cue/cmd/cue: disallow quoted identifiers by default

These were deprecated a while back. Now step up the
enforcement.

Also bumps the syntax check level.

Issue #339

Change-Id: I922bb075114c638e411eaf7d6e8418cf730578d5
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/5780
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

cmd/cue/cmd/common.go

@@ -43,7 +43,7 @@ import (
 // - block comments
 // - old-style field comprehensions
 // - space separator syntax
-const syntaxVersion = -1000 + 13
+const syntaxVersion = -1000 + 100*1 + 2
 
 var defaultConfig = config{
 	loadCfg: &load.Config{

cue/parser/parser.go

@@ -366,6 +366,10 @@ func (p *parser) next() {
 			p.comments.add(comment)
 		}
 	}
+
+	if p.tok == token.IDENT && p.lit[0] == '`' {
+		p.assertV0(p.pos, 0, 13, "quoted identifiers")
+	}
 }
 
 // assertV0 indicates the last version at which a certain feature was
@@ -1131,7 +1135,7 @@ func (p *parser) parseList() (expr ast.Expr) {
 
 	if clauses, _ := p.parseComprehensionClauses(false); clauses != nil {
 		var expr ast.Expr
-		p.assertV0(p.pos, 1, 1, "old-style list comprehensions")
+		p.assertV0(p.pos, 1, 3, "old-style list comprehensions")
 		if len(elts) != 1 {
 			p.errf(lbrack.Add(1), "list comprehension must have exactly one element")
 		}

doc/tutorial/kubernetes/manual/services/k8s.cue

@@ -10,7 +10,7 @@ kubernetes: services: {
 			metadata: labels: x.label
 			spec: selector:   x.label
 
-			spec: ports: [ p for p in x.port ] // convert struct to list
+			spec: ports: [ for p in x.port {p}] // convert struct to list
 		}
 	}
 	// Note that we cannot write
@@ -84,13 +84,13 @@ _k8sSpec: X: kubernetes: {
 			image: X.image
 			args:  X.args
 			if len(X.envSpec) > 0 {
-				env: [ for k, v in X.envSpec {v, name: k} ]
+				env: [ for k, v in X.envSpec {v, name: k}]
 			}
 
 			ports: [ for k, p in X.expose.port & X.port {
 				name:          k
 				containerPort: p
-			} ]
+			}]
 		}]
 	}
 
@@ -102,7 +102,7 @@ _k8sSpec: X: kubernetes: {
 					v.kubernetes
 
 					name: v.name
-				}
+				},
 			]
 		}
 
@@ -120,7 +120,7 @@ _k8sSpec: X: kubernetes: {
 						if v.readOnly {
 							readOnly: v.readOnly
 						}
-					}
+					},
 				]
 			}
 		}]