36     //     let _ = match x {} - 1;  // no parens
44     //     Example: `let _ = $match - 1;`
98     //     if let _ = (Struct {}) {}  // needs parens
101     //         () if let _ = Struct {} => {}  // no parens
127     //     let _ = (return) - 1;  // without paren, this would return -1
129     //     let _ = return + 1;  // no paren because '+' cannot begin expr
136     //     let _ = 1 + return 1;  // no parens if rightmost subexpression
138     //     let _ = 1 + (return 1) + 1;  // needs parens
145     //     let _ = x as u8 + T;
147     //     let _ = (x as u8) < T;
233         let fixup = FixupContext {  in leftmost_subexpression_with_operator()
263         let fixup = FixupContext {  in leftmost_subexpression_with_dot()
290             if let Scan::Bailout = scan_right(expr, self, Precedence::MIN, 0, 0) {  in leftmost_subexpression_precedence()
316         let fixup = self.rightmost_subexpression_fixup(  in rightmost_subexpression()
353         let default_prec = self.precedence(expr);  in rightmost_subexpression_precedence()
357             Precedence::Assign | Precedence::Let | Precedence::Prefix => {  in rightmost_subexpression_precedence()
365             if let Scan::Bailout | Scan::Fail = scan_right(expr, self, self.previous_operator, 1, 0)  in rightmost_subexpression_precedence()
381             || ((self.stmt || self.leftmost_subexpression_in_stmt) && matches!(expr, Expr::Let(_)))  in parenthesize()
411             if let Expr::Break(ExprBreak { expr: None, .. })  in precedence()
426                 | Expr::Let(_)  in precedence()
437             if let Expr::Cast(cast) = expr {  in precedence()
502     let consume_by_precedence = if match precedence {  in scan_right()
522             let right_fixup = fixup.rightmost_subexpression_fixup(false, false, Precedence::Assign);  in scan_right()
523             let scan = scan_right(  in scan_right()
533             if let Scan::Bailout | Scan::Consume = scan {  in scan_right()
535             } else if let Precedence::Unambiguous = fixup.next_operator {  in scan_right()
551             let binop_prec = Precedence::of_binop(&e.op);  in scan_right()
555             let right_fixup = fixup.rightmost_subexpression_fixup(false, false, binop_prec);  in scan_right()
556             let scan = scan_right(  in scan_right()
571             let right_needs_group = binop_prec != Precedence::Assign  in scan_right()
575             } else if let (Scan::Fail, Precedence::Unambiguous) = (scan, fixup.next_operator) {  in scan_right()
593             let right_fixup = fixup.rightmost_subexpression_fixup(false, false, Precedence::Prefix);  in scan_right()
594             let scan = scan_right(  in scan_right()
611             } else if let (Scan::Fail, Precedence::Unambiguous) = (scan, fixup.next_operator) {  in scan_right()
622                 let right_fixup =  in scan_right()
624                 let scan = scan_right(  in scan_right()
660                 let right_fixup = fixup.rightmost_subexpression_fixup(true, true, Precedence::Jump);  in scan_right()
676                 let right_fixup =  in scan_right()
695                 let right_fixup =  in scan_right()
705         Expr::Let(e) => {  in scan_right()
709             let right_fixup = fixup.rightmost_subexpression_fixup(false, false, Precedence::Let);  in scan_right()
710             let scan = scan_right(  in scan_right()
713                 Precedence::Let,  in scan_right()
715                 if fixup.next_operator < Precedence::Let {  in scan_right()
722                 Scan::Fail | Scan::Bailout if fixup.next_operator < Precedence::Let => {  in scan_right()
728             if right_fixup.rightmost_subexpression_precedence(&e.expr) < Precedence::Let {  in scan_right()
730             } else if let Scan::Fail = scan {  in scan_right()
769             _ if precedence == Precedence::Let && fixup.next_operator < Precedence::Let => {  in scan_right()