Mistakes

The mistakes section decides what to do with code that is most likely a mistake, whatever the style: $this in a static method, a catch that can never be reached, a loose search in in_array(), the @ operator, an invisible character in the code, two doc comments in a row when reflection sees only one of them, the global statement, and a forgotten debug output.

Most of these findings cannot be fixed, because the code does not show what the author had in mind: DressCode reports them and leaves them to you. Where a fix is possible, it is usually a risky fix. Adding the argument true to in_array() is safe only when all the values searched are of one type. With types from PHPStan, DressCode can tell this and makes the fix on its own; elsewhere it waits for your permission.

mistakes:
	thisOutsideObject: forbidden
	unreachableCatch: forbidden
	strictArgument: required
	errorSuppression: forbidden

class Mailer
{
	public static function create(): static
	{
		$this->connect();  // The `$this` stands in a static context, which has no object.
		return new static;
	}

	public function send(array $to): void
	{
		try {
			$this->transport->send($to);
		} catch (\Throwable $e) {
			throw $e;
		} catch (\RuntimeException $e) {  // Unreachable catch block, because a previous one catches `Throwable`.
			$this->log($e);
		}
		$found = in_array('admin', $to);  // The `in_array()` call must pass `$strict = true`.
		$data = @file_get_contents($this->path);  // The `@` operator must not be used.
	}
}

A project that uses the @ operator on purpose for some calls can say so with a comment and the suppressionComments key; the nette standard comes with such a pattern.

Two decisions of this section do not look for a mistake. Instead, they make explicit a guarantee that the code already keeps, but only silently: mistakes.readonlyProperty adds readonly to a property that only the constructor writes, and the group mistakes.neverReturnType adds the return type never to a function, a method or a closure that always throws an exception or exits. Once PHP knows the guarantee, every later write to such a property and every return from such a function ends with an error. The types set turns on mistakes.neverReturnType.function and mistakes.neverReturnType.method; no set turns on mistakes.readonlyProperty or never on closures, so a project turns them on itself.

mistakes.finalParent

A class extending a final one, which is only reported.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · needs types · standards: perCs keep, psr12 keep, nette keep, symfony keep, laravel keep

mistakes.__debugInfoReturningNull

The null that __debugInfo() returns, which becomes [].

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette forbidden, symfony keep, laravel keep

mistakes.thisOutsideObject

$this in a static method, a static closure or a function outside a class, which is only reported.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette forbidden, symfony keep, laravel keep · covers Squiz.Scope.StaticThisUsage

mistakes.unimplementedAbstractMethod

An inherited abstract method a class that is not abstract leaves unimplemented, typically after a library added it, which is only reported.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · needs types · standards: perCs keep, psr12 keep, nette keep, symfony keep, laravel keep

mistakes.readonlyProperty

A property written only in the constructor, or not at all.

• required: always there
• keep: nothing is enforced, the code stays as it is

Default keep · PHP 8.1 · standards: perCs keep, psr12 keep, nette keep, symfony keep, laravel keep

mistakes.__serialize

__serialize() and __unserialize() in a class implementing Serializable, whose absence is only reported.

• required: always there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette keep, symfony keep, laravel keep

mistakes.staticSetState

__set_state() declared static, as PHP calls it.

• required: always there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette required, symfony keep, laravel keep

mistakes.continueInSwitch

A continue that only leaves a switch, where break is meant, which is only reported.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette forbidden, symfony forbidden, laravel keep · covers switch_continue_to_break, SlevomatCodingStandard.ControlStructures.DisallowContinueWithoutIntegerOperandInSwitch

mistakes.unreachableCatch

A catch after one catching Throwable or a class it catches, which is only reported.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette forbidden, symfony keep, laravel keep · covers SlevomatCodingStandard.Exceptions.DeadCatch

mistakes.exceptionWhereThrowableBelongs

catch (Exception) and a parameter of the type Exception where Throwable is meant, which is only reported.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette forbidden, symfony keep, laravel keep · covers SlevomatCodingStandard.Exceptions.ReferenceThrowableOnly

mistakes.errorSuppression

The @ operator, which silences errors and is only reported.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette forbidden, symfony keep, laravel keep

mistakes.invisibleCharacter

Non-breaking, zero-width and bidi characters, replaced in comments and escaped in strings, which changes their text, and reported in names.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette forbidden, symfony keep, laravel keep · covers non_printable_character

mistakes.debugOutput

A statement calling a debugging function to print, changed into a comment, // var_dump($a);; a call that may return its output instead, print_r($a, true), stays.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette keep, symfony keep, laravel keep · covers PhpCsFixerCustomFixers/commented_out_function

mistakes.debugOutputFunctions

The debugging functions whose calls print.

• a list of names

Default [print_r, var_dump, var_export] · standards: perCs [print_r, var_dump, var_export], psr12 [print_r, var_dump, var_export], nette [print_r, var_dump, var_export], symfony [print_r, var_dump, var_export], laravel [print_r, var_dump, var_export] · covers PhpCsFixerCustomFixers/commented_out_function

mistakes.strictArgument

in_array(), array_search(), array_keys(), base64_decode(), mb_detect_encoding() pass strict: true; an explicit false is reported.

• required: always there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette required, symfony keep, laravel keep · covers strict_param, SlevomatCodingStandard.Functions.StrictCall

mistakes.trailingWhitespaceInString

At the end of the lines of a multi-line string or inline HTML, which changes their value.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette forbidden, symfony keep, laravel keep · covers no_trailing_whitespace_in_string

mistakes.consecutivePhpdocs

A doc comment followed by another one, the first lost to reflection, which is only reported.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette forbidden, symfony keep, laravel keep

mistakes.neverReturnType.function

The return type never of PHP 8.1 on a function that always throws or exits.

• required: always there
• keep: nothing is enforced, the code stays as it is

Default keep · PHP 8.1 · standards: perCs keep, psr12 keep, nette required, symfony keep, laravel keep

mistakes.neverReturnType.method

The return type never on a method that always throws or exits, only where no descendant can declare it again.

• required: always there
• keep: nothing is enforced, the code stays as it is

Default keep · PHP 8.1 · standards: perCs keep, psr12 keep, nette required, symfony keep, laravel keep

mistakes.neverReturnType.anonymousFunction

The return type never on a closure that always throws or exits, though its signature usually belongs to the call it is passed to.

• required: always there
• keep: nothing is enforced, the code stays as it is

Default keep · PHP 8.1 · standards: perCs keep, psr12 keep, nette keep, symfony keep, laravel keep

mistakes.globalStatement

The global statement, which is only reported.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette forbidden, symfony keep, laravel keep · covers Squiz.PHP.GlobalKeyword

mistakes.repeatedAssignment

A variable assigned twice in one expression, $a = $a = 1.

• forbidden: never there
• keep: nothing is enforced, the code stays as it is

Default keep · standards: perCs keep, psr12 keep, nette forbidden, symfony keep, laravel keep · covers SlevomatCodingStandard.Variables.DuplicateAssignmentToVariable