PHP 8.5 Void Cast: Explicitly Discarding Results

PHP 8.5 allows a (void) statement to explicitly discard a function result, including a NoDiscard return.

What It Does and When to Use It

Explicitly signal that the return value is intentionally unused. A minimum platform requirement controls what syntax can be parsed; target-version tests find runtime and extension incompatibilities.

Requirements, Inputs and Expected Behavior

The code using the pipe operator, NoDiscard, or void cast requires PHP 8.5 or later; code with older syntax can still run on earlier supported PHP releases. (void) is statement-only and does not produce a value or work in an assignment.

Example 1: Basic Operation

Explicitly signal that the return value is intentionally unused.

<?php
#[\NoDiscard]
 function queueMessage(): bool { return true; }
 (void) queueMessage();

Example 2: Behavior and Validation

Read the annotated function result when your control flow depends on success; PHP 8.5 supports the NoDiscard attribute.

<?php
#[\NoDiscard('Check the result before continuing')]
 function verifyTask(): bool { return true; }
 $result = verifyTask();
 if (!$result) throw new RuntimeException('Task failed');

Practical Example: Application Use

Remember (void) discards a result as a statement; it does not turn it into null.

<?php
function optionalDiagnostic(): string { return 'diagnostic'; }
 (void) optionalDiagnostic();
 echo 'Done';

Important Behavior and Edge Cases

The second example highlights: Read the annotated function result when your control flow depends on success; PHP 8.5 supports the NoDiscard attribute. The practical example adds: Remember (void) discards a result as a statement; it does not turn it into null.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• PHP 8.5 allows a (void) statement to explicitly discard a function result, including a NoDiscard return.
• Remember (void) discards a result as a statement; it does not turn it into null.
• Do not introduce syntax from a newer minor version before every production host supports it.