Now it's an error only during constant evaluation: https://godbolt.org/z/4Wz11ahWv

constexpr int uninit() {
  struct { int a; } s;
-  return s.a;                   // error: uninitialized read of s.a
+  return s.a;
}
+int x = uninit();
+constexpr int y = uninit();     // error: uninitialized read of s.a

I'm not sure what the initialization of x is.

Another point @zygoloid made was that the // OK examples in this subclause are becoming increasingly less useful, as more and more constructions involving constant expressions are now OK. Maybe some pruning is in order.