Fix incorrect narrowing of nested array after assignment

Author: staabm

src/Analyser/ExprHandler/AssignHandler.php

@@ -947,10 +947,11 @@ private function produceArrayDimFetchAssignValueToWrite(array $dimFetchStack, ar
 		$originalValueToWrite = $valueToWrite;
 
 		$offsetValueTypeStack = [$offsetValueType];
+		$overwrites = true;
 		foreach (array_slice($offsetTypes, 0, -1) as [$offsetType, $dimFetch]) {
 			if ($offsetType === null) {
 				$offsetValueType = new ConstantArrayType([], []);
-
+				$overwrites = false;
 			} else {
 				$has = $offsetValueType->hasOffsetValueType($offsetType);
 				if ($has->yes()) {
@@ -959,9 +960,11 @@ private function produceArrayDimFetchAssignValueToWrite(array $dimFetchStack, ar
 					if (!$scope->hasExpressionType($dimFetch)->yes()) {
 						$offsetValueType = TypeCombinator::union($offsetValueType->getOffsetValueType($offsetType), new ConstantArrayType([], []));
 					} else {
+						$overwrites = false;
 						$offsetValueType = $offsetValueType->getOffsetValueType($offsetType);
 					}
 				} else {
+					$overwrites = false;
 					$offsetValueType = new ConstantArrayType([], []);
 				}
 			}
@@ -1010,7 +1013,14 @@ private function produceArrayDimFetchAssignValueToWrite(array $dimFetchStack, ar
 				}
 
 			} else {
-				$valueToWrite = $offsetValueType->setOffsetValueType($offsetType, $valueToWrite, $i === 0);
+				$unionValues = false;
+				if ($i === 0) {
+					$unionValues = true;
+				} elseif ($overwrites === true && $i === count($offsetTypes) - 1) {
+					$unionValues = true;
+				}
+
+				$valueToWrite = $offsetValueType->setOffsetValueType($offsetType, $valueToWrite, $unionValues);
 			}
 
 			if ($arrayDimFetch === null || !$offsetValueType->isList()->yes()) {

tests/PHPStan/Analyser/nsrt/assign-nested-arrays.php

@@ -12,8 +12,9 @@ public function doFoo(int $i)
 		$array = [];
 
 		$array[$i]['bar'] = 1;
-		$array[$i]['baz'] = 2;
+		assertType('non-empty-array<int, array{bar: 1}>', $array);
 
+		$array[$i]['baz'] = 2;
 		assertType('non-empty-array<int, array{bar: 1, baz: 2}>', $array);
 	}
 

tests/PHPStan/Rules/Arrays/data/bug-11679.php

@@ -31,7 +31,8 @@ public function sayHello(int $index): bool
 		assertType('array<int, array{foo?: bool}>', $this->arr);
 		if (!isset($this->arr[$index]['foo'])) {
 			$this->arr[$index]['foo'] = true;
-			assertType('non-empty-array<int, array{foo: true}>', $this->arr);
+			assertType('non-empty-array<int, array{foo?: bool}>', $this->arr);
+			assertType('true', $this->arr[$index]['foo']);
 		}
 		assertType('array<int, array{foo?: bool}>', $this->arr);
 		return $this->arr[$index]['foo']; // PHPStan does not realize 'foo' is set