@psalm-external-mutation-free
The @psalm-external-mutation-free tag declares that a method never mutates state observable from outside the object. It is defined by the static analyzer Psalm.
"@psalm-external-mutation-free" [ <Description> ]
Parsing a @psalm-external-mutation-free tag produces a PsalmExternalMutationFreeTag instance. Being a pure marker, it adds nothing beyond the $name and optional $description every Tag already carries.
final class PsalmExternalMutationFreeTag extends FlagTag {}
See Psalm's supported annotations.
08 July 2026