SlevomatCodingStandard.Variables.DisallowVariableVariable: New sniff

Author: kukulich

SlevomatCodingStandard/Sniffs/Variables/DisallowVariableVariableSniff.php

@@ -0,0 +1,35 @@
+<?php declare(strict_types = 1);
+
+namespace SlevomatCodingStandard\Sniffs\Variables;
+
+use PHP_CodeSniffer\Files\File;
+use PHP_CodeSniffer\Sniffs\Sniff;
+use const T_DOLLAR;
+use const T_DOLLAR_OPEN_CURLY_BRACES;
+
+class DisallowVariableVariableSniff implements Sniff
+{
+
+	public const CODE_DISALLOWED_VARIABLE_VARIABLE = 'DisallowedVariableVariable';
+
+	/**
+	 * @return array<int, (int|string)>
+	 */
+	public function register(): array
+	{
+		return [
+			T_DOLLAR,
+			T_DOLLAR_OPEN_CURLY_BRACES,
+		];
+	}
+
+	/**
+	 * @phpcsSuppress SlevomatCodingStandard.TypeHints.ParameterTypeHint.MissingNativeTypeHint
+	 * @param int $pointer
+	 */
+	public function process(File $phpcsFile, $pointer): void
+	{
+		$phpcsFile->addError('Use of variable variable is disallowed.', $pointer, self::CODE_DISALLOWED_VARIABLE_VARIABLE);
+	}
+
+}

doc/variables.md

@@ -4,6 +4,10 @@
 
 Disallows use of super global variables.
 
+#### SlevomatCodingStandard.Variables.DisallowVariableVariable
+
+Disallows use of variable variables.
+
 #### SlevomatCodingStandard.Variables.DuplicateAssignmentToVariable
 
 Looks for duplicate assignments to a variable.

tests/Sniffs/Variables/DisallowVariableVariableSniffTest.php

@@ -0,0 +1,27 @@
+<?php declare(strict_types = 1);
+
+namespace SlevomatCodingStandard\Sniffs\Variables;
+
+use SlevomatCodingStandard\Sniffs\TestCase;
+
+class DisallowVariableVariableSniffTest extends TestCase
+{
+
+	public function testNoErrors(): void
+	{
+		$report = self::checkFile(__DIR__ . '/data/disallowVariableVariableNoErrors.php');
+		self::assertNoSniffErrorInFile($report);
+	}
+
+	public function testErrors(): void
+	{
+		$report = self::checkFile(__DIR__ . '/data/disallowVariableVariableErrors.php');
+
+		self::assertSame(3, $report->getErrorCount());
+
+		self::assertSniffError($report, 4, DisallowVariableVariableSniff::CODE_DISALLOWED_VARIABLE_VARIABLE);
+		self::assertSniffError($report, 13, DisallowVariableVariableSniff::CODE_DISALLOWED_VARIABLE_VARIABLE);
+		self::assertSniffError($report, 14, DisallowVariableVariableSniff::CODE_DISALLOWED_VARIABLE_VARIABLE);
+	}
+
+}

tests/Sniffs/Variables/data/disallowVariableVariableErrors.php

@@ -0,0 +1,17 @@
+<?php
+
+$a;
+$$a;
+
+class Foo
+{
+
+	private $foo;
+
+	public function setFoo($foo)
+	{
+		$this->${'foo'}
+			= $$foo;
+	}
+
+}

tests/Sniffs/Variables/data/disallowVariableVariableNoErrors.php

@@ -0,0 +1,15 @@
+<?php
+
+$a;
+
+class Foo
+{
+
+	private $foo;
+
+	public function setFoo($foo)
+	{
+		$this->foo = $foo;
+	}
+
+}