Add generated file

This PR adds generated files under pkg/client and vendor folder.

vendor/golang.org/x/tools/refactor/README

@@ -0,0 +1 @@
+golang.org/x/tools/refactor: libraries for refactoring tools.

vendor/golang.org/x/tools/refactor/eg/eg.go

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+// Copyright 2014 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 eg implements the example-based refactoring tool whose
+// command-line is defined in golang.org/x/tools/cmd/eg.
+package eg // import "golang.org/x/tools/refactor/eg"
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/format"
+	"go/printer"
+	"go/token"
+	"go/types"
+	"os"
+)
+
+const Help = `
+This tool implements example-based refactoring of expressions.
+
+The transformation is specified as a Go file defining two functions,
+'before' and 'after', of identical types.  Each function body consists
+of a single statement: either a return statement with a single
+(possibly multi-valued) expression, or an expression statement.  The
+'before' expression specifies a pattern and the 'after' expression its
+replacement.
+
+	package P
+ 	import ( "errors"; "fmt" )
+ 	func before(s string) error { return fmt.Errorf("%s", s) }
+ 	func after(s string)  error { return errors.New(s) }
+
+The expression statement form is useful when the expression has no
+result, for example:
+
+ 	func before(msg string) { log.Fatalf("%s", msg) }
+ 	func after(msg string)  { log.Fatal(msg) }
+
+The parameters of both functions are wildcards that may match any
+expression assignable to that type.  If the pattern contains multiple
+occurrences of the same parameter, each must match the same expression
+in the input for the pattern to match.  If the replacement contains
+multiple occurrences of the same parameter, the expression will be
+duplicated, possibly changing the side-effects.
+
+The tool analyses all Go code in the packages specified by the
+arguments, replacing all occurrences of the pattern with the
+substitution.
+
+So, the transform above would change this input:
+	err := fmt.Errorf("%s", "error: " + msg)
+to this output:
+	err := errors.New("error: " + msg)
+
+Identifiers, including qualified identifiers (p.X) are considered to
+match only if they denote the same object.  This allows correct
+matching even in the presence of dot imports, named imports and
+locally shadowed package names in the input program.
+
+Matching of type syntax is semantic, not syntactic: type syntax in the
+pattern matches type syntax in the input if the types are identical.
+Thus, func(x int) matches func(y int).
+
+This tool was inspired by other example-based refactoring tools,
+'gofmt -r' for Go and Refaster for Java.
+
+
+LIMITATIONS
+===========
+
+EXPRESSIVENESS
+
+Only refactorings that replace one expression with another, regardless
+of the expression's context, may be expressed.  Refactoring arbitrary
+statements (or sequences of statements) is a less well-defined problem
+and is less amenable to this approach.
+
+A pattern that contains a function literal (and hence statements)
+never matches.
+
+There is no way to generalize over related types, e.g. to express that
+a wildcard may have any integer type, for example.
+
+It is not possible to replace an expression by one of a different
+type, even in contexts where this is legal, such as x in fmt.Print(x).
+
+The struct literals T{x} and T{K: x} cannot both be matched by a single
+template.
+
+
+SAFETY
+
+Verifying that a transformation does not introduce type errors is very
+complex in the general case.  An innocuous-looking replacement of one
+constant by another (e.g. 1 to 2) may cause type errors relating to
+array types and indices, for example.  The tool performs only very
+superficial checks of type preservation.
+
+
+IMPORTS
+
+Although the matching algorithm is fully aware of scoping rules, the
+replacement algorithm is not, so the replacement code may contain
+incorrect identifier syntax for imported objects if there are dot
+imports, named imports or locally shadowed package names in the input
+program.
+
+Imports are added as needed, but they are not removed as needed.
+Run 'goimports' on the modified file for now.
+
+Dot imports are forbidden in the template.
+
+
+TIPS
+====
+
+Sometimes a little creativity is required to implement the desired
+migration.  This section lists a few tips and tricks.
+
+To remove the final parameter from a function, temporarily change the
+function signature so that the final parameter is variadic, as this
+allows legal calls both with and without the argument.  Then use eg to
+remove the final argument from all callers, and remove the variadic
+parameter by hand.  The reverse process can be used to add a final
+parameter.
+
+To add or remove parameters other than the final one, you must do it in
+stages: (1) declare a variant function f' with a different name and the
+desired parameters; (2) use eg to transform calls to f into calls to f',
+changing the arguments as needed; (3) change the declaration of f to
+match f'; (4) use eg to rename f' to f in all calls; (5) delete f'.
+`
+
+// TODO(adonovan): expand upon the above documentation as an HTML page.
+
+// A Transformer represents a single example-based transformation.
+type Transformer struct {
+	fset           *token.FileSet
+	verbose        bool
+	info           *types.Info // combined type info for template/input/output ASTs
+	seenInfos      map[*types.Info]bool
+	wildcards      map[*types.Var]bool                // set of parameters in func before()
+	env            map[string]ast.Expr                // maps parameter name to wildcard binding
+	importedObjs   map[types.Object]*ast.SelectorExpr // objects imported by after().
+	before, after  ast.Expr
+	afterStmts     []ast.Stmt
+	allowWildcards bool
+
+	// Working state of Transform():
+	nsubsts    int            // number of substitutions made
+	currentPkg *types.Package // package of current call
+}
+
+// NewTransformer returns a transformer based on the specified template,
+// a single-file package containing "before" and "after" functions as
+// described in the package documentation.
+// tmplInfo is the type information for tmplFile.
+//
+func NewTransformer(fset *token.FileSet, tmplPkg *types.Package, tmplFile *ast.File, tmplInfo *types.Info, verbose bool) (*Transformer, error) {
+	// Check the template.
+	beforeSig := funcSig(tmplPkg, "before")
+	if beforeSig == nil {
+		return nil, fmt.Errorf("no 'before' func found in template")
+	}
+	afterSig := funcSig(tmplPkg, "after")
+	if afterSig == nil {
+		return nil, fmt.Errorf("no 'after' func found in template")
+	}
+
+	// TODO(adonovan): should we also check the names of the params match?
+	if !types.Identical(afterSig, beforeSig) {
+		return nil, fmt.Errorf("before %s and after %s functions have different signatures",
+			beforeSig, afterSig)
+	}
+
+	for _, imp := range tmplFile.Imports {
+		if imp.Name != nil && imp.Name.Name == "." {
+			// Dot imports are currently forbidden.  We
+			// make the simplifying assumption that all
+			// imports are regular, without local renames.
+			return nil, fmt.Errorf("dot-import (of %s) in template", imp.Path.Value)
+		}
+	}
+	var beforeDecl, afterDecl *ast.FuncDecl
+	for _, decl := range tmplFile.Decls {
+		if decl, ok := decl.(*ast.FuncDecl); ok {
+			switch decl.Name.Name {
+			case "before":
+				beforeDecl = decl
+			case "after":
+				afterDecl = decl
+			}
+		}
+	}
+
+	before, err := soleExpr(beforeDecl)
+	if err != nil {
+		return nil, fmt.Errorf("before: %s", err)
+	}
+	afterStmts, after, err := stmtAndExpr(afterDecl)
+	if err != nil {
+		return nil, fmt.Errorf("after: %s", err)
+	}
+
+	wildcards := make(map[*types.Var]bool)
+	for i := 0; i < beforeSig.Params().Len(); i++ {
+		wildcards[beforeSig.Params().At(i)] = true
+	}
+
+	// checkExprTypes returns an error if Tb (type of before()) is not
+	// safe to replace with Ta (type of after()).
+	//
+	// Only superficial checks are performed, and they may result in both
+	// false positives and negatives.
+	//
+	// Ideally, we would only require that the replacement be assignable
+	// to the context of a specific pattern occurrence, but the type
+	// checker doesn't record that information and it's complex to deduce.
+	// A Go type cannot capture all the constraints of a given expression
+	// context, which may include the size, constness, signedness,
+	// namedness or constructor of its type, and even the specific value
+	// of the replacement.  (Consider the rule that array literal keys
+	// must be unique.)  So we cannot hope to prove the safety of a
+	// transformation in general.
+	Tb := tmplInfo.TypeOf(before)
+	Ta := tmplInfo.TypeOf(after)
+	if types.AssignableTo(Tb, Ta) {
+		// safe: replacement is assignable to pattern.
+	} else if tuple, ok := Tb.(*types.Tuple); ok && tuple.Len() == 0 {
+		// safe: pattern has void type (must appear in an ExprStmt).
+	} else {
+		return nil, fmt.Errorf("%s is not a safe replacement for %s", Ta, Tb)
+	}
+
+	tr := &Transformer{
+		fset:           fset,
+		verbose:        verbose,
+		wildcards:      wildcards,
+		allowWildcards: true,
+		seenInfos:      make(map[*types.Info]bool),
+		importedObjs:   make(map[types.Object]*ast.SelectorExpr),
+		before:         before,
+		after:          after,
+		afterStmts:     afterStmts,
+	}
+
+	// Combine type info from the template and input packages, and
+	// type info for the synthesized ASTs too.  This saves us
+	// having to book-keep where each ast.Node originated as we
+	// construct the resulting hybrid AST.
+	tr.info = &types.Info{
+		Types:      make(map[ast.Expr]types.TypeAndValue),
+		Defs:       make(map[*ast.Ident]types.Object),
+		Uses:       make(map[*ast.Ident]types.Object),
+		Selections: make(map[*ast.SelectorExpr]*types.Selection),
+	}
+	mergeTypeInfo(tr.info, tmplInfo)
+
+	// Compute set of imported objects required by after().
+	// TODO(adonovan): reject dot-imports in pattern
+	ast.Inspect(after, func(n ast.Node) bool {
+		if n, ok := n.(*ast.SelectorExpr); ok {
+			if _, ok := tr.info.Selections[n]; !ok {
+				// qualified ident
+				obj := tr.info.Uses[n.Sel]
+				tr.importedObjs[obj] = n
+				return false // prune
+			}
+		}
+		return true // recur
+	})
+
+	return tr, nil
+}
+
+// WriteAST is a convenience function that writes AST f to the specified file.
+func WriteAST(fset *token.FileSet, filename string, f *ast.File) (err error) {
+	fh, err := os.Create(filename)
+	if err != nil {
+		return err
+	}
+
+	defer func() {
+		if err2 := fh.Close(); err != nil {
+			err = err2 // prefer earlier error
+		}
+	}()
+	return format.Node(fh, fset, f)
+}
+
+// -- utilities --------------------------------------------------------
+
+// funcSig returns the signature of the specified package-level function.
+func funcSig(pkg *types.Package, name string) *types.Signature {
+	if f, ok := pkg.Scope().Lookup(name).(*types.Func); ok {
+		return f.Type().(*types.Signature)
+	}
+	return nil
+}
+
+// soleExpr returns the sole expression in the before/after template function.
+func soleExpr(fn *ast.FuncDecl) (ast.Expr, error) {
+	if fn.Body == nil {
+		return nil, fmt.Errorf("no body")
+	}
+	if len(fn.Body.List) != 1 {
+		return nil, fmt.Errorf("must contain a single statement")
+	}
+	switch stmt := fn.Body.List[0].(type) {
+	case *ast.ReturnStmt:
+		if len(stmt.Results) != 1 {
+			return nil, fmt.Errorf("return statement must have a single operand")
+		}
+		return stmt.Results[0], nil
+
+	case *ast.ExprStmt:
+		return stmt.X, nil
+	}
+
+	return nil, fmt.Errorf("must contain a single return or expression statement")
+}
+
+// stmtAndExpr returns the expression in the last return statement as well as the preceeding lines.
+func stmtAndExpr(fn *ast.FuncDecl) ([]ast.Stmt, ast.Expr, error) {
+	if fn.Body == nil {
+		return nil, nil, fmt.Errorf("no body")
+	}
+
+	n := len(fn.Body.List)
+	if n == 0 {
+		return nil, nil, fmt.Errorf("must contain at least one statement")
+	}
+
+	stmts, last := fn.Body.List[:n-1], fn.Body.List[n-1]
+
+	switch last := last.(type) {
+	case *ast.ReturnStmt:
+		if len(last.Results) != 1 {
+			return nil, nil, fmt.Errorf("return statement must have a single operand")
+		}
+		return stmts, last.Results[0], nil
+
+	case *ast.ExprStmt:
+		return stmts, last.X, nil
+	}
+
+	return nil, nil, fmt.Errorf("must end with a single return or expression statement")
+}
+
+// mergeTypeInfo adds type info from src to dst.
+func mergeTypeInfo(dst, src *types.Info) {
+	for k, v := range src.Types {
+		dst.Types[k] = v
+	}
+	for k, v := range src.Defs {
+		dst.Defs[k] = v
+	}
+	for k, v := range src.Uses {
+		dst.Uses[k] = v
+	}
+	for k, v := range src.Selections {
+		dst.Selections[k] = v
+	}
+}
+
+// (debugging only)
+func astString(fset *token.FileSet, n ast.Node) string {
+	var buf bytes.Buffer
+	printer.Fprint(&buf, fset, n)
+	return buf.String()
+}

vendor/golang.org/x/tools/refactor/eg/eg_test.go

@@ -0,0 +1,166 @@
+// Copyright 2014 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.
+
+// No testdata on Android.
+
+// +build !android
+
+package eg_test
+
+import (
+	"bytes"
+	"flag"
+	exact "go/constant"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+
+	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/refactor/eg"
+)
+
+// TODO(adonovan): more tests:
+// - of command-line tool
+// - of all parts of syntax
+// - of applying a template to a package it imports:
+//   the replacement syntax should use unqualified names for its objects.
+
+var (
+	updateFlag  = flag.Bool("update", false, "update the golden files")
+	verboseFlag = flag.Bool("verbose", false, "show matcher information")
+)
+
+func Test(t *testing.T) {
+	switch runtime.GOOS {
+	case "windows":
+		t.Skipf("skipping test on %q (no /usr/bin/diff)", runtime.GOOS)
+	}
+
+	conf := loader.Config{
+		Fset:       token.NewFileSet(),
+		ParserMode: parser.ParseComments,
+	}
+
+	// Each entry is a single-file package.
+	// (Multi-file packages aren't interesting for this test.)
+	// Order matters: each non-template package is processed using
+	// the preceding template package.
+	for _, filename := range []string{
+		"testdata/A.template",
+		"testdata/A1.go",
+		"testdata/A2.go",
+
+		"testdata/B.template",
+		"testdata/B1.go",
+
+		"testdata/C.template",
+		"testdata/C1.go",
+
+		"testdata/D.template",
+		"testdata/D1.go",
+
+		"testdata/E.template",
+		"testdata/E1.go",
+
+		"testdata/F.template",
+		"testdata/F1.go",
+
+		"testdata/G.template",
+		"testdata/G1.go",
+
+		"testdata/H.template",
+		"testdata/H1.go",
+
+		"testdata/I.template",
+		"testdata/I1.go",
+
+		"testdata/J.template",
+		"testdata/J1.go",
+
+		"testdata/bad_type.template",
+		"testdata/no_before.template",
+		"testdata/no_after_return.template",
+		"testdata/type_mismatch.template",
+		"testdata/expr_type_mismatch.template",
+	} {
+		pkgname := strings.TrimSuffix(filepath.Base(filename), ".go")
+		conf.CreateFromFilenames(pkgname, filename)
+	}
+	iprog, err := conf.Load()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var xform *eg.Transformer
+	for _, info := range iprog.Created {
+		file := info.Files[0]
+		filename := iprog.Fset.File(file.Pos()).Name() // foo.go
+
+		if strings.HasSuffix(filename, "template") {
+			// a new template
+			shouldFail, _ := info.Pkg.Scope().Lookup("shouldFail").(*types.Const)
+			xform, err = eg.NewTransformer(iprog.Fset, info.Pkg, file, &info.Info, *verboseFlag)
+			if err != nil {
+				if shouldFail == nil {
+					t.Errorf("NewTransformer(%s): %s", filename, err)
+				} else if want := exact.StringVal(shouldFail.Val()); !strings.Contains(err.Error(), want) {
+					t.Errorf("NewTransformer(%s): got error %q, want error %q", filename, err, want)
+				}
+			} else if shouldFail != nil {
+				t.Errorf("NewTransformer(%s) succeeded unexpectedly; want error %q",
+					filename, shouldFail.Val())
+			}
+			continue
+		}
+
+		if xform == nil {
+			t.Errorf("%s: no previous template", filename)
+			continue
+		}
+
+		// apply previous template to this package
+		n := xform.Transform(&info.Info, info.Pkg, file)
+		if n == 0 {
+			t.Errorf("%s: no matches", filename)
+			continue
+		}
+
+		got := filename + "t"       // foo.got
+		golden := filename + "lden" // foo.golden
+
+		// Write actual output to foo.got.
+		if err := eg.WriteAST(iprog.Fset, got, file); err != nil {
+			t.Error(err)
+		}
+		defer os.Remove(got)
+
+		// Compare foo.got with foo.golden.
+		var cmd *exec.Cmd
+		switch runtime.GOOS {
+		case "plan9":
+			cmd = exec.Command("/bin/diff", "-c", golden, got)
+		default:
+			cmd = exec.Command("/usr/bin/diff", "-u", golden, got)
+		}
+		buf := new(bytes.Buffer)
+		cmd.Stdout = buf
+		cmd.Stderr = os.Stderr
+		if err := cmd.Run(); err != nil {
+			t.Errorf("eg tests for %s failed: %s.\n%s\n", filename, err, buf)
+
+			if *updateFlag {
+				t.Logf("Updating %s...", golden)
+				if err := exec.Command("/bin/cp", got, golden).Run(); err != nil {
+					t.Errorf("Update failed: %s", err)
+				}
+			}
+		}
+	}
+}

vendor/golang.org/x/tools/refactor/eg/match.go

@@ -0,0 +1,249 @@
+// Copyright 2014 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 eg
+
+import (
+	"fmt"
+	"go/ast"
+	exact "go/constant"
+	"go/token"
+	"go/types"
+	"log"
+	"os"
+	"reflect"
+
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+// matchExpr reports whether pattern x matches y.
+//
+// If tr.allowWildcards, Idents in x that refer to parameters are
+// treated as wildcards, and match any y that is assignable to the
+// parameter type; matchExpr records this correspondence in tr.env.
+// Otherwise, matchExpr simply reports whether the two trees are
+// equivalent.
+//
+// A wildcard appearing more than once in the pattern must
+// consistently match the same tree.
+//
+func (tr *Transformer) matchExpr(x, y ast.Expr) bool {
+	if x == nil && y == nil {
+		return true
+	}
+	if x == nil || y == nil {
+		return false
+	}
+	x = unparen(x)
+	y = unparen(y)
+
+	// Is x a wildcard?  (a reference to a 'before' parameter)
+	if xobj, ok := tr.wildcardObj(x); ok {
+		return tr.matchWildcard(xobj, y)
+	}
+
+	// Object identifiers (including pkg-qualified ones)
+	// are handled semantically, not syntactically.
+	xobj := isRef(x, tr.info)
+	yobj := isRef(y, tr.info)
+	if xobj != nil {
+		return xobj == yobj
+	}
+	if yobj != nil {
+		return false
+	}
+
+	// TODO(adonovan): audit: we cannot assume these ast.Exprs
+	// contain non-nil pointers.  e.g. ImportSpec.Name may be a
+	// nil *ast.Ident.
+
+	if reflect.TypeOf(x) != reflect.TypeOf(y) {
+		return false
+	}
+	switch x := x.(type) {
+	case *ast.Ident:
+		log.Fatalf("unexpected Ident: %s", astString(tr.fset, x))
+
+	case *ast.BasicLit:
+		y := y.(*ast.BasicLit)
+		xval := exact.MakeFromLiteral(x.Value, x.Kind, 0)
+		yval := exact.MakeFromLiteral(y.Value, y.Kind, 0)
+		return exact.Compare(xval, token.EQL, yval)
+
+	case *ast.FuncLit:
+		// func literals (and thus statement syntax) never match.
+		return false
+
+	case *ast.CompositeLit:
+		y := y.(*ast.CompositeLit)
+		return (x.Type == nil) == (y.Type == nil) &&
+			(x.Type == nil || tr.matchType(x.Type, y.Type)) &&
+			tr.matchExprs(x.Elts, y.Elts)
+
+	case *ast.SelectorExpr:
+		y := y.(*ast.SelectorExpr)
+		return tr.matchSelectorExpr(x, y) &&
+			tr.info.Selections[x].Obj() == tr.info.Selections[y].Obj()
+
+	case *ast.IndexExpr:
+		y := y.(*ast.IndexExpr)
+		return tr.matchExpr(x.X, y.X) &&
+			tr.matchExpr(x.Index, y.Index)
+
+	case *ast.SliceExpr:
+		y := y.(*ast.SliceExpr)
+		return tr.matchExpr(x.X, y.X) &&
+			tr.matchExpr(x.Low, y.Low) &&
+			tr.matchExpr(x.High, y.High) &&
+			tr.matchExpr(x.Max, y.Max) &&
+			x.Slice3 == y.Slice3
+
+	case *ast.TypeAssertExpr:
+		y := y.(*ast.TypeAssertExpr)
+		return tr.matchExpr(x.X, y.X) &&
+			tr.matchType(x.Type, y.Type)
+
+	case *ast.CallExpr:
+		y := y.(*ast.CallExpr)
+		match := tr.matchExpr // function call
+		if tr.info.Types[x.Fun].IsType() {
+			match = tr.matchType // type conversion
+		}
+		return x.Ellipsis.IsValid() == y.Ellipsis.IsValid() &&
+			match(x.Fun, y.Fun) &&
+			tr.matchExprs(x.Args, y.Args)
+
+	case *ast.StarExpr:
+		y := y.(*ast.StarExpr)
+		return tr.matchExpr(x.X, y.X)
+
+	case *ast.UnaryExpr:
+		y := y.(*ast.UnaryExpr)
+		return x.Op == y.Op &&
+			tr.matchExpr(x.X, y.X)
+
+	case *ast.BinaryExpr:
+		y := y.(*ast.BinaryExpr)
+		return x.Op == y.Op &&
+			tr.matchExpr(x.X, y.X) &&
+			tr.matchExpr(x.Y, y.Y)
+
+	case *ast.KeyValueExpr:
+		y := y.(*ast.KeyValueExpr)
+		return tr.matchExpr(x.Key, y.Key) &&
+			tr.matchExpr(x.Value, y.Value)
+	}
+
+	panic(fmt.Sprintf("unhandled AST node type: %T", x))
+}
+
+func (tr *Transformer) matchExprs(xx, yy []ast.Expr) bool {
+	if len(xx) != len(yy) {
+		return false
+	}
+	for i := range xx {
+		if !tr.matchExpr(xx[i], yy[i]) {
+			return false
+		}
+	}
+	return true
+}
+
+// matchType reports whether the two type ASTs denote identical types.
+func (tr *Transformer) matchType(x, y ast.Expr) bool {
+	tx := tr.info.Types[x].Type
+	ty := tr.info.Types[y].Type
+	return types.Identical(tx, ty)
+}
+
+func (tr *Transformer) wildcardObj(x ast.Expr) (*types.Var, bool) {
+	if x, ok := x.(*ast.Ident); ok && x != nil && tr.allowWildcards {
+		if xobj, ok := tr.info.Uses[x].(*types.Var); ok && tr.wildcards[xobj] {
+			return xobj, true
+		}
+	}
+	return nil, false
+}
+
+func (tr *Transformer) matchSelectorExpr(x, y *ast.SelectorExpr) bool {
+	if xobj, ok := tr.wildcardObj(x.X); ok {
+		field := x.Sel.Name
+		yt := tr.info.TypeOf(y.X)
+		o, _, _ := types.LookupFieldOrMethod(yt, true, tr.currentPkg, field)
+		if o != nil {
+			tr.env[xobj.Name()] = y.X // record binding
+			return true
+		}
+	}
+	return tr.matchExpr(x.X, y.X)
+}
+
+func (tr *Transformer) matchWildcard(xobj *types.Var, y ast.Expr) bool {
+	name := xobj.Name()
+
+	if tr.verbose {
+		fmt.Fprintf(os.Stderr, "%s: wildcard %s -> %s?: ",
+			tr.fset.Position(y.Pos()), name, astString(tr.fset, y))
+	}
+
+	// Check that y is assignable to the declared type of the param.
+	yt := tr.info.TypeOf(y)
+	if yt == nil {
+		// y has no type.
+		// Perhaps it is an *ast.Ellipsis in [...]T{}, or
+		// an *ast.KeyValueExpr in T{k: v}.
+		// Clearly these pseudo-expressions cannot match a
+		// wildcard, but it would nice if we had a way to ignore
+		// the difference between T{v} and T{k:v} for structs.
+		return false
+	}
+	if !types.AssignableTo(yt, xobj.Type()) {
+		if tr.verbose {
+			fmt.Fprintf(os.Stderr, "%s not assignable to %s\n", yt, xobj.Type())
+		}
+		return false
+	}
+
+	// A wildcard matches any expression.
+	// If it appears multiple times in the pattern, it must match
+	// the same expression each time.
+	if old, ok := tr.env[name]; ok {
+		// found existing binding
+		tr.allowWildcards = false
+		r := tr.matchExpr(old, y)
+		if tr.verbose {
+			fmt.Fprintf(os.Stderr, "%t secondary match, primary was %s\n",
+				r, astString(tr.fset, old))
+		}
+		tr.allowWildcards = true
+		return r
+	}
+
+	if tr.verbose {
+		fmt.Fprintf(os.Stderr, "primary match\n")
+	}
+
+	tr.env[name] = y // record binding
+	return true
+}
+
+// -- utilities --------------------------------------------------------
+
+func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }
+
+// isRef returns the object referred to by this (possibly qualified)
+// identifier, or nil if the node is not a referring identifier.
+func isRef(n ast.Node, info *types.Info) types.Object {
+	switch n := n.(type) {
+	case *ast.Ident:
+		return info.Uses[n]
+
+	case *ast.SelectorExpr:
+		if _, ok := info.Selections[n]; !ok {
+			// qualified ident
+			return info.Uses[n.Sel]
+		}
+	}
+	return nil
+}

