Fix phpstan/phpstan#14449: Another false positive

src/Analyser/ExprHandler/AssignHandler.php

@@ -155,6 +155,31 @@ static function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $contex
 		);
 		$scope = $result->getScope();
 
+		if (
+			$expr instanceof AssignRef
+			&& $expr->var instanceof Variable
+			&& is_string($expr->var->name)
+			&& $expr->expr instanceof ArrayDimFetch
+		) {
+			$rootExpr = $expr->expr;
+			while ($rootExpr instanceof ArrayDimFetch) {
+				$rootExpr = $rootExpr->var;
+			}
+
+			if ($rootExpr instanceof Variable && is_string($rootExpr->name)) {
+				$varName = $expr->var->name;
+				$type = $scope->getType($expr->var);
+				$nativeType = $scope->getNativeType($expr->var);
+
+				// When $varName is assigned, update the ArrayDimFetch expression
+				$scope = $scope->assignExpression(
+					new IntertwinedVariableByReferenceWithExpr($varName, $expr->expr, new Variable($varName)),
+					$type,
+					$nativeType,
+				);
+			}
+		}
+
 		if (
 			$expr instanceof AssignRef
 			&& $expr->var instanceof Variable

src/Analyser/MutatingScope.php

@@ -2623,17 +2623,80 @@
 				if ($targetRootVar !== null && in_array($targetRootVar, $intertwinedPropagatedFrom, true)) {
 					continue;
 				}
-				$scope = $scope->assignExpression(
-					$expressionType->getExpr()->getExpr(),
-					$scope->getType($expressionType->getExpr()->getAssignedExpr()),
-					$scope->getNativeType($expressionType->getExpr()->getAssignedExpr()),
-				);
+				$targetExpr = $expressionType->getExpr()->getExpr();
+				$newType = $scope->getType($expressionType->getExpr()->getAssignedExpr());
+				$newNativeType = $scope->getNativeType($expressionType->getExpr()->getAssignedExpr());
+
+				if ($targetExpr instanceof Expr\ArrayDimFetch && $targetRootVar !== null && $this->hasConstantDimInChain($targetExpr)) {
+					$scope = $this->propagateRefTypeToArrayDimFetch($scope, $targetExpr, $newType, $newNativeType, $intertwinedPropagatedFrom, $variableName);
+				} else {
+					$scope = $scope->assignExpression(
+						$targetExpr,
+						$newType,
+						$newNativeType,
+					);
+				}
 			}
 		}
 
 		return $scope;
 	}
 
+	private function hasConstantDimInChain(Expr\ArrayDimFetch $dimFetch): bool
+	{
+		$current = $dimFetch;
+		while ($current instanceof Expr\ArrayDimFetch) {
+			if ($current->dim !== null) {
+				$dimType = $this->getType($current->dim)->toArrayKey();
+				if ($dimType->isConstantScalarValue()->yes()) {
+					return true;
+				}
+			}
+			$current = $current->var;
+		}
+
+		return false;
+	}
+
+	/**
+	 * @param list<string> $intertwinedPropagatedFrom
+	 */
+	private function propagateRefTypeToArrayDimFetch(
+		self $scope,
+		Expr\ArrayDimFetch $targetExpr,
+		Type $newType,
+		Type $newNativeType,
+		array $intertwinedPropagatedFrom,
+		string $variableName,
+	): self
+	{
+		$expr = $targetExpr;
+		$type = $newType;
+		$nativeType = $newNativeType;
+
+		while ($expr instanceof Expr\ArrayDimFetch) {
+			if ($expr->dim === null) {
+				return $scope->assignExpression($targetExpr, $newType, $newNativeType);
+			}
+			$dimType = $scope->getType($expr->dim)->toArrayKey();
+			$type = $scope->getType($expr->var)->setOffsetValueType($dimType, $type);
+			$nativeType = $scope->getNativeType($expr->var)->setOffsetValueType($dimType, $nativeType);
+			$expr = $expr->var;
+		}
+
+		if ($expr instanceof Variable && is_string($expr->name)) {
+			return $scope->assignVariable(
+				$expr->name,
+				$type,
+				$nativeType,
+				TrinaryLogic::createYes(),
+				array_merge($intertwinedPropagatedFrom, [$variableName]),
+			);
+		}
+
+		return $scope->assignExpression($targetExpr, $newType, $newNativeType);
+	}
+
 	private function isDimFetchPathReachable(self $scope, Expr\ArrayDimFetch $dimFetch): bool
 	{
 		if ($dimFetch->dim === null) {

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php

@@ -1226,4 +1226,10 @@ public function testBug12063(): void
 		$this->analyse([__DIR__ . '/data/bug-12063.php'], []);
 	}
 
+	public function testBug14449(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-14449.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Comparison/data/bug-14449.php

@@ -0,0 +1,36 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14449;
+
+/**
+ * @return \Generator<int,array{'id':int}>
+ */
+function DataGenerator() : \Generator
+{
+	yield [ 'id' => 1 ] ;
+	yield [ 'id' => 1 ] ;
+}
+
+function () : void {
+	$results = [];
+
+	$generator = DataGenerator();
+	foreach ( $generator as $data )
+	{
+		$id = $data['id'];
+		if ( !array_key_exists($id, $results ) )
+		{
+			$results[$id] = [];
+		}
+		if ( !array_key_exists('data',$results[$id]) )
+		{
+			$results[$id]['data'] = [];
+		}
+
+		$resultData = &$results[$id]['data'];
+		if ( !array_key_exists('id', $results[$id]['data']) )
+		{
+			$resultData['id'] = $id;
+		}
+	}
+};