DuplicateDeclarationRule checks duplicate enum cases as well

Author: kukulich

Makefile

@@ -28,6 +28,7 @@ lint:
 		--exclude tests/PHPStan/Rules/Operators/data/invalid-inc-dec.php \
 		--exclude tests/PHPStan/Rules/Arrays/data/offset-access-without-dim-for-reading.php \
 		--exclude tests/PHPStan/Rules/Classes/data/duplicate-declarations.php \
+		--exclude tests/PHPStan/Rules/Classes/data/duplicate-enum-cases.php \
 		--exclude tests/PHPStan/Rules/Classes/data/extends-error.php \
 		--exclude tests/PHPStan/Rules/Classes/data/implements-error.php \
 		--exclude tests/PHPStan/Rules/Classes/data/interface-extends-error.php \

src/Rules/Classes/DuplicateDeclarationRule.php

@@ -3,6 +3,7 @@
 namespace PHPStan\Rules\Classes;
 
 use PhpParser\Node;
+use PhpParser\Node\Stmt\EnumCase;
 use PHPStan\Analyser\Scope;
 use PHPStan\Node\InClassNode;
 use PHPStan\Rules\RuleErrorBuilder;
@@ -45,6 +46,23 @@ public function processNode(Node $node, Scope $scope): array
 			}
 		}
 
+		$declaredEnumCases = [];
+		foreach ($node->getOriginalNode()->stmts as $stmtNode) {
+			if (!$stmtNode instanceof EnumCase) {
+				continue;
+			}
+
+			if (array_key_exists($stmtNode->name->name, $declaredEnumCases)) {
+				$errors[] = RuleErrorBuilder::message(sprintf(
+					'Cannot redeclare enum case %s::%s.',
+					$classReflection->getDisplayName(),
+					$stmtNode->name->name
+				))->line($stmtNode->getLine())->nonIgnorable()->build();
+			} else {
+				$declaredEnumCases[$stmtNode->name->name] = true;
+			}
+		}
+
 		$declaredProperties = [];
 		foreach ($node->getOriginalNode()->getProperties() as $propertyDecl) {
 			foreach ($propertyDecl->props as $property) {

tests/PHPStan/Rules/Classes/DuplicateDeclarationRuleTest.php

@@ -73,4 +73,18 @@ public function testDuplicatePromotedProperty(): void
 		]);
 	}
 
+	public function testDuplicateEnumCase(): void
+	{
+		if (!self::$useStaticReflectionProvider) {
+			$this->markTestSkipped('This test needs static reflection');
+		}
+
+		$this->analyse([__DIR__ . '/data/duplicate-enum-cases.php'], [
+			[
+				'Cannot redeclare enum case DuplicatedEnumCase\Foo::BAR.',
+				9,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Classes/data/duplicate-enum-cases.php

@@ -0,0 +1,10 @@
+<?php // lint >= 8.1
+
+namespace DuplicatedEnumCase;
+
+enum Foo
+{
+	case BAR;
+	case FOO;
+	case BAR;
+}