vendor/golang.org/x/tools/refactor/eg/rewrite.go

@@ -0,0 +1,401 @@
+// Copyright 2014 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 eg
+
+// This file defines the AST rewriting pass.
+// Most of it was plundered directly from
+// $GOROOT/src/cmd/gofmt/rewrite.go (after convergent evolution).
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"os"
+	"reflect"
+	"sort"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+// transformItem takes a reflect.Value representing a variable of type ast.Node
+// transforms its child elements recursively with apply, and then transforms the
+// actual element if it contains an expression.
+func (tr *Transformer) transformItem(rv reflect.Value) (reflect.Value, bool, map[string]ast.Expr) {
+	// don't bother if val is invalid to start with
+	if !rv.IsValid() {
+		return reflect.Value{}, false, nil
+	}
+
+	rv, changed, newEnv := tr.apply(tr.transformItem, rv)
+
+	e := rvToExpr(rv)
+	if e == nil {
+		return rv, changed, newEnv
+	}
+
+	savedEnv := tr.env
+	tr.env = make(map[string]ast.Expr) // inefficient!  Use a slice of k/v pairs
+
+	if tr.matchExpr(tr.before, e) {
+		if tr.verbose {
+			fmt.Fprintf(os.Stderr, "%s matches %s",
+				astString(tr.fset, tr.before), astString(tr.fset, e))
+			if len(tr.env) > 0 {
+				fmt.Fprintf(os.Stderr, " with:")
+				for name, ast := range tr.env {
+					fmt.Fprintf(os.Stderr, " %s->%s",
+						name, astString(tr.fset, ast))
+				}
+			}
+			fmt.Fprintf(os.Stderr, "\n")
+		}
+		tr.nsubsts++
+
+		// Clone the replacement tree, performing parameter substitution.
+		// We update all positions to n.Pos() to aid comment placement.
+		rv = tr.subst(tr.env, reflect.ValueOf(tr.after),
+			reflect.ValueOf(e.Pos()))
+		changed = true
+		newEnv = tr.env
+	}
+	tr.env = savedEnv
+
+	return rv, changed, newEnv
+}
+
+// Transform applies the transformation to the specified parsed file,
+// whose type information is supplied in info, and returns the number
+// of replacements that were made.
+//
+// It mutates the AST in place (the identity of the root node is
+// unchanged), and may add nodes for which no type information is
+// available in info.
+//
+// Derived from rewriteFile in $GOROOT/src/cmd/gofmt/rewrite.go.
+//
+func (tr *Transformer) Transform(info *types.Info, pkg *types.Package, file *ast.File) int {
+	if !tr.seenInfos[info] {
+		tr.seenInfos[info] = true
+		mergeTypeInfo(tr.info, info)
+	}
+	tr.currentPkg = pkg
+	tr.nsubsts = 0
+
+	if tr.verbose {
+		fmt.Fprintf(os.Stderr, "before: %s\n", astString(tr.fset, tr.before))
+		fmt.Fprintf(os.Stderr, "after: %s\n", astString(tr.fset, tr.after))
+		fmt.Fprintf(os.Stderr, "afterStmts: %s\n", tr.afterStmts)
+	}
+
+	o, changed, _ := tr.apply(tr.transformItem, reflect.ValueOf(file))
+	if changed {
+		panic("BUG")
+	}
+	file2 := o.Interface().(*ast.File)
+
+	// By construction, the root node is unchanged.
+	if file != file2 {
+		panic("BUG")
+	}
+
+	// Add any necessary imports.
+	// TODO(adonovan): remove no-longer needed imports too.
+	if tr.nsubsts > 0 {
+		pkgs := make(map[string]*types.Package)
+		for obj := range tr.importedObjs {
+			pkgs[obj.Pkg().Path()] = obj.Pkg()
+		}
+
+		for _, imp := range file.Imports {
+			path, _ := strconv.Unquote(imp.Path.Value)
+			delete(pkgs, path)
+		}
+		delete(pkgs, pkg.Path()) // don't import self
+
+		// NB: AddImport may completely replace the AST!
+		// It thus renders info and tr.info no longer relevant to file.
+		var paths []string
+		for path := range pkgs {
+			paths = append(paths, path)
+		}
+		sort.Strings(paths)
+		for _, path := range paths {
+			astutil.AddImport(tr.fset, file, path)
+		}
+	}
+
+	tr.currentPkg = nil
+
+	return tr.nsubsts
+}
+
+// setValue is a wrapper for x.SetValue(y); it protects
+// the caller from panics if x cannot be changed to y.
+func setValue(x, y reflect.Value) {
+	// don't bother if y is invalid to start with
+	if !y.IsValid() {
+		return
+	}
+	defer func() {
+		if x := recover(); x != nil {
+			if s, ok := x.(string); ok &&
+				(strings.Contains(s, "type mismatch") || strings.Contains(s, "not assignable")) {
+				// x cannot be set to y - ignore this rewrite
+				return
+			}
+			panic(x)
+		}
+	}()
+	x.Set(y)
+}
+
+// Values/types for special cases.
+var (
+	objectPtrNil = reflect.ValueOf((*ast.Object)(nil))
+	scopePtrNil  = reflect.ValueOf((*ast.Scope)(nil))
+
+	identType        = reflect.TypeOf((*ast.Ident)(nil))
+	selectorExprType = reflect.TypeOf((*ast.SelectorExpr)(nil))
+	objectPtrType    = reflect.TypeOf((*ast.Object)(nil))
+	statementType    = reflect.TypeOf((*ast.Stmt)(nil)).Elem()
+	positionType     = reflect.TypeOf(token.NoPos)
+	scopePtrType     = reflect.TypeOf((*ast.Scope)(nil))
+)
+
+// apply replaces each AST field x in val with f(x), returning val.
+// To avoid extra conversions, f operates on the reflect.Value form.
+// f takes a reflect.Value representing the variable to modify of type ast.Node.
+// It returns a reflect.Value containing the transformed value of type ast.Node,
+// whether any change was made, and a map of identifiers to ast.Expr (so we can
+// do contextually correct substitutions in the parent statements).
+func (tr *Transformer) apply(f func(reflect.Value) (reflect.Value, bool, map[string]ast.Expr), val reflect.Value) (reflect.Value, bool, map[string]ast.Expr) {
+	if !val.IsValid() {
+		return reflect.Value{}, false, nil
+	}
+
+	// *ast.Objects introduce cycles and are likely incorrect after
+	// rewrite; don't follow them but replace with nil instead
+	if val.Type() == objectPtrType {
+		return objectPtrNil, false, nil
+	}
+
+	// similarly for scopes: they are likely incorrect after a rewrite;
+	// replace them with nil
+	if val.Type() == scopePtrType {
+		return scopePtrNil, false, nil
+	}
+
+	switch v := reflect.Indirect(val); v.Kind() {
+	case reflect.Slice:
+		// no possible rewriting of statements.
+		if v.Type().Elem() != statementType {
+			changed := false
+			var envp map[string]ast.Expr
+			for i := 0; i < v.Len(); i++ {
+				e := v.Index(i)
+				o, localchanged, env := f(e)
+				if localchanged {
+					changed = true
+					// we clobber envp here,
+					// which means if we have two sucessive
+					// replacements inside the same statement
+					// we will only generate the setup for one of them.
+					envp = env
+				}
+				setValue(e, o)
+			}
+			return val, changed, envp
+		}
+
+		// statements are rewritten.
+		var out []ast.Stmt
+		for i := 0; i < v.Len(); i++ {
+			e := v.Index(i)
+			o, changed, env := f(e)
+			if changed {
+				for _, s := range tr.afterStmts {
+					t := tr.subst(env, reflect.ValueOf(s), reflect.Value{}).Interface()
+					out = append(out, t.(ast.Stmt))
+				}
+			}
+			setValue(e, o)
+			out = append(out, e.Interface().(ast.Stmt))
+		}
+		return reflect.ValueOf(out), false, nil
+	case reflect.Struct:
+		changed := false
+		var envp map[string]ast.Expr
+		for i := 0; i < v.NumField(); i++ {
+			e := v.Field(i)
+			o, localchanged, env := f(e)
+			if localchanged {
+				changed = true
+				envp = env
+			}
+			setValue(e, o)
+		}
+		return val, changed, envp
+	case reflect.Interface:
+		e := v.Elem()
+		o, changed, env := f(e)
+		setValue(v, o)
+		return val, changed, env
+	}
+	return val, false, nil
+}
+
+// subst returns a copy of (replacement) pattern with values from env
+// substituted in place of wildcards and pos used as the position of
+// tokens from the pattern.  if env == nil, subst returns a copy of
+// pattern and doesn't change the line number information.
+func (tr *Transformer) subst(env map[string]ast.Expr, pattern, pos reflect.Value) reflect.Value {
+	if !pattern.IsValid() {
+		return reflect.Value{}
+	}
+
+	// *ast.Objects introduce cycles and are likely incorrect after
+	// rewrite; don't follow them but replace with nil instead
+	if pattern.Type() == objectPtrType {
+		return objectPtrNil
+	}
+
+	// similarly for scopes: they are likely incorrect after a rewrite;
+	// replace them with nil
+	if pattern.Type() == scopePtrType {
+		return scopePtrNil
+	}
+
+	// Wildcard gets replaced with map value.
+	if env != nil && pattern.Type() == identType {
+		id := pattern.Interface().(*ast.Ident)
+		if old, ok := env[id.Name]; ok {
+			return tr.subst(nil, reflect.ValueOf(old), reflect.Value{})
+		}
+	}
+
+	// Emit qualified identifiers in the pattern by appropriate
+	// (possibly qualified) identifier in the input.
+	//
+	// The template cannot contain dot imports, so all identifiers
+	// for imported objects are explicitly qualified.
+	//
+	// We assume (unsoundly) that there are no dot or named
+	// imports in the input code, nor are any imported package
+	// names shadowed, so the usual normal qualified identifier
+	// syntax may be used.
+	// TODO(adonovan): fix: avoid this assumption.
+	//
+	// A refactoring may be applied to a package referenced by the
+	// template.  Objects belonging to the current package are
+	// denoted by unqualified identifiers.
+	//
+	if tr.importedObjs != nil && pattern.Type() == selectorExprType {
+		obj := isRef(pattern.Interface().(*ast.SelectorExpr), tr.info)
+		if obj != nil {
+			if sel, ok := tr.importedObjs[obj]; ok {
+				var id ast.Expr
+				if obj.Pkg() == tr.currentPkg {
+					id = sel.Sel // unqualified
+				} else {
+					id = sel // pkg-qualified
+				}
+
+				// Return a clone of id.
+				saved := tr.importedObjs
+				tr.importedObjs = nil // break cycle
+				r := tr.subst(nil, reflect.ValueOf(id), pos)
+				tr.importedObjs = saved
+				return r
+			}
+		}
+	}
+
+	if pos.IsValid() && pattern.Type() == positionType {
+		// use new position only if old position was valid in the first place
+		if old := pattern.Interface().(token.Pos); !old.IsValid() {
+			return pattern
+		}
+		return pos
+	}
+
+	// Otherwise copy.
+	switch p := pattern; p.Kind() {
+	case reflect.Slice:
+		v := reflect.MakeSlice(p.Type(), p.Len(), p.Len())
+		for i := 0; i < p.Len(); i++ {
+			v.Index(i).Set(tr.subst(env, p.Index(i), pos))
+		}
+		return v
+
+	case reflect.Struct:
+		v := reflect.New(p.Type()).Elem()
+		for i := 0; i < p.NumField(); i++ {
+			v.Field(i).Set(tr.subst(env, p.Field(i), pos))
+		}
+		return v
+
+	case reflect.Ptr:
+		v := reflect.New(p.Type()).Elem()
+		if elem := p.Elem(); elem.IsValid() {
+			v.Set(tr.subst(env, elem, pos).Addr())
+		}
+
+		// Duplicate type information for duplicated ast.Expr.
+		// All ast.Node implementations are *structs,
+		// so this case catches them all.
+		if e := rvToExpr(v); e != nil {
+			updateTypeInfo(tr.info, e, p.Interface().(ast.Expr))
+		}
+		return v
+
+	case reflect.Interface:
+		v := reflect.New(p.Type()).Elem()
+		if elem := p.Elem(); elem.IsValid() {
+			v.Set(tr.subst(env, elem, pos))
+		}
+		return v
+	}
+
+	return pattern
+}
+
+// -- utilities -------------------------------------------------------
+
+func rvToExpr(rv reflect.Value) ast.Expr {
+	if rv.CanInterface() {
+		if e, ok := rv.Interface().(ast.Expr); ok {
+			return e
+		}
+	}
+	return nil
+}
+
+// updateTypeInfo duplicates type information for the existing AST old
+// so that it also applies to duplicated AST new.
+func updateTypeInfo(info *types.Info, new, old ast.Expr) {
+	switch new := new.(type) {
+	case *ast.Ident:
+		orig := old.(*ast.Ident)
+		if obj, ok := info.Defs[orig]; ok {
+			info.Defs[new] = obj
+		}
+		if obj, ok := info.Uses[orig]; ok {
+			info.Uses[new] = obj
+		}
+
+	case *ast.SelectorExpr:
+		orig := old.(*ast.SelectorExpr)
+		if sel, ok := info.Selections[orig]; ok {
+			info.Selections[new] = sel
+		}
+	}
+
+	if tv, ok := info.Types[old]; ok {
+		info.Types[new] = tv
+	}
+}

vendor/golang.org/x/tools/refactor/eg/testdata/A.template

@@ -0,0 +1,13 @@
+// +build ignore
+
+package template
+
+// Basic test of type-aware expression refactoring.
+
+import (
+	"errors"
+	"fmt"
+)
+
+func before(s string) error { return fmt.Errorf("%s", s) }
+func after(s string) error  { return errors.New(s) }

vendor/golang.org/x/tools/refactor/eg/testdata/A1.go

@@ -0,0 +1,51 @@
+// +build ignore
+
+package A1
+
+import (
+	. "fmt"
+	myfmt "fmt"
+	"os"
+	"strings"
+)
+
+func example(n int) {
+	x := "foo" + strings.Repeat("\t", n)
+	// Match, despite named import.
+	myfmt.Errorf("%s", x)
+
+	// Match, despite dot import.
+	Errorf("%s", x)
+
+	// Match: multiple matches in same function are possible.
+	myfmt.Errorf("%s", x)
+
+	// No match: wildcarded operand has the wrong type.
+	myfmt.Errorf("%s", 3)
+
+	// No match: function operand doesn't match.
+	myfmt.Printf("%s", x)
+
+	// No match again, dot import.
+	Printf("%s", x)
+
+	// Match.
+	myfmt.Fprint(os.Stderr, myfmt.Errorf("%s", x+"foo"))
+
+	// No match: though this literally matches the template,
+	// fmt doesn't resolve to a package here.
+	var fmt struct{ Errorf func(string, string) }
+	fmt.Errorf("%s", x)
+
+	// Recursive matching:
+
+	// Match: both matches are well-typed, so both succeed.
+	myfmt.Errorf("%s", myfmt.Errorf("%s", x+"foo").Error())
+
+	// Outer match succeeds, inner doesn't: 3 has wrong type.
+	myfmt.Errorf("%s", myfmt.Errorf("%s", 3).Error())
+
+	// Inner match succeeds, outer doesn't: the inner replacement
+	// has the wrong type (error not string).
+	myfmt.Errorf("%s", myfmt.Errorf("%s", x+"foo"))
+}

vendor/golang.org/x/tools/refactor/eg/testdata/A1.golden

@@ -0,0 +1,52 @@
+// +build ignore
+
+package A1
+
+import (
+	"errors"
+	. "fmt"
+	myfmt "fmt"
+	"os"
+	"strings"
+)
+
+func example(n int) {
+	x := "foo" + strings.Repeat("\t", n)
+	// Match, despite named import.
+	errors.New(x)
+
+	// Match, despite dot import.
+	errors.New(x)
+
+	// Match: multiple matches in same function are possible.
+	errors.New(x)
+
+	// No match: wildcarded operand has the wrong type.
+	myfmt.Errorf("%s", 3)
+
+	// No match: function operand doesn't match.
+	myfmt.Printf("%s", x)
+
+	// No match again, dot import.
+	Printf("%s", x)
+
+	// Match.
+	myfmt.Fprint(os.Stderr, errors.New(x+"foo"))
+
+	// No match: though this literally matches the template,
+	// fmt doesn't resolve to a package here.
+	var fmt struct{ Errorf func(string, string) }
+	fmt.Errorf("%s", x)
+
+	// Recursive matching:
+
+	// Match: both matches are well-typed, so both succeed.
+	errors.New(errors.New(x + "foo").Error())
+
+	// Outer match succeeds, inner doesn't: 3 has wrong type.
+	errors.New(myfmt.Errorf("%s", 3).Error())
+
+	// Inner match succeeds, outer doesn't: the inner replacement
+	// has the wrong type (error not string).
+	myfmt.Errorf("%s", errors.New(x+"foo"))
+}

vendor/golang.org/x/tools/refactor/eg/testdata/A2.go

@@ -0,0 +1,12 @@
+// +build ignore
+
+package A2
+
+// This refactoring causes addition of "errors" import.
+// TODO(adonovan): fix: it should also remove "fmt".
+
+import myfmt "fmt"
+
+func example(n int) {
+	myfmt.Errorf("%s", "")
+}

vendor/golang.org/x/tools/refactor/eg/testdata/A2.golden

@@ -0,0 +1,15 @@
+// +build ignore
+
+package A2
+
+// This refactoring causes addition of "errors" import.
+// TODO(adonovan): fix: it should also remove "fmt".
+
+import (
+	"errors"
+	myfmt "fmt"
+)
+
+func example(n int) {
+	errors.New("")
+}

vendor/golang.org/x/tools/refactor/eg/testdata/B.template

@@ -0,0 +1,9 @@
+package template
+
+// Basic test of expression refactoring.
+// (Types are not important in this case; it could be done with gofmt -r.)
+
+import "time"
+
+func before(t time.Time) time.Duration { return time.Now().Sub(t) }
+func after(t time.Time) time.Duration  { return time.Since(t) }

vendor/golang.org/x/tools/refactor/eg/testdata/B1.go

@@ -0,0 +1,17 @@
+// +build ignore
+
+package B1
+
+import "time"
+
+var startup = time.Now()
+
+func example() time.Duration {
+	before := time.Now()
+	time.Sleep(1)
+	return time.Now().Sub(before)
+}
+
+func msSinceStartup() int64 {
+	return int64(time.Now().Sub(startup) / time.Millisecond)
+}

vendor/golang.org/x/tools/refactor/eg/testdata/B1.golden

@@ -0,0 +1,17 @@
+// +build ignore
+
+package B1
+
+import "time"
+
+var startup = time.Now()
+
+func example() time.Duration {
+	before := time.Now()
+	time.Sleep(1)
+	return time.Since(before)
+}
+
+func msSinceStartup() int64 {
+	return int64(time.Since(startup) / time.Millisecond)
+}

vendor/golang.org/x/tools/refactor/eg/testdata/C.template

@@ -0,0 +1,10 @@
+package template
+
+// Test of repeated use of wildcard in pattern.
+
+// NB: multiple patterns would be required to handle variants such as
+// s[:len(s)], s[x:len(s)], etc, since a wildcard can't match nothing at all.
+// TODO(adonovan): support multiple templates in a single pass.
+
+func before(s string) string { return s[:len(s)] }
+func after(s string) string  { return s }

