cmd/cue: remove the need for embedpkg

Now that we have go:embed, use that directly.
The code becomes slightly more involved,
as we have to use a combination of ReadDir with path.Join and ReadFile,
but we're still deleting over a hundred lines of code.

I still think that this bit of code can be significantly improved,
but avoiding the unnecessary go:generate is a good first step.

Signed-off-by: Daniel Martí <[email protected]>
Change-Id: Iab4e9bf8da4684763e4ebd783896bf181a44ba26
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/537941
Unity-Result: CUEcueckoo <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Roger Peppe <[email protected]>

Author: mvdan

cmd/cue/cmd/get_go.go

@@ -16,6 +16,7 @@ package cmd
 
 import (
 	"bytes"
+	"embed"
 	"fmt"
 	"go/ast"
 	"go/token"
@@ -285,7 +286,8 @@ module cuelang.org/go
 go 1.14
 `
 
-//go:generate go run cuelang.org/go/internal/cmd/embedpkg cuelang.org/go/cmd/cue/cmd/interfaces
+//go:embed interfaces/*.go
+var interfacesFS embed.FS
 
 func initInterfaces() (err error) {
 	// tempdir needed for overlay
@@ -307,14 +309,26 @@ func initInterfaces() (err error) {
 		return err
 	}
 
-	for fn, contents := range interfacesFiles {
-		fn = filepath.Join(tmpDir, filepath.FromSlash(fn))
+	entries, err := interfacesFS.ReadDir("interfaces")
+	if err != nil {
+		return err
+	}
+	localPkgPath := "cmd/cue/cmd/interfaces"
+	fullPkgPath := "cuelang.org/go/" + localPkgPath
+	for _, entry := range entries {
+		name := entry.Name()
+
+		fn := filepath.Join(tmpDir, filepath.FromSlash(localPkgPath), name)
 		dir := filepath.Dir(fn)
 		if err := os.MkdirAll(dir, 0777); err != nil {
 			return err
 		}
+		contents, err := interfacesFS.ReadFile(path.Join("interfaces", name))
+		if err != nil {
+			return err
+		}
 
-		if err = ioutil.WriteFile(fn, contents, 0666); err != nil {
+		if err := ioutil.WriteFile(fn, contents, 0666); err != nil {
 			return err
 		}
 	}
@@ -326,16 +340,16 @@ func initInterfaces() (err error) {
 		Dir: filepath.Join(tmpDir),
 	}
 
-	p, err := packages.Load(cfg, "cuelang.org/go/cmd/cue/cmd/interfaces")
+	p, err := packages.Load(cfg, fullPkgPath)
 	if err != nil {
-		return fmt.Errorf("error loading embedded cuelang.org/go/cmd/cue/cmd/interfaces package: %w", err)
+		return fmt.Errorf("error loading embedded %s package: %w", fullPkgPath, err)
 	}
 	if len(p[0].Errors) > 0 {
 		var buf bytes.Buffer
 		for _, e := range p[0].Errors {
 			fmt.Fprintf(&buf, "\t%v\n", e)
 		}
-		return fmt.Errorf("error loading embedded cuelang.org/go/cmd/cue/cmd/interfaces package:\n%s", buf.String())
+		return fmt.Errorf("error loading embedded %s package:\n%s", fullPkgPath, buf.String())
 	}
 
 	for e, tt := range p[0].TypesInfo.Types {