Add linter banning PHP equality checks (#54)

* Add linter banning PHP equality checks

* Run linter, autofix, support <>

Add linter to default linter list, run it on hhast

src/Linters/NoPHPEqualityLinter.php

@@ -0,0 +1,74 @@
+<?hh // strict
+/*
+ *  Copyright (c) 2017-present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the MIT license found in the
+ *  LICENSE file in the root directory of this source tree.
+ *
+ */
+
+namespace Facebook\HHAST\Linters;
+
+use type Facebook\HHAST\{
+  BinaryExpression,
+  EditableNode,
+  EqualEqualToken,
+  EqualEqualEqualToken,
+  ExclamationEqualToken,
+  ExclamationEqualEqualToken,
+  LessThanGreaterThanToken,
+};
+use function Facebook\HHAST\Missing;
+use namespace Facebook\TypeAssert;
+use namespace HH\Lib\{C, Vec};
+
+final class NoPHPEqualityLinter
+  extends AutoFixingASTLinter<BinaryExpression> {
+  <<__Override>>
+  protected static function getTargetType(): classname<BinaryExpression> {
+    return BinaryExpression::class;
+  }
+
+  <<__Override>>
+  public function getLintErrorForNode(
+    BinaryExpression $expr,
+    vec<EditableNode> $_parents,
+  ): ?FixableASTLintError<BinaryExpression> {
+    $token = $expr->getOperator();
+    $replacement = null;
+    if ($token instanceof EqualEqualToken) {
+      $replacement = '===';
+    } else if (
+      $token instanceof ExclamationEqualToken
+      || $token instanceof LessThanGreaterThanToken) {
+      $replacement = '!==';
+    } else {
+      return null;
+    }
+
+    return new FixableASTLintError(
+      $this,
+      'Do not use PHP equality - use "'.$replacement.'" instead.',
+      $expr,
+    );
+    return null;
+  }
+
+  <<__Override>>
+  public function getFixedNode(BinaryExpression $expr): ?EditableNode {
+    $op = $expr->getOperator();
+    if ($op instanceof EqualEqualToken) {
+      $op = new EqualEqualEqualToken($op->getLeading(), $op->getTrailing());
+    } else if (
+      $op instanceof ExclamationEqualToken
+      || $op instanceof LessThanGreaterThanToken
+    ) {
+      $op =
+        new ExclamationEqualEqualToken($op->getLeading(), $op->getTrailing());
+    } else {
+      return null;
+    }
+    return $expr->withOperator($op);
+  }
+}

src/Linters/suppress_ast_linter_error.php

@@ -70,12 +70,12 @@ function is_linter_suppressed_in_sibling_node(
   string $ignore,
 ): bool {
   $parent = C\last($parents);
-  if ($parent == null) {
+  if ($parent === null) {
     return false;
   }
 
   $sibling = C\first($parent->getChildren());
-  if ($sibling == null) {
+  if ($sibling === null) {
     return false;
   }
 

src/__Private/LinterCLIConfig.php

@@ -65,6 +65,7 @@ final class LinterCLIConfig {
       Linters\NoBasicAssignmentFunctionParameterLinter::class,
       Linters\MustUseBracesForControlFlowLinter::class,
       Linters\MustUseOverrideAttributeLinter::class,
+      Linters\NoPHPEqualityLinter::class,
       Linters\NoWhitespaceAtEndOfLineLinter::class,
     ];
 

src/__Private/codegen/CodegenSyntax.php

@@ -118,7 +118,7 @@ private function generateFieldMethods(
             'static',
             Vec\map(
               $syntax['fields'],
-              $inner ==> $inner['field_name'] == $underscored
+              $inner ==> $inner['field_name'] === $underscored
                 ? '$value'
                 : '$this->_'.$inner['field_name'],
             ),

src/__Private/codegen/CodegenTokens.php

@@ -139,7 +139,7 @@ public function generateExtends(
       $cls = 'EditableTokenWithVariableText';
     } else {
       foreach ($token['fields'] as $field) {
-        if ($field['name'] == 'text'){
+        if ($field['name'] === 'text'){
           $cls = 'EditableTokenWithVariableText';
         }
       }

src/nodes/EditableNode.php

@@ -146,7 +146,7 @@ public function findWithParents(
     }
     foreach ($this->getChildren() as $child) {
       $result = $child->findWithParents($predicate, $new_parents);
-      if (\count($result) != 0) {
+      if (\count($result) !== 0) {
         return $result;
       }
     }

tests/NoPHPEqualityLinterTest.php

@@ -0,0 +1,29 @@
+<?hh // strict
+/*
+ *  Copyright (c) 2017-present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the MIT license found in the
+ *  LICENSE file in the root directory of this source tree.
+ *
+ */
+
+namespace Facebook\HHAST;
+
+final class NoPHPEqualityLinterTest extends TestCase {
+  use AutoFixingLinterTestTrait<Linters\FixableASTLintError<BinaryExpression>>;
+
+  protected function getLinter(
+    string $file,
+  ): Linters\NoPHPEqualityLinter{
+    return new Linters\NoPHPEqualityLinter($file);
+  }
+
+  public function getCleanExamples(): array<array<string>> {
+    return [
+      ['<?hh "foo" === "bar";'],
+      ['<?hh "foo" !== "bar";'],
+      ['<?hh "foo" > "bar";'],
+    ];
+  }
+}

tests/fixtures/NoPHPEqualityLinter/double_equals.php.autofix.expect

@@ -0,0 +1,15 @@
+<?hh // strict
+/*
+ *  Copyright (c) 2017-present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the MIT license found in the
+ *  LICENSE file in the root directory of this source tree.
+ *
+ */
+
+function foo(): void {
+  var_dump('0e123' === '0e456');
+  var_dump('0e123' !== '0e456');
+  var_dump('0e123' !== '0e456');
+}

tests/fixtures/NoPHPEqualityLinter/double_equals.php.expect

@@ -0,0 +1,17 @@
+[
+    {
+        "blame": "'0e123' == '0e456'",
+        "blame_pretty": "'0e123' == '0e456'",
+        "description": "Do not use PHP equality - use \"===\" instead."
+    },
+    {
+        "blame": "'0e123' != '0e456'",
+        "blame_pretty": "'0e123' != '0e456'",
+        "description": "Do not use PHP equality - use \"!==\" instead."
+    },
+    {
+        "blame": "'0e123' <> '0e456'",
+        "blame_pretty": "'0e123' <> '0e456'",
+        "description": "Do not use PHP equality - use \"!==\" instead."
+    }
+]

tests/fixtures/NoPHPEqualityLinter/double_equals.php.in

@@ -0,0 +1,15 @@
+<?hh // strict
+/*
+ *  Copyright (c) 2017-present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the MIT license found in the
+ *  LICENSE file in the root directory of this source tree.
+ *
+ */
+
+function foo(): void {
+  var_dump('0e123' == '0e456');
+  var_dump('0e123' != '0e456');
+  var_dump('0e123' <> '0e456');
+}