Yuta Saito

むかーしの記述 https://github.com/apple/swift/blob/9b42d1b273cb6e5554bb717ab31341f1db65689b/include/swift/AST/Expr.h#L121-L125

/// TupleExpr - Parenthesized expressions like '(a=x+x)' and '(x, y, 4)'. Tuple /// types automatically decay if they have a single element, this means that /// single element tuple literals, such as "(4)", will exist in the AST, but /// have a result type that is the same as the input operand type. /// /// When a tuple element is formed with a default value for the type, the /// corresponding SubExpr element will be null. class TupleExpr : public Expr {

なるほど、ラベル付きだけがNGだったんですか

記憶が混乱してたかもですね（なんか社内で自分と同じ記憶の人が他にも何人かいるのでもしやマンデラエフェクト？と言ってるところですw