There is still one problem, bug 10198. This currently compiles, and does something stupid:
---
struct U {
int [3][3] y;
}
U u = U(4);
---
What do you think should happen here?
Oh! I did not know it is currently accepted.
I think accepting multi-dimensional block initializing on StructLiteralExp arguments is very bug-prone behavior.
Different from variable declaration in statement scope, there is no target type we can look for. So inferring the cost of static array construction is difficult.
struct U { int[3][3][3][3] w; }
U u = U(1); // looks trivial, but actually costly operation.
int[3][3][3][3] w = 1; // initializing cost is very obvious
At most it would be better that it is restricted up to one-dimensional block initializing, same as StructInitializer.