SIFR-OWN-0014: Unsupported mutable receiver place. - Sifr

SIFR-OWN-0014 belongs to the Ownership and borrowing diagnostic family. It means: unsupported mutable receiver place.

Why It Happens

The ownership model would be violated. Move values only once, keep borrows scoped, and cross task/channel/IPC boundaries only with owned values that satisfy the required safety traits.

Use sifr --explain SIFR-OWN-0014 locally to see the renderer’s exact message template and any machine-applicable suggestions for the compiler version you are running.

Erroneous Code

class Counter:
    value: int

    def bump(self) -> None:
        self.value += 1

def update(maybe: Counter | None) -> None:
    if maybe is not None:
        maybe.bump()

How To Fix It

Call the mutating method through a stable owned local, mutable parameter, or a supported non-optional field place. In a constructor, initialize every declared field (and call super().__init__ for inherited storage) before the first statement that reads or mutates self.

Fixed Code

class Counter:
    value: int

    def bump(self) -> None:
        self.value += 1

def update(mut counter: Counter) -> None:
    counter.bump()

Details

Field	Value
Code	`SIFR-OWN-0014`
Family	`OWN`
Severity	Error
Stability	stable
Owner	`sifr_lowering::lower::method_receiver_places`
Representative fixture	`crates/sifr/tests/e2e/fail/unsupported_narrowed_optional_mutating_receiver.sifr`

See the Error Codes index for the complete catalog.