Fix codegen to not depend on namespace fallback

Author: fredemmott

src/RouterCLILookupCodegenBuilder.php

@@ -194,13 +194,13 @@ private function getInitCode(): string {
         HackBuilderValues::immSet(HackBuilderValues::literal()),
       )
       ->startForeachLoop('$autoloader_candidates', null, '$candidate')
-      ->startIfBlock('file_exists($candidate)')
+      ->startIfBlock('\\file_exists($candidate)')
       ->addAssignment('$autoloader', '$candidate', HackBuilderValues::literal())
       ->addLine('break;')
       ->endIfBlock()
       ->endForeachLoop()
       ->startIfBlock('$autoloader === null')
-      ->addLine('fwrite(STDERR, "Can\'t find autoloader.\n");')
+      ->addLine('\\fwrite(\\STDERR, "Can\'t find autoloader.\n");')
       ->addLine('exit(1);')
       ->endIfBlock()
       ->addLine('require_once($autoloader);')
@@ -220,7 +220,7 @@ private function getMainMethod(): CodegenMethod {
             HackBuilderValues::literal(),
           )
           ->startIfBlock('$path === null')
-          ->addLine('fprintf(STDERR, "Usage: %s PATH\n", $argv[0]);')
+          ->addLine('\\fprintf(\\STDERR, "Usage: %s PATH\n", $argv[0]);')
           ->addLine('exit(1);')
           ->endIfBlock()
           ->addAssignment(
@@ -229,7 +229,7 @@ private function getMainMethod(): CodegenMethod {
             HackBuilderValues::literal(),
           )
           ->startIfBlock('$controllers->isEmpty()')
-          ->addLine('printf("No controller found for \'%s\'.\n", $path);')
+          ->addLine('\\printf("No controller found for \'%s\'.\n", $path);')
           ->addLine('exit(1);')
           ->endIfBlock()
           ->startForeachLoop('$controllers', '$method', '$controller')
@@ -238,7 +238,7 @@ private function getMainMethod(): CodegenMethod {
             '$this->prettifyControllerName($controller)',
             HackBuilderValues::literal(),
           )
-          ->addLine('printf("%-8s %s\n", $method.\':\', $pretty);')
+          ->addLine('\\printf("%-8s %s\n", $method.\':\', $pretty);')
           ->endForeachLoop()
           ->getCode()
       );

tests/examples/codegen/lookup-path.php

@@ -7,7 +7,7 @@
  * To re-generate this file run vendor/phpunit/phpunit/phpunit
  *
  *
- * @partially-generated SignedSource<<b246f714d429fe5492522d5e9759fbfd>>
+ * @partially-generated SignedSource<<394f3dc7b352d127b17bdb87263351ef>>
  */
 namespace Facebook\HackRouter\CodeGen\Tests\Generated;
 /* BEGIN MANUAL SECTION init */
@@ -26,13 +26,13 @@ private function getRouter(
 
   private function prettifyControllerName(string $controller): string {
     /* BEGIN MANUAL SECTION MySiteRouterCLILookup::prettifyControllerName */
-    $parts = \explode('\\', $controller);
+    $parts = explode('\\', $controller);
     invariant(
-      \count($parts) > 3,
+      count($parts) > 3,
       'Too few NS parts found; expected everything to be in example NS',
     );
     $first = $parts[0];
-    $last = \array_pop(&$parts);
+    $last = array_pop(&$parts);
     return '\\'.$first.'\\...\\'.$last;
     /* END MANUAL SECTION */
   }