fix(gotool_extractor): when no global corpus is given, use package's …

…corpus for each file (#3290)

kythe/docs/schema/schema.txt

@@ -1939,7 +1939,7 @@ public class E {}
 //- Pkg.node/kind package
 package foo
 
-//- File = vname("", _, _, "kythe/schema/example.go", "").node/kind file
+//- File = vname("", _, _, "schema/example.go", "").node/kind file
 //- File childof Pkg
 --------------------------------------------------------------------------------
 

kythe/go/extractors/golang/golang.go

@@ -435,11 +435,25 @@ func (p *Package) addFiles(cu *apb.CompilationUnit, root, base string, names []s
 			path = filepath.Join(base, name)
 		}
 		trimmed := strings.TrimPrefix(path, root+"/")
+		vn := &spb.VName{
+			Corpus: p.ext.Corpus,
+			Path:   trimmed,
+		}
+		if vn.Corpus == "" {
+			// If no global corpus is specified, use the package's corpus for each of
+			// its files.  The package corpus is based on the rules in
+			// kythe/go/extractors/govname and is usually either the package's
+			// repository root (e.g. github.com/golang/protobuf) or a custom top-level
+			// domain (e.g. k8s.io).
+			vn.Corpus = p.VName.Corpus
+			components := strings.SplitN(vn.Path, string(filepath.Separator), 2)
+			vn.Path = strings.TrimPrefix(components[1], vn.Corpus+"/")
+			if components[0] != "src" {
+				vn.Root = components[0]
+			}
+		}
 		cu.RequiredInput = append(cu.RequiredInput, &apb.CompilationUnit_FileInput{
-			VName: &spb.VName{
-				Corpus: p.ext.Corpus,
-				Path:   trimmed,
-			},
+			VName: vn,
 			Info: &apb.FileInfo{
 				Path:   trimmed,
 				Digest: path, // provisional, until the file is loaded

kythe/go/indexer/cmd/go_example/go_example.go

@@ -72,15 +72,16 @@ func main() {
 	}
 
 	ctx := context.Background()
-	base, err := ioutil.TempDir("", "src")
+	base, err := ioutil.TempDir("", "go_example")
 	if err != nil {
 		log.Fatalf("Error creating temporary directory: %v", err)
 	}
 	defer os.RemoveAll(base) // best-effort
-	dir := filepath.Join(base, *importPath)
+	dir := filepath.Join(base, "src", *importPath)
 	if err := vfs.MkdirAll(ctx, dir, 0755); err != nil {
 		log.Fatalf("Error creating output directory: %v", err)
 	}
+	bc.GOPATH = base
 
 	for _, path := range flag.Args() {
 		if err := copyFile(ctx, path, dir); err != nil {
@@ -92,7 +93,7 @@ func main() {
 	if err := os.Chdir(base); err != nil {
 		log.Fatalf("Error changing directory to %q: %v", dir, err)
 	}
-	pkg, err := ext.ImportDir(*importPath)
+	pkg, err := ext.Locate(*importPath)
 	if err != nil {
 		log.Fatalf("Error locating package: %v", err)
 	}

kythe/go/indexer/testdata/basic/filenode.go

@@ -1,7 +1,7 @@
 // Package file verifies that a file node is generated by the indexer, and that
 // it has the correct relationship to its package.
 //
-//- File=vname("", _, "", "src/test/basic/filenode.go", "").node/kind file
+//- File=vname("", "test", "", "basic/filenode.go", "").node/kind file
 //- @file defines/binding Pkg
 package file
 

kythe/go/indexer/testdata/basic/packageinit.go

@@ -12,7 +12,7 @@ import "fmt"
 //- A childof PkgInit=vname("package.<init>@107", "test", _, "pkginit", "go")
 //- PkgInit.node/kind function
 //-
-//- InitDef=vname(_, _, "", "src/test/pkginit/packageinit.go", "go")
+//- InitDef=vname(_, "test", "", "pkginit/packageinit.go", "go")
 //-     defines PkgInit
 //- InitDef.node/kind anchor
 //- InitDef.loc/start 0

kythe/go/indexer/testdata/basic/packages.go

@@ -4,5 +4,5 @@ package pkg
 
 //- Pkg=vname("package", "test", _, "pkg", "go").node/kind package
 //- Pkg.doc/uri "http://godoc.org/test/pkg"
-//- File=vname("", _, _, "src/test/pkg/packages.go", "").node/kind file
+//- File=vname("", "test", _, "pkg/packages.go", "").node/kind file
 //- File childof Pkg