force a version of golang.org/x/tools due to an incompatibility with gqlgen

10 files changed, 998 insertions, 357 deletions

diff --git a/vendor/golang.org/x/tools/go/internal/cgo/cgo.go b/vendor/golang.org/x/tools/go/internal/cgo/cgo.go
deleted file mode 100644
index 0f652ea6..00000000
--- a/vendor/golang.org/x/tools/go/internal/cgo/cgo.go
+++ /dev/null
@@ -1,220 +0,0 @@
-// Copyright 2013 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 cgo
-
-// This file handles cgo preprocessing of files containing `import "C"`.
-//
-// DESIGN
-//
-// The approach taken is to run the cgo processor on the package's
-// CgoFiles and parse the output, faking the filenames of the
-// resulting ASTs so that the synthetic file containing the C types is
-// called "C" (e.g. "~/go/src/net/C") and the preprocessed files
-// have their original names (e.g. "~/go/src/net/cgo_unix.go"),
-// not the names of the actual temporary files.
-//
-// The advantage of this approach is its fidelity to 'go build'.  The
-// downside is that the token.Position.Offset for each AST node is
-// incorrect, being an offset within the temporary file.  Line numbers
-// should still be correct because of the //line comments.
-//
-// The logic of this file is mostly plundered from the 'go build'
-// tool, which also invokes the cgo preprocessor.
-//
-//
-// REJECTED ALTERNATIVE
-//
-// An alternative approach that we explored is to extend go/types'
-// Importer mechanism to provide the identity of the importing package
-// so that each time `import "C"` appears it resolves to a different
-// synthetic package containing just the objects needed in that case.
-// The loader would invoke cgo but parse only the cgo_types.go file
-// defining the package-level objects, discarding the other files
-// resulting from preprocessing.
-//
-// The benefit of this approach would have been that source-level
-// syntax information would correspond exactly to the original cgo
-// file, with no preprocessing involved, making source tools like
-// godoc, guru, and eg happy.  However, the approach was rejected
-// due to the additional complexity it would impose on go/types.  (It
-// made for a beautiful demo, though.)
-//
-// cgo files, despite their *.go extension, are not legal Go source
-// files per the specification since they may refer to unexported
-// members of package "C" such as C.int.  Also, a function such as
-// C.getpwent has in effect two types, one matching its C type and one
-// which additionally returns (errno C.int).  The cgo preprocessor
-// uses name mangling to distinguish these two functions in the
-// processed code, but go/types would need to duplicate this logic in
-// its handling of function calls, analogous to the treatment of map
-// lookups in which y=m[k] and y,ok=m[k] are both legal.
-
-import (
-	"fmt"
-	"go/ast"
-	"go/build"
-	"go/parser"
-	"go/token"
-	"io/ioutil"
-	"log"
-	"os"
-	"os/exec"
-	"path/filepath"
-	"regexp"
-	"strings"
-)
-
-// ProcessFiles invokes the cgo preprocessor on bp.CgoFiles, parses
-// the output and returns the resulting ASTs.
-//
-func ProcessFiles(bp *build.Package, fset *token.FileSet, DisplayPath func(path string) string, mode parser.Mode) ([]*ast.File, error) {
-	tmpdir, err := ioutil.TempDir("", strings.Replace(bp.ImportPath, "/", "_", -1)+"_C")
-	if err != nil {
-		return nil, err
-	}
-	defer os.RemoveAll(tmpdir)
-
-	pkgdir := bp.Dir
-	if DisplayPath != nil {
-		pkgdir = DisplayPath(pkgdir)
-	}
-
-	cgoFiles, cgoDisplayFiles, err := Run(bp, pkgdir, tmpdir, false)
-	if err != nil {
-		return nil, err
-	}
-	var files []*ast.File
-	for i := range cgoFiles {
-		rd, err := os.Open(cgoFiles[i])
-		if err != nil {
-			return nil, err
-		}
-		display := filepath.Join(bp.Dir, cgoDisplayFiles[i])
-		f, err := parser.ParseFile(fset, display, rd, mode)
-		rd.Close()
-		if err != nil {
-			return nil, err
-		}
-		files = append(files, f)
-	}
-	return files, nil
-}
-
-var cgoRe = regexp.MustCompile(`[/\\:]`)
-
-// Run invokes the cgo preprocessor on bp.CgoFiles and returns two
-// lists of files: the resulting processed files (in temporary
-// directory tmpdir) and the corresponding names of the unprocessed files.
-//
-// Run is adapted from (*builder).cgo in
-// $GOROOT/src/cmd/go/build.go, but these features are unsupported:
-// Objective C, CGOPKGPATH, CGO_FLAGS.
-//
-// If useabs is set to true, absolute paths of the bp.CgoFiles will be passed in
-// to the cgo preprocessor. This in turn will set the // line comments
-// referring to those files to use absolute paths. This is needed for
-// go/packages using the legacy go list support so it is able to find
-// the original files.
