x/tools/go/gcexportdata: drop experimental bundle API

[adonovan]

The gcexportdata package has two functions, WriteBundle and ReadBundle, that have always been marked as experimental and are not used within x/tools, nor, to my knowledge, anywhere else. The only match in GitHub was a single call from apidiff in the obsolete golang/exp repo (and forks thereof), which I have since updated.

package gcexportdata

func ReadBundle(in io.Reader, fset *token.FileSet, imports map[string]*types.Package) ([]*types.Package, error)
func WriteBundle(out io.Writer, fset *token.FileSet, pkgs []*types.Package) error

We propose to drop bundle functionality by making both functions return an error unconditionally.

Related:

• proposal: go/types: add Import, Export functions #69491

[gopherbot]

Change https://go.dev/cl/614815 mentions this issue: go/gcexportdata: drop experimental Bundle support

[ianlancetaylor]

CC @jba for apidiff

[jba]

Why do you describe golang.org/x/exp as obsolete? exp means "experimental,", not "expired."

apidiff has a few users, notably the Go client libraries for GCP. I don't think we should break it.

I'd be happy to rewrite Read/WriteBundle, if you could explain how to get the same effect.

[adonovan]

Why do you describe golang.org/x/exp as obsolete? exp means "experimental,", not "expired."

I misremembered. In any case, it's easy enough for me to fix this one instance. My point was more that no-one is really using this feature.

[rsc]

Given that it is experimental and we don't think anyone is using it, this seems fine.

[rsc]

This proposal has been added to the active column of the proposals project
and will now be reviewed at the weekly proposal review meetings.
— rsc for the proposal review group

[gopherbot]

Change https://go.dev/cl/634600 mentions this issue: cmd/apidiff: stop using gcexportdata.{Read,Write}Bundle

[aclements]

Based on the discussion above, this proposal seems like a likely accept.

The proposal is to make the unused and experimental functions WriteBundle and ReadBundle in golang.org/x/tools/go/gcexportdata always return an error.