Optional should not coerce to optional optional as null, if it is null

[ArborealAnole]

Zig Version

0.10.0-dev.108+7c1e17a84

Steps to Reproduce

const std = @import("std");
const print = std.debug.print;
const builtin = std.builtin;

const A = @Type(.{
    .Struct = .{
        .layout = .Auto,
        .fields = &[_]builtin.TypeInfo.StructField{
            .{ .name = "one", .field_type = ?i32, .default_value = @as(?i32, null), .is_comptime = false, .alignment = 0 },
        },
        .decls = &[_]builtin.TypeInfo.Declaration{},
        .is_tuple = false,
    },
});
pub fn main() !void {
    const a: A = .{ }; // error
    // const a: A = .{ .one = null }; // ok
    print("{}\n", .{a});
    print("{}\n", .{@TypeOf(@typeInfo(A).Struct.fields[0].default_value)});
    print("{}\n", .{@typeInfo(A).Struct.fields[0].default_value});
    print("{}\n", .{@TypeOf(@as(?i32, null))});
}

Expected Behavior

The optional ?i32 should coerce to a ??i32 but it should not be a null ??i32. Therefore, the default value of the one field of A should be null.

Actual Behavior

There is no default value for the one field in the reified A.

[InKryption]

#7091 Possibly related? Which also looks at not being able to represent a default value when creating a struct, but with undefined (with or without using @Type).

[Vexu]

The example in the issue no longer reproduces the issue due to changes to std.builtin.Type but the bug has been fixed in self-hosted.