Forget remembered specific type when entering arrow function with sam…

…e-named parameter

src/Analyser/MutatingScope.php

@@ -3677,6 +3677,7 @@ private function enterArrowFunctionWithoutReflection(Expr\ArrowFunction $arrowFu
 		$variableTypes = $this->variableTypes;
 		$mixed = new MixedType();
 		$parameterVariables = [];
+		$parameterVariableExpressions = [];
 		foreach ($arrowFunction->params as $i => $parameter) {
 			if ($parameter->type === null) {
 				$parameterType = $mixed;
@@ -3706,6 +3707,7 @@ private function enterArrowFunctionWithoutReflection(Expr\ArrowFunction $arrowFu
 
 			$variableTypes[$parameter->var->name] = VariableTypeHolder::createYes($parameterType);
 			$parameterVariables[] = $parameter->var->name;
+			$parameterVariableExpressions[] = $parameter->var;
 		}
 
 		if ($arrowFunction->static) {
@@ -3767,7 +3769,7 @@ private function enterArrowFunctionWithoutReflection(Expr\ArrowFunction $arrowFu
 			}
 		}
 
-		return $this->scopeFactory->create(
+		$scope = $this->scopeFactory->create(
 			$this->context,
 			$this->isDeclareStrictTypes(),
 			$this->constantTypes,
@@ -3785,6 +3787,12 @@ private function enterArrowFunctionWithoutReflection(Expr\ArrowFunction $arrowFu
 			$this->afterExtractCall,
 			$this->parentScope,
 		);
+
+		foreach ($parameterVariableExpressions as $expr) {
+			$scope = $scope->invalidateExpression($expr);
+		}
+
+		return $scope;
 	}
 
 	public function isParameterValueNullable(Node\Param $parameter): bool

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -684,6 +684,7 @@ public function dataFileAsserts(): iterable
 		}
 
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6500.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Comparison/data/bug-6473.php');
 	}
 
 	/**

tests/PHPStan/Rules/Comparison/BooleanNotConstantConditionRuleTest.php

@@ -113,4 +113,10 @@ public function testTreatPhpDocTypesAsCertainRegression(bool $treatPhpDocTypesAs
 		$this->analyse([__DIR__ . '/../DeadCode/data/bug-without-issue-1.php'], []);
 	}
 
+	public function testBug6473(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-6473.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Comparison/data/bug-6473.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace Bug6473;
+
+use function PHPStan\Testing\assertType;
+
+class Point {
+	public bool $visited = false;
+
+	/**
+	 * @return Point[]
+	 */
+	public function getNeighbours(): array {
+		return [ new Point ];
+	}
+
+	public function doFoo()
+	{
+		$seen = [];
+
+		foreach([new Point, new Point] as $p ) {
+
+			$p->visited = true;
+			assertType('true', $p->visited);
+			$seen = [
+				... $seen,
+				... array_filter( $p->getNeighbours(), static fn (Point $p) => !$p->visited )
+			];
+			assertType('true', $p->visited);
+		}
+	}
+
+	public function doFoo2()
+	{
+		$seen = [];
+
+		foreach([new Point, new Point] as $p ) {
+
+			$p->visited = true;
+			assertType('true', $p->visited);
+			$seen = [
+				... $seen,
+				... array_filter( $p->getNeighbours(), static fn (Point $p2) => !$p2->visited )
+			];
+			assertType('true', $p->visited);
+		}
+	}
+}