encoding/json: Unmarshal on unexported anonymous struct field panics

[northfun]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version go1.11 linux/amd64

Does this issue reproduce with the latest release?

yes. Does not happen with go1.9,but happen with go1.10

What operating system and processor architecture are you using (go env)?

ubuntu16.04 LTS

What did you do?

https://play.golang.org/p/Kw-Gm5YbkJw

What did you expect to see?

nil

This only happen when innerType has a method named with capital letter.If method replace to f(),the panic won't happen.

What did you see instead?

panic: reflect.Value.Interface: cannot return value obtained from unexported field or method

goroutine 1 [running]:
reflect.valueInterface(0x111880, 0x1f7264, 0x36, 0x1, 0x1, 0xe)
	/usr/local/go/src/reflect/value.go:989 +0x200
reflect.Value.Interface(0x111880, 0x1f7264, 0x36, 0x9, 0x152960, 0x111880)
	/usr/local/go/src/reflect/value.go:978 +0x40
encoding/json.indirect(0x110fe0, 0x1f7264, 0x1d9, 0x0, 0x416040, 0x5, 0x8, 0x18ec, 0x6c, 0x6c, ...)
	/usr/local/go/src/encoding/json/decode.go:486 +0x2c0
encoding/json.(*decodeState).object(0x44e060, 0x110fe0, 0x1f7264, 0x1d9, 0x44e078, 0x7b)
	/usr/local/go/src/encoding/json/decode.go:620 +0x60
encoding/json.(*decodeState).value(0x44e060, 0x110fe0, 0x1f7264, 0x1d9, 0x152960, 0x112dc0)
	/usr/local/go/src/encoding/json/decode.go:383 +0x60
encoding/json.(*decodeState).object(0x44e060, 0x111820, 0x1f7264, 0x16, 0x44e078, 0x7b)
	/usr/local/go/src/encoding/json/decode.go:781 +0x19c0
encoding/json.(*decodeState).value(0x44e060, 0x111820, 0x1f7264, 0x16, 0x44e078, 0x7d)
	/usr/local/go/src/encoding/json/decode.go:383 +0x60
encoding/json.(*decodeState).unmarshal(0x44e060, 0x111820, 0x1f7264, 0x44e078, 0x0, 0x0)
	/usr/local/go/src/encoding/json/decode.go:180 +0x240
encoding/json.Unmarshal(0x454000, 0x11a, 0x120, 0x111820, 0x1f7264, 0x11a, 0x120, 0x40e158)
	/usr/local/go/src/encoding/json/decode.go:107 +0x180
main.main()
	/tmp/sandbox652463797/main.go:27 +0xc0

[mvdan]

Thanks for reporting! Looks like a simple bug in the reflection code. Will send a CL shortly.

[gopherbot]

Change https://golang.org/cl/141537 mentions this issue: encoding/json: always verify we can get a field's value