Just a test balloon.

1. I'm using MX_ instead of "Mx" (temporarily) so I don't confuse the two different Mx's.
2. This doesn't compile:

# codeberg.org/miekg/dns
./zclone.go:86:3: cannot use rr.Preference (variable of type uint16) as MX_ value in struct literal
./zclone.go:87:3: too many values in struct literal of type MX

Maybe we should opt for different naming if you already get refused, like call the field Data or some such?

@miekg wrote in #313 (comment):

Maybe we should opt for different naming if you already get refused, like call the field Data or some such?

Oh yeah, then you can't embed...

@TomOnTime wrote in #313 (comment):

codeberg.org/miekg/dns

./zclone.go:86:3: cannot use rr.Preference (variable of type uint16) as MX_ value in struct literal
./zclone.go:87:3: too many values in struct literal of type MX

yes, you'll need to fix all generators as well
(note it helps e.g. to remove Cloner from the RR interface while fixing this, as you then sometimes can't run go generate, because the current version of zclone.go is broken/out of date)

All the generators are now fixed. (at least go test ./... thinks so!)

Feedback?

I converted "A" records and discovered that embedded structs don't work the same for struct literals, so I had to edit a lot of files:

https://go.dev/ref/spec#Struct_types

A field or method f of an embedded field in a struct x is called promoted if x.f is a legal selector that denotes that field or method f.

Promoted fields act like ordinary fields of a struct except that they cannot be used as field names in composite literals of the struct.

That's disappointing.

hrrmm, yep

- rr = &dns.A{Hdr: dns.Header{Name: dom, Class: dns.ClassINET}, A: a.To4()}
+ rr = &dns.A{Hdr: dns.Header{Name: dom, Class: dns.ClassINET}, A_: dns.A_{A: a.To4()}}

this is exactly the stottering we should not want, thought with embedding this would be OK, guess not.

Guess back to drawing board, and think about what do we actually need/want in this case and see what can be done.

Think with generics you ultimately run into the same thing, execpt A_ then is Fields (or whatever) in each case

Guess back to drawing board, and think about what do we actually need/want in this case and see what can be done.

Agreed.

To reset: What we're trying to achieve is (1) save memory by being able to allocate the struct without the header, (2) generate the .String() without a header.

@TomOnTime wrote in #313 (comment):

Guess back to drawing board, and think about what do we actually need/want in this case and see what can be done.

Agreed.

To reset: What we're trying to achieve is (1) save memory by being able to allocate the struct without the header, (2) generate the .String() without a header.

ack. Let's go back to the issue and close this.

mx1:=&_MX1{Hdr:Header{Name:"miek.nl.",Class:ClassINET},Flds:_Mx1{Preference:10,Mx:"mx.miek.nl"}}mx:=&MX{Hdr:Header{Name:"miek.nl.",Class:ClassINET},Preference:10,Mx:"mx.miek.nl"}

with generics you hit exactly the same issue (obvs)