internal/lsp: remove dead code

Running `staticcheck ./internal/lsp/...` turned up a few instances of
dead code. Remove them.

Change-Id: Ic53db59cd0959fad960b086158eb550a624a4d91
Reviewed-on: https://go-review.googlesource.com/c/tools/+/268580
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Robert Findley <rfindley@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>

internal/lsp/cache/workspace.go

@@ -308,11 +308,6 @@ func isGoMod(uri span.URI) bool {
 	return filepath.Base(uri.Filename()) == "go.mod"
 }
 
-// isGoMod reports if uri is a go.sum file.
-func isGoSum(uri span.URI) bool {
-	return filepath.Base(uri.Filename()) == "go.sum"
-}
-
 // fileExists reports if the file uri exists within source.
 func fileExists(ctx context.Context, uri span.URI, source source.FileSource) (bool, error) {
 	fh, err := source.GetFile(ctx, uri)

internal/lsp/general.go

@@ -13,7 +13,6 @@ import (
 	"os"
 	"path"
 	"path/filepath"
-	"strings"
 	"sync"
 
 	"golang.org/x/tools/internal/event"
@@ -409,11 +408,6 @@ func (s *Server) registerWatchedDirectoriesLocked(ctx context.Context, dirs map[
 	return nil
 }
 
-func isSubdirectory(root, leaf string) bool {
-	rel, err := filepath.Rel(root, leaf)
-	return err == nil && !strings.HasPrefix(rel, "..")
-}
-
 func (s *Server) fetchConfig(ctx context.Context, name string, folder span.URI, o *source.Options) error {
 	if !s.session.Options().ConfigurationSupported {
 		return nil

internal/lsp/semantic.go

@@ -126,8 +126,6 @@ const (
 	tokOperator  tokenType = "operator"
 )
 
-var lastPosition token.Position
-
 func (e *encoded) token(start token.Pos, leng int, typ tokenType, mods []string) {
 	if start == 0 {
 		e.unexpected("token at token.NoPos")