-func Run(bp *build.Package, pkgdir, tmpdir string, useabs bool) (files, displayFiles []string, err error) {
-	cgoCPPFLAGS, _, _, _ := cflags(bp, true)
-	_, cgoexeCFLAGS, _, _ := cflags(bp, false)
-
-	if len(bp.CgoPkgConfig) > 0 {
-		pcCFLAGS, err := pkgConfigFlags(bp)
-		if err != nil {
-			return nil, nil, err
-		}
-		cgoCPPFLAGS = append(cgoCPPFLAGS, pcCFLAGS...)
-	}
-
-	// Allows including _cgo_export.h from .[ch] files in the package.
-	cgoCPPFLAGS = append(cgoCPPFLAGS, "-I", tmpdir)
-
-	// _cgo_gotypes.go (displayed "C") contains the type definitions.
-	files = append(files, filepath.Join(tmpdir, "_cgo_gotypes.go"))
-	displayFiles = append(displayFiles, "C")
-	for _, fn := range bp.CgoFiles {
-		// "foo.cgo1.go" (displayed "foo.go") is the processed Go source.
-		f := cgoRe.ReplaceAllString(fn[:len(fn)-len("go")], "_")
-		files = append(files, filepath.Join(tmpdir, f+"cgo1.go"))
-		displayFiles = append(displayFiles, fn)
-	}
-
-	var cgoflags []string
-	if bp.Goroot && bp.ImportPath == "runtime/cgo" {
-		cgoflags = append(cgoflags, "-import_runtime_cgo=false")
-	}
-	if bp.Goroot && bp.ImportPath == "runtime/race" || bp.ImportPath == "runtime/cgo" {
-		cgoflags = append(cgoflags, "-import_syscall=false")
-	}
-
-	var cgoFiles []string = bp.CgoFiles
-	if useabs {
-		cgoFiles = make([]string, len(bp.CgoFiles))
-		for i := range cgoFiles {
-			cgoFiles[i] = filepath.Join(pkgdir, bp.CgoFiles[i])
-		}
-	}
-
-	args := stringList(
-		"go", "tool", "cgo", "-objdir", tmpdir, cgoflags, "--",
-		cgoCPPFLAGS, cgoexeCFLAGS, cgoFiles,
-	)
-	if false {
-		log.Printf("Running cgo for package %q: %s (dir=%s)", bp.ImportPath, args, pkgdir)
-	}
-	cmd := exec.Command(args[0], args[1:]...)
-	cmd.Dir = pkgdir
-	cmd.Stdout = os.Stderr
-	cmd.Stderr = os.Stderr
-	if err := cmd.Run(); err != nil {
-		return nil, nil, fmt.Errorf("cgo failed: %s: %s", args, err)
-	}
-
-	return files, displayFiles, nil
-}
-
-// -- unmodified from 'go build' ---------------------------------------
-
-// Return the flags to use when invoking the C or C++ compilers, or cgo.
-func cflags(p *build.Package, def bool) (cppflags, cflags, cxxflags, ldflags []string) {
-	var defaults string
-	if def {
-		defaults = "-g -O2"
-	}
-
-	cppflags = stringList(envList("CGO_CPPFLAGS", ""), p.CgoCPPFLAGS)
-	cflags = stringList(envList("CGO_CFLAGS", defaults), p.CgoCFLAGS)
-	cxxflags = stringList(envList("CGO_CXXFLAGS", defaults), p.CgoCXXFLAGS)
-	ldflags = stringList(envList("CGO_LDFLAGS", defaults), p.CgoLDFLAGS)
-	return
-}
-
-// envList returns the value of the given environment variable broken
-// into fields, using the default value when the variable is empty.
-func envList(key, def string) []string {
-	v := os.Getenv(key)
-	if v == "" {
-		v = def
-	}
-	return strings.Fields(v)
-}
-
-// stringList's arguments should be a sequence of string or []string values.
-// stringList flattens them into a single []string.
-func stringList(args ...interface{}) []string {
-	var x []string
-	for _, arg := range args {
-		switch arg := arg.(type) {
-		case []string:
-			x = append(x, arg...)
-		case string:
-			x = append(x, arg)
-		default:
-			panic("stringList: invalid argument")
-		}
-	}
-	return x
-}
diff --git a/vendor/golang.org/x/tools/go/internal/cgo/cgo_pkgconfig.go b/vendor/golang.org/x/tools/go/internal/cgo/cgo_pkgconfig.go
deleted file mode 100644
index b5bb95a6..00000000
--- a/vendor/golang.org/x/tools/go/internal/cgo/cgo_pkgconfig.go
+++ /dev/null
@@ -1,39 +0,0 @@
-// Copyright 2013 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 cgo
-
-import (
-	"errors"
-	"fmt"
-	"go/build"
-	"os/exec"
-	"strings"
-)
-
-// pkgConfig runs pkg-config with the specified arguments and returns the flags it prints.
-func pkgConfig(mode string, pkgs []string) (flags []string, err error) {
-	cmd := exec.Command("pkg-config", append([]string{mode}, pkgs...)...)
-	out, err := cmd.CombinedOutput()
-	if err != nil {
-		s := fmt.Sprintf("%s failed: %v", strings.Join(cmd.Args, " "), err)
-		if len(out) > 0 {
-			s = fmt.Sprintf("%s: %s", s, out)
-		}
-		return nil, errors.New(s)
-	}
-	if len(out) > 0 {
-		flags = strings.Fields(string(out))
-	}
-	return
-}
-
-// pkgConfigFlags calls pkg-config if needed and returns the cflags
-// needed to build the package.
-func pkgConfigFlags(p *build.Package) (cflags []string, err error) {
-	if len(p.CgoPkgConfig) == 0 {
-		return nil, nil
-	}
-	return pkgConfig("--cflags", p.CgoPkgConfig)
-}
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go b/vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go
index 6a9821ae..a807d0aa 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go
@@ -127,10 +127,10 @@ func BExportData(fset *token.FileSet, pkg *types.Package) (b []byte, err error)
 	// --- generic export data ---
 
