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// Copyright 2011 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 main
import (
"fmt"
"go/ast"
"go/token"
"path"
"strconv"
)
type fix struct {
name string
date string // date that fix was introduced, in YYYY-MM-DD format
f func(*ast.File) bool
desc string
disabled bool // whether this fix should be disabled by default
}
// main runs sort.Sort(byName(fixes)) before printing list of fixes.
type byName []fix
func (f byName) Len() int { return len(f) }
func (f byName) Swap(i, j int) { f[i], f[j] = f[j], f[i] }
func (f byName) Less(i, j int) bool { return f[i].name < f[j].name }
// main runs sort.Sort(byDate(fixes)) before applying fixes.
type byDate []fix
func (f byDate) Len() int { return len(f) }
func (f byDate) Swap(i, j int) { f[i], f[j] = f[j], f[i] }
func (f byDate) Less(i, j int) bool { return f[i].date < f[j].date }
var fixes []fix
func register(f fix) {
fixes = append(fixes, f)
}
// walk traverses the AST x, calling visit(y) for each node y in the tree but
// also with a pointer to each ast.Expr, ast.Stmt, and *ast.BlockStmt,
// in a bottom-up traversal.
func walk(x any, visit func(any)) {
walkBeforeAfter(x, nop, visit)
}
func nop(any) {}
// walkBeforeAfter is like walk but calls before(x) before traversing
// x's children and after(x) afterward.
func walkBeforeAfter(x any, before, after func(any)) {
before(x)
switch n := x.(type) {
default:
panic(fmt.Errorf("unexpected type %T in walkBeforeAfter", x))
case nil:
// pointers to interfaces
case *ast.Decl:
walkBeforeAfter(*n, before, after)
case *ast.Expr:
walkBeforeAfter(*n, before, after)
case *ast.Spec:
walkBeforeAfter(*n, before, after)
case *ast.Stmt:
walkBeforeAfter(*n, before, after)
// pointers to struct pointers
case **ast.BlockStmt:
walkBeforeAfter(*n, before, after)
case **ast.CallExpr:
walkBeforeAfter(*n, before, after)
case **ast.FieldList:
walkBeforeAfter(*n, before, after)
case **ast.FuncType:
walkBeforeAfter(*n, before, after)
case **ast.Ident:
walkBeforeAfter(*n, before, after)
case **ast.BasicLit:
walkBeforeAfter(*n, before, after)
// pointers to slices
case *[]ast.Decl:
walkBeforeAfter(*n, before, after)
case *[]ast.Expr:
walkBeforeAfter(*n, before, after)
case *[]*ast.File:
walkBeforeAfter(*n, before, after)
case *[]*ast.Ident:
walkBeforeAfter(*n, before, after)
case *[]ast.Spec:
walkBeforeAfter(*n, before, after)
case *[]ast.Stmt:
walkBeforeAfter(*n, before, after)
// These are ordered and grouped to match ../../go/ast/ast.go
case *ast.Field:
walkBeforeAfter(&n.Names, before, after)
walkBeforeAfter(&n.Type, before, after)
walkBeforeAfter(&n.Tag, before, after)
case *ast.FieldList:
for _, field := range n.List {
walkBeforeAfter(field, before, after)
}
case *ast.BadExpr:
case *ast.Ident:
case *ast.Ellipsis:
walkBeforeAfter(&n.Elt, before, after)
case *ast.BasicLit:
case *ast.FuncLit:
walkBeforeAfter(&n.Type, before, after)
walkBeforeAfter(&n.Body, before, after)
case *ast.CompositeLit:
walkBeforeAfter(&n.Type, before, after)
walkBeforeAfter(&n.Elts, before, after)
case *ast.ParenExpr:
walkBeforeAfter(&n.X, before, after)
case *ast.SelectorExpr:
walkBeforeAfter(&n.X, before, after)
case *ast.IndexExpr:
walkBeforeAfter(&n.X, before, after)
walkBeforeAfter(&n.Index, before, after)
case *ast.IndexListExpr:
walkBeforeAfter(&n.X, before, after)
walkBeforeAfter(&n.Indices, before, after)
case *ast.SliceExpr:
walkBeforeAfter(&n.X, before, after)
if n.Low != nil {
walkBeforeAfter(&n.Low, before, after)
