diff --git a/src/go/parser/parser.go b/src/go/parser/parser.go
index 26b9630cfc..3f2297c194 100644
--- a/src/go/parser/parser.go
+++ b/src/go/parser/parser.go
@@ -2695,6 +2695,9 @@ func extractName(x ast.Expr, force bool) (*ast.Ident, ast.Expr) {
 	case *ast.CallExpr:
 		if name, _ := x.Fun.(*ast.Ident); name != nil {
 			if len(x.Args) == 1 && x.Ellipsis == token.NoPos && (force || isTypeElem(x.Args[0])) {
+				// x = name (x.Args[0])
+				// (Note that the cmd/compile/internal/syntax parser does not care
+				// about syntax tree fidelity and does not preserve parentheses here.)
 				return name, &ast.ParenExpr{
 					Lparen: x.Lparen,
 					X:      x.Args[0],