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// Copyright 2021 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 safetoken_test
import (
"fmt"
"go/parser"
"go/token"
"go/types"
"os"
"testing"
"golang.org/x/tools/go/packages"
"golang.org/x/tools/gopls/internal/util/safetoken"
"golang.org/x/tools/internal/testenv"
)
func TestWorkaroundIssue57490(t *testing.T) {
// During error recovery the parser synthesizes various close
// tokens at EOF, causing the End position of incomplete
// syntax nodes, computed as Rbrace+len("}"), to be beyond EOF.
src := `package p; func f() { var x struct`
fset := token.NewFileSet()
file, _ := parser.ParseFile(fset, "a.go", src, 0)
tf := fset.File(file.Pos())
// Add another file to the FileSet.
file2, _ := parser.ParseFile(fset, "b.go", "package q", 0)
// This is the ambiguity of #57490...
if file.End() != file2.Pos() {
t.Errorf("file.End() %d != %d file2.Pos()", file.End(), file2.Pos())
}
// ...which causes these statements to panic.
if false {
tf.Offset(file.End()) // panic: invalid Pos value 36 (should be in [1, 35])
tf.Position(file.End()) // panic: invalid Pos value 36 (should be in [1, 35])
}
// The offset of the EOF position is the file size.
offset, err := safetoken.Offset(tf, file.End()-1)
if err != nil || offset != tf.Size() {
t.Errorf("Offset(EOF) = (%d, %v), want token.File.Size %d", offset, err, tf.Size())
}
// The offset of the file.End() position, 1 byte beyond EOF,
// is also the size of the file.
offset, err = safetoken.Offset(tf, file.End())
if err != nil || offset != tf.Size() {
t.Errorf("Offset(ast.File.End()) = (%d, %v), want token.File.Size %d", offset, err, tf.Size())
}
if got, want := safetoken.Position(tf, file.End()).String(), "a.go:1:35"; got != want {
t.Errorf("Position(ast.File.End()) = %s, want %s", got, want)
}
if got, want := safetoken.EndPosition(fset, file.End()).String(), "a.go:1:35"; got != want {
t.Errorf("EndPosition(ast.File.End()) = %s, want %s", got, want)
}
// Note that calling StartPosition on an end may yield the wrong file:
if got, want := safetoken.StartPosition(fset, file.End()).String(), "b.go:1:1"; got != want {
t.Errorf("StartPosition(ast.File.End()) = %s, want %s", got, want)
}
}
// To reduce the risk of panic, or bugs for which this package
// provides a workaround, this test statically reports references to
// forbidden methods of token.File or FileSet throughout gopls and
// suggests alternatives.
func TestGoplsSourceDoesNotCallTokenFileMethods(t *testing.T) {
testenv.NeedsGoPackages(t)
testenv.NeedsLocalXTools(t)
cfg := &packages.Config{
Mode: packages.NeedName | packages.NeedModule | packages.NeedCompiledGoFiles | packages.NeedTypes | packages.NeedTypesInfo | packages.NeedSyntax | packages.NeedImports | packages.NeedDeps,
}
cfg.Env = os.Environ()
cfg.Env = append(cfg.Env,
"GOPACKAGESDRIVER=off",
"GOWORK=off", // necessary for -mod=mod below
"GOFLAGS=-mod=mod",
)
pkgs, err := packages.Load(cfg, "go/token", "golang.org/x/tools/gopls/...")
if err != nil {
t.Fatal(err)
}
var tokenPkg *packages.Package
for _, pkg := range pkgs {
if pkg.PkgPath == "go/token" {
tokenPkg = pkg
break
}
}
if tokenPkg == nil {
t.Fatal("missing package go/token")
}
File := tokenPkg.Types.Scope().Lookup("File")
FileSet := tokenPkg.Types.Scope().Lookup("FileSet")
alternative := make(map[types.Object]string)
setAlternative := func(recv types.Object, old, new string) {
oldMethod, _, _ := types.LookupFieldOrMethod(recv.Type(), true, recv.Pkg(), old)
alternative[oldMethod] = new
}
setAlternative(File, "Line", "safetoken.Line")
setAlternative(File, "Offset", "safetoken.Offset")
setAlternative(File, "Position", "safetoken.Position")
setAlternative(File, "PositionFor", "safetoken.Position")
setAlternative(FileSet, "Position", "safetoken.StartPosition or EndPosition")
setAlternative(FileSet, "PositionFor", "safetoken.StartPosition or EndPosition")
for _, pkg := range pkgs {
switch pkg.PkgPath {
case "go/token", "golang.org/x/tools/gopls/internal/util/safetoken":
continue // allow calls within these packages
}
for ident, obj := range pkg.TypesInfo.Uses {
if alt, ok := alternative[obj]; ok {
posn := safetoken.StartPosition(pkg.Fset, ident.Pos())
fmt.Fprintf(os.Stderr, "%s: forbidden use of %v; use %s instead.\n", posn, obj, alt)
t.Fail()
}
}
}
}
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