Add generated file

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

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) }