@sizeOf is incorrect for optional unions

[jwhear]

Zig Version

0.11.0-dev.811+8ff9284c4

Steps to Reproduce and Observed Behavior

Using @sizeOf on an optional union produces a value of 1.

const std = @import("std");
pub fn main() !void {
    const Node = union {
        a: usize,
    };
    var output = std.io.getStdOut().writer();
    inline for (.{ ?Node, Node, }) |typ| {
        try output.print("{s} is {} bytes, align is {}\n", .{ @typeName(typ), @sizeOf(typ), @alignOf(typ) });
    }
}

With 0.11.0-dev.811+8ff9284c4 this prints

?test.main.Node is 1 bytes, align is 8
test.main.Node is 8 bytes, align is 8

With 0.10.0 and -fstage1 this prints

?Node is 16 bytes, align is 8
Node is 8 bytes, align is 8

Expected Behavior

The stage1 behavior appears correct.