Add Exception->getCode() return type provider

src/Psalm/Internal/Provider/FunctionReturnTypeProvider.php

@@ -23,6 +23,7 @@
 use Psalm\Internal\Provider\ReturnTypeProvider\ArraySpliceReturnTypeProvider;
 use Psalm\Internal\Provider\ReturnTypeProvider\ArrayUniqueReturnTypeProvider;
 use Psalm\Internal\Provider\ReturnTypeProvider\ArrayValuesReturnTypeProvider;
+use Psalm\Internal\Provider\ReturnTypeProvider\ExceptionCodeReturnTypeProvider;
 use Psalm\Internal\Provider\ReturnTypeProvider\ExplodeReturnTypeProvider;
 use Psalm\Internal\Provider\ReturnTypeProvider\FilterVarReturnTypeProvider;
 use Psalm\Internal\Provider\ReturnTypeProvider\FirstArgStringReturnTypeProvider;
@@ -109,6 +110,7 @@ public function __construct()
         $this->registerClass(TriggerErrorReturnTypeProvider::class);
         $this->registerClass(RandReturnTypeProvider::class);
         $this->registerClass(InArrayReturnTypeProvider::class);
+        $this->registerClass(ExceptionCodeReturnTypeProvider::class);
     }
 
     /**

src/Psalm/Internal/Provider/ReturnTypeProvider/ExceptionCodeReturnTypeProvider.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace Psalm\Internal\Provider\ReturnTypeProvider;
+
+use Psalm\Plugin\EventHandler\Event\MethodReturnTypeProviderEvent;
+use Psalm\Plugin\EventHandler\MethodReturnTypeProviderInterface;
+use Psalm\Type;
+use PDOException;
+
+use function is_a;
+
+class ExceptionCodeReturnTypeProvider implements MethodReturnTypeProviderInterface
+{
+    public static function getClassLikeNames(): array
+    {
+        return ['Throwable'];
+    }
+
+    public static function getMethodReturnType(MethodReturnTypeProviderEvent $event): ?Type\Union
+    {
+        $method_name_lowercase = $event->getMethodNameLowercase();
+        $fqcn = $event->getCalledFqClasslikeName();
+
+        if ($method_name_lowercase !== 'getcode') {
+            return null;
+        }
+
+        if ($fqcn === 'Exception' || $fqcn === 'Throwable') {
+            return null;
+        }
+
+        if (is_a($fqcn, PDOException::class, true)) {
+            return Type::parseString('string');
+        }
+
+        return Type::parseString('int');
+    }
+}

tests/ReturnTypeProvider/ExceptionCodeTest.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace Psalm\Tests\ReturnTypeProvider;
+
+use Psalm\Tests\TestCase;
+use Psalm\Tests\Traits\ValidCodeAnalysisTestTrait;
+
+class ExceptionCodeTest extends TestCase
+{
+    use ValidCodeAnalysisTestTrait;
+
+    public function providerValidCodeParse(): iterable
+    {
+        yield 'RuntimeException' => [
+            '<?php
+                function f(\RuntimeException $e): int {
+                    $code = $e->getCode();
+                    return $code;
+                }
+            ',
+            ['$code' => 'int'],
+        ];
+        yield 'LogicException' => [
+            '<?php
+                function f(\LogicException $e): int {
+                    $code = $e->getCode();
+                    return $code;
+                }
+            ',
+            ['$code' => 'int'],
+        ];
+        yield 'PDOException' => [
+            '<?php
+                function f(\PDOException $e): string {
+                    $code = $e->getCode();
+                    return $code;
+                }
+            ',
+            ['$code' => 'string'],
+        ];
+        yield 'Exception' => [
+            '<?php
+                /** @return int|string */
+                function f(\Exception $e) {
+                    $code = $e->getCode();
+                    return $code;
+                }
+            ',
+            ['$code' => 'int|string'],
+        ];
+        yield 'Throwable' => [
+            '<?php
+                /** @return int|string */
+                function f(\Throwable $e) {
+                    $code = $e->getCode();
+                    return $code;
+                }
+            ',
+            ['$code' => 'int|string'],
+        ];
+    }
+}