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go/internal/lsp/cmd/prepare_rename.go
Rob Findley de023d59a5 internal/lsp/protocol: unmarshal to pointers when dispatching requests
With #34111, we are forwarding the LSP from one gopls instance to
another. This exposed an asymmetry in our LSP dispatching: for both
ClientDispatcher and ServerDispatcher, we unmarshal to non-nil response
structs. This means that when forwarding the LSP, we translate empty
JSON responses (corresponding to nil values) into the non-nil zero
value.

This causes problems for some editors, as reported in #37570. Fix it by
instead unmarshaling to a pointer.

This is, of course, a somewhat dangerous change. I fixed the one NPE
that occurred in tests, and have done some mild manual testing.  I
wouldn't be surprised if we discover more NPEs later on, but I still
think this is the right change to make.

Updates golang/go#34111
Fixes golang/go#37570

Change-Id: Ie69e92d2821c829cdfc4f4ab303679a725f1f859
Reviewed-on: https://go-review.googlesource.com/c/tools/+/222058
Reviewed-by: Peter Weinberger <pjw@google.com>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2020-03-05 22:45:36 +00:00

86 lines
2.1 KiB
Go

// 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.
package cmd
import (
"context"
"errors"
"flag"
"fmt"
"golang.org/x/tools/internal/lsp/protocol"
"golang.org/x/tools/internal/span"
"golang.org/x/tools/internal/tool"
)
// prepareRename implements the prepare_rename verb for gopls.
type prepareRename struct {
app *Application
}
func (r *prepareRename) Name() string { return "prepare_rename" }
func (r *prepareRename) Usage() string { return "<position>" }
func (r *prepareRename) ShortHelp() string { return "test validity of a rename operation at location" }
func (r *prepareRename) DetailedHelp(f *flag.FlagSet) {
fmt.Fprint(f.Output(), `
Example:
$ # 1-indexed location (:line:column or :#offset) of the target identifier
$ gopls prepare_rename helper/helper.go:8:6
$ gopls prepare_rename helper/helper.go:#53
gopls prepare_rename flags are:
`)
f.PrintDefaults()
}
// ErrInvalidRenamePosition is returned when prepareRename is run at a position that
// is not a candidate for renaming.
var ErrInvalidRenamePosition = errors.New("request is not valid at the given position")
func (r *prepareRename) Run(ctx context.Context, args ...string) error {
if len(args) != 1 {
return tool.CommandLineErrorf("prepare_rename expects 1 argument (file)")
}
conn, err := r.app.connect(ctx)
if err != nil {
return err
}
defer conn.terminate(ctx)
from := span.Parse(args[0])
file := conn.AddFile(ctx, from.URI())
if file.err != nil {
return file.err
}
loc, err := file.mapper.Location(from)
if err != nil {
return err
}
p := protocol.PrepareRenameParams{
TextDocumentPositionParams: protocol.TextDocumentPositionParams{
TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
Position: loc.Range.Start,
},
}
result, err := conn.PrepareRename(ctx, &p)
if err != nil {
return fmt.Errorf("prepare_rename failed: %v", err)
}
if result == nil {
return ErrInvalidRenamePosition
}
l := protocol.Location{Range: *result}
s, err := file.mapper.Span(l)
if err != nil {
return err
}
fmt.Println(s)
return nil
}