Type $type): array
 return self::map(ConstantScalarType::class, $type, false);
 }
 
+/**
+ * @return EnumCaseObjectType[]
+ */
+public static function getEnumCaseObjects(Type $type): array
+{
+return self::map(EnumCaseObjectType::class, $type, false);
+}
+
 /**
  * @internal
  * @return ConstantArrayType[]

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -640,6 +640,7 @@ public function dataFileAsserts(): iterable
 if (PHP_VERSION_ID >= 80100) {
 yield from $this->gatherAssertTypes(__DIR__ . '/data/enums.php');
 yield from $this->gatherAssertTypes(__DIR__ . '/data/enums-import-alias.php');
+yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7176.php');
 }
 
 if (PHP_VERSION_ID >= 80000) {

tests/PHPStan/Analyser/data/bug-7176.php

@@ -0,0 +1,32 @@
+<?php declare(strict_types = 1); // lint >= 8.1
+
+namespace Bug7176;
+
+use function PHPStan\Testing\assertType;
+
+enum Suit
+{
+case Hearts;
+case Diamonds;
+case Clubs;
+case Spades;
+}
+
+function test(Suit $x): string {
+if ($x === Suit::Clubs) {
+assertType('Bug7176\Suit::Clubs', $x);
+return 'WORKS';
+}
+assertType('Bug7176\Suit::Diamonds|Bug7176\Suit::Hearts|Bug7176\Suit::Spades', $x);
+
+if (in_array($x, [Suit::Spades], true)) {
+assertType('Bug7176\Suit::Spades', $x);
+return 'DOES NOT WORK';
+}
+assertType('Bug7176\Suit::Diamonds|Bug7176\Suit::Hearts', $x);
+
+return match ($x) {
+Suit::Hearts => 'a',
+Suit::Diamonds => 'b',
+};
+}

tests/PHPStan/Rules/Comparison/MatchExpressionRuleTest.php

@@ -194,4 +194,12 @@ public function testBug7095(): void
 $this->analyse([__DIR__ . '/data/bug-7095.php'], []);
 }
 
+public function testBug7176(): void
+{
+if (PHP_VERSION_ID < 80100) {
+$this->markTestSkipped('Test requires PHP 8.1.');
+}
+$this->analyse([__DIR__ . '/data/bug-7176.php'], []);
+}
+
 }

tests/PHPStan/Rules/Comparison/data/bug-7176.php

@@ -0,0 +1,28 @@
+<?php declare(strict_types = 1); // lint >= 8.1
+
+namespace Bug7176;
+
+enum Suit
+{
+case Hearts;
+case Diamonds;
+case Clubs;
+case Spades;
+}
+
+function test(Suit $x): string {
+if ($x === Suit::Clubs) {
+return 'WORKS';
+}
+// Suit::Clubs is correctly eliminated from possible values
+
+if (in_array($x, [Suit::Spades], true)) {
+return 'DOES NOT WORK';
+}
+// Suit::Spades is not eliminated from possible values
+
+return match ($x) { // no error is expected here
+Suit::Hearts => 'a',
+Suit::Diamonds => 'b',
+};
+}