cmd/cue/cmd: get go: import files to cue module if in main module

Change-Id: I3a28e7daac8ae10b5c33ab0fed2ab50e2495f3e6
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/6343
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
diff --git a/cmd/cue/cmd/get_go.go b/cmd/cue/cmd/get_go.go
index 9cefa8a..759b154 100644
--- a/cmd/cue/cmd/get_go.go
+++ b/cmd/cue/cmd/get_go.go
@@ -211,11 +211,15 @@
 	cmd.Flags().StringP(string(flagExclude), "e", "",
 		"comma-separated list of regexps of entries")
 
+	cmd.Flags().Bool(string(flagLocal), false,
+		"generates files in the main module locally")
+
 	return cmd
 }
 
 const (
 	flagExclude flagName = "exclude"
+	flagLocal   flagName = "local"
 )
 
 var cueTestRoot string // the CUE module root for test purposes.
@@ -335,7 +339,7 @@
 	}
 
 	cfg := &packages.Config{
-		Mode: packages.LoadAllSyntax,
+		Mode: packages.LoadAllSyntax | packages.NeedModule,
 	}
 	pkgs, err := packages.Load(cfg, args...)
 	if err != nil {
@@ -396,6 +400,16 @@
 
 	pkg := p.PkgPath
 	dir := filepath.Join(load.GenPath(root), filepath.FromSlash(pkg))
+
+	isMain := flagLocal.Bool(e.cmd) && p.Module != nil && p.Module.Main
+	if isMain {
+		dir = p.Module.Dir
+		sub := p.PkgPath[len(p.Module.Path):]
+		if sub != "" {
+			dir = filepath.FromSlash(dir + sub)
+		}
+	}
+
 	if err := os.MkdirAll(dir, 0755); err != nil {
 		return err
 	}
@@ -487,6 +501,26 @@
 		}
 	}
 
+	if !isMain {
+		if err := e.importCUEFiles(p, dir, args); err != nil {
+			return err
+		}
+	}
+
+	for path := range e.usedPkgs {
+		if !e.done[path] {
+			e.done[path] = true
+			p := p.Imports[path]
+			if err := e.extractPkg(root, p); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+func (e *extractor) importCUEFiles(p *packages.Package, dir, args string) error {
 	for _, o := range p.CompiledGoFiles {
 		root := filepath.Dir(o)
 		err := filepath.Walk(root, func(path string, fi os.FileInfo, err error) error {
@@ -529,17 +563,6 @@
 			return err
 		}
 	}
-
-	for path := range e.usedPkgs {
-		if !e.done[path] {
-			e.done[path] = true
-			p := p.Imports[path]
-			if err := e.extractPkg(root, p); err != nil {
-				return err
-			}
-		}
-	}
-
 	return nil
 }
 
diff --git a/go.mod b/go.mod
index 6f88451..43b48b9 100644
--- a/go.mod
+++ b/go.mod
@@ -15,10 +15,10 @@
 	github.com/spf13/pflag v1.0.3
 	github.com/stretchr/testify v1.2.2
 	golang.org/x/exp v0.0.0-20200513190911-00229845015e
-	golang.org/x/net v0.0.0-20190620200207-3b0461eec859
-	golang.org/x/sync v0.0.0-20190423024810-112230192c58
+	golang.org/x/net v0.0.0-20200226121028-0de0cce0169b
+	golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e
 	golang.org/x/text v0.3.2
-	golang.org/x/tools v0.0.0-20200207183749-b753a1ba74fa
+	golang.org/x/tools v0.0.0-20200612220849-54c614fe050c
 	golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543
 	gopkg.in/yaml.v3 v3.0.0-20200121175148-a6ecf24a6d71
 )
diff --git a/go.sum b/go.sum
index 92d881e..519de26 100644
--- a/go.sum
+++ b/go.sum
@@ -112,6 +112,7 @@
 github.com/ugorji/go v1.1.4/go.mod h1:uQMGLiO92mf5W77hV/PUCpI3pbzQx3CRekS0kk+RGrc=
 github.com/xiang90/probing v0.0.0-20190116061207-43a291ad63a2/go.mod h1:UETIi67q53MR2AWcXfiuqkDkRtnGDLqkBTpCHuJHxtU=
 github.com/xordataexchange/crypt v0.0.3-0.20170626215501-b2862e3d0a77/go.mod h1:aYKd//L2LvnjZzWKhF00oedf4jCCReLcmhLdhm1A27Q=
+github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 go.etcd.io/bbolt v1.3.2/go.mod h1:IbVyRI1SCnLcuJnV2u8VeU0CEYM7e686BmAb1XKL+uU=
 go.uber.org/atomic v1.4.0/go.mod h1:gD2HeocX3+yG+ygLZcrzQJaqmWj9AIm7n08wl/qW/PE=
 go.uber.org/multierr v1.1.0/go.mod h1:wR5kodmAFQ0UK8QlbwjlSNy0Z68gJhDJUG5sjR94q/0=
@@ -130,6 +131,8 @@
 golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
 golang.org/x/mod v0.1.1-0.20191107180719-034126e5016b h1:GgiSbuUyC0BlbUmHQBgFqu32eiRR/CEYdjOjOd4zE6Y=
 golang.org/x/mod v0.1.1-0.20191107180719-034126e5016b/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
+golang.org/x/mod v0.2.0 h1:KU7oHjnv3XNWfa5COkzUifxZmxp1TyI7ImMXqFxLwvQ=
+golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20181114220301-adae6a3d119a/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20181220203305-927f97764cc3/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
@@ -138,12 +141,16 @@
 golang.org/x/net v0.0.0-20190522155817-f3200d17e092/go.mod h1:HSz+uSET+XFnRR8LxR5pz3Of3rY3CfYBVs4xY44aLks=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859 h1:R/3boaszxrf1GEUWTVDzSKVwLmSJpwZ1yqXm8j0v2QI=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20200226121028-0de0cce0169b h1:0mm1VjtFUOIlE1SbDlwjYaDxZVDP2S5ou6y0gSgXHu8=
+golang.org/x/net v0.0.0-20200226121028-0de0cce0169b/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEhagSSnXWGV915qUMm9mrU=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e h1:vcxGaoTs7kV8m5Np9uUNQin4BrLOthgV7252N8V+FwY=
+golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20181107165924-66b7b1311ac8/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
@@ -160,8 +167,12 @@
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20200207183749-b753a1ba74fa h1:5E4dL8+NgFOgjwbTKz+OOEGGhP+ectTmF842l6KjupQ=
 golang.org/x/tools v0.0.0-20200207183749-b753a1ba74fa/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
+golang.org/x/tools v0.0.0-20200612220849-54c614fe050c h1:g6oFfz6Cmw68izP3xsdud3Oxu145IPkeFzyRg58AKHM=
+golang.org/x/tools v0.0.0-20200612220849-54c614fe050c/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=