 	// populate type map with predeclared "known" types
-	for index, typ := range predeclared {
+	for index, typ := range predeclared() {
 		p.typIndex[typ] = index
 	}
-	if len(p.typIndex) != len(predeclared) {
+	if len(p.typIndex) != len(predeclared()) {
 		return nil, internalError("duplicate entries in type map?")
 	}
 
@@ -209,7 +209,7 @@ func (p *exporter) obj(obj types.Object) {
 		p.value(obj.Val())
 
 	case *types.TypeName:
-		if isAlias(obj) {
+		if obj.IsAlias() {
 			p.tag(aliasTag)
 			p.pos(obj)
 			p.qualifiedName(obj)
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/bimport.go b/vendor/golang.org/x/tools/go/internal/gcimporter/bimport.go
index b31eacfc..e3c31078 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/bimport.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/bimport.go
@@ -126,7 +126,7 @@ func BImportData(fset *token.FileSet, imports map[string]*types.Package, data []
 	// --- generic export data ---
 
 	// populate typList with predeclared "known" types
-	p.typList = append(p.typList, predeclared...)
+	p.typList = append(p.typList, predeclared()...)
 
 	// read package data
 	pkg = p.pkg()
@@ -976,50 +976,58 @@ const (
 	aliasTag
 )
 
-var predeclared = []types.Type{
-	// basic types
-	types.Typ[types.Bool],
-	types.Typ[types.Int],
-	types.Typ[types.Int8],
-	types.Typ[types.Int16],
-	types.Typ[types.Int32],
-	types.Typ[types.Int64],
-	types.Typ[types.Uint],
-	types.Typ[types.Uint8],
-	types.Typ[types.Uint16],
-	types.Typ[types.Uint32],
-	types.Typ[types.Uint64],
-	types.Typ[types.Uintptr],
-	types.Typ[types.Float32],
-	types.Typ[types.Float64],
-	types.Typ[types.Complex64],
-	types.Typ[types.Complex128],
-	types.Typ[types.String],
-
-	// basic type aliases
-	types.Universe.Lookup("byte").Type(),
-	types.Universe.Lookup("rune").Type(),
-
-	// error
-	types.Universe.Lookup("error").Type(),
-
-	// untyped types
-	types.Typ[types.UntypedBool],
-	types.Typ[types.UntypedInt],
-	types.Typ[types.UntypedRune],
-	types.Typ[types.UntypedFloat],
-	types.Typ[types.UntypedComplex],
-	types.Typ[types.UntypedString],
-	types.Typ[types.UntypedNil],
-
-	// package unsafe
-	types.Typ[types.UnsafePointer],
-
-	// invalid type
-	types.Typ[types.Invalid], // only appears in packages with errors
-
-	// used internally by gc; never used by this package or in .a files
-	anyType{},
+var predecl []types.Type // initialized lazily
+
+func predeclared() []types.Type {
+	if predecl == nil {
+		// initialize lazily to be sure that all
+		// elements have been initialized before
+		predecl = []types.Type{ // basic types
+			types.Typ[types.Bool],
+			types.Typ[types.Int],
+			types.Typ[types.Int8],
+			types.Typ[types.Int16],
+			types.Typ[types.Int32],
+			types.Typ[types.Int64],
+			types.Typ[types.Uint],
+			types.Typ[types.Uint8],
+			types.Typ[types.Uint16],
+			types.Typ[types.Uint32],
+			types.Typ[types.Uint64],
+			types.Typ[types.Uintptr],
+			types.Typ[types.Float32],
+			types.Typ[types.Float64],
+			types.Typ[types.Complex64],
+			types.Typ[types.Complex128],
+			types.Typ[types.String],
+
+			// basic type aliases
+			types.Universe.Lookup("byte").Type(),
+			types.Universe.Lookup("rune").Type(),
+
+			// error
+			types.Universe.Lookup("error").Type(),
+
+			// untyped types
+			types.Typ[types.UntypedBool],
+			types.Typ[types.UntypedInt],
+			types.Typ[types.UntypedRune],
+			types.Typ[types.UntypedFloat],
+			types.Typ[types.UntypedComplex],
+			types.Typ[types.UntypedString],
+			types.Typ[types.UntypedNil],
+
+			// package unsafe
+			types.Typ[types.UnsafePointer],
+
+			// invalid type
+			types.Typ[types.Invalid], // only appears in packages with errors
+
+			// used internally by gc; never used by this package or in .a files
+			anyType{},
+		}
+	}
+	return predecl
 }
 
 type anyType struct{}
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/gcimporter.go b/vendor/golang.org/x/tools/go/internal/gcimporter/gcimporter.go
index 47dd4613..9cf18660 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/gcimporter.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/gcimporter.go
@@ -128,42 +128,69 @@ func ImportData(packages map[string]*types.Package, filename, id string, data io
 // the corresponding package object to the packages map, and returns the object.
 // The packages map must contain all packages already imported.
 //
-func Import(packages map[string]*types.Package, path, srcDir string) (pkg *types.Package, err error) {
-	filename, id := FindPkg(path, srcDir)
-	if filename == "" {
+func Import(packages map[string]*types.Package, path, srcDir string, lookup func(path string) (io.ReadCloser, error)) (pkg *types.Package, err error) {
+	var rc io.ReadCloser
+	var filename, id string
+	if lookup != nil {
+		// With custom lookup specified, assume that caller has
+		// converted path to a canonical import path for use in the map.
 		if path == "unsafe" {
 			return types.Unsafe, nil
 		}
-		err = fmt.Errorf("can't find import: %q", id)
-		return
-	}
+		id = path
 
-	// no need to re-import if the package was imported completely before
-	if pkg = packages[id]; pkg != nil && pkg.Complete() {
-		return
-	}
+		// No need to re-import if the package was imported completely before.
+		if pkg = packages[id]; pkg != nil && pkg.Complete() {
+			return
+		}
+		f, err := lookup(path)
+		if err != nil {
+			return nil, err
+		}
+		rc = f
+	} else {
+		filename, id = FindPkg(path, srcDir)
+		if filename == "" {
+			if path == "unsafe" {
+				return types.Unsafe, nil
+			}
+			return nil, fmt.Errorf("can't find import: %q", id)
+		}
 
-	// open file
-	f, err := os.Open(filename)
-	if err != nil {
-		return
-	}
-	defer func() {
-		f.Close()
+		// no need to re-import if the package was imported completely before
+		if pkg = packages[id]; pkg != nil && pkg.Complete() {
+			return
+		}
+
+		// open file
+		f, err := os.Open(filename)
 		if err != nil {
-			// add file name to error
-			err = fmt.Errorf("reading export data: %s: %v", filename, err)
+			return nil, err
 		}
-	}()
+		defer func() {
+			if err != nil {
+				// add file name to error
+				err = fmt.Errorf("%s: %v", filename, err)
+			}
+		}()
+		rc = f
+	}
+	defer rc.Close()
 
 	var hdr string
-	buf := bufio.NewReader(f)
+	buf := bufio.NewReader(rc)
 	if hdr, err = FindExportData(buf); err != nil {
 		return
 	}
 
 	switch hdr {
 	case "$$\n":
+		// Work-around if we don't have a filename; happens only if lookup != nil.
+		// Either way, the filename is only needed for importer error messages, so
+		// this is fine.
+		if filename == "" {
+			filename = path
+		}
 		return ImportData(packages, filename, id, buf)
 
