Skip class name case check for type hints using explicit use ... as aliases

src/Parser/UseAliasVisitor.php

@@ -0,0 +1,73 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Parser;
+
+use Override;
+use PhpParser\Node;
+use PhpParser\Node\Name;
+use PhpParser\Node\Stmt\GroupUse;
+use PhpParser\Node\Stmt\Use_;
+use PhpParser\NodeVisitorAbstract;
+use PHPStan\DependencyInjection\AutowiredService;
+use function count;
+use function strtolower;
+
+#[AutowiredService]
+final class UseAliasVisitor extends NodeVisitorAbstract
+{
+
+	public const ATTRIBUTE_NAME = 'isExplicitUseAlias';
+
+	/** @var array<string, string> alias name (original case) keyed by lowercase alias name */
+	private array $explicitAliases = [];
+
+	#[Override]
+	public function enterNode(Node $node): ?Node
+	{
+		if ($node instanceof Node\Stmt\Namespace_) {
+			$this->explicitAliases = [];
+		}
+
+		if ($node instanceof Use_ && $node->type === Use_::TYPE_NORMAL) {
+			foreach ($node->uses as $use) {
+				if ($use->alias === null) {
+					continue;
+				}
+
+				$this->explicitAliases[strtolower($use->alias->name)] = $use->alias->name;
+			}
+		}
+
+		if ($node instanceof GroupUse) {
+			foreach ($node->uses as $use) {
+				if ($use->type !== Use_::TYPE_NORMAL && $node->type !== Use_::TYPE_NORMAL) {
+					continue;
+				}
+				if ($use->alias === null) {
+					continue;
+				}
+
+				$this->explicitAliases[strtolower($use->alias->name)] = $use->alias->name;
+			}
+		}
+
+		if ($node instanceof Name) {
+			$originalName = $node->getAttribute('originalName');
+			if ($originalName instanceof Name) {
+				$originalParts = $originalName->getParts();
+				if (count($originalParts) === 1) {
+					$lowerOriginal = strtolower($originalParts[0]);
+					if (
+						isset($this->explicitAliases[$lowerOriginal])
+						&& $this->explicitAliases[$lowerOriginal] === $originalParts[0]
+					) {
+						$node->setAttribute(self::ATTRIBUTE_NAME, true);
+					}
+				}
+			}
+		}
+
+		return null;
+	}
+
+}

src/Rules/ClassCaseSensitivityCheck.php

@@ -4,6 +4,7 @@
 
 use PHPStan\DependencyInjection\AutowiredParameter;
 use PHPStan\DependencyInjection\AutowiredService;
+use PHPStan\Parser\UseAliasVisitor;
 use PHPStan\Reflection\ReflectionProvider;
 use function sprintf;
 use function strtolower;
@@ -38,7 +39,10 @@ public function checkClassNames(array $pairs): array
 			}
 			$realClassName = $classReflection->getName();
 			if (strtolower($realClassName) !== strtolower($className)) {
-				continue; // skip class alias
+				continue; // skip class_alias() where the alias is a completely different name
+			}
+			if ($pair->getNode()->getAttribute(UseAliasVisitor::ATTRIBUTE_NAME) === true) {
+				continue;
 			}
 			if ($realClassName === $className) {
 				continue;

src/Rules/FunctionDefinitionCheck.php

@@ -866,11 +866,6 @@ private function getOriginalClassNamePairsFromTypeNode(Identifier|Name|ComplexTy
 				$originalCaseClassName = $originalName->toString();
 			}
 
-			if (strtolower($originalCaseClassName) !== strtolower($resolvedName)) {
-				// use alias, not just a case difference
-				return [];
-			}
-
 			if ($originalCaseClassName === $resolvedName) {
 				return [];
 			}

tests/PHPStan/Rules/Classes/ExistingClassInClassExtendsRuleTest.php

@@ -153,4 +153,9 @@ public function testReadonly(): void
 		]);
 	}
 
+	public function testBug14617(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-14617.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Classes/ExistingClassInInstanceOfRuleTest.php

@@ -86,4 +86,9 @@ public function testRememberClassExistsFromConstructor(): void
 		$this->analyse([__DIR__ . '/data/remember-class-exists-from-constructor.php'], []);
 	}
 
+	public function testBug14617(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-14617.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Classes/ExistingClassesInClassImplementsRuleTest.php

@@ -95,4 +95,9 @@ public function testBug8889(): void
 		]);
 	}
 
+	public function testBug14617(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-14617.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Classes/data/bug-14617.php

@@ -0,0 +1,21 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14617Classes;
+
+class MyClass {}
+
+interface MyInterface {}
+
+namespace Bug14617Classes\Consumer;
+
+use Bug14617Classes\MyClass as myclass;
+use Bug14617Classes\MyInterface as myinterface;
+
+class Foo extends myclass implements myinterface {
+	public myclass $prop;
+}
+
+function test(mixed $x): void {
+	if ($x instanceof myclass) {
+	}
+}

tests/PHPStan/Rules/Functions/ExistingClassesInClosureTypehintsRuleTest.php

@@ -73,6 +73,16 @@ public function testExistingClassInTypehint(): void
 		]);
 	}
 
+	public function testBug14617(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-14617-closure.php'], []);
+	}
+
+	public function testClassAliasCaseSensitivity(): void
+	{
+		$this->analyse([__DIR__ . '/data/class-alias-case-sensitivity.php'], []);
+	}
+
 	public function testValidTypehintPhp71(): void
 	{
 		$this->analyse([__DIR__ . '/data/closure-7.1-typehints.php'], [

tests/PHPStan/Rules/Functions/data/bug-14617-closure.php

@@ -0,0 +1,13 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14617Closure;
+
+class MyClass {}
+
+namespace Bug14617Closure\Consumer;
+
+use Bug14617Closure\MyClass as myclass;
+
+$callback = function (myclass $a): myclass {
+	return $a;
+};

tests/PHPStan/Rules/Functions/data/class-alias-case-sensitivity.php

@@ -0,0 +1,7 @@
+<?php declare(strict_types = 1);
+
+namespace ClassAliasCaseSensitivity;
+
+$callback = function (\ReturnTypes\FooAlias $a): \ReturnTypes\FooAlias {
+	return $a;
+};

tests/PHPStan/Rules/Methods/ExistingClassesInTypehintsRuleTest.php

@@ -662,4 +662,10 @@ public function testBug14205(): void
 		$this->analyse([__DIR__ . '/data/bug-14205.php'], []);
 	}
 
+	#[RequiresPhp('>= 8.0.0')]
+	public function testBug14617(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-14617.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Methods/data/bug-14617.php

@@ -0,0 +1,27 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14617;
+
+class MyClass {}
+
+namespace Bug14617\Consumer;
+
+use Bug14617\MyClass as myclass;
+
+function test(): myclass {
+	return new myclass();
+}
+
+class Foo {
+	public function bar(myclass $a): myclass {
+		return $a;
+	}
+
+	public function nullable(?myclass $a): ?myclass {
+		return $a;
+	}
+
+	public function union(myclass|string $a): myclass|int {
+		return $a;
+	}
+}

tests/PHPStan/Rules/Properties/ExistingClassesInPropertiesRuleTest.php

@@ -179,4 +179,9 @@ public function testIntersectionTypes(int $phpVersion, array $errors): void
 		$this->analyse([__DIR__ . '/data/intersection-types.php'], $errors);
 	}
 
+	public function testBug14617(): void
+	{
+		$this->analyse([__DIR__ . '/../Classes/data/bug-14617.php'], []);
+	}
+
 }