From f9eb45e14365f4bc9b558c714d79959d7ebfbb08 Mon Sep 17 00:00:00 2001
From: Shyamsundar Gadde <shyamsundar.gadde@rtcamp.com>
Date: Fri, 10 Jan 2025 01:12:12 +0530
Subject: [PATCH] Add custom sniff to warn about `empty()`

Signed-off-by: Shyamsundar Gadde <shyamsundar.gadde@rtcamp.com>
---
 .../PHP/RestrictedEmptyConstructSniff.php     | 40 +++++++++++++++++++
 tools/phpcs/phpcs.ruleset.xml                 |  8 ++++
 2 files changed, 48 insertions(+)
 create mode 100644 tools/phpcs/Sniffs/PHP/RestrictedEmptyConstructSniff.php

diff --git a/tools/phpcs/Sniffs/PHP/RestrictedEmptyConstructSniff.php b/tools/phpcs/Sniffs/PHP/RestrictedEmptyConstructSniff.php
new file mode 100644
index 0000000000..3963eb20cf
--- /dev/null
+++ b/tools/phpcs/Sniffs/PHP/RestrictedEmptyConstructSniff.php
@@ -0,0 +1,40 @@
+<?php
+/**
+ * Sniff to restrict usage of the empty() construct.
+ *
+ * @package performance
+ */
+
+namespace WPPCS\WPP\Sniffs\PHP;
+
+use PHP_CodeSniffer\Sniffs\Sniff;
+use PHP_CodeSniffer\Files\File;
+
+// phpcs:ignoreFile WordPress.NamingConventions.ValidVariableName -- required by the interface.
+
+/**
+ * Restricts usage of empty().
+ */
+class RestrictedEmptyConstructSniff implements Sniff {
+
+	/**
+	 * Registers the tokens that this sniff wants to listen for.
+	 */
+	public function register(): array {
+		return array( \T_EMPTY );
+	}
+
+	/**
+	 * Processes this sniff, when one of its tokens is encountered.
+	 *
+	 * @param File $phpcsFile The file being scanned.
+	 * @param int  $stackPtr  The position of the current token in the stack.
+	 */
+	public function process( File $phpcsFile, $stackPtr ): void { // phpcs:ignore SlevomatCodingStandard.TypeHints.ParameterTypeHint.MissingNativeTypeHint -- required by the interface.
+		$phpcsFile->addWarning(
+			'Usage of empty() can mask code problems. Consider explicit checks instead.',
+			$stackPtr,
+			'EmptyConstructUsage'
+		);
+	}
+}
diff --git a/tools/phpcs/phpcs.ruleset.xml b/tools/phpcs/phpcs.ruleset.xml
index 5d00f48b6d..f19fbbd484 100644
--- a/tools/phpcs/phpcs.ruleset.xml
+++ b/tools/phpcs/phpcs.ruleset.xml
@@ -113,6 +113,14 @@
 		<exclude name="SlevomatCodingStandard.TypeHints.PropertyTypeHint.MissingTraversableTypeHintSpecification" /><!-- TODO: Investigate this -->
 	</rule>
 
+	<!-- Do no apply for custom sniffs. -->
+	<rule ref="WordPress.Files.FileName.NotHyphenatedLowercase">
+		<exclude-pattern>./Sniffs/*</exclude-pattern>
+	</rule>
+	<rule ref="WordPress.Files.FileName.InvalidClassFileName">
+		<exclude-pattern>./Sniffs/*</exclude-pattern>
+	</rule>
+
 	<!-- Exclude built plugins and built assets in plugins. -->
 	<exclude-pattern>./build/*</exclude-pattern>