Add a flake8 linter

Summary: flake8 is the better maintained combination of pep8 and pyflakes

Test Plan: There's a test!

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin, jack

Differential Revision: https://secure.phabricator.com/D4082

src/__phutil_library_map__.php

@@ -53,6 +53,8 @@ phutil_register_library_map(array(
     'ArcanistExportWorkflow' => 'workflow/ArcanistExportWorkflow.php',
     'ArcanistFilenameLinter' => 'lint/linter/ArcanistFilenameLinter.php',
     'ArcanistFlagWorkflow' => 'workflow/ArcanistFlagWorkflow.php',
+    'ArcanistFlake8Linter' => 'lint/linter/ArcanistFlake8Linter.php',
+    'ArcanistFlake8LinterTestCase' => 'lint/linter/__tests__/ArcanistFlake8LinterTestCase.php',
     'ArcanistGeneratedLinter' => 'lint/linter/ArcanistGeneratedLinter.php',
     'ArcanistGetConfigWorkflow' => 'workflow/ArcanistGetConfigWorkflow.php',
     'ArcanistGitAPI' => 'repository/api/ArcanistGitAPI.php',
@@ -181,6 +183,8 @@ phutil_register_library_map(array(
     'ArcanistExportWorkflow' => 'ArcanistBaseWorkflow',
     'ArcanistFilenameLinter' => 'ArcanistLinter',
     'ArcanistFlagWorkflow' => 'ArcanistBaseWorkflow',
+    'ArcanistFlake8Linter' => 'ArcanistLinter',
+    'ArcanistFlake8LinterTestCase' => 'ArcanistArcanistLinterTestCase',
     'ArcanistGeneratedLinter' => 'ArcanistLinter',
     'ArcanistGetConfigWorkflow' => 'ArcanistBaseWorkflow',
     'ArcanistGitAPI' => 'ArcanistRepositoryAPI',

src/lint/linter/ArcanistFlake8Linter.php

@@ -0,0 +1,115 @@
+<?php
+
+/**
+ * Uses "flake8" to detect various errors in Python code.
+ * Requires version 1.7.0 or newer of flake8.
+ *
+ * @group linter
+ */
+final class ArcanistFlake8Linter extends ArcanistLinter {
+
+  public function willLintPaths(array $paths) {
+    return;
+  }
+
+  public function getLinterName() {
+    return 'flake8';
+  }
+
+  public function getFlake8Options() {
+    $working_copy = $this->getEngine()->getWorkingCopy();
+
+    $options = $working_copy->getConfig('lint.flake8.options', '');
+
+    return $options;
+  }
+
+  public function getFlake8Path() {
+    $working_copy = $this->getEngine()->getWorkingCopy();
+    $prefix = $working_copy->getConfig('lint.flake8.prefix');
+    $bin = $working_copy->getConfig('lint.flake8.bin');
+
+    if ($bin === null && $prefix === null) {
+      $bin = 'flake8';
+    } else {
+      if ($bin === null) {
+        $bin = 'flake8';
+      }
+
+      if ($prefix !== null) {
+        if (!Filesystem::pathExists($prefix.'/'.$bin)) {
+          throw new ArcanistUsageException(
+            "Unable to find flake8 binary in a specified directory. Make sure ".
+            "that 'lint.flake8.prefix' and 'lint.flake8.bin' keys are set ".
+            "correctly. If you'd rather use a copy of flake8 installed ".
+            "globally, you can just remove these keys from your .arcconfig");
+        }
+
+        $bin = csprintf("%s/%s", $prefix, $bin);
+
+        return $bin;
+      }
+
+      // Look for globally installed flake8
+      list($err) = exec_manual('which %s', $bin);
+      if ($err) {
+        throw new ArcanistUsageException(
+          "flake8 does not appear to be installed on this system. Install it ".
+          "(e.g., with 'easy_install flake8') or configure ".
+          "'lint.flake8.prefix' in your .arcconfig to point to the directory ".
+          "where it resides.");
+      }
+    }
+
+    return $bin;
+  }
+
+  public function lintPath($path) {
+    $flake8_bin = $this->getFlake8Path();
+    $options = $this->getFlake8Options();
+
+    $f = new ExecFuture("%C %C -", $flake8_bin, $options);
+    $f->write($this->getData($path));
+
+    list($err, $stdout, $stderr) = $f->resolve();
+
+    if ($err === 2) {
+      throw new Exception("flake8 failed to run correctly:\n".$stderr);
+    }
+
+    $lines = explode("\n", $stdout);
+    $messages = array();
+    foreach ($lines as $line) {
+      $matches = null;
+      // stdin:2: W802 undefined name 'foo'  # pyflakes
+      // stdin:3:1: E302 expected 2 blank lines, found 1  # pep8
+      if (!preg_match('/^(.*?):(\d+):(?:(\d+):)? (\S+) (.*)$/',
+                      $line, $matches)) {
+        continue;
+      }
+      foreach ($matches as $key => $match) {
+        $matches[$key] = trim($match);
+      }
+
+      $severity = ArcanistLintSeverity::SEVERITY_WARNING;
+      $description = $matches[3];
+
+      $error_regexp = '/(^undefined|^duplicate|before assignment$)/';
+      if (preg_match($error_regexp, $description)) {
+        $severity = ArcanistLintSeverity::SEVERITY_ERROR;
+      }
+
+      $message = new ArcanistLintMessage();
+      $message->setPath($path);
+      $message->setLine($matches[2]);
+      if (!empty($matches[3]))
+        $message->setChar($matches[3]);
+      $message->setCode($matches[4]);
+      $message->setName($this->getLinterName().' '.$matches[4]);
+      $message->setDescription($description);
+      $message->setSeverity($severity);
+      $this->addLintMessage($message);
+    }
+  }
+
+}

src/lint/linter/__tests__/ArcanistFlake8LinterTestCase.php

@@ -0,0 +1,19 @@
+<?php
+/**
+ * Test cases for @{class:ArcanistFlake8Linter}.
+ *
+ * @group testcase
+ */
+final class ArcanistFlake8LinterTestCase
+  extends ArcanistArcanistLinterTestCase {
+
+  public function testFlake8Lint() {
+    $linter = new ArcanistFlake8Linter();
+    $working_copy = ArcanistWorkingCopyIdentity::newFromPath(__FILE__);
+    return $this->executeTestsInDirectory(
+      dirname(__FILE__).'/python/',
+      $linter,
+      $working_copy);
+  }
+
+}

src/lint/linter/__tests__/python/undefined.lint-test

@@ -0,0 +1,7 @@
+x = 'y'
+
+def hello():
+    return foo
+~~~~~~~~~~
+warning:1:8
+warning:4: