Allow --rule option to take short rule names

.. but throw an exception if the name is ambiguous

src/Configuration/OnlyRuleResolver.php

@@ -6,6 +6,7 @@
 
 use Rector\Contract\Rector\RectorInterface;
 use Rector\Exception\Configuration\RectorRuleNotFoundException;
+use Rector\Exception\Configuration\RectorRuleNameAmbigiousException;
 
 /**
  * @see \Rector\Tests\Configuration\OnlyRuleResolverTest
@@ -38,6 +39,27 @@ public function resolve(string $rule): string
             }
         }
 
+        //allow short rule names if there are not duplicates
+        $matching = [];
+        foreach ($this->rectors as $rector) {
+            if (str_ends_with($rector::class, '\\' . $rule)) {
+                $matching[] = $rector::class;
+            }
+        }
+        $matching = array_unique($matching);
+
+        if (count($matching) == 1) {
+            return $matching[0];
+        } elseif (count($matching) > 1) {
+            sort($matching);
+            $message = sprintf(
+                'Short rule name "%s" is ambiguous. Specify the full rule name:' . PHP_EOL
+                    . '- ' . implode(PHP_EOL . '- ', $matching),
+                $rule
+            );
+            throw new RectorRuleNameAmbigiousException($message);
+        }
+
         if (strpos($rule, '\\') === false) {
             $message = sprintf(
                 'Rule "%s" was not found.%sThe rule has no namespace. Make sure to escape the backslashes, and add quotes around the rule name: --only="My\\Rector\\Rule"',

src/Exception/Configuration/RectorRuleNameAmbigiousException.php

@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Exception\Configuration;
+
+use Exception;
+
+final class RectorRuleNameAmbigiousException extends Exception
+{
+}

tests/Configuration/OnlyRuleResolverTest.php

@@ -6,6 +6,7 @@
 
 use Rector\Configuration\OnlyRuleResolver;
 use Rector\Contract\Rector\RectorInterface;
+use Rector\Exception\Configuration\RectorRuleNameAmbigiousException;
 use Rector\Exception\Configuration\RectorRuleNotFoundException;
 use Rector\Testing\PHPUnit\AbstractLazyTestCase;
 
@@ -76,4 +77,32 @@ public function testResolveNotFound(): void
 
         $this->resolver->resolve('This\\Rule\\Does\\Not\\Exist');
     }
+
+    public function testResolveShortOk(): void
+    {
+        $this->assertEquals(
+            \Rector\DeadCode\Rector\ClassMethod\RemoveUnusedPrivateMethodRector::class,
+            $this->resolver->resolve('RemoveUnusedPrivateMethodRector'),
+        );
+    }
+
+    public function testResolveShortOkTwoLevels(): void
+    {
+        $this->assertEquals(
+            \Rector\DeadCode\Rector\Assign\RemoveDoubleAssignRector::class,
+            $this->resolver->resolve('Assign\\RemoveDoubleAssignRector'),
+        );
+    }
+
+    public function testResolveShortAmbiguous(): void
+    {
+        $this->expectExceptionMessage(
+            'Short rule name "RemoveDoubleAssignRector" is ambiguous. Specify the full rule name:' . PHP_EOL
+                . '- Rector\\DeadCode\\Rector\\Assign\\RemoveDoubleAssignRector' . PHP_EOL
+                . '- Rector\\Tests\\Configuration\\Source\\RemoveDoubleAssignRector'
+        );
+        $this->expectException(RectorRuleNameAmbigiousException::class);
+
+        $this->resolver->resolve('RemoveDoubleAssignRector');
+    }
 }

tests/Configuration/Source/RemoveDoubleAssignRector.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Rector\Tests\Configuration\Source;
+
+use PhpParser\Node;
+use Rector\Rector\AbstractRector;
+use Symplify\RuleDocGenerator\ValueObject\RuleDefinition;
+
+/**
+ * Dummy rector with same class name as an official one
+ */
+class RemoveDoubleAssignRector extends AbstractRector
+{
+    public function getRuleDefinition(): RuleDefinition
+    {
+        return new RuleDefinition('Test short rule name conflicts', []);
+    }
+
+    public function getNodeTypes(): array
+    {
+        return [];
+    }
+
+    public function refactor(Node $node): ?Node
+    {
+        return $node;
+    }
+}

tests/Configuration/config/only_rule_resolver_config.php

@@ -5,6 +5,7 @@
 use Rector\Config\RectorConfig;
 use Rector\DeadCode\Rector\Assign\RemoveDoubleAssignRector;
 use Rector\DeadCode\Rector\ClassMethod\RemoveUnusedPrivateMethodRector;
+use Rector\Tests\Configuration\Source\RemoveDoubleAssignRector as RemoveDoubleAssignRectorTest;
 
 return RectorConfig::configure()
-    ->withRules([RemoveDoubleAssignRector::class, RemoveUnusedPrivateMethodRector::class]);
+    ->withRules([RemoveDoubleAssignRector::class, RemoveDoubleAssignRectorTest::class, RemoveUnusedPrivateMethodRector::class]);