time: document that RFC3339 accepts invalid formats when used with Parse #37616
Description
What version of Go are you using (go version)?
$ go version go version go1.13 darwin/amd64
Does this issue reproduce with the latest release?
It reproduces on play.golang.org and the underlying issue is still present in the source.
What operating system and processor architecture are you using (go env)?
darwin/amd64
What did you do?
Parsed a faulty ISO 8601 string with a single-digit hour using time.RFC3339. E.g. 2020-02-02T2:02:02Z.
What did you expect to see?
I expected this parse to error because RFC-3339 sec 5.6 defines the following token, requiring two digits for the hour:
time-hour = 2DIGIT ; 00-23
What did you see instead?
The parse succeeded.
This could be fixed by changing time.RFC3339 to 2006-01-02T03:04:05Z07:00. If this is deemed a backward incompatible change, adding a new time.RFC3339Strict constant would also be an acceptable option.
See https://play.golang.org/p/6qyFYfx6pMr for example with one and two-digit years with time.Parse3339 and the stricter version.