Add Exception->getCode() return type provider

src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallReturnTypeFetcher.php

@@ -2,6 +2,8 @@
 
 namespace Psalm\Internal\Analyzer\Statements\Expression\Call\Method;
 
+use Exception;
+use PDOException;
 use PhpParser;
 use Psalm\CodeLocation;
 use Psalm\Codebase;
@@ -27,6 +29,7 @@
 use Psalm\Type\Atomic\TNamedObject;
 use Psalm\Type\Atomic\TTemplateParam;
 use Psalm\Type\Union;
+use Throwable;
 use UnexpectedValueException;
 
 use function array_filter;
@@ -92,6 +95,16 @@ public static function fetch(
             }
         }
 
+        if ($premixin_method_id->method_name === 'getcode'
+            && $premixin_method_id->fq_class_name !== Exception::class
+            && in_array(Throwable::class, $class_storage->class_implements)) {
+            if ($premixin_method_id->fq_class_name === PDOException::class) {
+                return Type::getString();
+            } else {
+                return Type::getInt(true); // TODO: Remove the flag in Psalm 5
+            }
+        }
+
         if ($declaring_method_id && $declaring_method_id !== $method_id) {
             $declaring_fq_class_name = $declaring_method_id->fq_class_name;
             $declaring_method_name = $declaring_method_id->method_name;

tests/ReturnTypeProvider/ExceptionCodeTest.php

@@ -0,0 +1,53 @@
+<?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 {
+                    return $e->getCode();
+                }
+            ',
+            [],
+        ];
+        yield 'LogicException' => [
+            '<?php
+                function f(\LogicException $e): int {
+                    return $e->getCode();
+                }
+            ',
+            [],
+        ];
+        yield 'PDOException' => [
+            '<?php
+                function f(\PDOException $e): string {
+                    return $e->getCode();
+                }
+            ',
+            [],
+        ];
+        yield 'Exception' => [
+            '<?php
+                /** @var \Throwable $e */
+                $code = $e->getCode();
+            ',
+            ['$code' => 'int|string'],
+        ];
+        yield 'Throwable' => [
+            '<?php
+                /** @var \Exception $e */
+                $code = $e->getCode();
+            ',
+            ['$code' => 'int|string'],
+        ];
+    }
+}