Often I encounter the following problem:
I am happily using the readability benefit of designated initializers in my
struct.
Then I notice I must add a functionality that makes it a nonaggregate (for
example deleting copy constructor to prevent accidental expensive copy),
then all my nice initialization must go away and I am forced to write a
spammy "forwarding" constructor (one that does nothing, just initializes
all variables with mathiing arguments).

I am not sure what syntax would be best, maybe
[[agg_init]]
attribute?