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// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//
// Taken from golang.org/x/tools/refactor/rename.
package source
// This file defines the conflict-checking portion of the rename operation.
//
// The renamer works on a single package of type-checked syntax, and
// is called in parallel for all necessary packages in the workspace,
// possibly up to the transitive reverse dependencies of the
// declaration. Finally the union of all edits and errors is computed.
//
// Renaming one object may entail renaming of others. For example:
//
// - An embedded field couples a Var (field) and a TypeName.
// So, renaming either one requires renaming the other.
// If the initial object is an embedded field, we must add its
// TypeName (and its enclosing package) to the renaming set;
// this is easily discovered at the outset.
//
// Conversely, if the initial object is a TypeName, we must observe
// whether any of its references (from directly importing packages)
// is coincident with an embedded field Var and, if so, initiate a
// renaming of it.
//
// - A method of an interface type is coupled to all corresponding
// methods of types that are assigned to the interface (as
// discovered by the 'satisfy' pass). As a matter of usability, we
// require that such renamings be initiated from the interface
// method, not the concrete method.
import (
"fmt"
"go/ast"
"go/token"
"go/types"
"path/filepath"
"reflect"
"strings"
"unicode"
"golang.org/x/tools/go/ast/astutil"
"golang.org/x/tools/gopls/internal/lsp/safetoken"
"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{}) {
// Conflict error messages in the old gorename tool (whence this
// logic originated) contain rich information associated with
// multiple source lines, such as:
//
// p/a.go:1:2: renaming "x" to "y" here
// p/b.go:3:4: \t would cause this reference to "y"
// p/c.go:5:5: \t to become shadowed by this intervening declaration.
//
// Unfortunately LSP provides no means to transmit the
// structure of this error, so we format the positions briefly
// using dir/file.go where dir is the base name of the parent
// directory.
var conflict strings.Builder
// Add prefix of (truncated) position.
if pos != token.NoPos {
// TODO(adonovan): skip position of first error if it is
// on the same line as the renaming itself.
posn := safetoken.StartPosition(r.pkg.FileSet(), pos).String()
segments := strings.Split(filepath.ToSlash(posn), "/")
if n := len(segments); n > 2 {
segments = segments[n-2:]
}
posn = strings.Join(segments, "/")
fmt.Fprintf(&conflict, "%s:", posn)
if !strings.HasPrefix(format, "\t") {
conflict.WriteByte(' ')
}
}
fmt.Fprintf(&conflict, format, args...)
r.conflicts = append(r.conflicts, conflict.String())
}
// 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.checkInLexicalScope(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)
}
// 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 typ := r.pkg.GetTypes(); typ != from.Pkg() && ast.IsExported(r.from) && !ast.IsExported(r.to) {
if id := someUse(r.pkg.GetTypesInfo(), from); id != nil {
r.checkExport(id, typ, from)
}
}
// 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 r.pkg.GetTypesInfo().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 r.pkg.GetSyntax() {
fileScope := r.pkg.GetTypesInfo().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)
var prevPos token.Pos
if prev != nil {
prevPos = prev.Pos()
}
r.errorf(prevPos, "\twith this %s", objectKind(prev))
return // since checkInPackageBlock would report redundant errors
}
}
// Check for conflicts in lexical scope.
r.checkInLexicalScope(from)
}
// 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 shadows 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) {
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(r.pkg, to, func(id *ast.Ident, block *types.Scope) bool {
_, obj := block.LookupParent(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(r.pkg, from, func(id *ast.Ident, block *types.Scope) bool {
// Find the block that defines the found reference.
// It may be an ancestor.
fromBlock, _ := block.LookupParent(from.Name(), id.Pos())
// See what r.to would resolve to in the same scope.
toBlock, to := block.LookupParent(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 r.pkg.GetTypesInfo().Uses {
if obj == from {
if field := r.pkg.GetTypesInfo().Defs[id]; field != nil {
r.check(field)
}
}
}
}
}
// 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
// pkg 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(pkg Package, 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 pkg.GetTypesInfo().Uses[n] == obj {
block := enclosingBlock(pkg.GetTypesInfo(), 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, ok := pkg.GetTypesInfo().Types[n]
if !ok {
return visit(nil) // pop stack, don't descend
}
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 pkg.GetSyntax() {
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.
pgf, ok := enclosingFile(r.pkg, from.Pos())
if !ok {
return // not declared by syntax of this package
}
path, _ := astutil.PathEnclosingInterval(pgf.File, 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 := r.pkg.GetTypesInfo().Defs[spec.Name].Type()
prev, indices, _ := types.LookupFieldOrMethod(named, true, r.pkg.GetTypes(), 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 := r.pkg.GetTypesInfo().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)
}
// checkSelections 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) {
pkg := r.pkg
typ := pkg.GetTypes()
{
if id := someUse(pkg.GetTypesInfo(), from); id != nil {
if !r.checkExport(id, typ, from) {
return
}
}
for syntax, sel := range pkg.GetTypesInfo().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 types.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.
{
// Start with named interface types (better errors)
for _, obj := range r.pkg.GetTypesInfo().Defs {
if obj, ok := obj.(*types.TypeName); ok && types.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 r.pkg.GetTypesInfo().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 !types.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 types.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 %q to %q would make it unexported",
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
pkg := r.pkg
{
// From satisfy.Finder documentation:
//
// The package must be free of type errors, and
// info.{Defs,Uses,Selections,Types} must have been populated by the
// type-checker.
//
// Only proceed if all packages have no errors.
if pkg.HasParseErrors() || pkg.HasTypeErrors() {
r.errorf(token.NoPos, // we don't have a position for this error.
"renaming %q to %q not possible because %q has errors",
r.from, r.to, pkg.Metadata().PkgPath)
return nil
}
f.Find(pkg.GetTypesInfo(), pkg.GetSyntax())
}
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 *types.Info, obj types.Object) *ast.Ident {
for id, o := range info.Uses {
if o == obj {
return id
}
}
return nil
}
func objectKind(obj types.Object) string {
if obj == nil {
return "nil object"
}
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."))
}
// 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 {
if obj == nil {
return false
}
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)
}