Fix for inferring closure parameter type from callable union

Author: ondrejmirtes

src/Analyser/NodeScopeResolver.php

@@ -124,6 +124,7 @@
 use PHPStan\Reflection\MethodReflection;
 use PHPStan\Reflection\Native\NativeMethodReflection;
 use PHPStan\Reflection\Native\NativeParameterReflection;
+use PHPStan\Reflection\ParameterReflection;
 use PHPStan\Reflection\ParameterReflectionWithPhpDocs;
 use PHPStan\Reflection\ParametersAcceptor;
 use PHPStan\Reflection\ParametersAcceptorSelector;
@@ -3457,8 +3458,39 @@ private function processClosureNode(
 			}
 
 			$acceptors = $passedToType->getCallableParametersAcceptors($scope);
-			if (count($acceptors) === 1) {
-				$callableParameters = $acceptors[0]->getParameters();
+			if (count($acceptors) > 0) {
+				foreach ($acceptors as $acceptor) {
+					if ($callableParameters === null) {
+						$callableParameters = array_map(static fn (ParameterReflection $callableParameter) => new NativeParameterReflection(
+							$callableParameter->getName(),
+							$callableParameter->isOptional(),
+							$callableParameter->getType(),
+							$callableParameter->passedByReference(),
+							$callableParameter->isVariadic(),
+							$callableParameter->getDefaultValue(),
+						), $acceptor->getParameters());
+						continue;
+					}
+
+					$newParameters = [];
+					foreach ($acceptor->getParameters() as $i => $callableParameter) {
+						if (!array_key_exists($i, $callableParameters)) {
+							$newParameters[] = $callableParameter;
+							continue;
+						}
+
+						$newParameters[] = $callableParameters[$i]->union(new NativeParameterReflection(
+							$callableParameter->getName(),
+							$callableParameter->isOptional(),
+							$callableParameter->getType(),
+							$callableParameter->passedByReference(),
+							$callableParameter->isVariadic(),
+							$callableParameter->getDefaultValue(),
+						));
+					}
+
+					$callableParameters = $newParameters;
+				}
 			}
 		}
 
@@ -3639,8 +3671,39 @@ private function processArrowFunctionNode(
 			}
 
 			$acceptors = $passedToType->getCallableParametersAcceptors($scope);
-			if (count($acceptors) === 1) {
-				$callableParameters = $acceptors[0]->getParameters();
+			if (count($acceptors) > 0) {
+				foreach ($acceptors as $acceptor) {
+					if ($callableParameters === null) {
+						$callableParameters = array_map(static fn (ParameterReflection $callableParameter) => new NativeParameterReflection(
+							$callableParameter->getName(),
+							$callableParameter->isOptional(),
+							$callableParameter->getType(),
+							$callableParameter->passedByReference(),
+							$callableParameter->isVariadic(),
+							$callableParameter->getDefaultValue(),
+						), $acceptor->getParameters());
+						continue;
+					}
+
+					$newParameters = [];
+					foreach ($acceptor->getParameters() as $i => $callableParameter) {
+						if (!array_key_exists($i, $callableParameters)) {
+							$newParameters[] = $callableParameter;
+							continue;
+						}
+
+						$newParameters[] = $callableParameters[$i]->union(new NativeParameterReflection(
+							$callableParameter->getName(),
+							$callableParameter->isOptional(),
+							$callableParameter->getType(),
+							$callableParameter->passedByReference(),
+							$callableParameter->isVariadic(),
+							$callableParameter->getDefaultValue(),
+						));
+					}
+
+					$callableParameters = $newParameters;
+				}
 			}
 		}
 

src/Reflection/Native/NativeParameterReflection.php

@@ -5,6 +5,7 @@
 use PHPStan\Reflection\ParameterReflection;
 use PHPStan\Reflection\PassedByReference;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 
 class NativeParameterReflection implements ParameterReflection
 {
@@ -50,6 +51,18 @@ public function getDefaultValue(): ?Type
 		return $this->defaultValue;
 	}
 
+	public function union(self $other): self
+	{
+		return new self(
+			$this->name,
+			$this->optional && $other->optional,
+			TypeCombinator::union($this->type, $other->type),
+			$this->passedByReference->combine($other->passedByReference),
+			$this->variadic && $other->variadic,
+			$this->optional && $other->optional ? $this->defaultValue : null,
+		);
+	}
+
 	/**
 	 * @param mixed[] $properties
 	 */

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -824,7 +824,9 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6672.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6687.php');
 
-		yield from $this->gatherAssertTypes(__DIR__ . '/data/callable-in-union.php');
+		if (PHP_VERSION_ID >= 70400) {
+			yield from $this->gatherAssertTypes(__DIR__ . '/data/callable-in-union.php');
+		}
 
 		if (PHP_VERSION_ID < 80000) {
 			yield from $this->gatherAssertTypes(__DIR__ . '/data/preg_match_php7.php');

tests/PHPStan/Analyser/data/callable-in-union.php

@@ -1,4 +1,4 @@
-<?php
+<?php // lint >= 7.4
 
 namespace CallableInUnion;
 
@@ -15,3 +15,18 @@ function acceptArrayOrCallable($_)
 	assertType('array<string, mixed>', $parameter);
 	return $parameter;
 });
+
+/**
+ * @param (callable(string): void)|callable(int): void $a
+ * @return void
+ */
+function acceptCallableOrCallableLikeArray($a): void
+{
+
+}
+
+acceptCallableOrCallableLikeArray(function ($p) {
+	assertType('int|string', $p);
+});
+
+acceptCallableOrCallableLikeArray(fn ($p) => assertType('int|string', $p));