}
if n.High != nil {
walkBeforeAfter(&n.High, before, after)
}
case *ast.TypeAssertExpr:
walkBeforeAfter(&n.X, before, after)
walkBeforeAfter(&n.Type, before, after)
case *ast.CallExpr:
walkBeforeAfter(&n.Fun, before, after)
walkBeforeAfter(&n.Args, before, after)
case *ast.StarExpr:
walkBeforeAfter(&n.X, before, after)
case *ast.UnaryExpr:
walkBeforeAfter(&n.X, before, after)
case *ast.BinaryExpr:
walkBeforeAfter(&n.X, before, after)
walkBeforeAfter(&n.Y, before, after)
case *ast.KeyValueExpr:
walkBeforeAfter(&n.Key, before, after)
walkBeforeAfter(&n.Value, before, after)
case *ast.ArrayType:
walkBeforeAfter(&n.Len, before, after)
walkBeforeAfter(&n.Elt, before, after)
case *ast.StructType:
walkBeforeAfter(&n.Fields, before, after)
case *ast.FuncType:
if n.TypeParams != nil {
walkBeforeAfter(&n.TypeParams, before, after)
}
walkBeforeAfter(&n.Params, before, after)
if n.Results != nil {
walkBeforeAfter(&n.Results, before, after)
}
case *ast.InterfaceType:
walkBeforeAfter(&n.Methods, before, after)
case *ast.MapType:
walkBeforeAfter(&n.Key, before, after)
walkBeforeAfter(&n.Value, before, after)
case *ast.ChanType:
walkBeforeAfter(&n.Value, before, after)
case *ast.BadStmt:
case *ast.DeclStmt:
walkBeforeAfter(&n.Decl, before, after)
case *ast.EmptyStmt:
case *ast.LabeledStmt:
walkBeforeAfter(&n.Stmt, before, after)
case *ast.ExprStmt:
walkBeforeAfter(&n.X, before, after)
case *ast.SendStmt:
walkBeforeAfter(&n.Chan, before, after)
walkBeforeAfter(&n.Value, before, after)
case *ast.IncDecStmt:
walkBeforeAfter(&n.X, before, after)
case *ast.AssignStmt:
walkBeforeAfter(&n.Lhs, before, after)
walkBeforeAfter(&n.Rhs, before, after)
case *ast.GoStmt:
walkBeforeAfter(&n.Call, before, after)
case *ast.DeferStmt:
walkBeforeAfter(&n.Call, before, after)
case *ast.ReturnStmt:
walkBeforeAfter(&n.Results, before, after)
case *ast.BranchStmt:
case *ast.BlockStmt:
walkBeforeAfter(&n.List, before, after)
case *ast.IfStmt:
walkBeforeAfter(&n.Init, before, after)
walkBeforeAfter(&n.Cond, before, after)
walkBeforeAfter(&n.Body, before, after)
walkBeforeAfter(&n.Else, before, after)
case *ast.CaseClause:
walkBeforeAfter(&n.List, before, after)
walkBeforeAfter(&n.Body, before, after)
case *ast.SwitchStmt:
walkBeforeAfter(&n.Init, before, after)
walkBeforeAfter(&n.Tag, before, after)
walkBeforeAfter(&n.Body, before, after)
case *ast.TypeSwitchStmt:
walkBeforeAfter(&n.Init, before, after)
walkBeforeAfter(&n.Assign, before, after)
walkBeforeAfter(&n.Body, before, after)
case *ast.CommClause:
walkBeforeAfter(&n.Comm, before, after)
walkBeforeAfter(&n.Body, before, after)
case *ast.SelectStmt:
walkBeforeAfter(&n.Body, before, after)
case *ast.ForStmt:
walkBeforeAfter(&n.Init, before, after)
walkBeforeAfter(&n.Cond, before, after)
walkBeforeAfter(&n.Post, before, after)
walkBeforeAfter(&n.Body, before, after)
case *ast.RangeStmt:
walkBeforeAfter(&n.Key, before, after)
walkBeforeAfter(&n.Value, before, after)
walkBeforeAfter(&n.X, before, after)
walkBeforeAfter(&n.Body, before, after)
case *ast.ImportSpec:
case *ast.ValueSpec:
walkBeforeAfter(&n.Type, before, after)
walkBeforeAfter(&n.Values, before, after)
walkBeforeAfter(&n.Names, before, after)
case *ast.TypeSpec:
if n.TypeParams != nil {
walkBeforeAfter(&n.TypeParams, before, after)
}
walkBeforeAfter(&n.Type, before, after)
case *ast.BadDecl:
case *ast.GenDecl:
walkBeforeAfter(&n.Specs, before, after)
case *ast.FuncDecl:
if n.Recv != nil {
walkBeforeAfter(&n.Recv, before, after)
