That file is autogenerated. The original one has a comment explaining what's going on

https://github.com/golang/net/blob/a8e8f92cd65f5ff48599999fa4001d9b95ecea85/http2/server.go#L400

if sc.tlsState.ServerName == "" {
		// Client must use SNI, but we don't enforce that anymore,
		// since it was causing problems when connecting to bare IP
		// addresses during development.
		//
		// TODO: optionally enforce? Or enforce at the time we receive
		// a new request, and verify the the ServerName matches the :authority?
		// But that precludes proxy situations, perhaps.
		//
		// So for now, do nothing here again.
}

I guess the bundle script removes comments.

The bundle godoc (https://godoc.org/golang.org/x/tools/cmd/bundle) says that comments may not be preserved. I assume this is to save lines of code, since you can quickly end up with very large files. It does seem to keep comments that serve as godoc for package members, though.

I believe the h2_bundle.go file is not supposed to be human-readable or editable. After all, it sits at nearly 10k lines of code. You should look at the source files in golang.org/x/net/http2 instead.

Closing this, since 1) apparently there's no issue with the code 2) as mvdan says, autogenerated files are not really supposed to be readable and the header points to the original source

I'm going to reopen this and repurpose it towards fixing the bundle too.

I think h2_bundle.go should be readable or totally gibberish, not halfway in the middle. But I'd prefer readable since we're 95% of the way there.

@alandonovan, do you know why we're losing some comments but only a few?

Go doesn't permit circular dependencies so we can't have net/http import http2, since http2 already depends on net/http (for types, etc).

I'm not sure yet why bundle is losing some comments, but the way in which comments are associated with syntax nodes has always been a weak aspect of the design of the go/ast package.

Deleting all comments is not an option because several kinds of special comment have semantics in the compiler.

Maybe @griesemer could help.

x/tools/cmd/bundle's main.go contains a comment:

// TODO(adonovan): this may cause loss of comments
// preceding or associated with the package or import
// declarations or not associated with any declaration.
// Check.

i.e., this is a known problem.

As @adonovan pointed out, comment handling is a weak spot in the go/ast package (which is one of the very first Go packages ever and which is suffering a bit from age). The problem is that comments are not attached to ast nodes, unless they are documenting a declaration. Instead, they are "free-floating" in a list associated with the ast.File node, and must be "interspersed" at the right place based on their positions (and the respective node positions).

I haven't looked at main.go in detail but the call to format.Node (main.go:362) simply takes a declaration node which won't contain any inner comments.

There is (somewhat tedious) way to address this: The [begin, end[ source interval for each declaration node can be used to determine all the comments that belong to the declaration. That list of comments, together with the declaration node, may be be bundled up in a go/printer.CommentedNode, which in turn is provided to the format.Node call. If the node and comment positions are correct (unchanged), the comments should be correctly interspersed.

Leaving for somebody else to pick this up.

/cc @fatih @hirochachacha (if either of you are interested in helping)

CL https://golang.org/cl/45117 mentions this issue.

@bradfitz I'll take a look at it.

oops, seems like @hirochachacha was faster than me :)

It seems printer package already addressed @griesemer 's suggestion.
https://github.com/golang/go/blob/master/src/go/printer/printer.go#L1055-L1081
So the fix could be simple.

CL https://golang.org/cl/45158 mentions this issue.