x/tools/go/loader: needs to be updated to stdlib go/types

[sbinet]

hi,

with the upcoming go-1.5 and the import of (a modified version of) the x/tools/go/types package into the stdlib, golang.org/x/tools/go/loader needs to be updated.

the following program will fail to compile:

package main

import (
    "fmt"
    "go/build"
    "go/token"
    "go/types"
    "log"
    "os"

    "golang.org/x/tools/go/loader"
)

func main() {
    path := os.Args[1]
    fmt.Printf(">>> inspecting [%s]...\n", path)

    cwd, err := os.Getwd()
    if err != nil {
        log.Panicf("error: %v\n", err)
    }

    pkg, err := build.Import(path, cwd, 0)
    if err != nil {
        log.Panicf("error: %v\n", err)
    }

    conf := loader.Config{
        Fset: token.NewFileSet(),
    }

    prog, err := conf.Load()
    if err != nil {
        log.Panicf("error: %v\n", err)
    }

    var p *types.Package = prog.Created[0].Pkg
    fmt.Printf("pkg=%v\n", p)
}

with the following error:

sh> go run foo.go github.com/go-python/gopy/_examples/hi
# command-line-arguments
./foo.go:39: cannot use prog.Created[0].Pkg (type *"golang.org/x/tools/go/types".Package) as type *"go/types".Package in assignment

[sbinet]

FYI, I have been testing this against golang/tools@1c460ff and d23973d.

[josharian]

This is one of the unfortunate things about having two versions of the same packages. If this were to get fixed, then folks using the x/tools go/types would have breakage the other direction.

/cc @alandonovan @griesemer

[ianlancetaylor]

We should be able to use build tags in x/tools to make this work.

[sbinet]

using a go-1.5 build tag sounds good.
I can send a CL if nobody beats me to it.

[alandonovan]

I agree this needs to happen, but we cannot change the tools repo until after Go 1.5 has been released and has settled for at least a while. My plan is to update the whole tools repo in early September so that it no longer uses tools/go/types (though of course that package will remain there).

[dsymonds]

If build tags are used, there's no need to wait for Go 1.5. This is also not tied to the release.

[adonovan]

Fully one third of the ~350 *.go files in the tools repo import golang.org/x/tools/go/types. Are you suggesting that I make go1.5-tagged duplicates of all those files, and maintain them in parallel during several months of anticipated heavy churn? Or something else?

[dsymonds]

I didn't realise it was that many files. Yeah, build tags seem inappropriate. Let's just do the change after the release.

[dmitshur]

My plan is to update the whole tools repo in early September so that it no longer uses tools/go/types (though of course that package will remain there).

@adonovan, has that been done already, or not yet? If not, is there an updated estimate for when it'll happen?

[alandonovan]

I (finally) sent https://go-review.googlesource.com/#/c/18207/ for review today. I'll submit it after the holiday since it will require that all clients using tip (not go1.5) update to go/types too.

[dmitshur]

This issue has been resolved via golang/tools@542ffc7 and can be closed.