Lint against `quote::quote!`

What it does

Lints against quote::quote! and recommends quote::quote_spanned!

Advantage

Proc macros have essentially zero diagnostics unless they provide such themselves, and tracking Spans, feeding them forward, is a bare-minimum requirement for this. There is a massive number of crates in the ecosystem which use quote but have absolutely execrable diagnostics because they don't bother. Because quote! is easy to use but doesn't ask for a span, they probably don't even realize they need to do this. Proc macros are somewhat of a "dark art" of Rust and people often regard them as unapproachable, and this is probably part of why.

Drawbacks

In some cases, there is genuinely no useful span, so you would just be calling Span::call_site() and feeding it in to satisfy the lint. Oh well.

Example

quote! {
    pub extern "C" fn #new_wrapper_fn(#(#args)) -> #ret_ty {
        #wrapped_fn(#(#args_idents))
    }
}

Could be written as:

quote_spanned! { wrapped_fn_span => 
    pub extern "C" fn #new_wrapper_fn(#(#args)) -> #ret_ty {
        #wrapped_fn(#(#args_idents))
    }
}

Start by reviewing how Clippy implements lints for macro usage and how it tests suggested replacements. Use the issue's quote::quote! and quote::quote_spanned! examples to define the target pattern and expected recommendation. Done means the lint detects applicable quote! invocations, provides the suggested span-aware form, and covers cases where no useful span exists.