x/tools: remove dead code

These unused functions and methods were discovered by a (work in
progress) dead function analyzer.

Change-Id: Iaa9c5fd4f06bdcd5d7c6e194bcc24d6b37df8f4c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/639675
Auto-Submit: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

internal/jsonrpc2/jsonrpc2.go

@@ -112,15 +112,6 @@ func (a *async) done() {
 	close(a.ready)
 }
 
-func (a *async) isDone() bool {
-	select {
-	case <-a.ready:
-		return true
-	default:
-		return false
-	}
-}
-
 func (a *async) wait() error {
 	<-a.ready
 	err := <-a.firstErr

internal/jsonrpc2/serve_go116.go

@@ -8,12 +8,7 @@
 package jsonrpc2
 
 import (
-	"errors"
 	"net"
 )
 
 var errClosed = net.ErrClosed
-
-func isErrClosed(err error) bool {
-	return errors.Is(err, errClosed)
-}

internal/jsonrpc2/serve_pre116.go

@@ -9,22 +9,8 @@ package jsonrpc2
 
 import (
 	"errors"
-	"strings"
 )
 
 // errClosed is an error with the same string as net.ErrClosed,
 // which was added in Go 1.16.
 var errClosed = errors.New("use of closed network connection")
-
-// isErrClosed reports whether err ends in the same string as errClosed.
-func isErrClosed(err error) bool {
-	// As of Go 1.16, this could be 'errors.Is(err, net.ErrClosing)', but
-	// unfortunately gopls still requires compatibility with
-	// (otherwise-unsupported) older Go versions.
-	//
-	// In the meantime, this error string has not changed on any supported Go
-	// version, and is not expected to change in the future.
-	// This is not ideal, but since the worst that could happen here is some
-	// superfluous logging, it is acceptable.
-	return strings.HasSuffix(err.Error(), "use of closed network connection")
-}