arc lint: add support for PyFlakes

Summary:
Provide a simple linter wrapper around pyflakes.  This relies on finding
pyflakes via:
- lint.pyflakes.path - arcconfig setting of absolute path to pyflakes
- lint.pyflakes.prefix - arcconfig setting of the prefix that pyflakes
  was installed under
- users path

Test Plan:
linted python code with PyFlakes warnings

Reviewed By: epriestley
Reviewers: jungejason, epriestley
Commenters: jungejason
CC: aran, epriestley, andrewjcg, jungejason
Differential Revision: 310

src/__phutil_library_map__.php

@@ -61,6 +61,7 @@ phutil_register_library_map(array(
     'ArcanistPhutilModuleLinter' => 'lint/linter/phutilmodule',
     'ArcanistPhutilTestCase' => 'unit/engine/phutil/testcase',
     'ArcanistPhutilTestTerminatedException' => 'unit/engine/phutil/testcase/exception',
+    'ArcanistPyFlakesLinter' => 'lint/linter/pyflakes',
     'ArcanistRepositoryAPI' => 'repository/api/base',
     'ArcanistShellCompleteWorkflow' => 'workflow/shell-complete',
     'ArcanistSubversionAPI' => 'repository/api/subversion',
@@ -113,6 +114,7 @@ phutil_register_library_map(array(
     'ArcanistPEP8Linter' => 'ArcanistLinter',
     'ArcanistPatchWorkflow' => 'ArcanistBaseWorkflow',
     'ArcanistPhutilModuleLinter' => 'ArcanistLinter',
+    'ArcanistPyFlakesLinter' => 'ArcanistLinter',
     'ArcanistShellCompleteWorkflow' => 'ArcanistBaseWorkflow',
     'ArcanistSubversionAPI' => 'ArcanistRepositoryAPI',
     'ArcanistSvnHookPreCommitWorkflow' => 'ArcanistBaseWorkflow',

src/lint/linter/pyflakes/ArcanistPyFlakesLinter.php

@@ -0,0 +1,113 @@
+<?php
+
+/*
+ * Copyright 2011 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Uses "PyFlakes" to detect various errors in Python code.
+ *
+ * @group linter
+ */
+class ArcanistPyFlakesLinter extends ArcanistLinter {
+
+  public function willLintPaths(array $paths) {
+    return;
+  }
+
+  public function getLinterName() {
+    return 'PyFlakes';
+  }
+
+  public function getLintSeverityMap() {
+    return array();
+  }
+
+  public function getLintNameMap() {
+    return array(
+    );
+  }
+
+  public function getPyFlakesOptions() {
+    return null;
+  }
+
+  public function lintPath($path) {
+    $working_copy = $this->getEngine()->getWorkingCopy();
+    $pyflakes_path = $working_copy->getConfig('lint.pyflakes.path');
+    $pyflakes_prefix = $working_copy->getConfig('lint.pyflakes.prefix');
+
+    // Default to just finding pyflakes in the users path
+    $pyflakes_bin = 'pyflakes';
+    $python_path = '';
+
+    // If a pyflakes path was specified, then just use that as the
+    // pyflakes binary and assume that the libraries will be imported
+    // correctly.
+    //
+    // If no pyflakes path was specified and a pyflakes prefix was
+    // specified, then use the binary from this prefix and add it to
+    // the PYTHONPATH environment variable so that the libs are imported
+    // correctly.  This is useful when pyflakes is installed into a
+    // non-default location.
+    if ($pyflakes_path !== null) {
+      $pyflakes_bin = $pyflakes_path;
+    } else if ($pyflakes_prefix !== null) {
+      $pyflakes_bin = $pyflakes_prefix.'/bin/pyflakes';
+      $python_path = $pyflakes_prefix.'/lib/python2.6/site-packages:';
+    }
+
+    $options = $this->getPyFlakesOptions();
+
+    $f = new ExecFuture(
+          "/usr/bin/env PYTHONPATH=%s\$PYTHONPATH ".
+            "{$pyflakes_bin} {$options}", $python_path);
+    $f->write($this->getData($path));
+
+    try {
+      list($stdout, $_) = $f->resolvex();
+    } catch (CommandException $e) {
+      // PyFlakes will return an exit code of 1 if warnings/errors
+      // are found but print nothing to stderr in this case.  Therefore,
+      // if we see any output on stderr or a return code other than 1 or 0,
+      // pyflakes failed.
+      if ($e->getError() !== 1 || $e->getStderr() !== '') {
+        throw $e;
+      } else {
+        $stdout = $e->getStdout();
+      }
+    }
+
+    $lines = explode("\n", $stdout);
+    $messages = array();
+    foreach ($lines as $line) {
+      $matches = null;
+      if (!preg_match('/^(.*?):(\d+): (.*)$/', $line, $matches)) {
+        continue;
+      }
+      foreach ($matches as $key => $match) {
+        $matches[$key] = trim($match);
+      }
+      $message = new ArcanistLintMessage();
+      $message->setPath($path);
+      $message->setLine($matches[2]);
+      $message->setCode($this->getLinterName());
+      $message->setDescription($matches[3]);
+      $message->setSeverity(ArcanistLintSeverity::SEVERITY_WARNING);
+      $this->addLintMessage($message);
+    }
+  }
+
+}

src/lint/linter/pyflakes/__init__.php

@@ -0,0 +1,16 @@
+<?php
+/**
+ * This file is automatically generated. Lint this module to rebuild it.
+ * @generated
+ */
+
+
+
+phutil_require_module('arcanist', 'lint/linter/base');
+phutil_require_module('arcanist', 'lint/message');
+phutil_require_module('arcanist', 'lint/severity');
+
+phutil_require_module('phutil', 'future/exec');
+
+
+phutil_require_source('ArcanistPyFlakesLinter.php');