Arrow functions - allow more precise return type even when native ret…

…urn type is present
phpstan · Dec 22, 2020 · 3d0ac6f · 3d0ac6f
1 parent 94e3443
commit 3d0ac6f
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Showing 3 changed files with 12 additions and 3 deletions.
diff --git a/src/Analyser/MutatingScope.php b/src/Analyser/MutatingScope.php
@@ -80,6 +80,7 @@
 use PHPStan\Type\ThisType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\TypehintHelper;
 use PHPStan\Type\TypeTraverser;
 use PHPStan\Type\TypeUtils;
 use PHPStan\Type\TypeWithClassName;
@@ -1306,8 +1307,11 @@ private function resolveType(Expr $node): Type
 				);
 			}
 
-			if ($node->returnType === null && $node instanceof Expr\ArrowFunction) {
+			if ($node instanceof Expr\ArrowFunction) {
 				$returnType = $this->getType($node->expr);
+				if ($node->returnType !== null) {
+					$returnType = TypehintHelper::decideType($this->getFunctionType($node->returnType, false, false), $returnType);
+				}
 			} else {
 				$returnType = $this->getFunctionType($node->returnType, $node->returnType === null, false);
 			}

diff --git a/tests/PHPStan/Analyser/NodeScopeResolverTest.php b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
@@ -10915,13 +10915,17 @@ public function dataArrowFunctions(): array
 	{
 		return [
 			[
-				'Closure(string): int',
+				'Closure(string): 1',
 				'$x',
 			],
 			[
-				'int',
+				'1',
 				'$x()',
 			],
+			[
+				'array(\'a\' => 1, \'b\' => 2)',
+				'$y()',
+			],
 		];
 	}
 

diff --git a/tests/PHPStan/Analyser/data/arrow-functions.php b/tests/PHPStan/Analyser/data/arrow-functions.php
@@ -8,6 +8,7 @@ class Foo
 	public function doFoo()
 	{
 		$x = fn(string $str): int => 1;
+		$y = fn(): array => ['a' => 1, 'b' => 2];
 		die;
 	}