internal/lsp: rename all the package names in the renamed package

This CL contains a partial implementation of package renaming. Currently gopls is only able to rename references to the renaming package within the renaming package itself.

prepareRename is still expected to return an error for renaming a package.

For golang/go#41567

Change-Id: I3683a0a7128bba7620ef30db528f45b753e6c08f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/420219
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Dylan Le <dungtuanle@google.com>

gopls/internal/regtest/misc/rename_test.go

@@ -10,6 +10,7 @@ import (
 
 	"golang.org/x/tools/internal/lsp/protocol"
 	. "golang.org/x/tools/internal/lsp/regtest"
+	"golang.org/x/tools/internal/testenv"
 )
 
 func TestPrepareRenamePackage(t *testing.T) {
@@ -51,6 +52,41 @@ func main() {
 	})
 }
 
+func TestRenamePackageInRenamedPackage(t *testing.T) {
+	// Failed at Go 1.13; not investigated
+	testenv.NeedsGo1Point(t, 14)
+	const files = `
+-- go.mod --
+module mod.com
+
+go 1.18
+-- main.go --
+package main
+
+import (
+	"fmt"
+	"a.go"
+)
+
+func main() {
+	fmt.Println(a.C)
+}
+-- a.go --
+package main
+
+const C = 1
+`
+	Run(t, files, func(t *testing.T, env *Env) {
+		env.OpenFile("main.go")
+		pos := env.RegexpSearch("main.go", "main")
+		env.Rename("main.go", pos, "pkg")
+
+		// Check if the new package name exists.
+		env.RegexpSearch("main.go", "package pkg")
+		env.RegexpSearch("a.go", "package pkg")
+	})
+}
+
 // Test for golang/go#47564.
 func TestRenameInTestVariant(t *testing.T) {
 	const files = `

internal/lsp/source/rename.go

@@ -118,6 +118,41 @@ func Rename(ctx context.Context, s Snapshot, f FileHandle, pp protocol.Position,
 	ctx, done := event.Start(ctx, "source.Rename")
 	defer done()
 
+	pgf, err := s.ParseGo(ctx, f, ParseFull)
+	if err != nil {
+		return nil, err
+	}
+	inPackageName, err := isInPackageName(ctx, s, f, pgf, pp)
+	if err != nil {
+		return nil, err
+	}
+
+	if inPackageName {
+		renamingPkg, err := s.PackageForFile(ctx, f.URI(), TypecheckAll, NarrowestPackage)
+		if err != nil {
+			return nil, err
+		}
+
+		result := make(map[span.URI][]protocol.TextEdit)
+		// Rename internal references to the package in the renaming package
+		// Todo(dle): need more investigation on case when pkg.GoFiles != pkg.CompiledGoFiles if using cgo.
+		for _, f := range renamingPkg.CompiledGoFiles() {
+			pkgNameMappedRange := NewMappedRange(f.Tok, f.Mapper, f.File.Name.Pos(), f.File.Name.End())
+			rng, err := pkgNameMappedRange.Range()
+			if err != nil {
+				return nil, err
+			}
+			result[f.URI] = []protocol.TextEdit{
+				{
+					Range:   rng,
+					NewText: newName,
+				},
+			}
+		}
+
+		return result, nil
+	}
+
 	qos, err := qualifiedObjsAtProtocolPos(ctx, s, f.URI(), pp)
 	if err != nil {
 		return nil, err
@@ -182,6 +217,7 @@ func Rename(ctx context.Context, s Snapshot, f FileHandle, pp protocol.Position,
 	if err != nil {
 		return nil, err
 	}
+
 	result := make(map[span.URI][]protocol.TextEdit)
 	for uri, edits := range changes {
 		// These edits should really be associated with FileHandles for maximal correctness.