vendor/golang.org/x/tools/refactor/eg/testdata/C1.go

@@ -0,0 +1,22 @@
+// +build ignore
+
+package C1
+
+import "strings"
+
+func example() {
+	x := "foo"
+	println(x[:len(x)])
+
+	// Match, but the transformation is not sound w.r.t. possible side effects.
+	println(strings.Repeat("*", 3)[:len(strings.Repeat("*", 3))])
+
+	// No match, since second use of wildcard doesn't match first.
+	println(strings.Repeat("*", 3)[:len(strings.Repeat("*", 2))])
+
+	// Recursive match demonstrating bottom-up rewrite:
+	// only after the inner replacement occurs does the outer syntax match.
+	println((x[:len(x)])[:len(x[:len(x)])])
+	// -> (x[:len(x)])
+	// -> x
+}

vendor/golang.org/x/tools/refactor/eg/testdata/C1.golden

@@ -0,0 +1,22 @@
+// +build ignore
+
+package C1
+
+import "strings"
+
+func example() {
+	x := "foo"
+	println(x)
+
+	// Match, but the transformation is not sound w.r.t. possible side effects.
+	println(strings.Repeat("*", 3))
+
+	// No match, since second use of wildcard doesn't match first.
+	println(strings.Repeat("*", 3)[:len(strings.Repeat("*", 2))])
+
+	// Recursive match demonstrating bottom-up rewrite:
+	// only after the inner replacement occurs does the outer syntax match.
+	println(x)
+	// -> (x[:len(x)])
+	// -> x
+}

vendor/golang.org/x/tools/refactor/eg/testdata/D.template

@@ -0,0 +1,8 @@
+package template
+
+import "fmt"
+
+// Test of semantic (not syntactic) matching of basic literals.
+
+func before() (int, error) { return fmt.Println(123, "a") }
+func after() (int, error)  { return fmt.Println(456, "!") }

vendor/golang.org/x/tools/refactor/eg/testdata/D1.go

@@ -0,0 +1,12 @@
+// +build ignore
+
+package D1
+
+import "fmt"
+
+func example() {
+	fmt.Println(123, "a")         // match
+	fmt.Println(0x7b, `a`)        // match
+	fmt.Println(0173, "\x61")     // match
+	fmt.Println(100+20+3, "a"+"") // no match: constant expressions, but not basic literals
+}

vendor/golang.org/x/tools/refactor/eg/testdata/D1.golden

@@ -0,0 +1,12 @@
+// +build ignore
+
+package D1
+
+import "fmt"
+
+func example() {
+	fmt.Println(456, "!")         // match
+	fmt.Println(456, "!")         // match
+	fmt.Println(456, "!")         // match
+	fmt.Println(100+20+3, "a"+"") // no match: constant expressions, but not basic literals
+}

vendor/golang.org/x/tools/refactor/eg/testdata/E.template

@@ -0,0 +1,12 @@
+package template
+
+import (
+	"fmt"
+	"log"
+	"os"
+)
+
+// Replace call to void function by call to non-void function.
+
+func before(x interface{}) { log.Fatal(x) }
+func after(x interface{})  { fmt.Fprintf(os.Stderr, "warning: %v", x) }

vendor/golang.org/x/tools/refactor/eg/testdata/E1.go

@@ -0,0 +1,9 @@
+// +build ignore
+
+package E1
+
+import "log"
+
+func example() {
+	log.Fatal("oops") // match
+}

vendor/golang.org/x/tools/refactor/eg/testdata/E1.golden

@@ -0,0 +1,13 @@
+// +build ignore
+
+package E1
+
+import (
+	"fmt"
+	"log"
+	"os"
+)
+
+func example() {
+	fmt.Fprintf(os.Stderr, "warning: %v", "oops") // match
+}

vendor/golang.org/x/tools/refactor/eg/testdata/F.template

@@ -0,0 +1,8 @@
+package templates
+
+// Test 
+
+import "sync"
+
+func before(s sync.RWMutex) { s.Lock() }
+func after(s sync.RWMutex) { s.RLock() }

vendor/golang.org/x/tools/refactor/eg/testdata/F1.go

@@ -0,0 +1,48 @@
+// +build ignore
+
+package F1
+
+import "sync"
+
+func example(n int) {
+	var x struct {
+		mutex sync.RWMutex
+	}
+
+	var y struct {
+		sync.RWMutex
+	}
+
+	type l struct {
+		sync.RWMutex
+	}
+
+	var z struct {
+		l
+	}
+
+	var a struct {
+		*l
+	}
+
+	var b struct{ Lock func() }
+
+	// Match
+	x.mutex.Lock()
+
+	// Match
+	y.Lock()
+
+	// Match indirect
+	z.Lock()
+
+	// Should be no match however currently matches due to:
+	// https://golang.org/issue/8584
+	// Will start failing when this is fixed then just change golden to
+	// No match pointer indirect
+	// a.Lock()
+	a.Lock()
+
+	// No match
+	b.Lock()
+}

vendor/golang.org/x/tools/refactor/eg/testdata/F1.golden

@@ -0,0 +1,48 @@
+// +build ignore
+
+package F1
+
+import "sync"
+
+func example(n int) {
+	var x struct {
+		mutex sync.RWMutex
+	}
+
+	var y struct {
+		sync.RWMutex
+	}
+
+	type l struct {
+		sync.RWMutex
+	}
+
+	var z struct {
+		l
+	}
+
+	var a struct {
+		*l
+	}
+
+	var b struct{ Lock func() }
+
+	// Match
+	x.mutex.RLock()
+
+	// Match
+	y.RLock()
+
+	// Match indirect
+	z.RLock()
+
+	// Should be no match however currently matches due to:
+	// https://golang.org/issue/8584
+	// Will start failing when this is fixed then just change golden to
+	// No match pointer indirect
+	// a.Lock()
+	a.RLock()
+
+	// No match
+	b.Lock()
+}

vendor/golang.org/x/tools/refactor/eg/testdata/G.template

@@ -0,0 +1,10 @@
+package templates
+
+import (
+	"go/ast" // defines many unencapsulated structs
+	"go/token"
+)
+
+func before(from, to token.Pos) ast.BadExpr { return ast.BadExpr{From: from, To: to} }
+func after(from, to token.Pos) ast.BadExpr  { return ast.BadExpr{from, to} }
+     

vendor/golang.org/x/tools/refactor/eg/testdata/G1.go

@@ -0,0 +1,12 @@
+// +build ignore
+
+package G1
+
+import "go/ast"
+
+func example() {
+	_ = ast.BadExpr{From: 123, To: 456} // match
+	_ = ast.BadExpr{123, 456}           // no match
+	_ = ast.BadExpr{From: 123}          // no match
+	_ = ast.BadExpr{To: 456}            // no match
+}

vendor/golang.org/x/tools/refactor/eg/testdata/G1.golden

@@ -0,0 +1,12 @@
+// +build ignore
+
+package G1
+
+import "go/ast"
+
+func example() {
+	_ = ast.BadExpr{123, 456}  // match
+	_ = ast.BadExpr{123, 456}  // no match
+	_ = ast.BadExpr{From: 123} // no match
+	_ = ast.BadExpr{To: 456}   // no match
+}

vendor/golang.org/x/tools/refactor/eg/testdata/H.template

@@ -0,0 +1,9 @@
+package templates
+
+import (
+	"go/ast" // defines many unencapsulated structs
+	"go/token"
+)
+
+func before(from, to token.Pos) ast.BadExpr { return ast.BadExpr{from, to} }
+func after(from, to token.Pos) ast.BadExpr  { return ast.BadExpr{From: from, To: to} }

vendor/golang.org/x/tools/refactor/eg/testdata/H1.go

@@ -0,0 +1,12 @@
+// +build ignore
+
+package H1
+
+import "go/ast"
+
+func example() {
+	_ = ast.BadExpr{From: 123, To: 456} // no match
+	_ = ast.BadExpr{123, 456}           // match
+	_ = ast.BadExpr{From: 123}          // no match
+	_ = ast.BadExpr{To: 456}            // no match
+}

vendor/golang.org/x/tools/refactor/eg/testdata/H1.golden

@@ -0,0 +1,12 @@
+// +build ignore
+
+package H1
+
+import "go/ast"
+
+func example() {
+	_ = ast.BadExpr{From: 123, To: 456} // no match
+	_ = ast.BadExpr{From: 123, To: 456} // match
+	_ = ast.BadExpr{From: 123}          // no match
+	_ = ast.BadExpr{To: 456}            // no match
+}

vendor/golang.org/x/tools/refactor/eg/testdata/I.template

@@ -0,0 +1,14 @@
+// +build ignore
+
+package templates
+
+import (
+	"errors"
+	"fmt"
+)
+
+func before(s string) error { return fmt.Errorf("%s", s) }
+func after(s string) error {
+	n := fmt.Sprintf("error - %s", s)
+	return errors.New(n)
+}

vendor/golang.org/x/tools/refactor/eg/testdata/I1.go

@@ -0,0 +1,9 @@
+// +build ignore
+
+package I1
+
+import "fmt"
+
+func example() {
+	_ = fmt.Errorf("%s", "foo")
+}

vendor/golang.org/x/tools/refactor/eg/testdata/I1.golden

@@ -0,0 +1,14 @@
+// +build ignore
+
+package I1
+
+import (
+	"errors"
+	"fmt"
+)
+
+func example() {
+
+	n := fmt.Sprintf("error - %s", "foo")
+	_ = errors.New(n)
+}

vendor/golang.org/x/tools/refactor/eg/testdata/J.template

@@ -0,0 +1,11 @@
+// +build ignore
+
+package templates
+
+import ()
+
+func before(x int) int { return x + x + x }
+func after(x int) int {
+	temp := x + x
+	return temp + x
+}

vendor/golang.org/x/tools/refactor/eg/testdata/J1.go

@@ -0,0 +1,10 @@
+// +build ignore
+
+package I1
+
+import "fmt"
+
+func example() {
+	temp := 5
+	fmt.Print(temp + temp + temp)
+}

vendor/golang.org/x/tools/refactor/eg/testdata/J1.golden

@@ -0,0 +1,11 @@
+// +build ignore
+
+package I1
+
+import "fmt"
+
+func example() {
+	temp := 5
+	temp := temp + temp
+	fmt.Print(temp + temp)
+}

vendor/golang.org/x/tools/refactor/eg/testdata/bad_type.template

@@ -0,0 +1,8 @@
+package template
+
+// Test in which replacement has a different type.
+
+const shouldFail = "int is not a safe replacement for string"
+
+func before() interface{} { return "three" }
+func after() interface{}  { return 3 }

vendor/golang.org/x/tools/refactor/eg/testdata/expr_type_mismatch.template

@@ -0,0 +1,15 @@
+package template
+
+import (
+	"crypto/x509"
+	"fmt"
+)
+
+// This test demonstrates a false negative: according to the language
+// rules this replacement should be ok, but types.Assignable doesn't work
+// in the expected way (elementwise assignability) for tuples.
+// Perhaps that's even a type-checker bug?
+const shouldFail = "(n int, err error) is not a safe replacement for (key interface{}, err error)"
+
+func before() (interface{}, error) { return x509.ParsePKCS8PrivateKey(nil) }
+func after() (interface{}, error)  { return fmt.Print() }

vendor/golang.org/x/tools/refactor/eg/testdata/no_after_return.template

@@ -0,0 +1,4 @@
+package template
+
+func before() int { return 0 }
+func after() int  { println(); return 0 }

vendor/golang.org/x/tools/refactor/eg/testdata/no_before.template

@@ -0,0 +1,5 @@
+package template
+
+const shouldFail = "no 'before' func found in template"
+
+func Before() {}

vendor/golang.org/x/tools/refactor/eg/testdata/type_mismatch.template

@@ -0,0 +1,6 @@
+package template
+
+const shouldFail = "different signatures"
+
+func before() int   { return 0 }
+func after() string { return "" }

vendor/golang.org/x/tools/refactor/importgraph/graph.go

@@ -0,0 +1,167 @@
+// Copyright 2014 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 importgraph computes the forward and reverse import
+// dependency graphs for all packages in a Go workspace.
+package importgraph // import "golang.org/x/tools/refactor/importgraph"
+
+import (
+	"go/build"
+	"sync"
+
+	"golang.org/x/tools/go/buildutil"
+)
+
+// A Graph is an import dependency graph, either forward or reverse.
+//
+// The graph maps each node (a package import path) to the set of its
+// successors in the graph.  For a forward graph, this is the set of
+// imported packages (prerequisites); for a reverse graph, it is the set
+// of importing packages (clients).
+//
+// Graph construction inspects all imports in each package's directory,
+// including those in _test.go files, so the resulting graph may be cyclic.
+type Graph map[string]map[string]bool
+
+func (g Graph) addEdge(from, to string) {
+	edges := g[from]
+	if edges == nil {
+		edges = make(map[string]bool)
+		g[from] = edges
+	}
+	edges[to] = true
+}
+
+// Search returns all the nodes of the graph reachable from
+// any of the specified roots, by following edges forwards.
+// Relationally, this is the reflexive transitive closure.
+func (g Graph) Search(roots ...string) map[string]bool {
+	seen := make(map[string]bool)
+	var visit func(x string)
+	visit = func(x string) {
+		if !seen[x] {
+			seen[x] = true
+			for y := range g[x] {
+				visit(y)
+			}
+		}
+	}
+	for _, root := range roots {
+		visit(root)
+	}
+	return seen
+}
+
+// Build scans the specified Go workspace and builds the forward and
+// reverse import dependency graphs for all its packages.
+// It also returns a mapping from canonical import paths to errors for packages
+// whose loading was not entirely successful.
+// A package may appear in the graph and in the errors mapping.
+// All package paths are canonical and may contain "/vendor/".
+func Build(ctxt *build.Context) (forward, reverse Graph, errors map[string]error) {
+	type importEdge struct {
+		from, to string
+	}
+	type pathError struct {
+		path string
+		err  error
+	}
+
+	ch := make(chan interface{})
+
+	go func() {
+		sema := make(chan int, 20) // I/O concurrency limiting semaphore
+		var wg sync.WaitGroup
+		buildutil.ForEachPackage(ctxt, func(path string, err error) {
+			if err != nil {
+				ch <- pathError{path, err}
+				return
+			}
+
+			wg.Add(1)
+			go func() {
+				defer wg.Done()
+
+				sema <- 1
+				bp, err := ctxt.Import(path, "", 0)
+				<-sema
+
+				if err != nil {
+					if _, ok := err.(*build.NoGoError); ok {
+						// empty directory is not an error
+					} else {
+						ch <- pathError{path, err}
+					}
+					// Even in error cases, Import usually returns a package.
+				}
+
+				// absolutize resolves an import path relative
+				// to the current package bp.
+				// The absolute form may contain "vendor".
+				//
+				// The vendoring feature slows down Build by 3×.
+				// Here are timings from a 1400 package workspace:
+				//    1100ms: current code (with vendor check)
+				//     880ms: with a nonblocking cache around ctxt.IsDir
+				//     840ms: nonblocking cache with duplicate suppression
+				//     340ms: original code (no vendor check)
+				// TODO(adonovan): optimize, somehow.
+				memo := make(map[string]string)
+				absolutize := func(path string) string {
+					canon, ok := memo[path]
+					if !ok {
+						sema <- 1
+						bp2, _ := ctxt.Import(path, bp.Dir, build.FindOnly)
+						<-sema
+
+						if bp2 != nil {
+							canon = bp2.ImportPath
+						} else {
+							canon = path
+						}
+						memo[path] = canon
+					}
+					return canon
+				}
+
+				if bp != nil {
+					for _, imp := range bp.Imports {
+						ch <- importEdge{path, absolutize(imp)}
+					}
+					for _, imp := range bp.TestImports {
+						ch <- importEdge{path, absolutize(imp)}
+					}
+					for _, imp := range bp.XTestImports {
+						ch <- importEdge{path, absolutize(imp)}
+					}
+				}
+
+			}()
+		})
+		wg.Wait()
+		close(ch)
+	}()
+
+	forward = make(Graph)
+	reverse = make(Graph)
+
+	for e := range ch {
+		switch e := e.(type) {
+		case pathError:
+			if errors == nil {
+				errors = make(map[string]error)
+			}
+			errors[e.path] = e.err
+
+		case importEdge:
+			if e.to == "C" {
+				continue // "C" is fake
+			}
+			forward.addEdge(e.from, e.to)
+			reverse.addEdge(e.to, e.from)
+		}
+	}
+
+	return forward, reverse, errors
+}

vendor/golang.org/x/tools/refactor/importgraph/graph_test.go

@@ -0,0 +1,99 @@
+// Copyright 2015 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.
+
+// Incomplete std lib sources on Android.
+
+// +build !android
+
+package importgraph_test
+
+import (
+	"go/build"
+	"sort"
+	"testing"
+
+	"golang.org/x/tools/refactor/importgraph"
+
+	_ "crypto/hmac" // just for test, below
+)
+
+const this = "golang.org/x/tools/refactor/importgraph"
+
+func TestBuild(t *testing.T) {
+	forward, reverse, errors := importgraph.Build(&build.Default)
+
+	// Test direct edges.
+	// We throw in crypto/hmac to prove that external test files
+	// (such as this one) are inspected.
+	for _, p := range []string{"go/build", "testing", "crypto/hmac"} {
+		if !forward[this][p] {
+			t.Errorf("forward[importgraph][%s] not found", p)
+		}
+		if !reverse[p][this] {
+			t.Errorf("reverse[%s][importgraph] not found", p)
+		}
+	}
+
+	// Test non-existent direct edges
+	for _, p := range []string{"errors", "reflect"} {
+		if forward[this][p] {
+			t.Errorf("unexpected: forward[importgraph][%s] found", p)
+		}
+		if reverse[p][this] {
+			t.Errorf("unexpected: reverse[%s][importgraph] found", p)
+		}
+	}
+
+	// Test Search is reflexive.
+	if !forward.Search(this)[this] {
+		t.Errorf("irreflexive: forward.Search(importgraph)[importgraph] not found")
+	}
+	if !reverse.Search(this)[this] {
+		t.Errorf("irrefexive: reverse.Search(importgraph)[importgraph] not found")
+	}
+
+	// Test Search is transitive.  (There is no direct edge to these packages.)
+	for _, p := range []string{"errors", "reflect", "unsafe"} {
+		if !forward.Search(this)[p] {
+			t.Errorf("intransitive: forward.Search(importgraph)[%s] not found", p)
+		}
+		if !reverse.Search(p)[this] {
+			t.Errorf("intransitive: reverse.Search(%s)[importgraph] not found", p)
+		}
+	}
+
+	// Test strongly-connected components.  Because A's external
+	// test package can depend on B, and vice versa, most of the
+	// standard libraries are mutually dependent when their external
+	// tests are considered.
+	//
+	// For any nodes x, y in the same SCC, y appears in the results
+	// of both forward and reverse searches starting from x
+	if !forward.Search("fmt")["io"] ||
+		!forward.Search("io")["fmt"] ||
+		!reverse.Search("fmt")["io"] ||
+		!reverse.Search("io")["fmt"] {
+		t.Errorf("fmt and io are not mutually reachable despite being in the same SCC")
+	}
+
+	// debugging
+	if false {
+		for path, err := range errors {
+			t.Logf("%s: %s", path, err)
+		}
+		printSorted := func(direction string, g importgraph.Graph, start string) {
+			t.Log(direction)
+			var pkgs []string
+			for pkg := range g.Search(start) {
+				pkgs = append(pkgs, pkg)
+			}
+			sort.Strings(pkgs)
+			for _, pkg := range pkgs {
+				t.Logf("\t%s", pkg)
+			}
+		}
+		printSorted("forward", forward, this)
+		printSorted("reverse", reverse, this)
+	}
+}

