Re: [PATCH 2/4] rust: macros: refactor generics parsing of `#[pin_data]` into its own function

[Alice Ryhl <alice@ryhl.io>]

On 4/24/23 10:11, Benno Lossin wrote:
> Other macros might also want to parse generics. Additionally this makes
> the code easier to read, as the next commit will introduce more code in
> `#[pin_data]`. Also add more comments to explain how parsing generics
> work.
> 
> Signed-off-by: Benno Lossin <benno.lossin@proton.me>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>

> +/// Parses the given `TokenStream` into `Generics` and the rest.
> +///
> +/// The generics are not present in the rest, but a where clause might remain.
> +pub(crate) fn parse_generics(input: TokenStream) -> (Generics, Vec<TokenTree>) {
> +    // `impl_generics`, the declared generics with their bounds.
> +    let mut impl_generics = vec![];
> +    // Only the names of the generics, without any bounds.
> +    let mut ty_generics = vec![];
> +    // Tokens not related to the generics e.g. the `where` token and definition.
> +    let mut rest = vec![];
> +    // The current level of `<`.
> +    let mut nesting = 0;
> +    let mut toks = input.into_iter();
> +    // If we are at the beginning of a generic parameter.
> +    let mut at_start = true;
> +    for tt in &mut toks {
> +        match tt.clone() {

Do you need the call to `clone` here? Not a big deal either way.