#![feature(const_generics)]

trait Helper {
    type T;
}

struct ITE<True, False, const B: bool> (
    ::core::marker::PhantomData<(True, False)>,
);

impl<True, False> Helper
    for ITE<True, False, {true}>
{
    type T = True;
}

impl<True, False> Helper
    for ITE<True, False, {false}>
{
    type T = False;
}

struct Foo {
    // x: String,
}

macro_rules! type_level_conditional {(
    type $T:ident =
        if { $cond:expr } {
            $True:ty
        } else {
            $False:ty
        }
    ;
) => (
    type $T = <$crate::ITE<$True, $False, {
        ::core::mem::size_of::<Foo>() == 0
    }> as $crate::Helper>::T;
)}

type_level_conditional! {
    type T = if { ::core::mem::size_of::<Foo>() == 0 } {
        i32
    } else {
        f32
    };
}

fn is_i32 (_: &i32) {}
fn is_f32 (_: &f32) {}

fn check (x: T)
{
    is_i32(&x);
    is_f32(&x);
}