From: Bryan C. Mills <bcmills@google.com>
Date: Fri, 26 May 2023 18:48:22 +0000 (-0400)
Subject: cmd/go/internal/toolchain: avoid importing modcmd
X-Git-Tag: go1.21rc1~141
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=0a87fdc06e9c4ae73b31cd08c26ed32c8a80923b;p=gostls13.git

cmd/go/internal/toolchain: avoid importing modcmd

modcmd is a high-level command, but toolchain is a low-level building
block. A dependency from toolchain on modcmd makes it very difficult
to call from other lower-level packages without creating an import
cycle.

Instead, use modfetch.Download in place of modcmd.DownloadModule.

For #57001.

Change-Id: I9694706d7225b269f26dc68814894613a3329abb
Reviewed-on: https://go-review.googlesource.com/c/go/+/499316
Run-TryBot: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
---

diff --git a/src/cmd/go/internal/toolchain/toolchain.go b/src/cmd/go/internal/toolchain/toolchain.go
index ab03fbe4ff..757ab6977d 100644
--- a/src/cmd/go/internal/toolchain/toolchain.go
+++ b/src/cmd/go/internal/toolchain/toolchain.go
@@ -7,6 +7,7 @@ package toolchain
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"go/build"
 	"io/fs"
@@ -22,7 +23,6 @@ import (
 	"cmd/go/internal/base"
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/gover"
-	"cmd/go/internal/modcmd"
 	"cmd/go/internal/modfetch"
 	"cmd/go/internal/modload"
 	"cmd/go/internal/run"
@@ -410,22 +410,21 @@ func SwitchTo(gotoolchain string) {
 	// Download and unpack toolchain module into module cache.
 	// Note that multiple go commands might be doing this at the same time,
 	// and that's OK: the module cache handles that case correctly.
-	m := &modcmd.ModuleJSON{
+	m := module.Version{
 		Path:    gotoolchainModule,
 		Version: gotoolchainVersion + "-" + gotoolchain + "." + runtime.GOOS + "-" + runtime.GOARCH,
 	}
-	modcmd.DownloadModule(context.Background(), m)
-	if m.Error != "" {
-		if strings.Contains(m.Error, ".info: 404") {
+	dir, err := modfetch.Download(context.Background(), m)
+	if err != nil {
+		if errors.Is(err, fs.ErrNotExist) {
 			base.Fatalf("download %s for %s/%s: toolchain not available", gotoolchain, runtime.GOOS, runtime.GOARCH)
 		}
-		base.Fatalf("download %s: %v", gotoolchain, m.Error)
+		base.Fatalf("download %s: %v", gotoolchain, err)
 	}
 
 	// On first use after download, set the execute bits on the commands
 	// so that we can run them. Note that multiple go commands might be
 	// doing this at the same time, but if so no harm done.
-	dir := m.Dir
 	if runtime.GOOS != "windows" {
 		info, err := os.Stat(filepath.Join(dir, "bin/go"))
 		if err != nil {