 	case "$$B\n":
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/iexport.go b/vendor/golang.org/x/tools/go/internal/gcimporter/iexport.go
new file mode 100644
index 00000000..be671c79
--- /dev/null
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/iexport.go
@@ -0,0 +1,723 @@
+// Copyright 2019 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.
+
+// Indexed binary package export.
+// This file was derived from $GOROOT/src/cmd/compile/internal/gc/iexport.go;
+// see that file for specification of the format.
+
+// +build go1.11
+
+package gcimporter
+
+import (
+	"bytes"
+	"encoding/binary"
+	"go/ast"
+	"go/constant"
+	"go/token"
+	"go/types"
+	"io"
+	"math/big"
+	"reflect"
+	"sort"
+)
+
+// Current indexed export format version. Increase with each format change.
+// 0: Go1.11 encoding
+const iexportVersion = 0
+
+// IExportData returns the binary export data for pkg.
+// If no file set is provided, position info will be missing.
+func IExportData(fset *token.FileSet, pkg *types.Package) (b []byte, err error) {
+	defer func() {
+		if e := recover(); e != nil {
+			if ierr, ok := e.(internalError); ok {
+				err = ierr
+				return
+			}
+			// Not an internal error; panic again.
+			panic(e)
+		}
+	}()
+
+	p := iexporter{
+		out:         bytes.NewBuffer(nil),
+		fset:        fset,
+		allPkgs:     map[*types.Package]bool{},
+		stringIndex: map[string]uint64{},
+		declIndex:   map[types.Object]uint64{},
+		typIndex:    map[types.Type]uint64{},
+	}
+
+	for i, pt := range predeclared() {
+		p.typIndex[pt] = uint64(i)
+	}
+	if len(p.typIndex) > predeclReserved {
+		panic(internalErrorf("too many predeclared types: %d > %d", len(p.typIndex), predeclReserved))
+	}
+
+	// Initialize work queue with exported declarations.
+	scope := pkg.Scope()
+	for _, name := range scope.Names() {
+		if ast.IsExported(name) {
+			p.pushDecl(scope.Lookup(name))
+		}
+	}
+
+	// Loop until no more work.
+	for !p.declTodo.empty() {
+		p.doDecl(p.declTodo.popHead())
+	}
+
+	// Append indices to data0 section.
+	dataLen := uint64(p.data0.Len())
+	w := p.newWriter()
+	w.writeIndex(p.declIndex, pkg)
+	w.flush()
+
+	// Assemble header.
+	var hdr intWriter
+	hdr.WriteByte('i')
+	hdr.uint64(iexportVersion)
+	hdr.uint64(uint64(p.strings.Len()))
+	hdr.uint64(dataLen)
+
+	// Flush output.
+	io.Copy(p.out, &hdr)
+	io.Copy(p.out, &p.strings)
+	io.Copy(p.out, &p.data0)
+
+	return p.out.Bytes(), nil
+}
+
+// writeIndex writes out an object index. mainIndex indicates whether
+// we're writing out the main index, which is also read by
+// non-compiler tools and includes a complete package description
+// (i.e., name and height).
+func (w *exportWriter) writeIndex(index map[types.Object]uint64, localpkg *types.Package) {
+	// Build a map from packages to objects from that package.
+	pkgObjs := map[*types.Package][]types.Object{}
+
+	// For the main index, make sure to include every package that
+	// we reference, even if we're not exporting (or reexporting)
+	// any symbols from it.
+	pkgObjs[localpkg] = nil
+	for pkg := range w.p.allPkgs {
+		pkgObjs[pkg] = nil
+	}
+
+	for obj := range index {
+		pkgObjs[obj.Pkg()] = append(pkgObjs[obj.Pkg()], obj)
+	}
+
+	var pkgs []*types.Package
+	for pkg, objs := range pkgObjs {
+		pkgs = append(pkgs, pkg)
+
+		sort.Slice(objs, func(i, j int) bool {
+			return objs[i].Name() < objs[j].Name()
+		})
+	}
+
+	sort.Slice(pkgs, func(i, j int) bool {
+		return pkgs[i].Path() < pkgs[j].Path()
+	})
+
+	w.uint64(uint64(len(pkgs)))
+	for _, pkg := range pkgs {
+		w.string(pkg.Path())
+		w.string(pkg.Name())
+		w.uint64(uint64(0)) // package height is not needed for go/types
+
+		objs := pkgObjs[pkg]
+		w.uint64(uint64(len(objs)))
+		for _, obj := range objs {
+			w.string(obj.Name())
+			w.uint64(index[obj])
+		}
+	}
+}
+
+type iexporter struct {
+	fset *token.FileSet
+	out  *bytes.Buffer
+
+	// allPkgs tracks all packages that have been referenced by
+	// the export data, so we can ensure to include them in the
+	// main index.
+	allPkgs map[*types.Package]bool
+
+	declTodo objQueue
+
+	strings     intWriter
+	stringIndex map[string]uint64
+
+	data0     intWriter
+	declIndex map[types.Object]uint64
+	typIndex  map[types.Type]uint64
+}
+
+// stringOff returns the offset of s within the string section.
+// If not already present, it's added to the end.
+func (p *iexporter) stringOff(s string) uint64 {
+	off, ok := p.stringIndex[s]
+	if !ok {
+		off = uint64(p.strings.Len())
+		p.stringIndex[s] = off
+
+		p.strings.uint64(uint64(len(s)))