vendor/golang.org/x/tools/refactor/rename/check.go

@@ -0,0 +1,858 @@
+// Copyright 2014 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 rename
+
+// This file defines the safety checks for each kind of renaming.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/refactor/satisfy"
+)
+
+// errorf reports an error (e.g. conflict) and prevents file modification.
+func (r *renamer) errorf(pos token.Pos, format string, args ...interface{}) {
+	r.hadConflicts = true
+	reportError(r.iprog.Fset.Position(pos), fmt.Sprintf(format, args...))
+}
+
+// check performs safety checks of the renaming of the 'from' object to r.to.
+func (r *renamer) check(from types.Object) {
+	if r.objsToUpdate[from] {
+		return
+	}
+	r.objsToUpdate[from] = true
+
+	// NB: order of conditions is important.
+	if from_, ok := from.(*types.PkgName); ok {
+		r.checkInFileBlock(from_)
+	} else if from_, ok := from.(*types.Label); ok {
+		r.checkLabel(from_)
+	} else if isPackageLevel(from) {
+		r.checkInPackageBlock(from)
+	} else if v, ok := from.(*types.Var); ok && v.IsField() {
+		r.checkStructField(v)
+	} else if f, ok := from.(*types.Func); ok && recv(f) != nil {
+		r.checkMethod(f)
+	} else if isLocal(from) {
+		r.checkInLocalScope(from)
+	} else {
+		r.errorf(from.Pos(), "unexpected %s object %q (please report a bug)\n",
+			objectKind(from), from)
+	}
+}
+
+// checkInFileBlock performs safety checks for renames of objects in the file block,
+// i.e. imported package names.
+func (r *renamer) checkInFileBlock(from *types.PkgName) {
+	// Check import name is not "init".
+	if r.to == "init" {
+		r.errorf(from.Pos(), "%q is not a valid imported package name", r.to)
+	}
+
+	// Check for conflicts between file and package block.
+	if prev := from.Pkg().Scope().Lookup(r.to); prev != nil {
+		r.errorf(from.Pos(), "renaming this %s %q to %q would conflict",
+			objectKind(from), from.Name(), r.to)
+		r.errorf(prev.Pos(), "\twith this package member %s",
+			objectKind(prev))
+		return // since checkInPackageBlock would report redundant errors
+	}
+
+	// Check for conflicts in lexical scope.
+	r.checkInLexicalScope(from, r.packages[from.Pkg()])
+
+	// Finally, modify ImportSpec syntax to add or remove the Name as needed.
+	info, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos())
+	if from.Imported().Name() == r.to {
+		// ImportSpec.Name not needed
+		path[1].(*ast.ImportSpec).Name = nil
+	} else {
+		// ImportSpec.Name needed
+		if spec := path[1].(*ast.ImportSpec); spec.Name == nil {
+			spec.Name = &ast.Ident{NamePos: spec.Path.Pos(), Name: r.to}
+			info.Defs[spec.Name] = from
+		}
+	}
+}
+
+// checkInPackageBlock performs safety checks for renames of
+// func/var/const/type objects in the package block.
+func (r *renamer) checkInPackageBlock(from types.Object) {
+	// Check that there are no references to the name from another
+	// package if the renaming would make it unexported.
+	if ast.IsExported(from.Name()) && !ast.IsExported(r.to) {
+		for pkg, info := range r.packages {
+			if pkg == from.Pkg() {
+				continue
+			}
+			if id := someUse(info, from); id != nil &&
+				!r.checkExport(id, pkg, from) {
+				break
+			}
+		}
+	}
+
+	info := r.packages[from.Pkg()]
+
+	// Check that in the package block, "init" is a function, and never referenced.
+	if r.to == "init" {
+		kind := objectKind(from)
+		if kind == "func" {
+			// Reject if intra-package references to it exist.
+			for id, obj := range info.Uses {
+				if obj == from {
+					r.errorf(from.Pos(),
+						"renaming this func %q to %q would make it a package initializer",
+						from.Name(), r.to)
+					r.errorf(id.Pos(), "\tbut references to it exist")
+					break
+				}
+			}
+		} else {
+			r.errorf(from.Pos(), "you cannot have a %s at package level named %q",
+				kind, r.to)
+		}
+	}
+
+	// Check for conflicts between package block and all file blocks.
+	for _, f := range info.Files {
+		fileScope := info.Info.Scopes[f]
+		b, prev := fileScope.LookupParent(r.to, token.NoPos)
+		if b == fileScope {
+			r.errorf(from.Pos(), "renaming this %s %q to %q would conflict",
+				objectKind(from), from.Name(), r.to)
+			r.errorf(prev.Pos(), "\twith this %s",
+				objectKind(prev))
+			return // since checkInPackageBlock would report redundant errors
+		}
+	}
+
+	// Check for conflicts in lexical scope.
+	if from.Exported() {
+		for _, info := range r.packages {
+			r.checkInLexicalScope(from, info)
+		}
+	} else {
+		r.checkInLexicalScope(from, info)
+	}
+}
+
+func (r *renamer) checkInLocalScope(from types.Object) {
+	info := r.packages[from.Pkg()]
+
+	// Is this object an implicit local var for a type switch?
+	// Each case has its own var, whose position is the decl of y,
+	// but Ident in that decl does not appear in the Uses map.
+	//
+	//   switch y := x.(type) {	 // Defs[Ident(y)] is undefined
+	//   case int:    print(y)       // Implicits[CaseClause(int)]    = Var(y_int)
+	//   case string: print(y)       // Implicits[CaseClause(string)] = Var(y_string)
+	//   }
+	//
+	var isCaseVar bool
+	for syntax, obj := range info.Implicits {
+		if _, ok := syntax.(*ast.CaseClause); ok && obj.Pos() == from.Pos() {
+			isCaseVar = true
+			r.check(obj)
+		}
+	}
+
+	r.checkInLexicalScope(from, info)
+
+	// Finally, if this was a type switch, change the variable y.
+	if isCaseVar {
+		_, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos())
+		path[0].(*ast.Ident).Name = r.to // path is [Ident AssignStmt TypeSwitchStmt...]
+	}
+}
+
+// checkInLexicalScope performs safety checks that a renaming does not
+// change the lexical reference structure of the specified package.
+//
+// For objects in lexical scope, there are three kinds of conflicts:
+// same-, sub-, and super-block conflicts.  We will illustrate all three
+// using this example:
+//
+//	var x int
+//	var z int
+//
+//	func f(y int) {
+//		print(x)
+//		print(y)
+//	}
+//
+// Renaming x to z encounters a SAME-BLOCK CONFLICT, because an object
+// with the new name already exists, defined in the same lexical block
+// as the old object.
+//
+// Renaming x to y encounters a SUB-BLOCK CONFLICT, because there exists
+// a reference to x from within (what would become) a hole in its scope.
+// The definition of y in an (inner) sub-block would cast a shadow in
+// the scope of the renamed variable.
+//
+// Renaming y to x encounters a SUPER-BLOCK CONFLICT.  This is the
+// converse situation: there is an existing definition of the new name
+// (x) in an (enclosing) super-block, and the renaming would create a
+// hole in its scope, within which there exist references to it.  The
+// new name casts a shadow in scope of the existing definition of x in
+// the super-block.
+//
+// Removing the old name (and all references to it) is always safe, and
+// requires no checks.
+//
+func (r *renamer) checkInLexicalScope(from types.Object, info *loader.PackageInfo) {
+	b := from.Parent() // the block defining the 'from' object
+	if b != nil {
+		toBlock, to := b.LookupParent(r.to, from.Parent().End())
+		if toBlock == b {
+			// same-block conflict
+			r.errorf(from.Pos(), "renaming this %s %q to %q",
+				objectKind(from), from.Name(), r.to)
+			r.errorf(to.Pos(), "\tconflicts with %s in same block",
+				objectKind(to))
+			return
+		} else if toBlock != nil {
+			// Check for super-block conflict.
+			// The name r.to is defined in a superblock.
+			// Is that name referenced from within this block?
+			forEachLexicalRef(info, to, func(id *ast.Ident, block *types.Scope) bool {
+				_, obj := lexicalLookup(block, from.Name(), id.Pos())
+				if obj == from {
+					// super-block conflict
+					r.errorf(from.Pos(), "renaming this %s %q to %q",
+						objectKind(from), from.Name(), r.to)
+					r.errorf(id.Pos(), "\twould shadow this reference")
+					r.errorf(to.Pos(), "\tto the %s declared here",
+						objectKind(to))
+					return false // stop
+				}
+				return true
+			})
+		}
+	}
+
+	// Check for sub-block conflict.
+	// Is there an intervening definition of r.to between
+	// the block defining 'from' and some reference to it?
+	forEachLexicalRef(info, from, func(id *ast.Ident, block *types.Scope) bool {
+		// Find the block that defines the found reference.
+		// It may be an ancestor.
+		fromBlock, _ := lexicalLookup(block, from.Name(), id.Pos())
+
+		// See what r.to would resolve to in the same scope.
+		toBlock, to := lexicalLookup(block, r.to, id.Pos())
+		if to != nil {
+			// sub-block conflict
+			if deeper(toBlock, fromBlock) {
+				r.errorf(from.Pos(), "renaming this %s %q to %q",
+					objectKind(from), from.Name(), r.to)
+				r.errorf(id.Pos(), "\twould cause this reference to become shadowed")
+				r.errorf(to.Pos(), "\tby this intervening %s definition",
+					objectKind(to))
+				return false // stop
+			}
+		}
+		return true
+	})
+
+	// Renaming a type that is used as an embedded field
+	// requires renaming the field too. e.g.
+	// 	type T int // if we rename this to U..
+	// 	var s struct {T}
+	// 	print(s.T) // ...this must change too
+	if _, ok := from.(*types.TypeName); ok {
+		for id, obj := range info.Uses {
+			if obj == from {
+				if field := info.Defs[id]; field != nil {
+					r.check(field)
+				}
+			}
+		}
+	}
+}
+
+// lexicalLookup is like (*types.Scope).LookupParent but respects the
+// environment visible at pos.  It assumes the relative position
+// information is correct with each file.
+func lexicalLookup(block *types.Scope, name string, pos token.Pos) (*types.Scope, types.Object) {
+	for b := block; b != nil; b = b.Parent() {
+		obj := b.Lookup(name)
+		// The scope of a package-level object is the entire package,
+		// so ignore pos in that case.
+		// No analogous clause is needed for file-level objects
+		// since no reference can appear before an import decl.
+		if obj != nil && (b == obj.Pkg().Scope() || obj.Pos() < pos) {
+			return b, obj
+		}
+	}
+	return nil, nil
+}
+
+// deeper reports whether block x is lexically deeper than y.
+func deeper(x, y *types.Scope) bool {
+	if x == y || x == nil {
+		return false
+	} else if y == nil {
+		return true
+	} else {
+		return deeper(x.Parent(), y.Parent())
+	}
+}
+
+// forEachLexicalRef calls fn(id, block) for each identifier id in package
+// info that is a reference to obj in lexical scope.  block is the
+// lexical block enclosing the reference.  If fn returns false the
+// iteration is terminated and findLexicalRefs returns false.
+func forEachLexicalRef(info *loader.PackageInfo, obj types.Object, fn func(id *ast.Ident, block *types.Scope) bool) bool {
+	ok := true
+	var stack []ast.Node
+
+	var visit func(n ast.Node) bool
+	visit = func(n ast.Node) bool {
+		if n == nil {
+			stack = stack[:len(stack)-1] // pop
+			return false
+		}
+		if !ok {
+			return false // bail out
+		}
+
+		stack = append(stack, n) // push
+		switch n := n.(type) {
+		case *ast.Ident:
+			if info.Uses[n] == obj {
+				block := enclosingBlock(&info.Info, stack)
+				if !fn(n, block) {
+					ok = false
+				}
+			}
+			return visit(nil) // pop stack
+
+		case *ast.SelectorExpr:
+			// don't visit n.Sel
+			ast.Inspect(n.X, visit)
+			return visit(nil) // pop stack, don't descend
+
+		case *ast.CompositeLit:
+			// Handle recursion ourselves for struct literals
+			// so we don't visit field identifiers.
+			tv := info.Types[n]
+			if _, ok := deref(tv.Type).Underlying().(*types.Struct); ok {
+				if n.Type != nil {
+					ast.Inspect(n.Type, visit)
+				}
+				for _, elt := range n.Elts {
+					if kv, ok := elt.(*ast.KeyValueExpr); ok {
+						ast.Inspect(kv.Value, visit)
+					} else {
+						ast.Inspect(elt, visit)
+					}
+				}
+				return visit(nil) // pop stack, don't descend
+			}
+		}
+		return true
+	}
+
+	for _, f := range info.Files {
+		ast.Inspect(f, visit)
+		if len(stack) != 0 {
+			panic(stack)
+		}
+		if !ok {
+			break
+		}
+	}
+	return ok
+}
+
+// enclosingBlock returns the innermost block enclosing the specified
+// AST node, specified in the form of a path from the root of the file,
+// [file...n].
+func enclosingBlock(info *types.Info, stack []ast.Node) *types.Scope {
+	for i := range stack {
+		n := stack[len(stack)-1-i]
+		// For some reason, go/types always associates a
+		// function's scope with its FuncType.
+		// TODO(adonovan): feature or a bug?
+		switch f := n.(type) {
+		case *ast.FuncDecl:
+			n = f.Type
+		case *ast.FuncLit:
+			n = f.Type
+		}
+		if b := info.Scopes[n]; b != nil {
+			return b
+		}
+	}
+	panic("no Scope for *ast.File")
+}
+
+func (r *renamer) checkLabel(label *types.Label) {
+	// Check there are no identical labels in the function's label block.
+	// (Label blocks don't nest, so this is easy.)
+	if prev := label.Parent().Lookup(r.to); prev != nil {
+		r.errorf(label.Pos(), "renaming this label %q to %q", label.Name(), prev.Name())
+		r.errorf(prev.Pos(), "\twould conflict with this one")
+	}
+}
+
+// checkStructField checks that the field renaming will not cause
+// conflicts at its declaration, or ambiguity or changes to any selection.
+func (r *renamer) checkStructField(from *types.Var) {
+	// Check that the struct declaration is free of field conflicts,
+	// and field/method conflicts.
+
+	// go/types offers no easy way to get from a field (or interface
+	// method) to its declaring struct (or interface), so we must
+	// ascend the AST.
+	info, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos())
+	// path matches this pattern:
+	// [Ident SelectorExpr? StarExpr? Field FieldList StructType ParenExpr* ... File]
+
+	// Ascend to FieldList.
+	var i int
+	for {
+		if _, ok := path[i].(*ast.FieldList); ok {
+			break
+		}
+		i++
+	}
+	i++
+	tStruct := path[i].(*ast.StructType)
+	i++
+	// Ascend past parens (unlikely).
+	for {
+		_, ok := path[i].(*ast.ParenExpr)
+		if !ok {
+			break
+		}
+		i++
+	}
+	if spec, ok := path[i].(*ast.TypeSpec); ok {
+		// This struct is also a named type.
+		// We must check for direct (non-promoted) field/field
+		// and method/field conflicts.
+		named := info.Defs[spec.Name].Type()
+		prev, indices, _ := types.LookupFieldOrMethod(named, true, info.Pkg, r.to)
+		if len(indices) == 1 {
+			r.errorf(from.Pos(), "renaming this field %q to %q",
+				from.Name(), r.to)
+			r.errorf(prev.Pos(), "\twould conflict with this %s",
+				objectKind(prev))
+			return // skip checkSelections to avoid redundant errors
+		}
+	} else {
+		// This struct is not a named type.
+		// We need only check for direct (non-promoted) field/field conflicts.
+		T := info.Types[tStruct].Type.Underlying().(*types.Struct)
+		for i := 0; i < T.NumFields(); i++ {
+			if prev := T.Field(i); prev.Name() == r.to {
+				r.errorf(from.Pos(), "renaming this field %q to %q",
+					from.Name(), r.to)
+				r.errorf(prev.Pos(), "\twould conflict with this field")
+				return // skip checkSelections to avoid redundant errors
+			}
+		}
+	}
+
+	// Renaming an anonymous field requires renaming the type too. e.g.
+	// 	print(s.T)       // if we rename T to U,
+	// 	type T int       // this and
+	// 	var s struct {T} // this must change too.
+	if from.Anonymous() {
+		if named, ok := from.Type().(*types.Named); ok {
+			r.check(named.Obj())
+		} else if named, ok := deref(from.Type()).(*types.Named); ok {
+			r.check(named.Obj())
+		}
+	}
+
+	// Check integrity of existing (field and method) selections.
+	r.checkSelections(from)
+}
+
+// checkSelection checks that all uses and selections that resolve to
+// the specified object would continue to do so after the renaming.
+func (r *renamer) checkSelections(from types.Object) {
+	for pkg, info := range r.packages {
+		if id := someUse(info, from); id != nil {
+			if !r.checkExport(id, pkg, from) {
+				return
+			}
+		}
+
+		for syntax, sel := range info.Selections {
+			// There may be extant selections of only the old
+			// name or only the new name, so we must check both.
+			// (If neither, the renaming is sound.)
+			//
+			// In both cases, we wish to compare the lengths
+			// of the implicit field path (Selection.Index)
+			// to see if the renaming would change it.
+			//
+			// If a selection that resolves to 'from', when renamed,
+			// would yield a path of the same or shorter length,
+			// this indicates ambiguity or a changed referent,
+			// analogous to same- or sub-block lexical conflict.
+			//
+			// If a selection using the name 'to' would
+			// yield a path of the same or shorter length,
+			// this indicates ambiguity or shadowing,
+			// analogous to same- or super-block lexical conflict.
+
+			// TODO(adonovan): fix: derive from Types[syntax.X].Mode
+			// TODO(adonovan): test with pointer, value, addressable value.
+			isAddressable := true
+
+			if sel.Obj() == from {
+				if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), r.to); obj != nil {
+					// Renaming this existing selection of
+					// 'from' may block access to an existing
+					// type member named 'to'.
+					delta := len(indices) - len(sel.Index())
+					if delta > 0 {
+						continue // no ambiguity
+					}
+					r.selectionConflict(from, delta, syntax, obj)
+					return
+				}
+
+			} else if sel.Obj().Name() == r.to {
+				if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), from.Name()); obj == from {
+					// Renaming 'from' may cause this existing
+					// selection of the name 'to' to change
+					// its meaning.
+					delta := len(indices) - len(sel.Index())
+					if delta > 0 {
+						continue //  no ambiguity
+					}
+					r.selectionConflict(from, -delta, syntax, sel.Obj())
+					return
+				}
+			}
+		}
+	}
+}
+
+func (r *renamer) selectionConflict(from types.Object, delta int, syntax *ast.SelectorExpr, obj types.Object) {
+	r.errorf(from.Pos(), "renaming this %s %q to %q",
+		objectKind(from), from.Name(), r.to)
+
+	switch {
+	case delta < 0:
+		// analogous to sub-block conflict
+		r.errorf(syntax.Sel.Pos(),
+			"\twould change the referent of this selection")
+		r.errorf(obj.Pos(), "\tof this %s", objectKind(obj))
+	case delta == 0:
+		// analogous to same-block conflict
+		r.errorf(syntax.Sel.Pos(),
+			"\twould make this reference ambiguous")
+		r.errorf(obj.Pos(), "\twith this %s", objectKind(obj))
+	case delta > 0:
+		// analogous to super-block conflict
+		r.errorf(syntax.Sel.Pos(),
+			"\twould shadow this selection")
+		r.errorf(obj.Pos(), "\tof the %s declared here",
+			objectKind(obj))
+	}
+}
+
+// checkMethod performs safety checks for renaming a method.
+// There are three hazards:
+// - declaration conflicts
+// - selection ambiguity/changes
+// - entailed renamings of assignable concrete/interface types.
+//   We reject renamings initiated at concrete methods if it would
+//   change the assignability relation.  For renamings of abstract
+//   methods, we rename all methods transitively coupled to it via
+//   assignability.
+func (r *renamer) checkMethod(from *types.Func) {
+	// e.g. error.Error
+	if from.Pkg() == nil {
+		r.errorf(from.Pos(), "you cannot rename built-in method %s", from)
+		return
+	}
+
+	// ASSIGNABILITY: We reject renamings of concrete methods that
+	// would break a 'satisfy' constraint; but renamings of abstract
+	// methods are allowed to proceed, and we rename affected
+	// concrete and abstract methods as necessary.  It is the
+	// initial method that determines the policy.
+
+	// Check for conflict at point of declaration.
+	// Check to ensure preservation of assignability requirements.
+	R := recv(from).Type()
+	if isInterface(R) {
+		// Abstract method
+
+		// declaration
+		prev, _, _ := types.LookupFieldOrMethod(R, false, from.Pkg(), r.to)
+		if prev != nil {
+			r.errorf(from.Pos(), "renaming this interface method %q to %q",
+				from.Name(), r.to)
+			r.errorf(prev.Pos(), "\twould conflict with this method")
+			return
+		}
+
+		// Check all interfaces that embed this one for
+		// declaration conflicts too.
+		for _, info := range r.packages {
+			// Start with named interface types (better errors)
+			for _, obj := range info.Defs {
+				if obj, ok := obj.(*types.TypeName); ok && isInterface(obj.Type()) {
+					f, _, _ := types.LookupFieldOrMethod(
+						obj.Type(), false, from.Pkg(), from.Name())
+					if f == nil {
+						continue
+					}
+					t, _, _ := types.LookupFieldOrMethod(
+						obj.Type(), false, from.Pkg(), r.to)
+					if t == nil {
+						continue
+					}
+					r.errorf(from.Pos(), "renaming this interface method %q to %q",
+						from.Name(), r.to)
+					r.errorf(t.Pos(), "\twould conflict with this method")
+					r.errorf(obj.Pos(), "\tin named interface type %q", obj.Name())
+				}
+			}
+
+			// Now look at all literal interface types (includes named ones again).
+			for e, tv := range info.Types {
+				if e, ok := e.(*ast.InterfaceType); ok {
+					_ = e
+					_ = tv.Type.(*types.Interface)
+					// TODO(adonovan): implement same check as above.
+				}
+			}
+		}
+
+		// assignability
+		//
+		// Find the set of concrete or abstract methods directly
+		// coupled to abstract method 'from' by some
+		// satisfy.Constraint, and rename them too.
+		for key := range r.satisfy() {
+			// key = (lhs, rhs) where lhs is always an interface.
+
+			lsel := r.msets.MethodSet(key.LHS).Lookup(from.Pkg(), from.Name())
+			if lsel == nil {
+				continue
+			}
+			rmethods := r.msets.MethodSet(key.RHS)
+			rsel := rmethods.Lookup(from.Pkg(), from.Name())
+			if rsel == nil {
+				continue
+			}
+
+			// If both sides have a method of this name,
+			// and one of them is m, the other must be coupled.
+			var coupled *types.Func
+			switch from {
+			case lsel.Obj():
+				coupled = rsel.Obj().(*types.Func)
+			case rsel.Obj():
+				coupled = lsel.Obj().(*types.Func)
+			default:
+				continue
+			}
+
+			// We must treat concrete-to-interface
+			// constraints like an implicit selection C.f of
+			// each interface method I.f, and check that the
+			// renaming leaves the selection unchanged and
+			// unambiguous.
+			//
+			// Fun fact: the implicit selection of C.f
+			// 	type I interface{f()}
+			// 	type C struct{I}
+			// 	func (C) g()
+			//      var _ I = C{} // here
+			// yields abstract method I.f.  This can make error
+			// messages less than obvious.
+			//
+			if !isInterface(key.RHS) {
+				// The logic below was derived from checkSelections.
+
+				rtosel := rmethods.Lookup(from.Pkg(), r.to)
+				if rtosel != nil {
+					rto := rtosel.Obj().(*types.Func)
+					delta := len(rsel.Index()) - len(rtosel.Index())
+					if delta < 0 {
+						continue // no ambiguity
+					}
+
+					// TODO(adonovan): record the constraint's position.
+					keyPos := token.NoPos
+
+					r.errorf(from.Pos(), "renaming this method %q to %q",
+						from.Name(), r.to)
+					if delta == 0 {
+						// analogous to same-block conflict
+						r.errorf(keyPos, "\twould make the %s method of %s invoked via interface %s ambiguous",
+							r.to, key.RHS, key.LHS)
+						r.errorf(rto.Pos(), "\twith (%s).%s",
+							recv(rto).Type(), r.to)
+					} else {
+						// analogous to super-block conflict
+						r.errorf(keyPos, "\twould change the %s method of %s invoked via interface %s",
+							r.to, key.RHS, key.LHS)
+						r.errorf(coupled.Pos(), "\tfrom (%s).%s",
+							recv(coupled).Type(), r.to)
+						r.errorf(rto.Pos(), "\tto (%s).%s",
+							recv(rto).Type(), r.to)
+					}
+					return // one error is enough
+				}
+			}
+
+			if !r.changeMethods {
+				// This should be unreachable.
+				r.errorf(from.Pos(), "internal error: during renaming of abstract method %s", from)
+				r.errorf(coupled.Pos(), "\tchangedMethods=false, coupled method=%s", coupled)
+				r.errorf(from.Pos(), "\tPlease file a bug report")
+				return
+			}
+
+			// Rename the coupled method to preserve assignability.
+			r.check(coupled)
+		}
+	} else {
+		// Concrete method
+
+		// declaration
+		prev, indices, _ := types.LookupFieldOrMethod(R, true, from.Pkg(), r.to)
+		if prev != nil && len(indices) == 1 {
+			r.errorf(from.Pos(), "renaming this method %q to %q",
+				from.Name(), r.to)
+			r.errorf(prev.Pos(), "\twould conflict with this %s",
+				objectKind(prev))
+			return
+		}
+
+		// assignability
+		//
+		// Find the set of abstract methods coupled to concrete
+		// method 'from' by some satisfy.Constraint, and rename
+		// them too.
+		//
+		// Coupling may be indirect, e.g. I.f <-> C.f via type D.
+		//
+		// 	type I interface {f()}
+		//	type C int
+		//	type (C) f()
+		//	type D struct{C}
+		//	var _ I = D{}
+		//
+		for key := range r.satisfy() {
+			// key = (lhs, rhs) where lhs is always an interface.
+			if isInterface(key.RHS) {
+				continue
+			}
+			rsel := r.msets.MethodSet(key.RHS).Lookup(from.Pkg(), from.Name())
+			if rsel == nil || rsel.Obj() != from {
+				continue // rhs does not have the method
+			}
+			lsel := r.msets.MethodSet(key.LHS).Lookup(from.Pkg(), from.Name())
+			if lsel == nil {
+				continue
+			}
+			imeth := lsel.Obj().(*types.Func)
+
+			// imeth is the abstract method (e.g. I.f)
+			// and key.RHS is the concrete coupling type (e.g. D).
+			if !r.changeMethods {
+				r.errorf(from.Pos(), "renaming this method %q to %q",
+					from.Name(), r.to)
+				var pos token.Pos
+				var iface string
+
+				I := recv(imeth).Type()
+				if named, ok := I.(*types.Named); ok {
+					pos = named.Obj().Pos()
+					iface = "interface " + named.Obj().Name()
+				} else {
+					pos = from.Pos()
+					iface = I.String()
+				}
+				r.errorf(pos, "\twould make %s no longer assignable to %s",
+					key.RHS, iface)
+				r.errorf(imeth.Pos(), "\t(rename %s.%s if you intend to change both types)",
+					I, from.Name())
+				return // one error is enough
+			}
+
+			// Rename the coupled interface method to preserve assignability.
+			r.check(imeth)
+		}
+	}
+
+	// Check integrity of existing (field and method) selections.
+	// We skip this if there were errors above, to avoid redundant errors.
+	r.checkSelections(from)
+}
+
+func (r *renamer) checkExport(id *ast.Ident, pkg *types.Package, from types.Object) bool {
+	// Reject cross-package references if r.to is unexported.
+	// (Such references may be qualified identifiers or field/method
+	// selections.)
+	if !ast.IsExported(r.to) && pkg != from.Pkg() {
+		r.errorf(from.Pos(),
+			"renaming this %s %q to %q would make it unexported",
+			objectKind(from), from.Name(), r.to)
+		r.errorf(id.Pos(), "\tbreaking references from packages such as %q",
+			pkg.Path())
+		return false
+	}
+	return true
+}
+
+// satisfy returns the set of interface satisfaction constraints.
+func (r *renamer) satisfy() map[satisfy.Constraint]bool {
+	if r.satisfyConstraints == nil {
+		// Compute on demand: it's expensive.
+		var f satisfy.Finder
+		for _, info := range r.packages {
+			f.Find(&info.Info, info.Files)
+		}
+		r.satisfyConstraints = f.Result
+	}
+	return r.satisfyConstraints
+}
+
+// -- helpers ----------------------------------------------------------
+
+// recv returns the method's receiver.
+func recv(meth *types.Func) *types.Var {
+	return meth.Type().(*types.Signature).Recv()
+}
+
+// someUse returns an arbitrary use of obj within info.
+func someUse(info *loader.PackageInfo, obj types.Object) *ast.Ident {
+	for id, o := range info.Uses {
+		if o == obj {
+			return id
+		}
+	}
+	return nil
+}
+
+// -- Plundered from golang.org/x/tools/go/ssa -----------------
+
+func isInterface(T types.Type) bool { return types.IsInterface(T) }
+
+func deref(typ types.Type) types.Type {
+	if p, _ := typ.(*types.Pointer); p != nil {
+		return p.Elem()
+	}
+	return typ
+}

