Repeat trait fn name collision

[Goncalerta]

Although __proc_macro__as_repeat is a very unique name, in theory it can collide if the struct being interpolated in a repetition also implements some function with that name.

Trying to solve this with the fully qualified syntax Repeat::__proc_macro__as_repeat(something), would raise a new issue.

While iterators have to be consumed to be used (transfer ownership), slices and ToTokens shouldn't (borrow reference). On the other hand, the macro must generate code that simultaneously can work in both situations. This means Repeat::__proc_macro__as_repeat(&something) couldn't be generated, otherwise iterators wouldn't work. On the other hand, using Repeat::__proc_macro__as_repeat(something), the compiler doesn't infer the reference for some reason (while something.__proc_macro__as_repeat() does), so slices and ToTokens wouldn't work directly.

The user would need to borrow the variables before passing them into the macro, which could get very annoying:

let a = vec!["a", "b", "c"];
let b = [5,6,7];
let c = 5;
let d = "a";
let e = X;

let a = &a;
let b = &b;
let c = &c;
let d = &d;
let e = &e;
let q = quote!{ #(#a #b #c #d #e)* };