Support arc lint --output none

Summary:
I want to run lint on background and I'm interested only in side effect of caching (and maybe exit status).
This is better than discarding stdout later because we don't do unnecessary work and error conditions are still printed.

Test Plan:
  $ arc lint --output none # with error
  $ echo $?
  $ arc lint --output none # with no lintable paths
  $ arc lint --output none # witout errors

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5106

src/__phutil_library_map__.php

@@ -84,6 +84,7 @@ phutil_register_library_map(array(
     'ArcanistLintJSONRenderer' => 'lint/renderer/ArcanistLintJSONRenderer.php',
     'ArcanistLintLikeCompilerRenderer' => 'lint/renderer/ArcanistLintLikeCompilerRenderer.php',
     'ArcanistLintMessage' => 'lint/ArcanistLintMessage.php',
+    'ArcanistLintNoneRenderer' => 'lint/renderer/ArcanistLintNoneRenderer.php',
     'ArcanistLintPatcher' => 'lint/ArcanistLintPatcher.php',
     'ArcanistLintRenderer' => 'lint/renderer/ArcanistLintRenderer.php',
     'ArcanistLintResult' => 'lint/ArcanistLintResult.php',
@@ -225,6 +226,7 @@ phutil_register_library_map(array(
     'ArcanistLintConsoleRenderer' => 'ArcanistLintRenderer',
     'ArcanistLintJSONRenderer' => 'ArcanistLintRenderer',
     'ArcanistLintLikeCompilerRenderer' => 'ArcanistLintRenderer',
+    'ArcanistLintNoneRenderer' => 'ArcanistLintRenderer',
     'ArcanistLintSummaryRenderer' => 'ArcanistLintRenderer',
     'ArcanistLintWorkflow' => 'ArcanistBaseWorkflow',
     'ArcanistLinterTestCase' => 'ArcanistPhutilTestCase',

src/lint/linter/ArcanistPhutilXHPASTLinter.php

@@ -65,7 +65,12 @@ final class ArcanistPhutilXHPASTLinter extends ArcanistBaseXHPASTLinter {
   }
 
   public function getCacheVersion() {
-    return 2;
+    $version = '2';
+    $path = xhpast_get_binary_path();
+    if (Filesystem::pathExists($path)) {
+      $version .= '-'.md5_file($path);
+    }
+    return $version;
   }
 
   protected function buildFutures(array $paths) {

src/lint/renderer/ArcanistLintNoneRenderer.php

@@ -0,0 +1,16 @@
+<?php
+
+/**
+ * @group lint
+ */
+final class ArcanistLintNoneRenderer extends ArcanistLintRenderer {
+
+  public function renderLintResult(ArcanistLintResult $result) {
+    return '';
+  }
+
+  public function renderOkayResult() {
+    return '';
+  }
+
+}

src/workflow/ArcanistLintWorkflow.php

@@ -81,6 +81,7 @@ EOTEXT
         'help' =>
           "With 'summary', show lint warnings in a more compact format. ".
           "With 'json', show lint warnings in machine-readable JSON format. ".
+          "With 'none', show no lint warnings. ".
           "With 'compiler', show lint warnings in suitable for your editor."
       ),
       'only-new' => array(
@@ -384,6 +385,11 @@ EOTEXT
       case 'summary':
         $renderer = new ArcanistLintSummaryRenderer();
         break;
+      case 'none':
+        $prompt_patches = false;
+        $apply_patches = $this->getArgument('apply-patches');
+        $renderer = new ArcanistLintNoneRenderer();
+        break;
       case 'compiler':
         $renderer = new ArcanistLintLikeCompilerRenderer();
         $prompt_patches = false;
@@ -480,6 +486,11 @@ EOTEXT
     }
 
     if ($failed) {
+      if ($failed instanceof ArcanistNoEffectException) {
+        if ($renderer instanceof ArcanistLintNoneRenderer) {
+          return 0;
+        }
+      }
       throw $failed;
     }