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Merge pull request #116 from PHPCSStandards/universal/new-nostaticinf…
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…inalclass-sniff

New `Universal.CodeAnalysis.StaticInFinalClass` sniff
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@jrfnl
jrfnl committed Jun 13, 2022
2 parents 9d8ad67 + ba28f73 commit ef25b47
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40 changes: 40 additions & 0 deletions Universal/Docs/CodeAnalysis/StaticInFinalClassStandard.xml
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<?xml version="1.0"?>
<documentation title="Static in Final Class">
<standard>
<![CDATA[
When a class is declared as final, using the `static` keyword for late static binding is unnecessary and redundant.
This rule also covers using `static` in a comparison with `instanceof`, using `static` for class instantiations or as a return type.
`self` should be used instead.
This applies to final classes, anonymous classes (final by nature) and enums (final by design).
]]>
</standard>
<code_comparison>
<code title="Valid: Using 'self' in a final OO constuct.">
<![CDATA[
final class Foo
{
public function myMethod($param) : <em>self</em>
{
$var = <em>self</em>::functionCall();
$var = $obj instanceof <em>self</em>;
$var = new <em>self</em>;
}
}
]]>
</code>
<code title="Invalid: Using 'static' in a final OO constuct.">
<![CDATA[
$anon = new class {
public function myMethod(
): int|<em>static</em>|false {
$var = <em>static</em>::$prop;
$var = $obj instanceof <em>static</em>;
$var = new <em>static</em>();
}
};
]]>
</code>
</code_comparison>
</documentation>
205 changes: 205 additions & 0 deletions Universal/Sniffs/CodeAnalysis/StaticInFinalClassSniff.php
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<?php
/**
* PHPCSExtra, a collection of sniffs and standards for use with PHP_CodeSniffer.
*
* @package PHPCSExtra
* @copyright 2020 PHPCSExtra Contributors
* @license https://opensource.org/licenses/LGPL-3.0 LGPL3
* @link https://github.com/PHPCSStandards/PHPCSExtra
*/

namespace PHPCSExtra\Universal\Sniffs\CodeAnalysis;

use PHP_CodeSniffer\Files\File;
use PHP_CodeSniffer\Sniffs\Sniff;
use PHP_CodeSniffer\Util\Tokens;
use PHPCSUtils\Utils\Conditions;
use PHPCSUtils\Utils\FunctionDeclarations;
use PHPCSUtils\Utils\GetTokensAsString;
use PHPCSUtils\Utils\ObjectDeclarations;
use PHPCSUtils\Utils\Scopes;

/**
* Forbid the use of the `static` keyword for late static binding in OO constructs which are final.
*
* @since 1.0.0
*/
final class StaticInFinalClassSniff implements Sniff
{

/**
* OO Scopes in which late static binding is useless.
*
* @var int|string[]
*/
private $validOOScopes = [
\T_CLASS, // Only if final.
\T_ANON_CLASS, // Final by nature.
\T_ENUM, // Final by design.
];

/**
* Returns an array of tokens this test wants to listen for.
*
* @since 1.0.0
*
* @return array
*/
public function register()
{
return [
// This token is used to retrieve return types reliably.
\T_FUNCTION,
// While this is our "real" target.
\T_STATIC,
// But we also need this as after "instanceof", `static` is tokenized as `T_STRING in PHPCS < 4.0.0.
// See: https://github.com/squizlabs/PHP_CodeSniffer/pull/3121
\T_STRING,
];
}

/**
* Processes this test, when one of its tokens is encountered.
*
* @since 1.0.0
*
* @param \PHP_CodeSniffer\Files\File $phpcsFile The file being scanned.
* @param int $stackPtr The position of the current token
* in the stack passed in $tokens.
*
* @return int|void Integer stack pointer to skip forward or void to continue
* normal file processing.
*/
public function process(File $phpcsFile, $stackPtr)
{
$tokens = $phpcsFile->getTokens();

if ($tokens[$stackPtr]['code'] === \T_STRING
&& \strtolower($tokens[$stackPtr]['content']) !== 'static'
) {
return;
}

if ($tokens[$stackPtr]['code'] === \T_FUNCTION) {
/*
* Check return types for methods in final classes, anon classes and enums.
*
* Will return the scope opener of the function to prevent potential duplicate notifications.
*/
$scopeOpener = $stackPtr;
if (isset($tokens[$stackPtr]['scope_opener']) === true) {
$scopeOpener = $tokens[$stackPtr]['scope_opener'];
}

