> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sifr.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# SIFR-ASYNC-0001: Async function body has no real suspension effect.

> Async function body has no real suspension effect.

`SIFR-ASYNC-0001` belongs to the **Async effect and awaitability** diagnostic family. It means: async function body has no real suspension effect.

## Why It Happens

Sifr tracks suspension and blocking effects statically. This diagnostic fires when async code either does not really suspend, awaits work that cannot suspend, or calls blocking/CPU-heavy work without an explicit offload boundary.

<Info>
  Use `sifr --explain SIFR-ASYNC-0001` locally to see the renderer's exact message template and any machine-applicable suggestions for the compiler version you are running.
</Info>

## Erroneous Code

```python theme={null}
async def cached() -> int:
    return 1
```

## How To Fix It

Make the function synchronous when it never suspends, or add a real asynchronous operation if it truly belongs in async code.

## Fixed Code

```python theme={null}
def cached() -> int:
    return 1
```

## Details

| Field                  | Value                                                       |
| ---------------------- | ----------------------------------------------------------- |
| Code                   | `SIFR-ASYNC-0001`                                           |
| Family                 | `ASYNC`                                                     |
| Severity               | Error                                                       |
| Stability              | stable                                                      |
| Owner                  | `sifr_lowering::lower::typing_and_functions`                |
| Representative fixture | `crates/sifr/tests/e2e/fail/async_no_suspend_rejected.sifr` |

See the [Error Codes index](/diagnostics/error-codes) for the complete catalog.