1struct S1 { int x; }; 2struct S2 { S1 x; }; 3struct S3 { S2 x; }; 4struct S4 { S3 x; }; 5struct S5 { S4 x; }; 6struct S6 { S5 x; }; 7struct S7 { S6 x; }; 8struct S8 { S7 x; }; 9struct too_deep { S8 x; }; 10