+		p.strings.WriteString(s)
+	}
+	return off
+}
+
+// pushDecl adds n to the declaration work queue, if not already present.
+func (p *iexporter) pushDecl(obj types.Object) {
+	// Package unsafe is known to the compiler and predeclared.
+	assert(obj.Pkg() != types.Unsafe)
+
+	if _, ok := p.declIndex[obj]; ok {
+		return
+	}
+
+	p.declIndex[obj] = ^uint64(0) // mark n present in work queue
+	p.declTodo.pushTail(obj)
+}
+
+// exportWriter handles writing out individual data section chunks.
+type exportWriter struct {
+	p *iexporter
+
+	data     intWriter
+	currPkg  *types.Package
+	prevFile string
+	prevLine int64
+}
+
+func (p *iexporter) doDecl(obj types.Object) {
+	w := p.newWriter()
+	w.setPkg(obj.Pkg(), false)
+
+	switch obj := obj.(type) {
+	case *types.Var:
+		w.tag('V')
+		w.pos(obj.Pos())
+		w.typ(obj.Type(), obj.Pkg())
+
+	case *types.Func:
+		sig, _ := obj.Type().(*types.Signature)
+		if sig.Recv() != nil {
+			panic(internalErrorf("unexpected method: %v", sig))
+		}
+		w.tag('F')
+		w.pos(obj.Pos())
+		w.signature(sig)
+
+	case *types.Const:
+		w.tag('C')
+		w.pos(obj.Pos())
+		w.value(obj.Type(), obj.Val())
+
+	case *types.TypeName:
+		if obj.IsAlias() {
+			w.tag('A')
+			w.pos(obj.Pos())
+			w.typ(obj.Type(), obj.Pkg())
+			break
+		}
+
+		// Defined type.
+		w.tag('T')
+		w.pos(obj.Pos())
+
+		underlying := obj.Type().Underlying()
+		w.typ(underlying, obj.Pkg())
+
+		t := obj.Type()
+		if types.IsInterface(t) {
+			break
+		}
+
+		named, ok := t.(*types.Named)
+		if !ok {
+			panic(internalErrorf("%s is not a defined type", t))
+		}
+
+		n := named.NumMethods()
+		w.uint64(uint64(n))
+		for i := 0; i < n; i++ {
+			m := named.Method(i)
+			w.pos(m.Pos())
+			w.string(m.Name())
+			sig, _ := m.Type().(*types.Signature)
+			w.param(sig.Recv())
+			w.signature(sig)
+		}
+
+	default:
+		panic(internalErrorf("unexpected object: %v", obj))
+	}
+
+	p.declIndex[obj] = w.flush()
+}
+
+func (w *exportWriter) tag(tag byte) {
+	w.data.WriteByte(tag)
+}
+
+func (w *exportWriter) pos(pos token.Pos) {
+	p := w.p.fset.Position(pos)
+	file := p.Filename
+	line := int64(p.Line)
+
+	// When file is the same as the last position (common case),
+	// we can save a few bytes by delta encoding just the line
+	// number.
+	//
+	// Note: Because data objects may be read out of order (or not
+	// at all), we can only apply delta encoding within a single
+	// object. This is handled implicitly by tracking prevFile and
+	// prevLine as fields of exportWriter.
+
+	if file == w.prevFile {
+		delta := line - w.prevLine
+		w.int64(delta)
+		if delta == deltaNewFile {
+			w.int64(-1)
+		}
+	} else {
+		w.int64(deltaNewFile)
+		w.int64(line) // line >= 0
+		w.string(file)
+		w.prevFile = file
+	}
+	w.prevLine = line
+}
+
+func (w *exportWriter) pkg(pkg *types.Package) {
+	// Ensure any referenced packages are declared in the main index.
+	w.p.allPkgs[pkg] = true
+
+	w.string(pkg.Path())
+}
+
+func (w *exportWriter) qualifiedIdent(obj types.Object) {
+	// Ensure any referenced declarations are written out too.
+	w.p.pushDecl(obj)
+
+	w.string(obj.Name())
+	w.pkg(obj.Pkg())
+}
+
+func (w *exportWriter) typ(t types.Type, pkg *types.Package) {
+	w.data.uint64(w.p.typOff(t, pkg))
+}
+
+func (p *iexporter) newWriter() *exportWriter {
+	return &exportWriter{p: p}
+}
+
+func (w *exportWriter) flush() uint64 {
+	off := uint64(w.p.data0.Len())
+	io.Copy(&w.p.data0, &w.data)
+	return off
+}
+
+func (p *iexporter) typOff(t types.Type, pkg *types.Package) uint64 {
+	off, ok := p.typIndex[t]
+	if !ok {
+		w := p.newWriter()
+		w.doTyp(t, pkg)
+		off = predeclReserved + w.flush()
+		p.typIndex[t] = off
+	}
+	return off
+}
+
+func (w *exportWriter) startType(k itag) {
+	w.data.uint64(uint64(k))
+}
+
+func (w *exportWriter) doTyp(t types.Type, pkg *types.Package) {
+	switch t := t.(type) {
+	case *types.Named:
+		w.startType(definedType)
+		w.qualifiedIdent(t.Obj())
+
+	case *types.Pointer:
+		w.startType(pointerType)
+		w.typ(t.Elem(), pkg)
+
+	case *types.Slice:
+		w.startType(sliceType)
+		w.typ(t.Elem(), pkg)
+
+	case *types.Array:
+		w.startType(arrayType)
+		w.uint64(uint64(t.Len()))
+		w.typ(t.Elem(), pkg)
+
+	case *types.Chan:
+		w.startType(chanType)
+		// 1 RecvOnly; 2 SendOnly; 3 SendRecv
+		var dir uint64
+		switch t.Dir() {
+		case types.RecvOnly:
+			dir = 1
+		case types.SendOnly:
+			dir = 2
+		case types.SendRecv:
+			dir = 3
+		}
+		w.uint64(dir)
+		w.typ(t.Elem(), pkg)
+
+	case *types.Map:
+		w.startType(mapType)
