fieldParentPointer.zig

const std = @import("std");

const Foo = struct {
    bar: usize,
    bytes: []u8
};

pub fn foo(bytes: []u8) void {
    var boo = @fieldParentPtr(Foo, "bytes", &bytes);
    std.debug.warn("{}\n", @ptrToInt(boo));
}

pub fn main() !void {
    var bax = try std.debug.global_allocator.create(Foo);
    bax.bytes = try std.debug.global_allocator.alloc(u8, 10);
    std.debug.warn("{}\n", @ptrToInt(bax));
    foo(bax.bytes);
}