Forget remembered specific type when entering arrow function with same-named parameter

Author: ondrejmirtes

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);
+}
+}
+}