field is only used during parsing, when it is populated with policy OIDs, but
not used during marshaling. It can be used to marshal these larger OIDs, instead
of the existing PolicyIdentifiers field, by using the
[`x509usepolicies` setting.](/pkg/crypto/x509/#CreateCertificate).


### Go 1.21

Go 1.21 made it a run-time error to call `panic` with a nil interface value,

The new [ParseCookie] function parses a Cookie header value and
returns all the cookies which were set in it. Since the same cookie
name can appear multiple times the returned Values can contain
more than one value for a given key.

The new [ParseSetCookie] function parses a Set-Cookie header value and

by the `go` directive in the file's enclosing `go.mod` file, and
by any [`//go:build` constraints](https://pkg.go.dev/cmd/go#hdr-Build_constraints)
in the file.)

For example, it will report a diagnostic for a reference to the
`reflect.TypeFor` function (introduced in go1.22) from a file in a
module whose go.mod file specifies `go 1.21`.