I've started debugging the unit test failures in std.datetime:
We have this Date struct:
-----
struct Date
{
this(int a){}
short _year = 2;
ubyte _month = 1;
ubyte _day = 1;
}
-----
It's passed to D runtime variadic functions. It's 4 bytes in total so
GCC passes this struct in registers on x86_64 and it's therefore saved
in reg_save_area.
But our va_arg implementation using TypeInfo calls TypeInfo.argTypes()
to check if the type can be passed in parameters. This check returns
false as it depends on the dmd check sym->isPOD. Therefore our va_arg
tries to load the Date instance from the overflow_arg / stack save area
instead of the register save area.
What would be the correct way to tell the gcc backend not to pass !isPOD
structs in registers? Using TREE_ADDRESSABLE?
OT: I think a simple constructor shouldn't prevent a type from being a
POD, but that should be defined by dmd /frontend.
