DX: Report more precise errors in `VerifyRectorServiceExistsCompilerP…

…ass` (#97)

phpstan.neon

@@ -212,6 +212,11 @@ parameters:
             message: '#Call to function is_string\(\) with float will always evaluate to false#'
             path: src/PhpParser/Printer/BetterStandardPrinter.php
 
+        # class_exists is forbidden to enforce static reflection, but in a compiler pass we want runtime autoloading
+        -
+            message:  '#Function "class_exists\(\)" cannot be used/left in the code#'
+            path: src/DependencyInjection/CompilerPass/VerifyRectorServiceExistsCompilerPass.php         
+
         # known values from other methods
         -
             message: '#Negated boolean expression is always true#'

src/DependencyInjection/CompilerPass/VerifyRectorServiceExistsCompilerPass.php

@@ -6,6 +6,7 @@
 
 use Rector\Core\Contract\Rector\RectorInterface;
 use Rector\Core\Exception\ShouldNotHappenException;
+use Rector\Core\Rector\AbstractRector;
 use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 
@@ -23,9 +24,15 @@ public function process(ContainerBuilder $containerBuilder): void
                 continue;
             }
 
+            if (!class_exists($class)) {
+                throw new ShouldNotHappenException(
+                    sprintf('Rector rule "%s" not found, please verify that the class exists and is autoloadable.', $class)
+                );
+            }
+
             if (! is_a($class, RectorInterface::class, true)) {
                 throw new ShouldNotHappenException(
-                    sprintf('Rector rule "%s" not found, please verify that the rule exists', $class)
+                    sprintf('Rector rule "%s" should extend "%s" or implement "%s".', $class, AbstractRector::class, RectorInterface::class)
                 );
             }
         }