encoding/json: export func Valid([]byte) bool

[sj26]

I'm running go version go1.7.1 darwin/amd64 on macOS 10.12.1.

I'm trying to validate some a byte array is valid JSON so it can be marshalled literally like RawMessage. The only way to do this at the moment is to create a Decoder and fully decode the bytes causing many useless allocations, or write a custom scanner.

But there's a lovely, allocation-free function for scanning a byte array to see if it's valid JSON tucked away inside the encoding/json package (checkValid), and used in several places within the package. It'd be great to expose this for general use as something like IsValid(data []byte) bool.

I proposed this change a while back but I didn't understand the contribution process sorry! Is this the right place to file the issue @bradfitz?

[bradfitz]

@sj26, we just had a proposal review meeting today, so this'll be discussed at the next one, usually weekly.

I'll let others chime in here in the meantime.

[rsc]

By analogy with unicode/utf8's func Valid, it seems like this should be encoding/json's func Valid.

[rsc]

If you (or anyone else) would like to send a CL, please do, for Go 1.9.

[gopherbot]

CL https://golang.org/cl/34202 mentions this issue.