Fixed inferring return type coming from array_map

src/Analyser/MutatingScope.php

@@ -37,6 +37,7 @@
 use PHPStan\Reflection\ParametersAcceptor;
 use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Reflection\PassedByReference;
+use PHPStan\Reflection\Php\DummyParameter;
 use PHPStan\Reflection\Php\PhpFunctionFromParserNodeReflection;
 use PHPStan\Reflection\Php\PhpMethodFromParserNodeReflection;
 use PHPStan\Reflection\PropertyReflection;
@@ -1281,7 +1282,25 @@ private function resolveType(Expr $node): Type
 					$returnType = TypehintHelper::decideType($this->getFunctionType($node->returnType, false, false), $returnType);
 				}
 			} else {
-				$closureScope = $this->enterAnonymousFunctionWithoutReflection($node);
+				$callableParameters = null;
+				$arg = $node->getAttribute('parent');
+				if ($arg instanceof Arg) {
+					$funcCall = $arg->getAttribute('parent');
+					$argOrder = $arg->getAttribute('expressionOrder');
+					if ($funcCall instanceof FuncCall && $funcCall->name instanceof Name) {
+						$functionName = $this->reflectionProvider->resolveFunctionName($funcCall->name, $this);
+						if (
+							$functionName === 'array_map'
+							&& $argOrder === 0
+							&& isset($funcCall->args[1])
+						) {
+							$callableParameters = [
+								new DummyParameter('item', $this->getType($funcCall->args[1]->value)->getIterableValueType(), false, PassedByReference::createNo(), false, null),
+							];
+						}
+					}
+				}
+				$closureScope = $this->enterAnonymousFunctionWithoutReflection($node, $callableParameters);
 				$closureReturnStatements = [];
 				$closureYieldStatements = [];
 				$closureExecutionEnds = [];

src/NodeVisitor/StatementOrderVisitor.php

@@ -40,7 +40,10 @@ public function enterNode(Node $node)
 		$node->setAttribute('statementOrder', $order);
 		$node->setAttribute('statementDepth', $this->depth);
 
-		if ($node instanceof Node\Expr && count($this->expressionOrderStack) > 0) {
+		if (
+			($node instanceof Node\Expr || $node instanceof Node\Arg)
+			&& count($this->expressionOrderStack) > 0
+		) {
 			$expressionOrder = $this->expressionOrderStack[count($this->expressionOrderStack) - 1];
 			$node->setAttribute('expressionOrder', $expressionOrder);
 			$node->setAttribute('expressionDepth', $this->expressionDepth);

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -10923,6 +10923,11 @@ public function dataBug4498(): array
 		return $this->gatherAssertTypes(__DIR__ . '/data/bug-4498.php');
 	}
 
+	public function dataBug4587(): array
+	{
+		return $this->gatherAssertTypes(__DIR__ . '/data/bug-4587.php');
+	}
+
 	/**
 	 * @param string $file
 	 * @return array<string, mixed[]>
@@ -11169,6 +11174,7 @@ private function gatherAssertTypes(string $file): array
 	 * @dataProvider dataBug3769
 	 * @dataProvider dataBugInstanceOfClassString
 	 * @dataProvider dataBug4498
+	 * @dataProvider dataBug4587
 	 * @param string $assertType
 	 * @param string $file
 	 * @param mixed ...$args

tests/PHPStan/Analyser/data/bug-4587.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace Bug4587;
+
+use function PHPStan\Analyser\assertType;
+
+class HelloWorld
+{
+	public function a(): void
+	{
+		/** @var list<array{a: int}> $results */
+		$results = [];
+
+		$type = array_map(static function (array $result): array {
+			assertType('array(\'a\' => int)', $result);
+			return $result;
+		}, $results);
+
+		assertType('array<int, array(\'a\' => int)>', $type);
+	}
+
+	public function b(): void
+	{
+		/** @var list<array{a: int}> $results */
+		$results = [];
+
+		$type = array_map(static function (array $result): array {
+			assertType('array(\'a\' => int)', $result);
+			$result['a'] = (string) $result['a'];
+			assertType('array(\'a\' => string&numeric)', $result);
+
+			return $result;
+		}, $results);
+
+		assertType('array<int, array(\'a\' => string&numeric)>', $type);
+	}
+}

tests/PHPStan/Analyser/data/generics.php

@@ -218,7 +218,7 @@ function testArrayMap(array $listOfIntegers)
 
 		return (string) $int;
 	}, $listOfIntegers);
-	assertType('array<string>', $strings);
+	assertType('array<string&numeric>', $strings);
 }
 
 /**