digraph "ABI diff" {
  "0" [shape=rectangle, label="'interface'"]
  "1" [label="'struct S1 v1' → 'struct { int a1; } v1'"]
  "2" [color=red, label="'struct S1' → 'struct { int a1; }'"]
  "1" -> "2" [label=""]
  "0" -> "1" [label=""]
  "3" [label="'struct { int a2; } v2' → 'struct S2 v2'"]
  "4" [color=red, label="'struct { int a2; }' → 'struct S2'"]
  "3" -> "4" [label=""]
  "0" -> "3" [label=""]
}