package main

import (
   "fmt"
   "bytes"
   "encoding/gob"
   "time"
)

type X struct {
   T time.Time
   S string
   I int
}

func main() {
   var buffer bytes.Buffer
   encoder := gob.NewEncoder(&buffer)
   x := X{time.Now(), "hello", -55}
   fmt.Println(x)
   fmt.Println(encoder.Encode(x))
   fmt.Println(buffer)
   decoder := gob.NewDecoder(&buffer)
   var y X
   fmt.Println(decoder.Decode(&y))
   fmt.Println(y)
}

Reported by Mark Summerfield.

panic: unknown type in isZero time.Time [recovered]  <<<<<
    panic: interface conversion: interface is string, not gob.gobError

goroutine 1 [running]:
encoding/gob.catchError(0xf840022090, 0x216f100)
    /Users/rsc/g/go/src/pkg/encoding/gob/error.go:36 +0x67
----- stack segment boundary -----
encoding/gob.isZero(0x9f208, 0xf84002a7b0, 0x192, 0xf84002a7b0, 0x192, ...)
    /Users/rsc/g/go/src/pkg/encoding/gob/encode.go:487 +0x14d
encoding/gob._func_018(0xf84001b368, 0xf840002510, 0x2ae96, 0xf8400273c0, 0xf84002a120,
...)
    /Users/rsc/g/go/src/pkg/encoding/gob/encode.go:638 +0xcd
encoding/gob.(*Encoder).encodeStruct(0xf840022000, 0xf840022030, 0xf8400024f0,
0xf84002a7b0, 0x93758, ...)
    /Users/rsc/g/go/src/pkg/encoding/gob/encode.go:370 +0xf4
encoding/gob.(*Encoder).encode(0xf840022000, 0xf840022030, 0x93758, 0xf84002a2a0, 0x192,
...)
    /Users/rsc/g/go/src/pkg/encoding/gob/encode.go:713 +0x172
encoding/gob.(*Encoder).EncodeValue(0xf840022000, 0x93758, 0xf84002a2a0, 0x192, 0x0, ...)
    /Users/rsc/g/go/src/pkg/encoding/gob/encoder.go:246 +0x247
encoding/gob.(*Encoder).Encode(0xf840022000, 0x93748, 0xf84002a2a0, 0x114ba8, 0xaaf44,
...)
    /Users/rsc/g/go/src/pkg/encoding/gob/encoder.go:177 +0x50
main.main()
    /Users/rsc/x.go:21 +0x1ae