vendor/golang.org/x/tools/refactor/rename/mvpkg.go

@@ -0,0 +1,375 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// licence that can be found in the LICENSE file.
+
+// This file contains the implementation of the 'gomvpkg' command
+// whose main function is in golang.org/x/tools/cmd/gomvpkg.
+
+package rename
+
+// TODO(matloob):
+// - think about what happens if the package is moving across version control systems.
+// - think about windows, which uses "\" as its directory separator.
+// - dot imports are not supported. Make sure it's clearly documented.
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/format"
+	"go/token"
+	"log"
+	"os"
+	"os/exec"
+	"path"
+	"path/filepath"
+	"regexp"
+	"runtime"
+	"strconv"
+	"strings"
+	"text/template"
+
+	"golang.org/x/tools/go/buildutil"
+	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/refactor/importgraph"
+)
+
+// Move, given a package path and a destination package path, will try
+// to move the given package to the new path. The Move function will
+// first check for any conflicts preventing the move, such as a
+// package already existing at the destination package path. If the
+// move can proceed, it builds an import graph to find all imports of
+// the packages whose paths need to be renamed. This includes uses of
+// the subpackages of the package to be moved as those packages will
+// also need to be moved. It then renames all imports to point to the
+// new paths, and then moves the packages to their new paths.
+func Move(ctxt *build.Context, from, to, moveTmpl string) error {
+	srcDir, err := srcDir(ctxt, from)
+	if err != nil {
+		return err
+	}
+
+	// This should be the only place in the program that constructs
+	// file paths.
+	// TODO(matloob): test on Microsoft Windows.
+	fromDir := buildutil.JoinPath(ctxt, srcDir, filepath.FromSlash(from))
+	toDir := buildutil.JoinPath(ctxt, srcDir, filepath.FromSlash(to))
+	toParent := filepath.Dir(toDir)
+	if !buildutil.IsDir(ctxt, toParent) {
+		return fmt.Errorf("parent directory does not exist for path %s", toDir)
+	}
+
+	// Build the import graph and figure out which packages to update.
+	_, rev, errors := importgraph.Build(ctxt)
+	if len(errors) > 0 {
+		// With a large GOPATH tree, errors are inevitable.
+		// Report them but proceed.
+		fmt.Fprintf(os.Stderr, "While scanning Go workspace:\n")
+		for path, err := range errors {
+			fmt.Fprintf(os.Stderr, "Package %q: %s.\n", path, err)
+		}
+	}
+
+	// Determine the affected packages---the set of packages whose import
+	// statements need updating.
+	affectedPackages := map[string]bool{from: true}
+	destinations := make(map[string]string) // maps old import path to new import path
+	for pkg := range subpackages(ctxt, srcDir, from) {
+		for r := range rev[pkg] {
+			affectedPackages[r] = true
+		}
+		// Ensure directories have a trailing separator.
+		dest := strings.Replace(pkg,
+			filepath.Join(from, ""),
+			filepath.Join(to, ""),
+			1)
+		destinations[pkg] = filepath.ToSlash(dest)
+	}
+
+	// Load all the affected packages.
+	iprog, err := loadProgram(ctxt, affectedPackages)
+	if err != nil {
+		return err
+	}
+
+	// Prepare the move command, if one was supplied.
+	var cmd string
+	if moveTmpl != "" {
+		if cmd, err = moveCmd(moveTmpl, fromDir, toDir); err != nil {
+			return err
+		}
+	}
+
+	m := mover{
+		ctxt:             ctxt,
+		rev:              rev,
+		iprog:            iprog,
+		from:             from,
+		to:               to,
+		fromDir:          fromDir,
+		toDir:            toDir,
+		affectedPackages: affectedPackages,
+		destinations:     destinations,
+		cmd:              cmd,
+	}
+
+	if err := m.checkValid(); err != nil {
+		return err
+	}
+
+	m.move()
+
+	return nil
+}
+
+// srcDir returns the absolute path of the srcdir containing pkg.
+func srcDir(ctxt *build.Context, pkg string) (string, error) {
+	for _, srcDir := range ctxt.SrcDirs() {
+		path := buildutil.JoinPath(ctxt, srcDir, pkg)
+		if buildutil.IsDir(ctxt, path) {
+			return srcDir, nil
+		}
+	}
+	return "", fmt.Errorf("src dir not found for package: %s", pkg)
+}
+
+// subpackages returns the set of packages in the given srcDir whose
+// import paths start with dir.
+func subpackages(ctxt *build.Context, srcDir string, dir string) map[string]bool {
+	subs := map[string]bool{dir: true}
+
+	// Find all packages under srcDir whose import paths start with dir.
+	buildutil.ForEachPackage(ctxt, func(pkg string, err error) {
+		if err != nil {
+			log.Fatalf("unexpected error in ForEachPackage: %v", err)
+		}
+
+		// Only process the package or a sub-package
+		if !(strings.HasPrefix(pkg, dir) &&
+			(len(pkg) == len(dir) || pkg[len(dir)] == '/')) {
+			return
+		}
+
+		p, err := ctxt.Import(pkg, "", build.FindOnly)
+		if err != nil {
+			log.Fatalf("unexpected: package %s can not be located by build context: %s", pkg, err)
+		}
+		if p.SrcRoot == "" {
+			log.Fatalf("unexpected: could not determine srcDir for package %s: %s", pkg, err)
+		}
+		if p.SrcRoot != srcDir {
+			return
+		}
+
+		subs[pkg] = true
+	})
+
+	return subs
+}
+
+type mover struct {
+	// iprog contains all packages whose contents need to be updated
+	// with new package names or import paths.
+	iprog *loader.Program
+	ctxt  *build.Context
+	// rev is the reverse import graph.
+	rev importgraph.Graph
+	// from and to are the source and destination import
+	// paths. fromDir and toDir are the source and destination
+	// absolute paths that package source files will be moved between.
+	from, to, fromDir, toDir string
+	// affectedPackages is the set of all packages whose contents need
+	// to be updated to reflect new package names or import paths.
+	affectedPackages map[string]bool
+	// destinations maps each subpackage to be moved to its
+	// destination path.
+	destinations map[string]string
+	// cmd, if not empty, will be executed to move fromDir to toDir.
+	cmd string
+}
+
+func (m *mover) checkValid() error {
+	const prefix = "invalid move destination"
+
+	match, err := regexp.MatchString("^[_\\pL][_\\pL\\p{Nd}]*$", path.Base(m.to))
+	if err != nil {
+		panic("regexp.MatchString failed")
+	}
+	if !match {
+		return fmt.Errorf("%s: %s; gomvpkg does not support move destinations "+
+			"whose base names are not valid go identifiers", prefix, m.to)
+	}
+
+	if buildutil.FileExists(m.ctxt, m.toDir) {
+		return fmt.Errorf("%s: %s conflicts with file %s", prefix, m.to, m.toDir)
+	}
+	if buildutil.IsDir(m.ctxt, m.toDir) {
+		return fmt.Errorf("%s: %s conflicts with directory %s", prefix, m.to, m.toDir)
+	}
+
+	for _, toSubPkg := range m.destinations {
+		if _, err := m.ctxt.Import(toSubPkg, "", build.FindOnly); err == nil {
+			return fmt.Errorf("%s: %s; package or subpackage %s already exists",
+				prefix, m.to, toSubPkg)
+		}
+	}
+
+	return nil
+}
+
+// moveCmd produces the version control move command used to move fromDir to toDir by
+// executing the given template.
+func moveCmd(moveTmpl, fromDir, toDir string) (string, error) {
+	tmpl, err := template.New("movecmd").Parse(moveTmpl)
+	if err != nil {
+		return "", err
+	}
+
+	var buf bytes.Buffer
+	err = tmpl.Execute(&buf, struct {
+		Src string
+		Dst string
+	}{fromDir, toDir})
+	return buf.String(), err
+}
+
+func (m *mover) move() error {
+	filesToUpdate := make(map[*ast.File]bool)
+
+	// Change the moved package's "package" declaration to its new base name.
+	pkg, ok := m.iprog.Imported[m.from]
+	if !ok {
+		log.Fatalf("unexpected: package %s is not in import map", m.from)
+	}
+	newName := filepath.Base(m.to)
+	for _, f := range pkg.Files {
+		// Update all import comments.
+		for _, cg := range f.Comments {
+			c := cg.List[0]
+			if c.Slash >= f.Name.End() &&
+				sameLine(m.iprog.Fset, c.Slash, f.Name.End()) &&
+				(f.Decls == nil || c.Slash < f.Decls[0].Pos()) {
+				if strings.HasPrefix(c.Text, `// import "`) {
+					c.Text = `// import "` + m.to + `"`
+					break
+				}
+				if strings.HasPrefix(c.Text, `/* import "`) {
+					c.Text = `/* import "` + m.to + `" */`
+					break
+				}
+			}
+		}
+		f.Name.Name = newName // change package decl
+		filesToUpdate[f] = true
+	}
+
+	// Look through the external test packages (m.iprog.Created contains the external test packages).
+	for _, info := range m.iprog.Created {
+		// Change the "package" declaration of the external test package.
+		if info.Pkg.Path() == m.from+"_test" {
+			for _, f := range info.Files {
+				f.Name.Name = newName + "_test" // change package decl
+				filesToUpdate[f] = true
+			}
+		}
+
+		// Mark all the loaded external test packages, which import the "from" package,
+		// as affected packages and update the imports.
+		for _, imp := range info.Pkg.Imports() {
+			if imp.Path() == m.from {
+				m.affectedPackages[info.Pkg.Path()] = true
+				m.iprog.Imported[info.Pkg.Path()] = info
+				if err := importName(m.iprog, info, m.from, path.Base(m.from), newName); err != nil {
+					return err
+				}
+			}
+		}
+	}
+
+	// Update imports of that package to use the new import name.
+	// None of the subpackages will change their name---only the from package
+	// itself will.
+	for p := range m.rev[m.from] {
+		if err := importName(m.iprog, m.iprog.Imported[p], m.from, path.Base(m.from), newName); err != nil {
+			return err
+		}
+	}
+
+	// Update import paths for all imports by affected packages.
+	for ap := range m.affectedPackages {
+		info, ok := m.iprog.Imported[ap]
+		if !ok {
+			log.Fatalf("unexpected: package %s is not in import map", ap)
+		}
+		for _, f := range info.Files {
+			for _, imp := range f.Imports {
+				importPath, _ := strconv.Unquote(imp.Path.Value)
+				if newPath, ok := m.destinations[importPath]; ok {
+					imp.Path.Value = strconv.Quote(newPath)
+
+					oldName := path.Base(importPath)
+					if imp.Name != nil {
+						oldName = imp.Name.Name
+					}
+
+					newName := path.Base(newPath)
+					if imp.Name == nil && oldName != newName {
+						imp.Name = ast.NewIdent(oldName)
+					} else if imp.Name == nil || imp.Name.Name == newName {
+						imp.Name = nil
+					}
+					filesToUpdate[f] = true
+				}
+			}
+		}
+	}
+
+	for f := range filesToUpdate {
+		var buf bytes.Buffer
+		if err := format.Node(&buf, m.iprog.Fset, f); err != nil {
+			log.Printf("failed to pretty-print syntax tree: %v", err)
+			continue
+		}
+		tokenFile := m.iprog.Fset.File(f.Pos())
+		writeFile(tokenFile.Name(), buf.Bytes())
+	}
+
+	// Move the directories.
+	// If either the fromDir or toDir are contained under version control it is
+	// the user's responsibility to provide a custom move command that updates
+	// version control to reflect the move.
+	// TODO(matloob): If the parent directory of toDir does not exist, create it.
+	//      For now, it's required that it does exist.
+
+	if m.cmd != "" {
+		// TODO(matloob): Verify that the windows and plan9 cases are correct.
+		var cmd *exec.Cmd
+		switch runtime.GOOS {
+		case "windows":
+			cmd = exec.Command("cmd", "/c", m.cmd)
+		case "plan9":
+			cmd = exec.Command("rc", "-c", m.cmd)
+		default:
+			cmd = exec.Command("sh", "-c", m.cmd)
+		}
+		cmd.Stderr = os.Stderr
+		cmd.Stdout = os.Stdout
+		if err := cmd.Run(); err != nil {
+			return fmt.Errorf("version control system's move command failed: %v", err)
+		}
+
+		return nil
+	}
+
+	return moveDirectory(m.fromDir, m.toDir)
+}
+
+// sameLine reports whether two positions in the same file are on the same line.
+func sameLine(fset *token.FileSet, x, y token.Pos) bool {
+	return fset.Position(x).Line == fset.Position(y).Line
+}
+
+var moveDirectory = func(from, to string) error {
+	return os.Rename(from, to)
+}

vendor/golang.org/x/tools/refactor/rename/mvpkg_test.go

@@ -0,0 +1,463 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// licence that can be found in the LICENSE file.
+
+package rename
+
+import (
+	"fmt"
+	"go/build"
+	"go/token"
+	"io/ioutil"
+	"path/filepath"
+	"reflect"
+	"regexp"
+	"runtime"
+	"strings"
+	"testing"
+
+	"golang.org/x/tools/go/buildutil"
+)
+
+func TestErrors(t *testing.T) {
+	tests := []struct {
+		ctxt     *build.Context
+		from, to string
+		want     string // regexp to match error, or "OK"
+	}{
+		// Simple example.
+		{
+			ctxt: fakeContext(map[string][]string{
+				"foo": {`package foo; type T int`},
+				"bar": {`package bar`},
+				"main": {`package main
+
+import "foo"
+
+var _ foo.T
+`},
+			}),
+			from: "foo", to: "bar",
+			want: `invalid move destination: bar conflicts with directory .go.src.bar`,
+		},
+		// Subpackage already exists.
+		{
+			ctxt: fakeContext(map[string][]string{
+				"foo":     {`package foo; type T int`},
+				"foo/sub": {`package sub`},
+				"bar/sub": {`package sub`},
+				"main": {`package main
+
+import "foo"
+
+var _ foo.T
+`},
+			}),
+			from: "foo", to: "bar",
+			want: "invalid move destination: bar; package or subpackage bar/sub already exists",
+		},
+		// Invalid base name.
+		{
+			ctxt: fakeContext(map[string][]string{
+				"foo": {`package foo; type T int`},
+				"main": {`package main
+
+import "foo"
+
+var _ foo.T
+`},
+			}),
+			from: "foo", to: "bar-v2.0",
+			want: "invalid move destination: bar-v2.0; gomvpkg does not " +
+				"support move destinations whose base names are not valid " +
+				"go identifiers",
+		},
+		{
+			ctxt: fakeContext(map[string][]string{
+				"foo": {``},
+				"bar": {`package bar`},
+			}),
+			from: "foo", to: "bar",
+			want: `no initial packages were loaded`,
+		},
+	}
+
+	for _, test := range tests {
+		ctxt := test.ctxt
+
+		got := make(map[string]string)
+		writeFile = func(filename string, content []byte) error {
+			got[filename] = string(content)
+			return nil
+		}
+		moveDirectory = func(from, to string) error {
+			for path, contents := range got {
+				if strings.HasPrefix(path, from) {
+					newPath := strings.Replace(path, from, to, 1)
+					delete(got, path)
+					got[newPath] = contents
+				}
+			}
+			return nil
+		}
+
+		err := Move(ctxt, test.from, test.to, "")
+		prefix := fmt.Sprintf("-from %q -to %q", test.from, test.to)
+		if err == nil {
+			t.Errorf("%s: nil error. Expected error: %s", prefix, test.want)
+			continue
+		}
+		matched, err2 := regexp.MatchString(test.want, err.Error())
+		if err2 != nil {
+			t.Errorf("regexp.MatchString failed %s", err2)
+			continue
+		}
+		if !matched {
+			t.Errorf("%s: conflict does not match expectation:\n"+
+				"Error: %q\n"+
+				"Pattern: %q",
+				prefix, err.Error(), test.want)
+		}
+	}
+}
+
+func TestMoves(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("broken on Windows; see golang.org/issue/16384")
+	}
+	tests := []struct {
+		ctxt         *build.Context
+		from, to     string
+		want         map[string]string
+		wantWarnings []string
+	}{
+		// Simple example.
+		{
+			ctxt: fakeContext(map[string][]string{
+				"foo": {`package foo; type T int`},
+				"main": {`package main
+
+import "foo"
+
+var _ foo.T
+`},
+			}),
+			from: "foo", to: "bar",
+			want: map[string]string{
+				"/go/src/main/0.go": `package main
+
+import "bar"
+
+var _ bar.T
+`,
+				"/go/src/bar/0.go": `package bar
+
+type T int
+`,
+			},
+		},
+
+		// Example with subpackage.
+		{
+			ctxt: fakeContext(map[string][]string{
+				"foo":     {`package foo; type T int`},
+				"foo/sub": {`package sub; type T int`},
+				"main": {`package main
+
+import "foo"
+import "foo/sub"
+
+var _ foo.T
+var _ sub.T
+`},
+			}),
+			from: "foo", to: "bar",
+			want: map[string]string{
+				"/go/src/main/0.go": `package main
+
+import "bar"
+import "bar/sub"
+
+var _ bar.T
+var _ sub.T
+`,
+				"/go/src/bar/0.go": `package bar
+
+type T int
+`,
+				"/go/src/bar/sub/0.go": `package sub; type T int`,
+			},
+		},
+
+		// References into subpackages
+		{
+			ctxt: fakeContext(map[string][]string{
+				"foo":   {`package foo; import "foo/a"; var _ a.T`},
+				"foo/a": {`package a; type T int`},
+				"foo/b": {`package b; import "foo/a"; var _ a.T`},
+			}),
+			from: "foo", to: "bar",
+			want: map[string]string{
+				"/go/src/bar/0.go": `package bar
+
+import "bar/a"
+
+var _ a.T
+`,
+				"/go/src/bar/a/0.go": `package a; type T int`,
+				"/go/src/bar/b/0.go": `package b
+
+import "bar/a"
+
+var _ a.T
+`,
+			},
+		},
+
+		// References into subpackages where directories have overlapped names
+		{
+			ctxt: fakeContext(map[string][]string{
+				"foo":    {},
+				"foo/a":  {`package a`},
+				"foo/aa": {`package bar`},
+				"foo/c":  {`package c; import _ "foo/bar";`},
+			}),
+			from: "foo/a", to: "foo/spam",
+			want: map[string]string{
+				"/go/src/foo/spam/0.go": `package spam
+`,
+				"/go/src/foo/aa/0.go": `package bar`,
+				"/go/src/foo/c/0.go":  `package c; import _ "foo/bar";`,
+			},
+		},
+
+		// External test packages
+		{
+			ctxt: buildutil.FakeContext(map[string]map[string]string{
+				"foo": {
+					"0.go":      `package foo; type T int`,
+					"0_test.go": `package foo_test; import "foo"; var _ foo.T`,
+				},
+				"baz": {
+					"0_test.go": `package baz_test; import "foo"; var _ foo.T`,
+				},
+			}),
+			from: "foo", to: "bar",
+			want: map[string]string{
+				"/go/src/bar/0.go": `package bar
+
+type T int
+`,
+				"/go/src/bar/0_test.go": `package bar_test
+
+import "bar"
+
+var _ bar.T
+`,
+				"/go/src/baz/0_test.go": `package baz_test
+
+import "bar"
+
+var _ bar.T
+`,
+			},
+		},
+		// package import comments
+		{
+			ctxt: fakeContext(map[string][]string{"foo": {`package foo // import "baz"`}}),
+			from: "foo", to: "bar",
+			want: map[string]string{"/go/src/bar/0.go": `package bar // import "bar"
+`},
+		},
+		{
+			ctxt: fakeContext(map[string][]string{"foo": {`package foo /* import "baz" */`}}),
+			from: "foo", to: "bar",
+			want: map[string]string{"/go/src/bar/0.go": `package bar /* import "bar" */
+`},
+		},
+		{
+			ctxt: fakeContext(map[string][]string{"foo": {`package foo       // import "baz"`}}),
+			from: "foo", to: "bar",
+			want: map[string]string{"/go/src/bar/0.go": `package bar // import "bar"
+`},
+		},
+		{
+			ctxt: fakeContext(map[string][]string{"foo": {`package foo
+// import " this is not an import comment`}}),
+			from: "foo", to: "bar",
+			want: map[string]string{"/go/src/bar/0.go": `package bar
+
+// import " this is not an import comment
+`},
+		},
+		{
+			ctxt: fakeContext(map[string][]string{"foo": {`package foo
+/* import " this is not an import comment */`}}),
+			from: "foo", to: "bar",
+			want: map[string]string{"/go/src/bar/0.go": `package bar
+
+/* import " this is not an import comment */
+`},
+		},
+		// Import name conflict generates a warning, not an error.
+		{
+			ctxt: fakeContext(map[string][]string{
+				"x": {},
+				"a": {`package a; type A int`},
+				"b": {`package b; type B int`},
+				"conflict": {`package conflict
+
+import "a"
+import "b"
+var _ a.A
+var _ b.B
+`},
+				"ok": {`package ok
+import "b"
+var _ b.B
+`},
+			}),
+			from: "b", to: "x/a",
+			want: map[string]string{
+				"/go/src/a/0.go": `package a; type A int`,
+				"/go/src/ok/0.go": `package ok
+
+import "x/a"
+
+var _ a.B
+`,
+				"/go/src/conflict/0.go": `package conflict
+
+import "a"
+import "x/a"
+
+var _ a.A
+var _ b.B
+`,
+				"/go/src/x/a/0.go": `package a
+
+type B int
+`,
+			},
+			wantWarnings: []string{
+				`/go/src/conflict/0.go:4:8: renaming this imported package name "b" to "a"`,
+				`/go/src/conflict/0.go:3:8: 	conflicts with imported package name in same block`,
+				`/go/src/conflict/0.go:3:8: skipping update of this file`,
+			},
+		},
+		// Rename with same base name.
+		{
+			ctxt: fakeContext(map[string][]string{
+				"x": {},
+				"y": {},
+				"x/foo": {`package foo
+
+type T int
+`},
+				"main": {`package main; import "x/foo"; var _ foo.T`},
+			}),
+			from: "x/foo", to: "y/foo",
+			want: map[string]string{
+				"/go/src/y/foo/0.go": `package foo
+
+type T int
+`,
+				"/go/src/main/0.go": `package main
+
+import "y/foo"
+
+var _ foo.T
+`,
+			},
+		},
+	}
+
+	for _, test := range tests {
+		ctxt := test.ctxt
+
+		got := make(map[string]string)
+		// Populate got with starting file set. rewriteFile and moveDirectory
+		// will mutate got to produce resulting file set.
+		buildutil.ForEachPackage(ctxt, func(importPath string, err error) {
+			if err != nil {
+				return
+			}
+			path := filepath.Join("/go/src", importPath, "0.go")
+			if !buildutil.FileExists(ctxt, path) {
+				return
+			}
+			f, err := ctxt.OpenFile(path)
+			if err != nil {
+				t.Errorf("unexpected error opening file: %s", err)
+				return
+			}
+			bytes, err := ioutil.ReadAll(f)
+			f.Close()
+			if err != nil {
+				t.Errorf("unexpected error reading file: %s", err)
+				return
+			}
+			got[path] = string(bytes)
+		})
+		var warnings []string
+		reportError = func(posn token.Position, message string) {
+			warning := fmt.Sprintf("%s:%d:%d: %s",
+				filepath.ToSlash(posn.Filename), // for MS Windows
+				posn.Line,
+				posn.Column,
+				message)
+			warnings = append(warnings, warning)
+
+		}
+		writeFile = func(filename string, content []byte) error {
+			got[filename] = string(content)
+			return nil
+		}
+		moveDirectory = func(from, to string) error {
+			for path, contents := range got {
+				if !(strings.HasPrefix(path, from) &&
+					(len(path) == len(from) || path[len(from)] == filepath.Separator)) {
+					continue
+				}
+				newPath := strings.Replace(path, from, to, 1)
+				delete(got, path)
+				got[newPath] = contents
+			}
+			return nil
+		}
+
+		err := Move(ctxt, test.from, test.to, "")
+		prefix := fmt.Sprintf("-from %q -to %q", test.from, test.to)
+		if err != nil {
+			t.Errorf("%s: unexpected error: %s", prefix, err)
+			continue
+		}
+
+		if !reflect.DeepEqual(warnings, test.wantWarnings) {
+			t.Errorf("%s: unexpected warnings:\n%s\nwant:\n%s",
+				prefix,
+				strings.Join(warnings, "\n"),
+				strings.Join(test.wantWarnings, "\n"))
+		}
+
+		for file, wantContent := range test.want {
+			k := filepath.FromSlash(file)
+			gotContent, ok := got[k]
+			delete(got, k)
+			if !ok {
+				// TODO(matloob): some testcases might have files that won't be
+				// rewritten
+				t.Errorf("%s: file %s not rewritten", prefix, file)
+				continue
+			}
+			if gotContent != wantContent {
+				t.Errorf("%s: rewritten file %s does not match expectation; got <<<%s>>>\n"+
+					"want <<<%s>>>", prefix, file, gotContent, wantContent)
+			}
+		}
+		// got should now be empty
+		for file := range got {
+			t.Errorf("%s: unexpected rewrite of file %s", prefix, file)
+		}
+	}
+}