+		w.typ(t.Key(), pkg)
+		w.typ(t.Elem(), pkg)
+
+	case *types.Signature:
+		w.startType(signatureType)
+		w.setPkg(pkg, true)
+		w.signature(t)
+
+	case *types.Struct:
+		w.startType(structType)
+		w.setPkg(pkg, true)
+
+		n := t.NumFields()
+		w.uint64(uint64(n))
+		for i := 0; i < n; i++ {
+			f := t.Field(i)
+			w.pos(f.Pos())
+			w.string(f.Name())
+			w.typ(f.Type(), pkg)
+			w.bool(f.Embedded())
+			w.string(t.Tag(i)) // note (or tag)
+		}
+
+	case *types.Interface:
+		w.startType(interfaceType)
+		w.setPkg(pkg, true)
+
+		n := t.NumEmbeddeds()
+		w.uint64(uint64(n))
+		for i := 0; i < n; i++ {
+			f := t.Embedded(i)
+			w.pos(f.Obj().Pos())
+			w.typ(f.Obj().Type(), f.Obj().Pkg())
+		}
+
+		n = t.NumExplicitMethods()
+		w.uint64(uint64(n))
+		for i := 0; i < n; i++ {
+			m := t.ExplicitMethod(i)
+			w.pos(m.Pos())
+			w.string(m.Name())
+			sig, _ := m.Type().(*types.Signature)
+			w.signature(sig)
+		}
+
+	default:
+		panic(internalErrorf("unexpected type: %v, %v", t, reflect.TypeOf(t)))
+	}
+}
+
+func (w *exportWriter) setPkg(pkg *types.Package, write bool) {
+	if write {
+		w.pkg(pkg)
+	}
+
+	w.currPkg = pkg
+}
+
+func (w *exportWriter) signature(sig *types.Signature) {
+	w.paramList(sig.Params())
+	w.paramList(sig.Results())
+	if sig.Params().Len() > 0 {
+		w.bool(sig.Variadic())
+	}
+}
+
+func (w *exportWriter) paramList(tup *types.Tuple) {
+	n := tup.Len()
+	w.uint64(uint64(n))
+	for i := 0; i < n; i++ {
+		w.param(tup.At(i))
+	}
+}
+
+func (w *exportWriter) param(obj types.Object) {
+	w.pos(obj.Pos())
+	w.localIdent(obj)
+	w.typ(obj.Type(), obj.Pkg())
+}
+
+func (w *exportWriter) value(typ types.Type, v constant.Value) {
+	w.typ(typ, nil)
+
+	switch v.Kind() {
+	case constant.Bool:
+		w.bool(constant.BoolVal(v))
+	case constant.Int:
+		var i big.Int
+		if i64, exact := constant.Int64Val(v); exact {
+			i.SetInt64(i64)
+		} else if ui64, exact := constant.Uint64Val(v); exact {
+			i.SetUint64(ui64)
+		} else {
+			i.SetString(v.ExactString(), 10)
+		}
+		w.mpint(&i, typ)
+	case constant.Float:
+		f := constantToFloat(v)
+		w.mpfloat(f, typ)
+	case constant.Complex:
+		w.mpfloat(constantToFloat(constant.Real(v)), typ)
+		w.mpfloat(constantToFloat(constant.Imag(v)), typ)
+	case constant.String:
+		w.string(constant.StringVal(v))
+	case constant.Unknown:
+		// package contains type errors
+	default:
+		panic(internalErrorf("unexpected value %v (%T)", v, v))
+	}
+}
+
+// constantToFloat converts a constant.Value with kind constant.Float to a
+// big.Float.
+func constantToFloat(x constant.Value) *big.Float {
+	assert(x.Kind() == constant.Float)
+	// Use the same floating-point precision (512) as cmd/compile
+	// (see Mpprec in cmd/compile/internal/gc/mpfloat.go).
+	const mpprec = 512
+	var f big.Float
+	f.SetPrec(mpprec)
+	if v, exact := constant.Float64Val(x); exact {
+		// float64
+		f.SetFloat64(v)
+	} else if num, denom := constant.Num(x), constant.Denom(x); num.Kind() == constant.Int {
+		// TODO(gri): add big.Rat accessor to constant.Value.
+		n := valueToRat(num)
+		d := valueToRat(denom)
+		f.SetRat(n.Quo(n, d))
+	} else {
+		// Value too large to represent as a fraction => inaccessible.
+		// TODO(gri): add big.Float accessor to constant.Value.
+		_, ok := f.SetString(x.ExactString())
+		assert(ok)
+	}
+	return &f
+}
+
+// mpint exports a multi-precision integer.
+//
+// For unsigned types, small values are written out as a single
+// byte. Larger values are written out as a length-prefixed big-endian
+// byte string, where the length prefix is encoded as its complement.
+// For example, bytes 0, 1, and 2 directly represent the integer
+// values 0, 1, and 2; while bytes 255, 254, and 253 indicate a 1-,
+// 2-, and 3-byte big-endian string follow.
+//
+// Encoding for signed types use the same general approach as for
+// unsigned types, except small values use zig-zag encoding and the
+// bottom bit of length prefix byte for large values is reserved as a
+// sign bit.
+//
+// The exact boundary between small and large encodings varies
+// according to the maximum number of bytes needed to encode a value
+// of type typ. As a special case, 8-bit types are always encoded as a
+// single byte.
+//
+// TODO(mdempsky): Is this level of complexity really worthwhile?
+func (w *exportWriter) mpint(x *big.Int, typ types.Type) {
+	basic, ok := typ.Underlying().(*types.Basic)
+	if !ok {
+		panic(internalErrorf("unexpected type %v (%T)", typ.Underlying(), typ.Underlying()))
+	}
+
+	signed, maxBytes := intSize(basic)
