Add a rector to replace negated boolean literals

Replaces `! true` with `false` and replaces
`! false` with `true`. This lets other rectors
like dead code elimination work better.

Author: john-shaffer

rector.php

@@ -3,6 +3,7 @@
 require_once __DIR__ . '/util/rector/RemoveAlwaysFalseIfStatementRector.php';
 require_once __DIR__ . '/util/rector/RemoveAlwaysTrueIfConditionRector2.php';
 require_once __DIR__ . '/util/rector/ReplaceKnownDefinedWithBooleanRector.php';
+require_once __DIR__ . '/util/rector/ReplaceNegatedBooleanRector.php';
 
 use Rector\Config\RectorConfig;
 use Rector\Constants\Rector\FuncCall\ReplaceKnownDefinedWithBooleanRector;
@@ -11,6 +12,7 @@
 use Rector\DeadCode\Rector\If_\RemoveAlwaysTrueIfConditionRector2;
 use Rector\Php53\Rector\Ternary\TernaryToElvisRector;
 use Rector\Set\ValueObject\SetList;
+use Rector\Transform\Rector\BooleanNot\ReplaceNegatedBooleanRector;
 
 // Search rules at https://getrector.com/find-rule
 
@@ -34,6 +36,7 @@
             RemoveAlwaysFalseIfStatementRector::class,
             RemoveAlwaysTrueIfConditionRector2::class,
             ReplaceKnownDefinedWithBooleanRector::class,
+            ReplaceNegatedBooleanRector::class,
         ]
     )
     ->withSets(

util/rector/ReplaceNegatedBooleanRector.php

@@ -0,0 +1,87 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Transform\Rector\BooleanNot;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr;
+use PhpParser\Node\Expr\BooleanNot;
+use PhpParser\Node\Expr\ConstFetch;
+use PhpParser\Node\Name;
+use Rector\Rector\AbstractRector;
+use Symplify\RuleDocGenerator\ValueObject\CodeSample\CodeSample;
+use Symplify\RuleDocGenerator\ValueObject\RuleDefinition;
+
+/**
+ * Replace negated boolean literals with their simplified equivalents
+ *
+ * @see \Rector\Tests\DeadCode\Rector\BooleanNot\ReplaceNegatedBooleanRector\ReplaceNegatedBooleanRectorTest
+ */
+final class ReplaceNegatedBooleanRector extends AbstractRector
+{
+    public function getRuleDefinition(): RuleDefinition
+    {
+        return new RuleDefinition('Replace negated boolean literals (!false, !true) with their simplified equivalents (true, false)', [
+            new CodeSample(
+                <<<'CODE_SAMPLE'
+if (!false) {
+    return 'always true';
+}
+
+if (!true) {
+    return 'never reached';
+}
+CODE_SAMPLE
+                ,
+                <<<'CODE_SAMPLE'
+if (true) {
+    return 'always true';
+}
+
+if (false) {
+    return 'never reached';
+}
+CODE_SAMPLE
+            )
+        ]);
+    }
+
+    /**
+     * @return array<class-string<Node>>
+     */
+    public function getNodeTypes(): array
+    {
+        return [BooleanNot::class];
+    }
+
+    /**
+     * @param BooleanNot $node
+     */
+    public function refactor(Node $node): ?Node
+    {
+        if (!$node instanceof BooleanNot) {
+            return null;
+        }
+
+        if (!$node->expr instanceof ConstFetch) {
+            return null;
+        }
+
+        $constantName = $this->getName($node->expr);
+
+        /** @var ConstFetch $constFetch */
+        $constFetch = $node->expr;
+        $constantName = $this->getName($constFetch);
+
+        if ($constantName === 'false') {
+            return new ConstFetch(new Name('true'));
+        }
+
+        if ($constantName === 'true') {
+            return new ConstFetch(new Name('false'));
+        }
+
+        return null;
+    }
+}