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

$ go version
go version go1.18.1 linux/amd64

Does this issue reproduce with the latest release?

Yes.

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

n/a

What did you do?

If you pass an *os.File (which implements io.Reader) to gzip.Reader and disable multi-stream (.Multistream(false)), the .Reset(r) call will return EOF after the first gzip stream despite there being more streams in the file.

https://go.dev/play/p/NEdhYQNfKds

Notice that we wrote two chunks to the file (named "hello" and "world") but only one was read (the first, "hello").

What did you expect to see?

One of two things:

• a read of every gzip stream in the file
• an error indicating that the reader does not implement io.ByteReader

What did you see instead?

Only the first stream is read.

This behavior is very subtly noted in the documentation:

The underlying reader must implement io.ByteReader in order to be left positioned just after the gzip stream.

However, a runtime check and error for interface compatibility would be far more intuitive.