export fn foo() void {
    var ptr = &[_]u8{0,0,0,0};
    ptr[1] = 2;
}
export fn bar() void {
    var ptr = &@as(u32, 2);
    ptr.* = 2;
}
export fn baz() void {
    var ptr = &true;
    ptr.* = false;
}
export fn qux() void {
    const S = struct{
        x: usize,
        y: usize,
    };
    var ptr = &S{.x=1,.y=2};
    ptr.x = 2;
}

// error
// backend=stage2
// target=native
//
// :3:14: error: cannot assign to constant
// :7:13: error: cannot assign to constant
// :11:13: error: cannot assign to constant
// :19:13: error: cannot assign to constant