}
walkBeforeAfter(&n.Type, before, after)
if n.Body != nil {
walkBeforeAfter(&n.Body, before, after)
}
case *ast.File:
walkBeforeAfter(&n.Decls, before, after)
case *ast.Package:
walkBeforeAfter(&n.Files, before, after)
case []*ast.File:
for i := range n {
walkBeforeAfter(&n[i], before, after)
}
case []ast.Decl:
for i := range n {
walkBeforeAfter(&n[i], before, after)
}
case []ast.Expr:
for i := range n {
walkBeforeAfter(&n[i], before, after)
}
case []*ast.Ident:
for i := range n {
walkBeforeAfter(&n[i], before, after)
}
case []ast.Stmt:
for i := range n {
walkBeforeAfter(&n[i], before, after)
}
case []ast.Spec:
for i := range n {
walkBeforeAfter(&n[i], before, after)
}
}
after(x)
}
// imports reports whether f imports path.
func imports(f *ast.File, path string) bool {
return importSpec(f, path) != nil
}
// importSpec returns the import spec if f imports path,
// or nil otherwise.
func importSpec(f *ast.File, path string) *ast.ImportSpec {
for _, s := range f.Imports {
if importPath(s) == path {
return s
}
}
return nil
}
// importPath returns the unquoted import path of s,
// or "" if the path is not properly quoted.
func importPath(s *ast.ImportSpec) string {
t, err := strconv.Unquote(s.Path.Value)
if err == nil {
return t
}
return ""
}
// declImports reports whether gen contains an import of path.
func declImports(gen *ast.GenDecl, path string) bool {
if gen.Tok != token.IMPORT {
return false
}
for _, spec := range gen.Specs {
impspec := spec.(*ast.ImportSpec)
if importPath(impspec) == path {
return true
}
}
return false
}
// isTopName reports whether n is a top-level unresolved identifier with the given name.
func isTopName(n ast.Expr, name string) bool {
id, ok := n.(*ast.Ident)
return ok && id.Name == name && id.Obj == nil
}
// renameTop renames all references to the top-level name old.
// It reports whether it makes any changes.
func renameTop(f *ast.File, old, new string) bool {
var fixed bool
// Rename any conflicting imports
// (assuming package name is last element of path).
for _, s := range f.Imports {
if s.Name != nil {
if s.Name.Name == old {
s.Name.Name = new
fixed = true
}
} else {
_, thisName := path.Split(importPath(s))
if thisName == old {
s.Name = ast.NewIdent(new)
fixed = true
}
}
}
// Rename any top-level declarations.
for _, d := range f.Decls {
switch d := d.(type) {
case *ast.FuncDecl:
if d.Recv == nil && d.Name.Name == old {
d.Name.Name = new
d.Name.Obj.Name = new
fixed = true
}
case *ast.GenDecl:
for _, s := range d.Specs {
switch s := s.(type) {
case *ast.TypeSpec:
if s.Name.Name == old {
s.Name.Name = new
s.Name.Obj.Name = new
fixed = true
}
case *ast.ValueSpec:
for _, n := range s.Names {
if n.Name == old {
n.Name = new
n.Obj.Name = new
fixed = true
}
}
}
}
}
}
// Rename top-level old to new, both unresolved names
// (probably defined in another file) and names that resolve
// to a declaration we renamed.
walk(f, func(n any) {
id, ok := n.(*ast.Ident)
if ok && isTopName(id, old) {
id.Name = new
fixed = true
}
if ok && id.Obj != nil && id.Name == old && id.Obj.Name == new {
id.Name = id.Obj.Name
fixed = true
}
})
return fixed
}
// matchLen returns the length of the longest prefix shared by x and y.
func matchLen(x, y string) int {
i := 0
for i < len(x) && i < len(y) && x[i] == y[i] {
i++
}
return i
}
// addImport adds the import path to the file f, if absent.
func addImport(f *ast.File, ipath string) (added bool) {
if imports(f, ipath) {
return false
}
// Determine name of import.
