[dev.cmdgo] cmd/go: add go mod initwork command

This command is used to create a go.work file with a set of modules
given in the arguments to the command.

For #45713
Change-Id: I09f8cefc5849dd43c234dc4a37091791fcc02ebe
Reviewed-on: https://go-review.googlesource.com/c/go/+/334936
Trust: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/cmd/go/internal/modload/init.go b/src/cmd/go/internal/modload/init.go
index 607054d1eb..18f0f2b8f8 100644
--- a/src/cmd/go/internal/modload/init.go
+++ b/src/cmd/go/internal/modload/init.go
@@ -767,6 +767,24 @@ func CreateModFile(ctx context.Context, modPath string) {
 	}
 }
 
+// CreateWorkFile initializes a new workspace by creating a go.work file.
+func CreateWorkFile(ctx context.Context, workFile string, modDirs []string) {
+	_ = TODOWorkspaces("Report an error if the file already exists.")
+
+	goV := LatestGoVersion() // Use current Go version by default
+	workF := new(modfile.WorkFile)
+	workF.Syntax = new(modfile.FileSyntax)
+	workF.AddGoStmt(goV)
+
+	for _, dir := range modDirs {
+		_ = TODOWorkspaces("Add the module path of the module.")
+		workF.AddDirectory(dir, "")
+	}
+
+	data := modfile.Format(workF.Syntax)
+	lockedfile.Write(workFile, bytes.NewReader(data), 0644)
+}
+
 // fixVersion returns a modfile.VersionFixer implemented using the Query function.
 //
 // It resolves commit hashes and branch names to versions,