Generic function question

generic.zig

fn S(comptime T: type) type {
    return struct {
        const Self = @This();

        foo: fn (a: T, b: T) bool,

        fn init(foo: fn (a: T, b: T) bool) Self {
            return Self {
                .foo = foo
            };
        }
    };
}

fn greaterThan1(a: u32, b: u32) bool {
    return a > b;
}

fn greaterThan2(a: var, b: @typeOf(a)) bool {
    return a > b;
}

fn greaterThan3(comptime T: type, a: T, b: T) bool {
    return a > b;
}

// This works
pub fn main() void {
    const s = S(u32).init(greaterThan1);
    warn("{}", s);
}


// ➜  deflate git:(master) ✗ zig build-exe priority_queue.zig && ./priority_queue
// S(u32){ .foo = fn(u32, u32) bool@10c843850 }%


// // No dice!
pub fn main() void {
    const s = S(u32).init(greaterThan2);
    warn("{}", s);
}


// ➜  deflate git:(master) ✗ zig build-exe priority_queue.zig && ./priority_queue
// /Users/john.schmidt/personal_programming/zig/deflate/priority_queue.zig:380:27: error: expected type 'fn(u32, u32) bool', found 'fn(var,var)var'
//     const s = S(u32).init(greaterThan2);
//                           ^
// /Users/john.schmidt/personal_programming/zig/deflate/priority_queue.zig:380:27: note: only one of the functions is generic
//     const s = S(u32).init(greaterThan2);
                          ^
    
// Naturally, this doesn't work either
pub fn main() void {
    const s = S(u32).init(greaterThan3);
    warn("{}", s);
}

// ➜  deflate git:(master) ✗ zig build-exe priority_queue.zig && ./priority_queue
// /Users/john.schmidt/personal_programming/zig/deflate/priority_queue.zig:380:27: error: expected type 'fn(u32, u32) bool', found 'fn(type,var,var)var'
//     const s = S(u32).init(greaterThan3);
//                           ^
// /Users/john.schmidt/personal_programming/zig/deflate/priority_queue.zig:380:27: note: only one of the functions is generic
//     const s = S(u32).init(greaterThan3);