type info example of polystructs

package test

import "core:fmt"
import "core:runtime"

Bar :: struct(T: typeid) #packed {
    val: T,
    other_data: int,
}

Foo :: struct(T: typeid) #packed {
    bar: Bar(T),
    t: u64,
}

main :: proc() {
    // T = int
    fmt.printf("type_info_of(Foo(int))                      = %v\n", type_info_of(Foo(int))^);
    fmt.printf("type_info_of(Foo(int)).variant              = %v\n", type_info_of(Foo(int))^.variant);
    fmt.printf("type_info_of(Foo(int)).variant.base         = %v\n", type_info_of(Foo(int))^.variant.(runtime.Type_Info_Named).base^);
    fmt.printf("type_info_of(Foo(int)).variant.base.variant = %v\n", type_info_of(Foo(int))^.variant.(runtime.Type_Info_Named).base^.variant);

    // T = u8
    fmt.printf("type_info_of(Foo(u8 ))                      = %v\n", type_info_of(Foo(u8))^);
    fmt.printf("type_info_of(Foo(u8 )).variant              = %v\n", type_info_of(Foo(u8))^.variant);
    fmt.printf("type_info_of(Foo(u8 )).variant.base         = %v\n", type_info_of(Foo(u8))^.variant.(runtime.Type_Info_Named).base^);
    fmt.printf("type_info_of(Foo(u8 )).variant.base.variant = %v\n", type_info_of(Foo(u8))^.variant.(runtime.Type_Info_Named).base^.variant);
}

/* Output:

type_info_of(Foo(int))                      = Type_Info{size = 24, align = 1, id = Foo(int), variant = Type_Info_Named{name = Foo(int), base = struct #packed {bar: Bar(T), t: u64}}}
type_info_of(Foo(int)).variant              = Type_Info_Named{name = Foo(int), base = struct #packed {bar: Bar(T), t: u64}}
type_info_of(Foo(int)).variant.base         = Type_Info{size = 24, align = 1, id = struct #packed {bar: Bar(T), t: u64}, variant = Type_Info_Struct{types = [Bar(T), u64], names = [bar, t], offsets = [0, 16], usings = [false, false], is_packed = true, is_raw_union = false, custom_align = false}}
type_info_of(Foo(int)).variant.base.variant = Type_Info_Struct{types = [Bar(T), u64], names = [bar, t], offsets = [0, 16], usings = [false, false], is_packed = true, is_raw_union = false, custom_align = false}
                                                                                                                      ^
                                                                                                                      Notice how the offsets differ

type_info_of(Foo(u8 ))                      = Type_Info{size = 17, align = 1, id = Foo(u8), variant = Type_Info_Named{name = Foo(u8), base = struct #packed {bar: Bar(T), t: u64}}}
type_info_of(Foo(u8 )).variant              = Type_Info_Named{name = Foo(u8), base = struct #packed {bar: Bar(T), t: u64}}
type_info_of(Foo(u8 )).variant.base         = Type_Info{size = 17, align = 1, id = struct #packed {bar: Bar(T), t: u64}, variant = Type_Info_Struct{types = [Bar(T), u64], names = [bar, t], offsets = [0, 9], usings = [false, false], is_packed = true, is_raw_union = false, custom_align = false}}
type_info_of(Foo(u8 )).variant.base.variant = Type_Info_Struct{types = [Bar(T), u64], names = [bar, t], offsets = [0, 9], usings = [false, false], is_packed = true, is_raw_union = false, custom_align = false}
                                                                                                                      ^
                                                                                                                      Different offset
*/