1 files changed, 96 insertions, 0 deletions
diff --git a/libgo/go/cmd/go/internal/imports/scan.go b/libgo/go/cmd/go/internal/imports/scan.go
new file mode 100644
index 00000000000..d944e95724e
--- /dev/null
+++ b/libgo/go/cmd/go/internal/imports/scan.go
@@ -0,0 +1,96 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package imports
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+func ScanDir(dir string, tags map[string]bool) ([]string, []string, error) {
+	infos, err := ioutil.ReadDir(dir)
+	if err != nil {
+		return nil, nil, err
+	}
+	var files []string
+	for _, info := range infos {
+		name := info.Name()
+		if info.Mode().IsRegular() && !strings.HasPrefix(name, "_") && strings.HasSuffix(name, ".go") && MatchFile(name, tags) {
+			files = append(files, filepath.Join(dir, name))
+		}
+	}
+	return scanFiles(files, tags, false)
+}
+
+func ScanFiles(files []string, tags map[string]bool) ([]string, []string, error) {
+	return scanFiles(files, tags, true)
+}
+
+func scanFiles(files []string, tags map[string]bool, explicitFiles bool) ([]string, []string, error) {
+	imports := make(map[string]bool)
+	testImports := make(map[string]bool)
+	numFiles := 0
+Files:
+	for _, name := range files {
+		r, err := os.Open(name)
+		if err != nil {
+			return nil, nil, err
+		}
+		var list []string
+		data, err := ReadImports(r, false, &list)
+		r.Close()
+		if err != nil {
+			return nil, nil, fmt.Errorf("reading %s: %v", name, err)
+		}
+
+		// import "C" is implicit requirement of cgo tag.
+		// When listing files on the command line (explicitFiles=true)
+		// we do not apply build tag filtering but we still do apply
+		// cgo filtering, so no explicitFiles check here.
+		// Why? Because we always have, and it's not worth breaking
+		// that behavior now.
+		for _, path := range list {
+			if path == `"C"` && !tags["cgo"] && !tags["*"] {
+				continue Files
+			}
+		}
+
+		if !explicitFiles && !ShouldBuild(data, tags) {
+			continue
+		}
+		numFiles++
+		m := imports
+		if strings.HasSuffix(name, "_test.go") {
+			m = testImports
+		}
+		for _, p := range list {
+			q, err := strconv.Unquote(p)
+			if err != nil {
+				continue
+			}
+			m[q] = true
+		}
+	}
+	if numFiles == 0 {
+		return nil, nil, ErrNoGo
+	}
+	return keys(imports), keys(testImports), nil
+}
+
+var ErrNoGo = fmt.Errorf("no Go source files")
+
+func keys(m map[string]bool) []string {
+	var list []string
+	for k := range m {
+		list = append(list, k)
+	}
+	sort.Strings(list)
+	return list
+}