vendor/golang.org/x/tools/refactor/rename/rename.go

@@ -0,0 +1,603 @@
+// Copyright 2014 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 rename contains the implementation of the 'gorename' command
+// whose main function is in golang.org/x/tools/cmd/gorename.
+// See the Usage constant for the command documentation.
+package rename // import "golang.org/x/tools/refactor/rename"
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/format"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/go/types/typeutil"
+	"golang.org/x/tools/refactor/importgraph"
+	"golang.org/x/tools/refactor/satisfy"
+)
+
+const Usage = `gorename: precise type-safe renaming of identifiers in Go source code.
+
+Usage:
+
+ gorename (-from <spec> | -offset <file>:#<byte-offset>) -to <name> [-force]
+
+You must specify the object (named entity) to rename using the -offset
+or -from flag.  Exactly one must be specified.
+
+Flags:
+
+-offset    specifies the filename and byte offset of an identifier to rename.
+           This form is intended for use by text editors.
+
+-from      specifies the object to rename using a query notation;
+           This form is intended for interactive use at the command line.
+           A legal -from query has one of the following forms:
+
+  "encoding/json".Decoder.Decode        method of package-level named type
+  (*"encoding/json".Decoder).Decode     ditto, alternative syntax
+  "encoding/json".Decoder.buf           field of package-level named struct type
+  "encoding/json".HTMLEscape            package member (const, func, var, type)
+  "encoding/json".Decoder.Decode::x     local object x within a method
+  "encoding/json".HTMLEscape::x         local object x within a function
+  "encoding/json"::x                    object x anywhere within a package
+  json.go::x                            object x within file json.go
+
+           Double-quotes must be escaped when writing a shell command.
+           Quotes may be omitted for single-segment import paths such as "fmt".
+
+           For methods, the parens and '*' on the receiver type are both
+           optional.
+
+           It is an error if one of the ::x queries matches multiple
+           objects.
+
+-to        the new name.
+
+-force     causes the renaming to proceed even if conflicts were reported.
+           The resulting program may be ill-formed, or experience a change
+           in behaviour.
+
+           WARNING: this flag may even cause the renaming tool to crash.
+           (In due course this bug will be fixed by moving certain
+           analyses into the type-checker.)
+
+-d         display diffs instead of rewriting files
+
+-v         enables verbose logging.
+
+gorename automatically computes the set of packages that might be
+affected.  For a local renaming, this is just the package specified by
+-from or -offset, but for a potentially exported name, gorename scans
+the workspace ($GOROOT and $GOPATH).
+
+gorename rejects renamings of concrete methods that would change the
+assignability relation between types and interfaces.  If the interface
+change was intentional, initiate the renaming at the interface method.
+
+gorename rejects any renaming that would create a conflict at the point
+of declaration, or a reference conflict (ambiguity or shadowing), or
+anything else that could cause the resulting program not to compile.
+
+
+Examples:
+
+$ gorename -offset file.go:#123 -to foo
+
+  Rename the object whose identifier is at byte offset 123 within file file.go.
+
+$ gorename -from '"bytes".Buffer.Len' -to Size
+
+  Rename the "Len" method of the *bytes.Buffer type to "Size".
+
+---- TODO ----
+
+Correctness:
+- handle dot imports correctly
+- document limitations (reflection, 'implements' algorithm).
+- sketch a proof of exhaustiveness.
+
+Features:
+- support running on packages specified as *.go files on the command line
+- support running on programs containing errors (loader.Config.AllowErrors)
+- allow users to specify a scope other than "global" (to avoid being
+  stuck by neglected packages in $GOPATH that don't build).
+- support renaming the package clause (no object)
+- support renaming an import path (no ident or object)
+  (requires filesystem + SCM updates).
+- detect and reject edits to autogenerated files (cgo, protobufs)
+  and optionally $GOROOT packages.
+- report all conflicts, or at least all qualitatively distinct ones.
+  Sometimes we stop to avoid redundancy, but
+  it may give a disproportionate sense of safety in -force mode.
+- support renaming all instances of a pattern, e.g.
+  all receiver vars of a given type,
+  all local variables of a given type,
+  all PkgNames for a given package.
+- emit JSON output for other editors and tools.
+`
+
+var (
+	// Force enables patching of the source files even if conflicts were reported.
+	// The resulting program may be ill-formed.
+	// It may even cause gorename to crash.  TODO(adonovan): fix that.
+	Force bool
+
+	// Diff causes the tool to display diffs instead of rewriting files.
+	Diff bool
+
+	// DiffCmd specifies the diff command used by the -d feature.
+	// (The command must accept a -u flag and two filename arguments.)
+	DiffCmd = "diff"
+
+	// ConflictError is returned by Main when it aborts the renaming due to conflicts.
+	// (It is distinguished because the interesting errors are the conflicts themselves.)
+	ConflictError = errors.New("renaming aborted due to conflicts")
+
+	// Verbose enables extra logging.
+	Verbose bool
+)
+
+var stdout io.Writer = os.Stdout
+
+type renamer struct {
+	iprog              *loader.Program
+	objsToUpdate       map[types.Object]bool
+	hadConflicts       bool
+	from, to           string
+	satisfyConstraints map[satisfy.Constraint]bool
+	packages           map[*types.Package]*loader.PackageInfo // subset of iprog.AllPackages to inspect
+	msets              typeutil.MethodSetCache
+	changeMethods      bool
+}
+
+var reportError = func(posn token.Position, message string) {
+	fmt.Fprintf(os.Stderr, "%s: %s\n", posn, message)
+}
+
+// importName renames imports of fromPath within the package specified by info.
+// If fromName is not empty, importName renames only imports as fromName.
+// If the renaming would lead to a conflict, the file is left unchanged.
+func importName(iprog *loader.Program, info *loader.PackageInfo, fromPath, fromName, to string) error {
+	if fromName == to {
+		return nil // no-op (e.g. rename x/foo to y/foo)
+	}
+	for _, f := range info.Files {
+		var from types.Object
+		for _, imp := range f.Imports {
+			importPath, _ := strconv.Unquote(imp.Path.Value)
+			importName := path.Base(importPath)
+			if imp.Name != nil {
+				importName = imp.Name.Name
+			}
+			if importPath == fromPath && (fromName == "" || importName == fromName) {
+				from = info.Implicits[imp]
+				break
+			}
+		}
+		if from == nil {
+			continue
+		}
+		r := renamer{
+			iprog:        iprog,
+			objsToUpdate: make(map[types.Object]bool),
+			to:           to,
+			packages:     map[*types.Package]*loader.PackageInfo{info.Pkg: info},
+		}
+		r.check(from)
+		if r.hadConflicts {
+			reportError(iprog.Fset.Position(f.Imports[0].Pos()),
+				"skipping update of this file")
+			continue // ignore errors; leave the existing name
+		}
+		if err := r.update(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func Main(ctxt *build.Context, offsetFlag, fromFlag, to string) error {
+	// -- Parse the -from or -offset specifier ----------------------------
+
+	if (offsetFlag == "") == (fromFlag == "") {
+		return fmt.Errorf("exactly one of the -from and -offset flags must be specified")
+	}
+
+	if !isValidIdentifier(to) {
+		return fmt.Errorf("-to %q: not a valid identifier", to)
+	}
+
+	if Diff {
+		defer func(saved func(string, []byte) error) { writeFile = saved }(writeFile)
+		writeFile = diff
+	}
+
+	var spec *spec
+	var err error
+	if fromFlag != "" {
+		spec, err = parseFromFlag(ctxt, fromFlag)
+	} else {
+		spec, err = parseOffsetFlag(ctxt, offsetFlag)
+	}
+	if err != nil {
+		return err
+	}
+
+	if spec.fromName == to {
+		return fmt.Errorf("the old and new names are the same: %s", to)
+	}
+
+	// -- Load the program consisting of the initial package  -------------
+
+	iprog, err := loadProgram(ctxt, map[string]bool{spec.pkg: true})
+	if err != nil {
+		return err
+	}
+
+	fromObjects, err := findFromObjects(iprog, spec)
+	if err != nil {
+		return err
+	}
+
+	// -- Load a larger program, for global renamings ---------------------
+
+	if requiresGlobalRename(fromObjects, to) {
+		// For a local refactoring, we needn't load more
+		// packages, but if the renaming affects the package's
+		// API, we we must load all packages that depend on the
+		// package defining the object, plus their tests.
+
+		if Verbose {
+			log.Print("Potentially global renaming; scanning workspace...")
+		}
+
+		// Scan the workspace and build the import graph.
+		_, rev, errors := importgraph.Build(ctxt)
+		if len(errors) > 0 {
+			// With a large GOPATH tree, errors are inevitable.
+			// Report them but proceed.
+			fmt.Fprintf(os.Stderr, "While scanning Go workspace:\n")
+			for path, err := range errors {
+				fmt.Fprintf(os.Stderr, "Package %q: %s.\n", path, err)
+			}
+		}
+
+		// Enumerate the set of potentially affected packages.
+		affectedPackages := make(map[string]bool)
+		for _, obj := range fromObjects {
+			// External test packages are never imported,
+			// so they will never appear in the graph.
+			for path := range rev.Search(obj.Pkg().Path()) {
+				affectedPackages[path] = true
+			}
+		}
+
+		// TODO(adonovan): allow the user to specify the scope,
+		// or -ignore patterns?  Computing the scope when we
+		// don't (yet) support inputs containing errors can make
+		// the tool rather brittle.
+
+		// Re-load the larger program.
+		iprog, err = loadProgram(ctxt, affectedPackages)
+		if err != nil {
+			return err
+		}
+
+		fromObjects, err = findFromObjects(iprog, spec)
+		if err != nil {
+			return err
+		}
+	}
+
+	// -- Do the renaming -------------------------------------------------
+
+	r := renamer{
+		iprog:        iprog,
+		objsToUpdate: make(map[types.Object]bool),
+		from:         spec.fromName,
+		to:           to,
+		packages:     make(map[*types.Package]*loader.PackageInfo),
+	}
+
+	// A renaming initiated at an interface method indicates the
+	// intention to rename abstract and concrete methods as needed
+	// to preserve assignability.
+	for _, obj := range fromObjects {
+		if obj, ok := obj.(*types.Func); ok {
+			recv := obj.Type().(*types.Signature).Recv()
+			if recv != nil && isInterface(recv.Type().Underlying()) {
+				r.changeMethods = true
+				break
+			}
+		}
+	}
+
+	// Only the initially imported packages (iprog.Imported) and
+	// their external tests (iprog.Created) should be inspected or
+	// modified, as only they have type-checked functions bodies.
+	// The rest are just dependencies, needed only for package-level
+	// type information.
+	for _, info := range iprog.Imported {
+		r.packages[info.Pkg] = info
+	}
+	for _, info := range iprog.Created { // (tests)
+		r.packages[info.Pkg] = info
+	}
+
+	for _, from := range fromObjects {
+		r.check(from)
+	}
+	if r.hadConflicts && !Force {
+		return ConflictError
+	}
+	return r.update()
+}
+
+// loadProgram loads the specified set of packages (plus their tests)
+// and all their dependencies, from source, through the specified build
+// context.  Only packages in pkgs will have their functions bodies typechecked.
+func loadProgram(ctxt *build.Context, pkgs map[string]bool) (*loader.Program, error) {
+	conf := loader.Config{
+		Build:      ctxt,
+		ParserMode: parser.ParseComments,
+
+		// TODO(adonovan): enable this.  Requires making a lot of code more robust!
+		AllowErrors: false,
+	}
+	// Optimization: don't type-check the bodies of functions in our
+	// dependencies, since we only need exported package members.
+	conf.TypeCheckFuncBodies = func(p string) bool {
+		return pkgs[p] || pkgs[strings.TrimSuffix(p, "_test")]
+	}
+
+	if Verbose {
+		var list []string
+		for pkg := range pkgs {
+			list = append(list, pkg)
+		}
+		sort.Strings(list)
+		for _, pkg := range list {
+			log.Printf("Loading package: %s", pkg)
+		}
+	}
+
+	for pkg := range pkgs {
+		conf.ImportWithTests(pkg)
+	}
+
+	// Ideally we would just return conf.Load() here, but go/types
+	// reports certain "soft" errors that gc does not (Go issue 14596).
+	// As a workaround, we set AllowErrors=true and then duplicate
+	// the loader's error checking but allow soft errors.
+	// It would be nice if the loader API permitted "AllowErrors: soft".
+	conf.AllowErrors = true
+	prog, err := conf.Load()
+	if err != nil {
+		return nil, err
+	}
+
+	var errpkgs []string
+	// Report hard errors in indirectly imported packages.
+	for _, info := range prog.AllPackages {
+		if containsHardErrors(info.Errors) {
+			errpkgs = append(errpkgs, info.Pkg.Path())
+		}
+	}
+	if errpkgs != nil {
+		var more string
+		if len(errpkgs) > 3 {
+			more = fmt.Sprintf(" and %d more", len(errpkgs)-3)
+			errpkgs = errpkgs[:3]
+		}
+		return nil, fmt.Errorf("couldn't load packages due to errors: %s%s",
+			strings.Join(errpkgs, ", "), more)
+	}
+	return prog, nil
+}
+
+func containsHardErrors(errors []error) bool {
+	for _, err := range errors {
+		if err, ok := err.(types.Error); ok && err.Soft {
+			continue
+		}
+		return true
+	}
+	return false
+}
+
+// requiresGlobalRename reports whether this renaming could potentially
+// affect other packages in the Go workspace.
+func requiresGlobalRename(fromObjects []types.Object, to string) bool {
+	var tfm bool
+	for _, from := range fromObjects {
+		if from.Exported() {
+			return true
+		}
+		switch objectKind(from) {
+		case "type", "field", "method":
+			tfm = true
+		}
+	}
+	if ast.IsExported(to) && tfm {
+		// A global renaming may be necessary even if we're
+		// exporting a previous unexported name, since if it's
+		// the name of a type, field or method, this could
+		// change selections in other packages.
+		// (We include "type" in this list because a type
+		// used as an embedded struct field entails a field
+		// renaming.)
+		return true
+	}
+	return false
+}
+
+// update updates the input files.
+func (r *renamer) update() error {
+	// We use token.File, not filename, since a file may appear to
+	// belong to multiple packages and be parsed more than once.
+	// token.File captures this distinction; filename does not.
+
+	var nidents int
+	var filesToUpdate = make(map[*token.File]bool)
+	docRegexp := regexp.MustCompile(`\b` + r.from + `\b`)
+	for _, info := range r.packages {
+		// Mutate the ASTs and note the filenames.
+		for id, obj := range info.Defs {
+			if r.objsToUpdate[obj] {
+				nidents++
+				id.Name = r.to
+				filesToUpdate[r.iprog.Fset.File(id.Pos())] = true
+				// Perform the rename in doc comments too.
+				if doc := r.docComment(id); doc != nil {
+					for _, comment := range doc.List {
+						comment.Text = docRegexp.ReplaceAllString(comment.Text, r.to)
+					}
+				}
+			}
+		}
+
+		for id, obj := range info.Uses {
+			if r.objsToUpdate[obj] {
+				nidents++
+				id.Name = r.to
+				filesToUpdate[r.iprog.Fset.File(id.Pos())] = true
+			}
+		}
+	}
+
+	// Renaming not supported if cgo files are affected.
+	var generatedFileNames []string
+	for _, info := range r.packages {
+		for _, f := range info.Files {
+			tokenFile := r.iprog.Fset.File(f.Pos())
+			if filesToUpdate[tokenFile] && generated(f, tokenFile) {
+				generatedFileNames = append(generatedFileNames, tokenFile.Name())
+			}
+		}
+	}
+	if !Force && len(generatedFileNames) > 0 {
+		return fmt.Errorf("refusing to modify generated file%s containing DO NOT EDIT marker: %v", plural(len(generatedFileNames)), generatedFileNames)
+	}
+
+	// Write affected files.
+	var nerrs, npkgs int
+	for _, info := range r.packages {
+		first := true
+		for _, f := range info.Files {
+			tokenFile := r.iprog.Fset.File(f.Pos())
+			if filesToUpdate[tokenFile] {
+				if first {
+					npkgs++
+					first = false
+					if Verbose {
+						log.Printf("Updating package %s", info.Pkg.Path())
+					}
+				}
+
+				filename := tokenFile.Name()
+				var buf bytes.Buffer
+				if err := format.Node(&buf, r.iprog.Fset, f); err != nil {
+					log.Printf("failed to pretty-print syntax tree: %v", err)
+					nerrs++
+					continue
+				}
+				if err := writeFile(filename, buf.Bytes()); err != nil {
+					log.Print(err)
+					nerrs++
+				}
+			}
+		}
+	}
+	if !Diff {
+		fmt.Printf("Renamed %d occurrence%s in %d file%s in %d package%s.\n",
+			nidents, plural(nidents),
+			len(filesToUpdate), plural(len(filesToUpdate)),
+			npkgs, plural(npkgs))
+	}
+	if nerrs > 0 {
+		return fmt.Errorf("failed to rewrite %d file%s", nerrs, plural(nerrs))
+	}
+	return nil
+}
+
+// docComment returns the doc for an identifier.
+func (r *renamer) docComment(id *ast.Ident) *ast.CommentGroup {
+	_, nodes, _ := r.iprog.PathEnclosingInterval(id.Pos(), id.End())
+	for _, node := range nodes {
+		switch decl := node.(type) {
+		case *ast.FuncDecl:
+			return decl.Doc
+		case *ast.Field:
+			return decl.Doc
+		case *ast.GenDecl:
+			return decl.Doc
+		// For {Type,Value}Spec, if the doc on the spec is absent,
+		// search for the enclosing GenDecl
+		case *ast.TypeSpec:
+			if decl.Doc != nil {
+				return decl.Doc
+			}
+		case *ast.ValueSpec:
+			if decl.Doc != nil {
+				return decl.Doc
+			}
+		case *ast.Ident:
+		default:
+			return nil
+		}
+	}
+	return nil
+}
+
+func plural(n int) string {
+	if n != 1 {
+		return "s"
+	}
+	return ""
+}
+
+// writeFile is a seam for testing and for the -d flag.
+var writeFile = reallyWriteFile
+
+func reallyWriteFile(filename string, content []byte) error {
+	return ioutil.WriteFile(filename, content, 0644)
+}
+
+func diff(filename string, content []byte) error {
+	renamed := fmt.Sprintf("%s.%d.renamed", filename, os.Getpid())
+	if err := ioutil.WriteFile(renamed, content, 0644); err != nil {
+		return err
+	}
+	defer os.Remove(renamed)
+
+	diff, err := exec.Command(DiffCmd, "-u", filename, renamed).CombinedOutput()
+	if len(diff) > 0 {
+		// diff exits with a non-zero status when the files don't match.
+		// Ignore that failure as long as we get output.
+		stdout.Write(diff)
+		return nil
+	}
+	if err != nil {
+		return fmt.Errorf("computing diff: %v", err)
+	}
+	return nil
+}