+
+	negative := x.Sign() < 0
+	if !signed && negative {
+		panic(internalErrorf("negative unsigned integer; type %v, value %v", typ, x))
+	}
+
+	b := x.Bytes()
+	if len(b) > 0 && b[0] == 0 {
+		panic(internalErrorf("leading zeros"))
+	}
+	if uint(len(b)) > maxBytes {
+		panic(internalErrorf("bad mpint length: %d > %d (type %v, value %v)", len(b), maxBytes, typ, x))
+	}
+
+	maxSmall := 256 - maxBytes
+	if signed {
+		maxSmall = 256 - 2*maxBytes
+	}
+	if maxBytes == 1 {
+		maxSmall = 256
+	}
+
+	// Check if x can use small value encoding.
+	if len(b) <= 1 {
+		var ux uint
+		if len(b) == 1 {
+			ux = uint(b[0])
+		}
+		if signed {
+			ux <<= 1
+			if negative {
+				ux--
+			}
+		}
+		if ux < maxSmall {
+			w.data.WriteByte(byte(ux))
+			return
+		}
+	}
+
+	n := 256 - uint(len(b))
+	if signed {
+		n = 256 - 2*uint(len(b))
+		if negative {
+			n |= 1
+		}
+	}
+	if n < maxSmall || n >= 256 {
+		panic(internalErrorf("encoding mistake: %d, %v, %v => %d", len(b), signed, negative, n))
+	}
+
+	w.data.WriteByte(byte(n))
+	w.data.Write(b)
+}
+
+// mpfloat exports a multi-precision floating point number.
+//
+// The number's value is decomposed into mantissa × 2**exponent, where
+// mantissa is an integer. The value is written out as mantissa (as a
+// multi-precision integer) and then the exponent, except exponent is
+// omitted if mantissa is zero.
+func (w *exportWriter) mpfloat(f *big.Float, typ types.Type) {
+	if f.IsInf() {
+		panic("infinite constant")
+	}
+
+	// Break into f = mant × 2**exp, with 0.5 <= mant < 1.
+	var mant big.Float
+	exp := int64(f.MantExp(&mant))
+
+	// Scale so that mant is an integer.
+	prec := mant.MinPrec()
+	mant.SetMantExp(&mant, int(prec))
+	exp -= int64(prec)
+
+	manti, acc := mant.Int(nil)
+	if acc != big.Exact {
+		panic(internalErrorf("mantissa scaling failed for %f (%s)", f, acc))
+	}
+	w.mpint(manti, typ)
+	if manti.Sign() != 0 {
+		w.int64(exp)
+	}
+}
+
+func (w *exportWriter) bool(b bool) bool {
+	var x uint64
+	if b {
+		x = 1
+	}
+	w.uint64(x)
+	return b
+}
+
+func (w *exportWriter) int64(x int64)   { w.data.int64(x) }
+func (w *exportWriter) uint64(x uint64) { w.data.uint64(x) }
+func (w *exportWriter) string(s string) { w.uint64(w.p.stringOff(s)) }
+
+func (w *exportWriter) localIdent(obj types.Object) {
+	// Anonymous parameters.
+	if obj == nil {
+		w.string("")
+		return
+	}
+
+	name := obj.Name()
+	if name == "_" {
+		w.string("_")
+		return
+	}
+
+	w.string(name)
+}
+
+type intWriter struct {
+	bytes.Buffer
+}
+
+func (w *intWriter) int64(x int64) {
+	var buf [binary.MaxVarintLen64]byte
+	n := binary.PutVarint(buf[:], x)
+	w.Write(buf[:n])
+}
+
+func (w *intWriter) uint64(x uint64) {
+	var buf [binary.MaxVarintLen64]byte
+	n := binary.PutUvarint(buf[:], x)
+	w.Write(buf[:n])
+}
+
+func assert(cond bool) {
+	if !cond {
+		panic("internal error: assertion failed")
+	}
+}
+
+// The below is copied from go/src/cmd/compile/internal/gc/syntax.go.
+
+// objQueue is a FIFO queue of types.Object. The zero value of objQueue is
+// a ready-to-use empty queue.
+type objQueue struct {
+	ring       []types.Object
+	head, tail int
+}
+
+// empty returns true if q contains no Nodes.
+func (q *objQueue) empty() bool {
+	return q.head == q.tail
+}
+
+// pushTail appends n to the tail of the queue.
+func (q *objQueue) pushTail(obj types.Object) {
+	if len(q.ring) == 0 {
+		q.ring = make([]types.Object, 16)
+	} else if q.head+len(q.ring) == q.tail {
+		// Grow the ring.
+		nring := make([]types.Object, len(q.ring)*2)
+		// Copy the old elements.
+		part := q.ring[q.head%len(q.ring):]
+		if q.tail-q.head <= len(part) {
+			part = part[:q.tail-q.head]
+			copy(nring, part)
+		} else {
+			pos := copy(nring, part)
+			copy(nring[pos:], q.ring[:q.tail%len(q.ring)])
+		}
+		q.ring, q.head, q.tail = nring, 0, q.tail-q.head
+	}
+
+	q.ring[q.tail%len(q.ring)] = obj
+	q.tail++
+}
+
+// popHead pops a node from the head of the queue. It panics if q is empty.
+func (q *objQueue) popHead() types.Object {
+	if q.empty() {
+		panic("dequeue empty")
+	}
+	obj := q.ring[q.head%len(q.ring)]
+	q.head++
+	return obj
+}
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/iimport.go b/vendor/golang.org/x/tools/go/internal/gcimporter/iimport.go
index 0fd22bb0..3cb7ae5b 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/iimport.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/iimport.go
@@ -109,7 +109,7 @@ func IImportData(fset *token.FileSet, imports map[string]*types.Package, data []
 		},
 	}
 
