# panic: receive from closed channel (in range)

- **ID:** `go/goroutine-range-over-closed-channel`
- **Domain:** go
- **Category:** runtime_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Iterating over a channel with range after it has been closed; range receives zero values until channel is drained.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 1.0 | active | — | — |
| 1.20 | active | — | — |

## Workarounds

1. **Use for with ok pattern instead of range** (95% success)
   ```
   for {
    val, ok := <-ch
    if !ok {
        break
    }
    // process val
}
   ```
2. **Ensure channel is closed only after all sends are done** (90% success)
   ```
   var wg sync.WaitGroup
for i := 0; i < 5; i++ {
    wg.Add(1)
    go func() {
        defer wg.Done()
        ch <- i
    }()
}
wg.Wait()
close(ch)
for val := range ch {
    // process
}
   ```

## Dead Ends

- **Using recover() to catch panic from zero value** — Range over closed channel doesn't panic; it returns zero values, which may cause logic errors. (90% fail)
- **Checking channel length before range** — len(ch) doesn't indicate closed state; closed channel can have buffered data. (80% fail)