cue/parser: always allow predeclared identifiers on RHS

CUE reserves identifiers starting with __ for builtin functionality. A bug in the parser currently disallows them to be used by themselves on the RHS of a field. Signed-off-by: Marcel van Lohuizen <[email protected]> Change-Id: I5c71a8931ea19104735a43211580fbe6e09f8b6a Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1205229 Reviewed-by: Matthew Sackman <[email protected]> Unity-Result: CUE porcuepine <[email protected]> TryBot-Result: CUEcueckoo <[email protected]>
cue-lang · Dec 7, 2024 · ec9117a · ec9117a
1 parent 46c1cb2
commit ec9117a
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Showing 2 changed files with 6 additions and 1 deletion.
diff --git a/cue/parser/parser.go b/cue/parser/parser.go
@@ -1007,7 +1007,7 @@ func (p *parser) parseLabel(rhs bool) (label ast.Label, expr ast.Expr, decl ast.
 		}
 
 	case *ast.Ident:
-		if strings.HasPrefix(x.Name, "__") {
+		if strings.HasPrefix(x.Name, "__") && !rhs {
 			p.errf(x.NamePos, "identifiers starting with '__' are reserved")
 		}
 

diff --git a/cue/parser/parser_test.go b/cue/parser/parser_test.go
@@ -260,6 +260,11 @@ func TestParse(t *testing.T) {
 			[X=_]: X
 		`,
 		"a: {b: {c: d}}, c: a, d: a.b, e: a.b.c, \"f\": f, [X=_]: X",
+	}, {
+		"predeclared identifiers",
+		`a:    __string
+		__int: 2`,
+		"a: __string, __int: 2\nidentifiers starting with '__' are reserved",
 	}, {
 		"empty fields",
 		`