// Assume added imports follow convention of using last element.
_, name := path.Split(ipath)
// Rename any conflicting top-level references from name to name_.
renameTop(f, name, name+"_")
newImport := &ast.ImportSpec{
Path: &ast.BasicLit{
Kind: token.STRING,
Value: strconv.Quote(ipath),
},
}
// Find an import decl to add to.
var (
bestMatch = -1
lastImport = -1
impDecl *ast.GenDecl
impIndex = -1
)
for i, decl := range f.Decls {
gen, ok := decl.(*ast.GenDecl)
if ok && gen.Tok == token.IMPORT {
lastImport = i
// Do not add to import "C", to avoid disrupting the
// association with its doc comment, breaking cgo.
if declImports(gen, "C") {
continue
}
// Compute longest shared prefix with imports in this block.
for j, spec := range gen.Specs {
impspec := spec.(*ast.ImportSpec)
n := matchLen(importPath(impspec), ipath)
if n > bestMatch {
bestMatch = n
impDecl = gen
impIndex = j
}
}
}
}
// If no import decl found, add one after the last import.
if impDecl == nil {
impDecl = &ast.GenDecl{
Tok: token.IMPORT,
}
f.Decls = append(f.Decls, nil)
copy(f.Decls[lastImport+2:], f.Decls[lastImport+1:])
f.Decls[lastImport+1] = impDecl
}
// Ensure the import decl has parentheses, if needed.
if len(impDecl.Specs) > 0 && !impDecl.Lparen.IsValid() {
impDecl.Lparen = impDecl.Pos()
}
insertAt := impIndex + 1
if insertAt == 0 {
insertAt = len(impDecl.Specs)
}
impDecl.Specs = append(impDecl.Specs, nil)
copy(impDecl.Specs[insertAt+1:], impDecl.Specs[insertAt:])
impDecl.Specs[insertAt] = newImport
if insertAt > 0 {
// Assign same position as the previous import,
// so that the sorter sees it as being in the same block.
prev := impDecl.Specs[insertAt-1]
newImport.Path.ValuePos = prev.Pos()
newImport.EndPos = prev.Pos()
}
f.Imports = append(f.Imports, newImport)
return true
}
// deleteImport deletes the import path from the file f, if present.
func deleteImport(f *ast.File, path string) (deleted bool) {
oldImport := importSpec(f, path)
// Find the import node that imports path, if any.
for i, decl := range f.Decls {
gen, ok := decl.(*ast.GenDecl)
if !ok || gen.Tok != token.IMPORT {
continue
}
for j, spec := range gen.Specs {
impspec := spec.(*ast.ImportSpec)
if oldImport != impspec {
continue
}
// We found an import spec that imports path.
// Delete it.
deleted = true
copy(gen.Specs[j:], gen.Specs[j+1:])
gen.Specs = gen.Specs[:len(gen.Specs)-1]
// If this was the last import spec in this decl,
// delete the decl, too.
if len(gen.Specs) == 0 {
copy(f.Decls[i:], f.Decls[i+1:])
f.Decls = f.Decls[:len(f.Decls)-1]
} else if len(gen.Specs) == 1 {
gen.Lparen = token.NoPos // drop parens
}
if j > 0 {
// We deleted an entry but now there will be
// a blank line-sized hole where the import was.
// Close the hole by making the previous
// import appear to "end" where this one did.
gen.Specs[j-1].(*ast.ImportSpec).EndPos = impspec.End()
}
break
}
}
// Delete it from f.Imports.
for i, imp := range f.Imports {
if imp == oldImport {
copy(f.Imports[i:], f.Imports[i+1:])
f.Imports = f.Imports[:len(f.Imports)-1]
break
}
}
return
}
// rewriteImport rewrites any import of path oldPath to path newPath.
func rewriteImport(f *ast.File, oldPath, newPath string) (rewrote bool) {
for _, imp := range f.Imports {
if importPath(imp) == oldPath {
rewrote = true
// record old End, because the default is to compute
// it using the length of imp.Path.Value.
imp.EndPos = imp.End()
imp.Path.Value = strconv.Quote(newPath)
}
}
return
}