internal/godoc: fix codec generation test

ast.BasicLit has a new field. While we figure out what to do with this,
update the test to pass.

Updates golang/go#76350

Change-Id: Iaffabd1335dd17143d08fcd677c0f4ed6296a50f
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/721800
Reviewed-by: Ethan Lee <[email protected]>
Auto-Submit: Robert Findley <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
TryBot-Bypass: Robert Findley <[email protected]>

Author: findleyr

internal/godoc/codec/generate_test.go

@@ -7,7 +7,6 @@ package codec
 import (
 	"bytes"
 	"flag"
-	"go/ast"
 	"go/token"
 	"io"
 	"reflect"
@@ -46,7 +45,18 @@ func TestGoName(t *testing.T) {
 func TestGenerate(t *testing.T) {
 	testGenerate(t, "slice", [][]int(nil))
 	testGenerate(t, "map", map[string]bool(nil))
-	testGenerate(t, "struct", ast.BasicLit{})
+	testGenerate(t, "struct", BasicLit{})
+}
+
+// Copy of ast.BasicLit before ValueEnd was added in golang/go#76031.
+// This largely preserves the previous test data.
+//
+// See also golang/go#76350: we should figure out what to do with new fields,
+// in general. In this case we can probably just safely skip the field.
+type BasicLit struct {
+	ValuePos token.Pos // literal position
+	Kind     token.Token
+	Value    string
 }
 
 func testGenerate(t *testing.T, name string, x any) {