cmd/cue: remove CUE_SYNTAX_OVERRIDE support

The parser does not do anything in response to `FromVersion`
any more and hasn't for some time. Although we might
want to provide explicit syntax overriding again in the
future in some form, we will soon have support for per-file
experiments and module-declared versions, so the need
is likely to be considerably less.

Signed-off-by: Roger Peppe <[email protected]>
Change-Id: I97d6fe3cc830ab816fc8808e2eff044813ea735b
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1217210
Reviewed-by: Daniel Martí <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>

Author: rogpeppe

cmd/cue/cmd/common.go

@@ -32,14 +32,11 @@ import (
 	"cuelang.org/go/cue/load"
 	"cuelang.org/go/cue/parser"
 	"cuelang.org/go/cue/token"
-	"cuelang.org/go/internal"
 	"cuelang.org/go/internal/cuedebug"
 	"cuelang.org/go/internal/encoding"
 	"cuelang.org/go/internal/filetypes"
 )
 
-var requestedVersion = os.Getenv("CUE_SYNTAX_OVERRIDE")
-
 func defaultConfig() (*config, error) {
 	reg, err := getCachedRegistry()
 	if err != nil {
@@ -48,15 +45,7 @@ func defaultConfig() (*config, error) {
 	return &config{
 		loadCfg: &load.Config{
 			ParseFile: func(name string, src interface{}) (*ast.File, error) {
-				version := internal.APIVersionSupported
-				if requestedVersion != "" {
-					switch {
-					case strings.HasPrefix(requestedVersion, "v0.1"):
-						version = -1000 + 100
-					}
-				}
 				options := []parser.Option{
-					parser.FromVersion(version),
 					parser.ParseComments,
 				}
 				cuedebug.Init()