-	for i, pt := range predeclared {
+	for i, pt := range predeclared() {
 		p.typCache[uint64(i)] = pt
 	}
 
@@ -142,8 +142,12 @@ func IImportData(fset *token.FileSet, imports map[string]*types.Package, data []
 		p.pkgIndex[pkg] = nameIndex
 		pkgList[i] = pkg
 	}
-
-	localpkg := pkgList[0]
+	var localpkg *types.Package
+	for _, pkg := range pkgList {
+		if pkg.Path() == path {
+			localpkg = pkg
+		}
+	}
 
 	names := make([]string, 0, len(p.pkgIndex[localpkg]))
 	for name := range p.pkgIndex[localpkg] {
@@ -330,6 +334,10 @@ func (r *importReader) value() (typ types.Type, val constant.Value) {
 		val = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
 
 	default:
+		if b.Kind() == types.Invalid {
+			val = constant.MakeUnknown()
+			return
+		}
 		errorf("unexpected type %v", typ) // panics
 		panic("unreachable")
 	}
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/isAlias18.go b/vendor/golang.org/x/tools/go/internal/gcimporter/isAlias18.go
deleted file mode 100644
index 225ffeed..00000000
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/isAlias18.go
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2017 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.
-
-// +build !go1.9
-
-package gcimporter
-
-import "go/types"
-
-func isAlias(obj *types.TypeName) bool {
-	return false // there are no type aliases before Go 1.9
-}
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/isAlias19.go b/vendor/golang.org/x/tools/go/internal/gcimporter/isAlias19.go
deleted file mode 100644
index c2025d84..00000000
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/isAlias19.go
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2017 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.
-
-// +build go1.9
-
-package gcimporter
-
-import "go/types"
-
-func isAlias(obj *types.TypeName) bool {
-	return obj.IsAlias()
-}
diff --git a/vendor/golang.org/x/tools/go/internal/packagesdriver/sizes.go b/vendor/golang.org/x/tools/go/internal/packagesdriver/sizes.go
new file mode 100644
index 00000000..fdc7da05
--- /dev/null
+++ b/vendor/golang.org/x/tools/go/internal/packagesdriver/sizes.go
@@ -0,0 +1,160 @@
+// 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 packagesdriver fetches type sizes for go/packages and go/analysis.
+package packagesdriver
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"go/types"
+	"log"
+	"os"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+var debug = false
+
+// GetSizes returns the sizes used by the underlying driver with the given parameters.
+func GetSizes(ctx context.Context, buildFlags, env []string, dir string, usesExportData bool) (types.Sizes, error) {
+	// TODO(matloob): Clean this up. This code is mostly a copy of packages.findExternalDriver.
+	const toolPrefix = "GOPACKAGESDRIVER="
+	tool := ""
+	for _, env := range env {
+		if val := strings.TrimPrefix(env, toolPrefix); val != env {
+			tool = val
+		}
+	}
+
+	if tool == "" {
+		var err error
+		tool, err = exec.LookPath("gopackagesdriver")
+		if err != nil {
+			// We did not find the driver, so use "go list".
+			tool = "off"
+		}
+	}
+
+	if tool == "off" {
+		return GetSizesGolist(ctx, buildFlags, env, dir, usesExportData)
+	}
+
+	req, err := json.Marshal(struct {
+		Command    string   `json:"command"`
+		Env        []string `json:"env"`
+		BuildFlags []string `json:"build_flags"`
+	}{
+		Command:    "sizes",
+		Env:        env,
+		BuildFlags: buildFlags,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to encode message to driver tool: %v", err)
+	}
+
+	buf := new(bytes.Buffer)
+	cmd := exec.CommandContext(ctx, tool)
+	cmd.Dir = dir
+	cmd.Env = env
+	cmd.Stdin = bytes.NewReader(req)
+	cmd.Stdout = buf
+	cmd.Stderr = new(bytes.Buffer)
+	if err := cmd.Run(); err != nil {
+		return nil, fmt.Errorf("%v: %v: %s", tool, err, cmd.Stderr)
+	}
+	var response struct {
+		// Sizes, if not nil, is the types.Sizes to use when type checking.
+		Sizes *types.StdSizes
+	}
+	if err := json.Unmarshal(buf.Bytes(), &response); err != nil {
+		return nil, err
+	}
+	return response.Sizes, nil
+}
+
+func GetSizesGolist(ctx context.Context, buildFlags, env []string, dir string, usesExportData bool) (types.Sizes, error) {
+	args := []string{"list", "-f", "{{context.GOARCH}} {{context.Compiler}}"}
+	args = append(args, buildFlags...)
+	args = append(args, "--", "unsafe")
+	stdout, err := InvokeGo(ctx, env, dir, usesExportData, args...)
+	if err != nil {
+		return nil, err
+	}
+	fields := strings.Fields(stdout.String())
+	if len(fields) < 2 {
+		return nil, fmt.Errorf("could not determine GOARCH and Go compiler")
+	}
+	goarch := fields[0]
+	compiler := fields[1]
+	return types.SizesFor(compiler, goarch), nil
+}
+
+// InvokeGo returns the stdout of a go command invocation.
+func InvokeGo(ctx context.Context, env []string, dir string, usesExportData bool, args ...string) (*bytes.Buffer, error) {
+	if debug {
+		defer func(start time.Time) { log.Printf("%s for %v", time.Since(start), cmdDebugStr(env, args...)) }(time.Now())
+	}
+	stdout := new(bytes.Buffer)
+	stderr := new(bytes.Buffer)
+	cmd := exec.CommandContext(ctx, "go", args...)
+	// On darwin the cwd gets resolved to the real path, which breaks anything that
+	// expects the working directory to keep the original path, including the
+	// go command when dealing with modules.
+	// The Go stdlib has a special feature where if the cwd and the PWD are the
+	// same node then it trusts the PWD, so by setting it in the env for the child
+	// process we fix up all the paths returned by the go command.
+	cmd.Env = append(append([]string{}, env...), "PWD="+dir)
+	cmd.Dir = dir
+	cmd.Stdout = stdout
+	cmd.Stderr = stderr
+	if err := cmd.Run(); err != nil {
+		exitErr, ok := err.(*exec.ExitError)
+		if !ok {
+			// Catastrophic error:
+			// - executable not found
+			// - context cancellation
+			return nil, fmt.Errorf("couldn't exec 'go %v': %s %T", args, err, err)
+		}
+
+		// Export mode entails a build.
+		// If that build fails, errors appear on stderr
+		// (despite the -e flag) and the Export field is blank.
+		// Do not fail in that case.
+		if !usesExportData {
+			return nil, fmt.Errorf("go %v: %s: %s", args, exitErr, stderr)
+		}
+	}
+
+	// As of writing, go list -export prints some non-fatal compilation
+	// errors to stderr, even with -e set. We would prefer that it put
+	// them in the Package.Error JSON (see https://golang.org/issue/26319).
+	// In the meantime, there's nowhere good to put them, but they can
+	// be useful for debugging. Print them if $GOPACKAGESPRINTGOLISTERRORS
+	// is set.
+	if len(stderr.Bytes()) != 0 && os.Getenv("GOPACKAGESPRINTGOLISTERRORS") != "" {
+		fmt.Fprintf(os.Stderr, "%s stderr: <<%s>>\n", cmdDebugStr(env, args...), stderr)
+	}
+
+	// debugging
+	if false {
+		fmt.Fprintf(os.Stderr, "%s stdout: <<%s>>\n", cmdDebugStr(env, args...), stdout)
+	}
+
+	return stdout, nil
+}
+
+func cmdDebugStr(envlist []string, args ...string) string {
+	env := make(map[string]string)
+	for _, kv := range envlist {
+		split := strings.Split(kv, "=")
+		k, v := split[0], split[1]
+		env[k] = v
+	}
+
+	return fmt.Sprintf("GOROOT=%v GOPATH=%v GO111MODULE=%v PWD=%v go %v", env["GOROOT"], env["GOPATH"], env["GO111MODULE"], env["PWD"], args)
+}