Method %s::%s cannot be #[\NoDiscard]

Description

The #[\NoDiscard] attribute marks a function, method or closure so that the engine emits a warning whenever a caller ignores its return value. Certain magic methods, such as __construct, __destruct, __clone and __wakeup, are always invoked for their side effect and never return a usable value to the caller (new returns the object itself, not the constructor’s return value), so attaching #[\NoDiscard] to them is meaningless and rejected at compile time.

Example

<?php

class X {
    #[\NoDiscard]
    public function __construct() {}
}

new X();

?>

Literal Examples

• Method X::__construct cannot be #[\NoDiscard]

Alternatives

• Remove the #[\NoDiscard] attribute from the magic method.
• If a discardable-value warning is needed, move the logic to a regular, non-magic method and mark that one instead.

Related error messages

• a-void-%s-does-not-return-a-value
• a-never-returning-%s-does-not-return-a-value
• method-%s::%s-cannot-be-#[–nodiscard]-error_type

Changed Behavior

This error may appear following an evolution in behavior, in previous versions. See