vendor/golang.org/x/tools/refactor/rename/spec.go

@@ -0,0 +1,593 @@
+// Copyright 2014 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 rename
+
+// This file contains logic related to specifying a renaming: parsing of
+// the flags as a form of query, and finding the object(s) it denotes.
+// See Usage for flag details.
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"log"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/go/buildutil"
+	"golang.org/x/tools/go/loader"
+)
+
+// A spec specifies an entity to rename.
+//
+// It is populated from an -offset flag or -from query;
+// see Usage for the allowed -from query forms.
+//
+type spec struct {
+	// pkg is the package containing the position
+	// specified by the -from or -offset flag.
+	// If filename == "", our search for the 'from' entity
+	// is restricted to this package.
+	pkg string
+
+	// The original name of the entity being renamed.
+	// If the query had a ::from component, this is that;
+	// otherwise it's the last segment, e.g.
+	//   (encoding/json.Decoder).from
+	//   encoding/json.from
+	fromName string
+
+	// -- The remaining fields are private to this file.  All are optional. --
+
+	// The query's ::x suffix, if any.
+	searchFor string
+
+	// e.g. "Decoder" in "(encoding/json.Decoder).fieldOrMethod"
+	//                or "encoding/json.Decoder
+	pkgMember string
+
+	// e.g. fieldOrMethod in "(encoding/json.Decoder).fieldOrMethod"
+	typeMember string
+
+	// Restricts the query to this file.
+	// Implied by -from="file.go::x" and -offset flags.
+	filename string
+
+	// Byte offset of the 'from' identifier within the file named 'filename'.
+	// -offset mode only.
+	offset int
+}
+
+// parseFromFlag interprets the "-from" flag value as a renaming specification.
+// See Usage in rename.go for valid formats.
+func parseFromFlag(ctxt *build.Context, fromFlag string) (*spec, error) {
+	var spec spec
+	var main string // sans "::x" suffix
+	switch parts := strings.Split(fromFlag, "::"); len(parts) {
+	case 1:
+		main = parts[0]
+	case 2:
+		main = parts[0]
+		spec.searchFor = parts[1]
+		if parts[1] == "" {
+			// error
+		}
+	default:
+		return nil, fmt.Errorf("-from %q: invalid identifier specification (see -help for formats)", fromFlag)
+	}
+
+	if strings.HasSuffix(main, ".go") {
+		// main is "filename.go"
+		if spec.searchFor == "" {
+			return nil, fmt.Errorf("-from: filename %q must have a ::name suffix", main)
+		}
+		spec.filename = main
+		if !buildutil.FileExists(ctxt, spec.filename) {
+			return nil, fmt.Errorf("no such file: %s", spec.filename)
+		}
+
+		bp, err := buildutil.ContainingPackage(ctxt, wd, spec.filename)
+		if err != nil {
+			return nil, err
+		}
+		spec.pkg = bp.ImportPath
+
+	} else {
+		// main is one of:
+		//  "importpath"
+		//  "importpath".member
+		//  (*"importpath".type).fieldormethod           (parens and star optional)
+		if err := parseObjectSpec(&spec, main); err != nil {
+			return nil, err
+		}
+	}
+
+	if spec.searchFor != "" {
+		spec.fromName = spec.searchFor
+	}
+
+	cwd, err := os.Getwd()
+	if err != nil {
+		return nil, err
+	}
+
+	// Sanitize the package.
+	bp, err := ctxt.Import(spec.pkg, cwd, build.FindOnly)
+	if err != nil {
+		return nil, fmt.Errorf("can't find package %q", spec.pkg)
+	}
+	spec.pkg = bp.ImportPath
+
+	if !isValidIdentifier(spec.fromName) {
+		return nil, fmt.Errorf("-from: invalid identifier %q", spec.fromName)
+	}
+
+	if Verbose {
+		log.Printf("-from spec: %+v", spec)
+	}
+
+	return &spec, nil
+}
+
+// parseObjectSpec parses main as one of the non-filename forms of
+// object specification.
+func parseObjectSpec(spec *spec, main string) error {
+	// Parse main as a Go expression, albeit a strange one.
+	e, _ := parser.ParseExpr(main)
+
+	if pkg := parseImportPath(e); pkg != "" {
+		// e.g. bytes or "encoding/json": a package
+		spec.pkg = pkg
+		if spec.searchFor == "" {
+			return fmt.Errorf("-from %q: package import path %q must have a ::name suffix",
+				main, main)
+		}
+		return nil
+	}
+
+	if e, ok := e.(*ast.SelectorExpr); ok {
+		x := unparen(e.X)
+
+		// Strip off star constructor, if any.
+		if star, ok := x.(*ast.StarExpr); ok {
+			x = star.X
+		}
+
+		if pkg := parseImportPath(x); pkg != "" {
+			// package member e.g. "encoding/json".HTMLEscape
+			spec.pkg = pkg              // e.g. "encoding/json"
+			spec.pkgMember = e.Sel.Name // e.g. "HTMLEscape"
+			spec.fromName = e.Sel.Name
+			return nil
+		}
+
+		if x, ok := x.(*ast.SelectorExpr); ok {
+			// field/method of type e.g. ("encoding/json".Decoder).Decode
+			y := unparen(x.X)
+			if pkg := parseImportPath(y); pkg != "" {
+				spec.pkg = pkg               // e.g. "encoding/json"
+				spec.pkgMember = x.Sel.Name  // e.g. "Decoder"
+				spec.typeMember = e.Sel.Name // e.g. "Decode"
+				spec.fromName = e.Sel.Name
+				return nil
+			}
+		}
+	}
+
+	return fmt.Errorf("-from %q: invalid expression", main)
+}
+
+// parseImportPath returns the import path of the package denoted by e.
+// Any import path may be represented as a string literal;
+// single-segment import paths (e.g. "bytes") may also be represented as
+// ast.Ident.  parseImportPath returns "" for all other expressions.
+func parseImportPath(e ast.Expr) string {
+	switch e := e.(type) {
+	case *ast.Ident:
+		return e.Name // e.g. bytes
+
+	case *ast.BasicLit:
+		if e.Kind == token.STRING {
+			pkgname, _ := strconv.Unquote(e.Value)
+			return pkgname // e.g. "encoding/json"
+		}
+	}
+	return ""
+}
+
+// parseOffsetFlag interprets the "-offset" flag value as a renaming specification.
+func parseOffsetFlag(ctxt *build.Context, offsetFlag string) (*spec, error) {
+	var spec spec
+	// Validate -offset, e.g. file.go:#123
+	parts := strings.Split(offsetFlag, ":#")
+	if len(parts) != 2 {
+		return nil, fmt.Errorf("-offset %q: invalid offset specification", offsetFlag)
+	}
+
+	spec.filename = parts[0]
+	if !buildutil.FileExists(ctxt, spec.filename) {
+		return nil, fmt.Errorf("no such file: %s", spec.filename)
+	}
+
+	bp, err := buildutil.ContainingPackage(ctxt, wd, spec.filename)
+	if err != nil {
+		return nil, err
+	}
+	spec.pkg = bp.ImportPath
+
+	for _, r := range parts[1] {
+		if !isDigit(r) {
+			return nil, fmt.Errorf("-offset %q: non-numeric offset", offsetFlag)
+		}
+	}
+	spec.offset, err = strconv.Atoi(parts[1])
+	if err != nil {
+		return nil, fmt.Errorf("-offset %q: non-numeric offset", offsetFlag)
+	}
+
+	// Parse the file and check there's an identifier at that offset.
+	fset := token.NewFileSet()
+	f, err := buildutil.ParseFile(fset, ctxt, nil, wd, spec.filename, parser.ParseComments)
+	if err != nil {
+		return nil, fmt.Errorf("-offset %q: cannot parse file: %s", offsetFlag, err)
+	}
+
+	id := identAtOffset(fset, f, spec.offset)
+	if id == nil {
+		return nil, fmt.Errorf("-offset %q: no identifier at this position", offsetFlag)
+	}
+
+	spec.fromName = id.Name
+
+	return &spec, nil
+}
+
+var wd = func() string {
+	wd, err := os.Getwd()
+	if err != nil {
+		panic("cannot get working directory: " + err.Error())
+	}
+	return wd
+}()
+
+// For source trees built with 'go build', the -from or -offset
+// spec identifies exactly one initial 'from' object to rename ,
+// but certain proprietary build systems allow a single file to
+// appear in multiple packages (e.g. the test package contains a
+// copy of its library), so there may be multiple objects for
+// the same source entity.
+
+func findFromObjects(iprog *loader.Program, spec *spec) ([]types.Object, error) {
+	if spec.filename != "" {
+		return findFromObjectsInFile(iprog, spec)
+	}
+
+	// Search for objects defined in specified package.
+
+	// TODO(adonovan): the iprog.ImportMap has an entry {"main": ...}
+	// for main packages, even though that's not an import path.
+	// Seems like a bug.
+	//
+	// pkg := iprog.ImportMap[spec.pkg]
+	// if pkg == nil {
+	// 	return fmt.Errorf("cannot find package %s", spec.pkg) // can't happen?
+	// }
+	// info := iprog.AllPackages[pkg]
+
+	// Workaround: lookup by value.
+	var info *loader.PackageInfo
+	var pkg *types.Package
+	for pkg, info = range iprog.AllPackages {
+		if pkg.Path() == spec.pkg {
+			break
+		}
+	}
+	if info == nil {
+		return nil, fmt.Errorf("package %q was not loaded", spec.pkg)
+	}
+
+	objects, err := findObjects(info, spec)
+	if err != nil {
+		return nil, err
+	}
+	if len(objects) > 1 {
+		// ambiguous "*" scope query
+		return nil, ambiguityError(iprog.Fset, objects)
+	}
+	return objects, nil
+}
+
+func findFromObjectsInFile(iprog *loader.Program, spec *spec) ([]types.Object, error) {
+	var fromObjects []types.Object
+	for _, info := range iprog.AllPackages {
+		// restrict to specified filename
+		// NB: under certain proprietary build systems, a given
+		// filename may appear in multiple packages.
+		for _, f := range info.Files {
+			thisFile := iprog.Fset.File(f.Pos())
+			if !sameFile(thisFile.Name(), spec.filename) {
+				continue
+			}
+			// This package contains the query file.
+
+			if spec.offset != 0 {
+				// We cannot refactor generated files since position information is invalidated.
+				if generated(f, thisFile) {
+					return nil, fmt.Errorf("cannot rename identifiers in generated file containing DO NOT EDIT marker: %s", thisFile.Name())
+				}
+
+				// Search for a specific ident by file/offset.
+				id := identAtOffset(iprog.Fset, f, spec.offset)
+				if id == nil {
+					// can't happen?
+					return nil, fmt.Errorf("identifier not found")
+				}
+				obj := info.Uses[id]
+				if obj == nil {
+					obj = info.Defs[id]
+					if obj == nil {
+						// Ident without Object.
+
+						// Package clause?
+						pos := thisFile.Pos(spec.offset)
+						_, path, _ := iprog.PathEnclosingInterval(pos, pos)
+						if len(path) == 2 { // [Ident File]
+							// TODO(adonovan): support this case.
+							return nil, fmt.Errorf("cannot rename %q: renaming package clauses is not yet supported",
+								path[1].(*ast.File).Name.Name)
+						}
+
+						// Implicit y in "switch y := x.(type) {"?
+						if obj := typeSwitchVar(&info.Info, path); obj != nil {
+							return []types.Object{obj}, nil
+						}
+
+						// Probably a type error.
+						return nil, fmt.Errorf("cannot find object for %q", id.Name)
+					}
+				}
+				if obj.Pkg() == nil {
+					return nil, fmt.Errorf("cannot rename predeclared identifiers (%s)", obj)
+
+				}
+
+				fromObjects = append(fromObjects, obj)
+			} else {
+				// do a package-wide query
+				objects, err := findObjects(info, spec)
+				if err != nil {
+					return nil, err
+				}
+
+				// filter results: only objects defined in thisFile
+				var filtered []types.Object
+				for _, obj := range objects {
+					if iprog.Fset.File(obj.Pos()) == thisFile {
+						filtered = append(filtered, obj)
+					}
+				}
+				if len(filtered) == 0 {
+					return nil, fmt.Errorf("no object %q declared in file %s",
+						spec.fromName, spec.filename)
+				} else if len(filtered) > 1 {
+					return nil, ambiguityError(iprog.Fset, filtered)
+				}
+				fromObjects = append(fromObjects, filtered[0])
+			}
+			break
+		}
+	}
+	if len(fromObjects) == 0 {
+		// can't happen?
+		return nil, fmt.Errorf("file %s was not part of the loaded program", spec.filename)
+	}
+	return fromObjects, nil
+}
+
+func typeSwitchVar(info *types.Info, path []ast.Node) types.Object {
+	if len(path) > 3 {
+		// [Ident AssignStmt TypeSwitchStmt...]
+		if sw, ok := path[2].(*ast.TypeSwitchStmt); ok {
+			// choose the first case.
+			if len(sw.Body.List) > 0 {
+				obj := info.Implicits[sw.Body.List[0].(*ast.CaseClause)]
+				if obj != nil {
+					return obj
+				}
+			}
+		}
+	}
+	return nil
+}
+
+// On success, findObjects returns the list of objects named
+// spec.fromName matching the spec.  On success, the result has exactly
+// one element unless spec.searchFor!="", in which case it has at least one
+// element.
+//
+func findObjects(info *loader.PackageInfo, spec *spec) ([]types.Object, error) {
+	if spec.pkgMember == "" {
+		if spec.searchFor == "" {
+			panic(spec)
+		}
+		objects := searchDefs(&info.Info, spec.searchFor)
+		if objects == nil {
+			return nil, fmt.Errorf("no object %q declared in package %q",
+				spec.searchFor, info.Pkg.Path())
+		}
+		return objects, nil
+	}
+
+	pkgMember := info.Pkg.Scope().Lookup(spec.pkgMember)
+	if pkgMember == nil {
+		return nil, fmt.Errorf("package %q has no member %q",
+			info.Pkg.Path(), spec.pkgMember)
+	}
+
+	var searchFunc *types.Func
+	if spec.typeMember == "" {
+		// package member
+		if spec.searchFor == "" {
+			return []types.Object{pkgMember}, nil
+		}
+
+		// Search within pkgMember, which must be a function.
+		searchFunc, _ = pkgMember.(*types.Func)
+		if searchFunc == nil {
+			return nil, fmt.Errorf("cannot search for %q within %s %q",
+				spec.searchFor, objectKind(pkgMember), pkgMember)
+		}
+	} else {
+		// field/method of type
+		// e.g. (encoding/json.Decoder).Decode
+		// or ::x within it.
+
+		tName, _ := pkgMember.(*types.TypeName)
+		if tName == nil {
+			return nil, fmt.Errorf("%s.%s is a %s, not a type",
+				info.Pkg.Path(), pkgMember.Name(), objectKind(pkgMember))
+		}
+
+		// search within named type.
+		obj, _, _ := types.LookupFieldOrMethod(tName.Type(), true, info.Pkg, spec.typeMember)
+		if obj == nil {
+			return nil, fmt.Errorf("cannot find field or method %q of %s %s.%s",
+				spec.typeMember, typeKind(tName.Type()), info.Pkg.Path(), tName.Name())
+		}
+
+		if spec.searchFor == "" {
+			// If it is an embedded field, return the type of the field.
+			if v, ok := obj.(*types.Var); ok && v.Anonymous() {
+				switch t := v.Type().(type) {
+				case *types.Pointer:
+					return []types.Object{t.Elem().(*types.Named).Obj()}, nil
+				case *types.Named:
+					return []types.Object{t.Obj()}, nil
+				}
+			}
+			return []types.Object{obj}, nil
+		}
+
+		searchFunc, _ = obj.(*types.Func)
+		if searchFunc == nil {
+			return nil, fmt.Errorf("cannot search for local name %q within %s (%s.%s).%s; need a function",
+				spec.searchFor, objectKind(obj), info.Pkg.Path(), tName.Name(),
+				obj.Name())
+		}
+		if isInterface(tName.Type()) {
+			return nil, fmt.Errorf("cannot search for local name %q within abstract method (%s.%s).%s",
+				spec.searchFor, info.Pkg.Path(), tName.Name(), searchFunc.Name())
+		}
+	}
+
+	// -- search within function or method --
+
+	decl := funcDecl(info, searchFunc)
+	if decl == nil {
+		return nil, fmt.Errorf("cannot find syntax for %s", searchFunc) // can't happen?
+	}
+
+	var objects []types.Object
+	for _, obj := range searchDefs(&info.Info, spec.searchFor) {
+		// We use positions, not scopes, to determine whether
+		// the obj is within searchFunc.  This is clumsy, but the
+		// alternative, using the types.Scope tree, doesn't
+		// account for non-lexical objects like fields and
+		// interface methods.
+		if decl.Pos() <= obj.Pos() && obj.Pos() < decl.End() && obj != searchFunc {
+			objects = append(objects, obj)
+		}
+	}
+	if objects == nil {
+		return nil, fmt.Errorf("no local definition of %q within %s",
+			spec.searchFor, searchFunc)
+	}
+	return objects, nil
+}
+
+func funcDecl(info *loader.PackageInfo, fn *types.Func) *ast.FuncDecl {
+	for _, f := range info.Files {
+		for _, d := range f.Decls {
+			if d, ok := d.(*ast.FuncDecl); ok && info.Defs[d.Name] == fn {
+				return d
+			}
+		}
+	}
+	return nil
+}
+
+func searchDefs(info *types.Info, name string) []types.Object {
+	var objects []types.Object
+	for id, obj := range info.Defs {
+		if obj == nil {
+			// e.g. blank ident.
+			// TODO(adonovan): but also implicit y in
+			//    switch y := x.(type)
+			// Needs some thought.
+			continue
+		}
+		if id.Name == name {
+			objects = append(objects, obj)
+		}
+	}
+	return objects
+}
+
+func identAtOffset(fset *token.FileSet, f *ast.File, offset int) *ast.Ident {
+	var found *ast.Ident
+	ast.Inspect(f, func(n ast.Node) bool {
+		if id, ok := n.(*ast.Ident); ok {
+			idpos := fset.Position(id.Pos()).Offset
+			if idpos <= offset && offset < idpos+len(id.Name) {
+				found = id
+			}
+		}
+		return found == nil // keep traversing only until found
+	})
+	return found
+}
+
+// ambiguityError returns an error describing an ambiguous "*" scope query.
+func ambiguityError(fset *token.FileSet, objects []types.Object) error {
+	var buf bytes.Buffer
+	for i, obj := range objects {
+		if i > 0 {
+			buf.WriteString(", ")
+		}
+		posn := fset.Position(obj.Pos())
+		fmt.Fprintf(&buf, "%s at %s:%d:%d",
+			objectKind(obj), filepath.Base(posn.Filename), posn.Line, posn.Column)
+	}
+	return fmt.Errorf("ambiguous specifier %s matches %s",
+		objects[0].Name(), buf.String())
+}
+
+// Matches cgo generated comment as well as the proposed standard:
+//	https://golang.org/s/generatedcode
+var generatedRx = regexp.MustCompile(`// .*DO NOT EDIT\.?`)
+
+// generated reports whether ast.File is a generated file.
+func generated(f *ast.File, tokenFile *token.File) bool {
+
+	// Iterate over the comments in the file
+	for _, commentGroup := range f.Comments {
+		for _, comment := range commentGroup.List {
+			if matched := generatedRx.MatchString(comment.Text); matched {
+				// Check if comment is at the beginning of the line in source
+				if pos := tokenFile.Position(comment.Slash); pos.Column == 1 {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}

vendor/golang.org/x/tools/refactor/rename/util.go

@@ -0,0 +1,105 @@
+// Copyright 2014 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 rename
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+	"os"
+	"path/filepath"
+	"reflect"
+	"runtime"
+	"strings"
+	"unicode"
+
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+func objectKind(obj types.Object) string {
+	switch obj := obj.(type) {
+	case *types.PkgName:
+		return "imported package name"
+	case *types.TypeName:
+		return "type"
+	case *types.Var:
+		if obj.IsField() {
+			return "field"
+		}
+	case *types.Func:
+		if obj.Type().(*types.Signature).Recv() != nil {
+			return "method"
+		}
+	}
+	// label, func, var, const
+	return strings.ToLower(strings.TrimPrefix(reflect.TypeOf(obj).String(), "*types."))
+}
+
+func typeKind(T types.Type) string {
+	return strings.ToLower(strings.TrimPrefix(reflect.TypeOf(T.Underlying()).String(), "*types."))
+}
+
+// NB: for renamings, blank is not considered valid.
+func isValidIdentifier(id string) bool {
+	if id == "" || id == "_" {
+		return false
+	}
+	for i, r := range id {
+		if !isLetter(r) && (i == 0 || !isDigit(r)) {
+			return false
+		}
+	}
+	return token.Lookup(id) == token.IDENT
+}
+
+// isLocal reports whether obj is local to some function.
+// Precondition: not a struct field or interface method.
+func isLocal(obj types.Object) bool {
+	// [... 5=stmt 4=func 3=file 2=pkg 1=universe]
+	var depth int
+	for scope := obj.Parent(); scope != nil; scope = scope.Parent() {
+		depth++
+	}
+	return depth >= 4
+}
+
+func isPackageLevel(obj types.Object) bool {
+	return obj.Pkg().Scope().Lookup(obj.Name()) == obj
+}
+
+// -- Plundered from go/scanner: ---------------------------------------
+
+func isLetter(ch rune) bool {
+	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= 0x80 && unicode.IsLetter(ch)
+}
+
+func isDigit(ch rune) bool {
+	return '0' <= ch && ch <= '9' || ch >= 0x80 && unicode.IsDigit(ch)
+}
+
+// -- Plundered from golang.org/x/tools/cmd/guru -----------------
+
+// sameFile returns true if x and y have the same basename and denote
+// the same file.
+//
+func sameFile(x, y string) bool {
+	if runtime.GOOS == "windows" {
+		x = filepath.ToSlash(x)
+		y = filepath.ToSlash(y)
+	}
+	if x == y {
+		return true
+	}
+	if filepath.Base(x) == filepath.Base(y) { // (optimisation)
+		if xi, err := os.Stat(x); err == nil {
+			if yi, err := os.Stat(y); err == nil {
+				return os.SameFile(xi, yi)
+			}
+		}
+	}
+	return false
+}
+
+func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }

