From eac798582cf1f0110144248d85cfe595f94c8239 Mon Sep 17 00:00:00 2001
From: Markus Staab <maggus.staab@googlemail.com>
Date: Sat, 11 Jul 2026 17:40:24 +0200
Subject: [PATCH 1/3] Faster DuplicateClassDeclarationRule

---
 .../Classes/DuplicateClassDeclarationRule.php | 23 +++++++++++--------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/src/Rules/Classes/DuplicateClassDeclarationRule.php b/src/Rules/Classes/DuplicateClassDeclarationRule.php
index 72632aedc24..543f745d16c 100644
--- a/src/Rules/Classes/DuplicateClassDeclarationRule.php
+++ b/src/Rules/Classes/DuplicateClassDeclarationRule.php
@@ -24,6 +24,7 @@
 #[ValidatesStubFiles]
 final class DuplicateClassDeclarationRule implements Rule
 {
+	private ?array $classMap = null;
 
 	public function __construct(private Reflector $reflector, private RelativePathHelper $relativePathHelper)
 	{
@@ -38,21 +39,25 @@ public function processNode(Node $node, Scope $scope): array
 	{
 		$thisClass = $node->getClassReflection();
 		$className = $thisClass->getName();
-		$allClasses = $this->reflector->reflectAllClasses();
-		$filteredClasses = [];
-		foreach ($allClasses as $reflectionClass) {
-			if ($reflectionClass->getName() !== $className) {
-				continue;
-			}
 
-			$filteredClasses[] = $reflectionClass;
+		if ($this->classMap === null) {
+			$this->classMap = [];
+
+			$allClasses = $this->reflector->reflectAllClasses();
+			foreach ($allClasses as $reflectionClass) {
+				$reflectionClassName = $reflectionClass->getName();
+				if (!isset($this->classMap[$reflectionClassName])) {
+					$this->classMap[$reflectionClassName] = [];
+				}
+				$this->classMap[$reflectionClassName][] = $reflectionClass;
+			}
 		}
 
-		if (count($filteredClasses) < 2) {
+		if (!isset($this->classMap[$className]) || count($this->classMap[$className]) < 2) {
 			return [];
 		}
 
-		$filteredClasses = array_filter($filteredClasses, static fn (ReflectionClass $class) => $class->getStartLine() !== $thisClass->getNativeReflection()->getStartLine());
+		$filteredClasses = array_filter($this->classMap[$className], static fn (ReflectionClass $class) => $class->getStartLine() !== $thisClass->getNativeReflection()->getStartLine());
 
 		$identifierType = strtolower($thisClass->getClassTypeDescription());
 

From 3c870426e413e8e76822db6ac1acad3f9a2557ab Mon Sep 17 00:00:00 2001
From: Markus Staab <maggus.staab@googlemail.com>
Date: Sat, 11 Jul 2026 17:47:03 +0200
Subject: [PATCH 2/3] fix build

---
 src/Rules/Classes/DuplicateClassDeclarationRule.php | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/Rules/Classes/DuplicateClassDeclarationRule.php b/src/Rules/Classes/DuplicateClassDeclarationRule.php
index 543f745d16c..282834b72b4 100644
--- a/src/Rules/Classes/DuplicateClassDeclarationRule.php
+++ b/src/Rules/Classes/DuplicateClassDeclarationRule.php
@@ -9,6 +9,7 @@
 use PHPStan\DependencyInjection\ValidatesStubFiles;
 use PHPStan\File\RelativePathHelper;
 use PHPStan\Node\InClassNode;
+use PHPStan\Reflection\ClassReflection;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
 use function array_filter;
@@ -24,6 +25,8 @@
 #[ValidatesStubFiles]
 final class DuplicateClassDeclarationRule implements Rule
 {
+
+	/** @var array<class-string|trait-string, list<ReflectionClass>>|null */
 	private ?array $classMap = null;
 
 	public function __construct(private Reflector $reflector, private RelativePathHelper $relativePathHelper)
@@ -40,6 +43,8 @@ public function processNode(Node $node, Scope $scope): array
 		$thisClass = $node->getClassReflection();
 		$className = $thisClass->getName();
 
+		// this rule runs at the very end of the analysis,
+		// so all classes already have been discovered at this point.
 		if ($this->classMap === null) {
 			$this->classMap = [];
 

From 827a51a26c30d0a7ab965deaa4bab75793cd9a61 Mon Sep 17 00:00:00 2001
From: Markus Staab <maggus.staab@googlemail.com>
Date: Sat, 11 Jul 2026 17:51:13 +0200
Subject: [PATCH 3/3] cs

---
 src/Rules/Classes/DuplicateClassDeclarationRule.php | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/Rules/Classes/DuplicateClassDeclarationRule.php b/src/Rules/Classes/DuplicateClassDeclarationRule.php
index 282834b72b4..a07a63c00a9 100644
--- a/src/Rules/Classes/DuplicateClassDeclarationRule.php
+++ b/src/Rules/Classes/DuplicateClassDeclarationRule.php
@@ -9,7 +9,6 @@
 use PHPStan\DependencyInjection\ValidatesStubFiles;
 use PHPStan\File\RelativePathHelper;
 use PHPStan\Node\InClassNode;
-use PHPStan\Reflection\ClassReflection;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
 use function array_filter;