$ooPtr = Scopes::validDirectScope($phpcsFile, $stackPtr, $this->validOOScopes);
if ($ooPtr === false) {
// Method in a trait (not known where it is used), interface (never final) or not in an OO scope.
return $scopeOpener;
}

if ($tokens[$ooPtr]['code'] === \T_CLASS) {
$classProps = ObjectDeclarations::getClassProperties($phpcsFile, $ooPtr);
if ($classProps['is_final'] === false) {
// Method in a non-final class.
return $scopeOpener;
}
}

$functionProps = FunctionDeclarations::getProperties($phpcsFile, $stackPtr);
if ($functionProps['return_type'] === '') {
return $scopeOpener;
}

$staticPtr = $phpcsFile->findNext(
\T_STATIC,
$functionProps['return_type_token'],
($functionProps['return_type_end_token'] + 1)
);

if ($staticPtr === false) {
return $scopeOpener;
}

// Found a return type containing the `static` type.
$this->handleError($phpcsFile, $staticPtr, 'ReturnType', '"static" return type');

return $scopeOpener;
}

/*
* Check other uses of static.
*/
$functionPtr = Conditions::getLastCondition($phpcsFile, $stackPtr, [\T_FUNCTION, \T_CLOSURE]);
if ($functionPtr === false || $tokens[$functionPtr]['code'] === \T_CLOSURE) {
/*
* When `false`, this code is absolutely invalid, but not something to be addressed via this sniff.
* When a closure, we're not interested in it. The closure class is final, but closures
* can be bound to other classes. This needs further research and should maybe get its own sniff.
*/
return;
}

$ooPtr = Scopes::validDirectScope($phpcsFile, $functionPtr, $this->validOOScopes);
if ($ooPtr === false) {
// Not in an OO context.
return;
}

if ($tokens[$ooPtr]['code'] === \T_CLASS) {
$classProps = ObjectDeclarations::getClassProperties($phpcsFile, $ooPtr);
if ($classProps['is_final'] === false) {
// Token in a non-final class.
return;
}
}

$prevNonEmpty = $phpcsFile->findPrevious(Tokens::$emptyTokens, ($stackPtr - 1), null, true);
if ($prevNonEmpty !== false) {
if ($tokens[$prevNonEmpty]['code'] === \T_INSTANCEOF) {
$prevPrevNonEmpty = $phpcsFile->findPrevious(Tokens::$emptyTokens, ($prevNonEmpty - 1), null, true);
$extraMsg = GetTokensAsString::compact($phpcsFile, $prevPrevNonEmpty, $stackPtr, true);
$this->handleError($phpcsFile, $stackPtr, 'InstanceOf', '"' . $extraMsg . '"');
return;
}

if ($tokens[$prevNonEmpty]['code'] === \T_NEW) {
$this->handleError($phpcsFile, $stackPtr, 'NewInstance', '"new static"');
return;
}
}

$nextNonEmpty = $phpcsFile->findNext(Tokens::$emptyTokens, ($stackPtr + 1), null, true);
if ($nextNonEmpty !== false && $tokens[$nextNonEmpty]['code'] === \T_DOUBLE_COLON) {
$nextNextNonEmpty = $phpcsFile->findNext(Tokens::$emptyTokens, ($nextNonEmpty + 1), null, true);
$extraMsg = GetTokensAsString::compact($phpcsFile, $stackPtr, $nextNextNonEmpty, true);
$this->handleError($phpcsFile, $stackPtr, 'ScopeResolution', '"' . $extraMsg . '"');
return;
}
}

/**
* Throw and potentially fix the error.
*
* @since 1.0.0
*
* @param \PHP_CodeSniffer\Files\File $phpcsFile The file being scanned.
* @param int $stackPtr The position of erroneous `T_STATIC` token.
* @param string $errorCode The error code for the message.
* @param string $extraMsg Addition to the error message.
*
* @return void
*/
private function handleError($phpcsFile, $stackPtr, $errorCode, $extraMsg)
{
$fix = $phpcsFile->addFixableError(
'Use "self" instead of "static" when using late static binding in a final OO construct. Found: %s',
$stackPtr,
$errorCode,
[$extraMsg]
);

if ($fix === true) {
$phpcsFile->fixer->replaceToken($stackPtr, 'self');
}
}
}

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