vendor/golang.org/x/tools/refactor/satisfy/find.go

@@ -0,0 +1,705 @@
+// Copyright 2014 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 satisfy inspects the type-checked ASTs of Go packages and
+// reports the set of discovered type constraints of the form (lhs, rhs
+// Type) where lhs is a non-trivial interface, rhs satisfies this
+// interface, and this fact is necessary for the package to be
+// well-typed.
+//
+// THIS PACKAGE IS EXPERIMENTAL AND MAY CHANGE AT ANY TIME.
+//
+// It is provided only for the gorename tool.  Ideally this
+// functionality will become part of the type-checker in due course,
+// since it is computing it anyway, and it is robust for ill-typed
+// inputs, which this package is not.
+//
+package satisfy // import "golang.org/x/tools/refactor/satisfy"
+
+// NOTES:
+//
+// We don't care about numeric conversions, so we don't descend into
+// types or constant expressions.  This is unsound because
+// constant expressions can contain arbitrary statements, e.g.
+//   const x = len([1]func(){func() {
+//     ...
+//   }})
+//
+// TODO(adonovan): make this robust against ill-typed input.
+// Or move it into the type-checker.
+//
+// Assignability conversions are possible in the following places:
+// - in assignments y = x, y := x, var y = x.
+// - from call argument types to formal parameter types
+// - in append and delete calls
+// - from return operands to result parameter types
+// - in composite literal T{k:v}, from k and v to T's field/element/key type
+// - in map[key] from key to the map's key type
+// - in comparisons x==y and switch x { case y: }.
+// - in explicit conversions T(x)
+// - in sends ch <- x, from x to the channel element type
+// - in type assertions x.(T) and switch x.(type) { case T: }
+//
+// The results of this pass provide information equivalent to the
+// ssa.MakeInterface and ssa.ChangeInterface instructions.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/tools/go/ast/astutil"
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+// A Constraint records the fact that the RHS type does and must
+// satisify the LHS type, which is an interface.
+// The names are suggestive of an assignment statement LHS = RHS.
+type Constraint struct {
+	LHS, RHS types.Type
+}
+
+// A Finder inspects the type-checked ASTs of Go packages and
+// accumulates the set of type constraints (x, y) such that x is
+// assignable to y, y is an interface, and both x and y have methods.
+//
+// In other words, it returns the subset of the "implements" relation
+// that is checked during compilation of a package.  Refactoring tools
+// will need to preserve at least this part of the relation to ensure
+// continued compilation.
+//
+type Finder struct {
+	Result    map[Constraint]bool
+	msetcache typeutil.MethodSetCache
+
+	// per-Find state
+	info *types.Info
+	sig  *types.Signature
+}
+
+// Find inspects a single package, populating Result with its pairs of
+// constrained types.
+//
+// The result is non-canonical and thus may contain duplicates (but this
+// tends to preserves names of interface types better).
+//
+// The package must be free of type errors, and
+// info.{Defs,Uses,Selections,Types} must have been populated by the
+// type-checker.
+//
+func (f *Finder) Find(info *types.Info, files []*ast.File) {
+	if f.Result == nil {
+		f.Result = make(map[Constraint]bool)
+	}
+
+	f.info = info
+	for _, file := range files {
+		for _, d := range file.Decls {
+			switch d := d.(type) {
+			case *ast.GenDecl:
+				if d.Tok == token.VAR { // ignore consts
+					for _, spec := range d.Specs {
+						f.valueSpec(spec.(*ast.ValueSpec))
+					}
+				}
+
+			case *ast.FuncDecl:
+				if d.Body != nil {
+					f.sig = f.info.Defs[d.Name].Type().(*types.Signature)
+					f.stmt(d.Body)
+					f.sig = nil
+				}
+			}
+		}
+	}
+	f.info = nil
+}
+
+var (
+	tInvalid     = types.Typ[types.Invalid]
+	tUntypedBool = types.Typ[types.UntypedBool]
+	tUntypedNil  = types.Typ[types.UntypedNil]
+)
+
+// exprN visits an expression in a multi-value context.
+func (f *Finder) exprN(e ast.Expr) types.Type {
+	typ := f.info.Types[e].Type.(*types.Tuple)
+	switch e := e.(type) {
+	case *ast.ParenExpr:
+		return f.exprN(e.X)
+
+	case *ast.CallExpr:
+		// x, err := f(args)
+		sig := f.expr(e.Fun).Underlying().(*types.Signature)
+		f.call(sig, e.Args)
+
+	case *ast.IndexExpr:
+		// y, ok := x[i]
+		x := f.expr(e.X)
+		f.assign(f.expr(e.Index), x.Underlying().(*types.Map).Key())
+
+	case *ast.TypeAssertExpr:
+		// y, ok := x.(T)
+		f.typeAssert(f.expr(e.X), typ.At(0).Type())
+
+	case *ast.UnaryExpr: // must be receive <-
+		// y, ok := <-x
+		f.expr(e.X)
+
+	default:
+		panic(e)
+	}
+	return typ
+}
+
+func (f *Finder) call(sig *types.Signature, args []ast.Expr) {
+	if len(args) == 0 {
+		return
+	}
+
+	// Ellipsis call?  e.g. f(x, y, z...)
+	if _, ok := args[len(args)-1].(*ast.Ellipsis); ok {
+		for i, arg := range args {
+			// The final arg is a slice, and so is the final param.
+			f.assign(sig.Params().At(i).Type(), f.expr(arg))
+		}
+		return
+	}
+
+	var argtypes []types.Type
+
+	// Gather the effective actual parameter types.
+	if tuple, ok := f.info.Types[args[0]].Type.(*types.Tuple); ok {
+		// f(g()) call where g has multiple results?
+		f.expr(args[0])
+		// unpack the tuple
+		for i := 0; i < tuple.Len(); i++ {
+			argtypes = append(argtypes, tuple.At(i).Type())
+		}
+	} else {
+		for _, arg := range args {
+			argtypes = append(argtypes, f.expr(arg))
+		}
+	}
+
+	// Assign the actuals to the formals.
+	if !sig.Variadic() {
+		for i, argtype := range argtypes {
+			f.assign(sig.Params().At(i).Type(), argtype)
+		}
+	} else {
+		// The first n-1 parameters are assigned normally.
+		nnormals := sig.Params().Len() - 1
+		for i, argtype := range argtypes[:nnormals] {
+			f.assign(sig.Params().At(i).Type(), argtype)
+		}
+		// Remaining args are assigned to elements of varargs slice.
+		tElem := sig.Params().At(nnormals).Type().(*types.Slice).Elem()
+		for i := nnormals; i < len(argtypes); i++ {
+			f.assign(tElem, argtypes[i])
+		}
+	}
+}
+
+func (f *Finder) builtin(obj *types.Builtin, sig *types.Signature, args []ast.Expr, T types.Type) types.Type {
+	switch obj.Name() {
+	case "make", "new":
+		// skip the type operand
+		for _, arg := range args[1:] {
+			f.expr(arg)
+		}
+
+	case "append":
+		s := f.expr(args[0])
+		if _, ok := args[len(args)-1].(*ast.Ellipsis); ok && len(args) == 2 {
+			// append(x, y...)   including append([]byte, "foo"...)
+			f.expr(args[1])
+		} else {
+			// append(x, y, z)
+			tElem := s.Underlying().(*types.Slice).Elem()
+			for _, arg := range args[1:] {
+				f.assign(tElem, f.expr(arg))
+			}
+		}
+
+	case "delete":
+		m := f.expr(args[0])
+		k := f.expr(args[1])
+		f.assign(m.Underlying().(*types.Map).Key(), k)
+
+	default:
+		// ordinary call
+		f.call(sig, args)
+	}
+
+	return T
+}
+
+func (f *Finder) extract(tuple types.Type, i int) types.Type {
+	if tuple, ok := tuple.(*types.Tuple); ok && i < tuple.Len() {
+		return tuple.At(i).Type()
+	}
+	return tInvalid
+}
+
+func (f *Finder) valueSpec(spec *ast.ValueSpec) {
+	var T types.Type
+	if spec.Type != nil {
+		T = f.info.Types[spec.Type].Type
+	}
+	switch len(spec.Values) {
+	case len(spec.Names): // e.g. var x, y = f(), g()
+		for _, value := range spec.Values {
+			v := f.expr(value)
+			if T != nil {
+				f.assign(T, v)
+			}
+		}
+
+	case 1: // e.g. var x, y = f()
+		tuple := f.exprN(spec.Values[0])
+		for i := range spec.Names {
+			if T != nil {
+				f.assign(T, f.extract(tuple, i))
+			}
+		}
+	}
+}
+
+// assign records pairs of distinct types that are related by
+// assignability, where the left-hand side is an interface and both
+// sides have methods.
+//
+// It should be called for all assignability checks, type assertions,
+// explicit conversions and comparisons between two types, unless the
+// types are uninteresting (e.g. lhs is a concrete type, or the empty
+// interface; rhs has no methods).
+//
+func (f *Finder) assign(lhs, rhs types.Type) {
+	if types.Identical(lhs, rhs) {
+		return
+	}
+	if !isInterface(lhs) {
+		return
+	}
+
+	if f.msetcache.MethodSet(lhs).Len() == 0 {
+		return
+	}
+	if f.msetcache.MethodSet(rhs).Len() == 0 {
+		return
+	}
+	// record the pair
+	f.Result[Constraint{lhs, rhs}] = true
+}
+
+// typeAssert must be called for each type assertion x.(T) where x has
+// interface type I.
+func (f *Finder) typeAssert(I, T types.Type) {
+	// Type assertions are slightly subtle, because they are allowed
+	// to be "impossible", e.g.
+	//
+	// 	var x interface{f()}
+	//	_ = x.(interface{f()int}) // legal
+	//
+	// (In hindsight, the language spec should probably not have
+	// allowed this, but it's too late to fix now.)
+	//
+	// This means that a type assert from I to T isn't exactly a
+	// constraint that T is assignable to I, but for a refactoring
+	// tool it is a conditional constraint that, if T is assignable
+	// to I before a refactoring, it should remain so after.
+
+	if types.AssignableTo(T, I) {
+		f.assign(I, T)
+	}
+}
+
+// compare must be called for each comparison x==y.
+func (f *Finder) compare(x, y types.Type) {
+	if types.AssignableTo(x, y) {
+		f.assign(y, x)
+	} else if types.AssignableTo(y, x) {
+		f.assign(x, y)
+	}
+}
+
+// expr visits a true expression (not a type or defining ident)
+// and returns its type.
+func (f *Finder) expr(e ast.Expr) types.Type {
+	tv := f.info.Types[e]
+	if tv.Value != nil {
+		return tv.Type // prune the descent for constants
+	}
+
+	// tv.Type may be nil for an ast.Ident.
+
+	switch e := e.(type) {
+	case *ast.BadExpr, *ast.BasicLit:
+		// no-op
+
+	case *ast.Ident:
+		// (referring idents only)
+		if obj, ok := f.info.Uses[e]; ok {
+			return obj.Type()
+		}
+		if e.Name == "_" { // e.g. "for _ = range x"
+			return tInvalid
+		}
+		panic("undefined ident: " + e.Name)
+
+	case *ast.Ellipsis:
+		if e.Elt != nil {
+			f.expr(e.Elt)
+		}
+
+	case *ast.FuncLit:
+		saved := f.sig
+		f.sig = tv.Type.(*types.Signature)
+		f.stmt(e.Body)
+		f.sig = saved
+
+	case *ast.CompositeLit:
+		switch T := deref(tv.Type).Underlying().(type) {
+		case *types.Struct:
+			for i, elem := range e.Elts {
+				if kv, ok := elem.(*ast.KeyValueExpr); ok {
+					f.assign(f.info.Uses[kv.Key.(*ast.Ident)].Type(), f.expr(kv.Value))
+				} else {
+					f.assign(T.Field(i).Type(), f.expr(elem))
+				}
+			}
+
+		case *types.Map:
+			for _, elem := range e.Elts {
+				elem := elem.(*ast.KeyValueExpr)
+				f.assign(T.Key(), f.expr(elem.Key))
+				f.assign(T.Elem(), f.expr(elem.Value))
+			}
+
+		case *types.Array, *types.Slice:
+			tElem := T.(interface {
+				Elem() types.Type
+			}).Elem()
+			for _, elem := range e.Elts {
+				if kv, ok := elem.(*ast.KeyValueExpr); ok {
+					// ignore the key
+					f.assign(tElem, f.expr(kv.Value))
+				} else {
+					f.assign(tElem, f.expr(elem))
+				}
+			}
+
+		default:
+			panic("unexpected composite literal type: " + tv.Type.String())
+		}
+
+	case *ast.ParenExpr:
+		f.expr(e.X)
+
+	case *ast.SelectorExpr:
+		if _, ok := f.info.Selections[e]; ok {
+			f.expr(e.X) // selection
+		} else {
+			return f.info.Uses[e.Sel].Type() // qualified identifier
+		}
+
+	case *ast.IndexExpr:
+		x := f.expr(e.X)
+		i := f.expr(e.Index)
+		if ux, ok := x.Underlying().(*types.Map); ok {
+			f.assign(ux.Key(), i)
+		}
+
+	case *ast.SliceExpr:
+		f.expr(e.X)
+		if e.Low != nil {
+			f.expr(e.Low)
+		}
+		if e.High != nil {
+			f.expr(e.High)
+		}
+		if e.Max != nil {
+			f.expr(e.Max)
+		}
+
+	case *ast.TypeAssertExpr:
+		x := f.expr(e.X)
+		f.typeAssert(x, f.info.Types[e.Type].Type)
+
+	case *ast.CallExpr:
+		if tvFun := f.info.Types[e.Fun]; tvFun.IsType() {
+			// conversion
+			arg0 := f.expr(e.Args[0])
+			f.assign(tvFun.Type, arg0)
+		} else {
+			// function call
+			if id, ok := unparen(e.Fun).(*ast.Ident); ok {
+				if obj, ok := f.info.Uses[id].(*types.Builtin); ok {
+					sig := f.info.Types[id].Type.(*types.Signature)
+					return f.builtin(obj, sig, e.Args, tv.Type)
+				}
+			}
+			// ordinary call
+			f.call(f.expr(e.Fun).Underlying().(*types.Signature), e.Args)
+		}
+
+	case *ast.StarExpr:
+		f.expr(e.X)
+
+	case *ast.UnaryExpr:
+		f.expr(e.X)
+
+	case *ast.BinaryExpr:
+		x := f.expr(e.X)
+		y := f.expr(e.Y)
+		if e.Op == token.EQL || e.Op == token.NEQ {
+			f.compare(x, y)
+		}
+
+	case *ast.KeyValueExpr:
+		f.expr(e.Key)
+		f.expr(e.Value)
+
+	case *ast.ArrayType,
+		*ast.StructType,
+		*ast.FuncType,
+		*ast.InterfaceType,
+		*ast.MapType,
+		*ast.ChanType:
+		panic(e)
+	}
+
+	if tv.Type == nil {
+		panic(fmt.Sprintf("no type for %T", e))
+	}
+
+	return tv.Type
+}
+
+func (f *Finder) stmt(s ast.Stmt) {
+	switch s := s.(type) {
+	case *ast.BadStmt,
+		*ast.EmptyStmt,
+		*ast.BranchStmt:
+		// no-op
+
+	case *ast.DeclStmt:
+		d := s.Decl.(*ast.GenDecl)
+		if d.Tok == token.VAR { // ignore consts
+			for _, spec := range d.Specs {
+				f.valueSpec(spec.(*ast.ValueSpec))
+			}
+		}
+
+	case *ast.LabeledStmt:
+		f.stmt(s.Stmt)
+
+	case *ast.ExprStmt:
+		f.expr(s.X)
+
+	case *ast.SendStmt:
+		ch := f.expr(s.Chan)
+		val := f.expr(s.Value)
+		f.assign(ch.Underlying().(*types.Chan).Elem(), val)
+
+	case *ast.IncDecStmt:
+		f.expr(s.X)
+
+	case *ast.AssignStmt:
+		switch s.Tok {
+		case token.ASSIGN, token.DEFINE:
+			// y := x   or   y = x
+			var rhsTuple types.Type
+			if len(s.Lhs) != len(s.Rhs) {
+				rhsTuple = f.exprN(s.Rhs[0])
+			}
+			for i := range s.Lhs {
+				var lhs, rhs types.Type
+				if rhsTuple == nil {
+					rhs = f.expr(s.Rhs[i]) // 1:1 assignment
+				} else {
+					rhs = f.extract(rhsTuple, i) // n:1 assignment
+				}
+
+				if id, ok := s.Lhs[i].(*ast.Ident); ok {
+					if id.Name != "_" {
+						if obj, ok := f.info.Defs[id]; ok {
+							lhs = obj.Type() // definition
+						}
+					}
+				}
+				if lhs == nil {
+					lhs = f.expr(s.Lhs[i]) // assignment
+				}
+				f.assign(lhs, rhs)
+			}
+
+		default:
+			// y op= x
+			f.expr(s.Lhs[0])
+			f.expr(s.Rhs[0])
+		}
+
+	case *ast.GoStmt:
+		f.expr(s.Call)
+
+	case *ast.DeferStmt:
+		f.expr(s.Call)
+
+	case *ast.ReturnStmt:
+		formals := f.sig.Results()
+		switch len(s.Results) {
+		case formals.Len(): // 1:1
+			for i, result := range s.Results {
+				f.assign(formals.At(i).Type(), f.expr(result))
+			}
+
+		case 1: // n:1
+			tuple := f.exprN(s.Results[0])
+			for i := 0; i < formals.Len(); i++ {
+				f.assign(formals.At(i).Type(), f.extract(tuple, i))
+			}
+		}
+
+	case *ast.SelectStmt:
+		f.stmt(s.Body)
+
+	case *ast.BlockStmt:
+		for _, s := range s.List {
+			f.stmt(s)
+		}
+
+	case *ast.IfStmt:
+		if s.Init != nil {
+			f.stmt(s.Init)
+		}
+		f.expr(s.Cond)
+		f.stmt(s.Body)
+		if s.Else != nil {
+			f.stmt(s.Else)
+		}
+
+	case *ast.SwitchStmt:
+		if s.Init != nil {
+			f.stmt(s.Init)
+		}
+		var tag types.Type = tUntypedBool
+		if s.Tag != nil {
+			tag = f.expr(s.Tag)
+		}
+		for _, cc := range s.Body.List {
+			cc := cc.(*ast.CaseClause)
+			for _, cond := range cc.List {
+				f.compare(tag, f.info.Types[cond].Type)
+			}
+			for _, s := range cc.Body {
+				f.stmt(s)
+			}
+		}
+
+	case *ast.TypeSwitchStmt:
+		if s.Init != nil {
+			f.stmt(s.Init)
+		}
+		var I types.Type
+		switch ass := s.Assign.(type) {
+		case *ast.ExprStmt: // x.(type)
+			I = f.expr(unparen(ass.X).(*ast.TypeAssertExpr).X)
+		case *ast.AssignStmt: // y := x.(type)
+			I = f.expr(unparen(ass.Rhs[0]).(*ast.TypeAssertExpr).X)
+		}
+		for _, cc := range s.Body.List {
+			cc := cc.(*ast.CaseClause)
+			for _, cond := range cc.List {
+				tCase := f.info.Types[cond].Type
+				if tCase != tUntypedNil {
+					f.typeAssert(I, tCase)
+				}
+			}
+			for _, s := range cc.Body {
+				f.stmt(s)
+			}
+		}
+
+	case *ast.CommClause:
+		if s.Comm != nil {
+			f.stmt(s.Comm)
+		}
+		for _, s := range s.Body {
+			f.stmt(s)
+		}
+
+	case *ast.ForStmt:
+		if s.Init != nil {
+			f.stmt(s.Init)
+		}
+		if s.Cond != nil {
+			f.expr(s.Cond)
+		}
+		if s.Post != nil {
+			f.stmt(s.Post)
+		}
+		f.stmt(s.Body)
+
+	case *ast.RangeStmt:
+		x := f.expr(s.X)
+		// No conversions are involved when Tok==DEFINE.
+		if s.Tok == token.ASSIGN {
+			if s.Key != nil {
+				k := f.expr(s.Key)
+				var xelem types.Type
+				// keys of array, *array, slice, string aren't interesting
+				switch ux := x.Underlying().(type) {
+				case *types.Chan:
+					xelem = ux.Elem()
+				case *types.Map:
+					xelem = ux.Key()
+				}
+				if xelem != nil {
+					f.assign(xelem, k)
+				}
+			}
+			if s.Value != nil {
+				val := f.expr(s.Value)
+				var xelem types.Type
+				// values of strings aren't interesting
+				switch ux := x.Underlying().(type) {
+				case *types.Array:
+					xelem = ux.Elem()
+				case *types.Chan:
+					xelem = ux.Elem()
+				case *types.Map:
+					xelem = ux.Elem()
+				case *types.Pointer: // *array
+					xelem = deref(ux).(*types.Array).Elem()
+				case *types.Slice:
+					xelem = ux.Elem()
+				}
+				if xelem != nil {
+					f.assign(xelem, val)
+				}
+			}
+		}
+		f.stmt(s.Body)
+
+	default:
+		panic(s)
+	}
+}
+
+// -- Plundered from golang.org/x/tools/go/ssa -----------------
+
+// deref returns a pointer's element type; otherwise it returns typ.
+func deref(typ types.Type) types.Type {
+	if p, ok := typ.Underlying().(*types.Pointer); ok {
+		return p.Elem()
+	}
+	return typ
+}
+
+func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }
+
+func isInterface(T types.Type) bool { return types.IsInterface(T) }