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|
// compile-flags: --emit=link
// no-prefer-dynamic
#![crate_type = "proc-macro"]
#![feature(repr128, proc_macro_hygiene, proc_macro_quote, box_patterns)]
#![allow(incomplete_features)]
#![allow(clippy::useless_conversion, clippy::uninlined_format_args)]
extern crate proc_macro;
extern crate quote;
extern crate syn;
use proc_macro::TokenStream;
use quote::{quote, quote_spanned};
use syn::parse_macro_input;
use syn::spanned::Spanned;
use syn::token::Star;
use syn::{
parse_quote, FnArg, ImplItem, ItemImpl, ItemTrait, Lifetime, Pat, PatIdent, PatType, Signature, TraitItem, Type,
};
#[proc_macro_attribute]
pub fn dummy(_args: TokenStream, input: TokenStream) -> TokenStream {
input
}
#[proc_macro_attribute]
pub fn fake_async_trait(_args: TokenStream, input: TokenStream) -> TokenStream {
let mut item = parse_macro_input!(input as ItemTrait);
for inner in &mut item.items {
if let TraitItem::Method(method) = inner {
let sig = &method.sig;
let block = &mut method.default;
if let Some(block) = block {
let brace = block.brace_token;
let my_block = quote_spanned!( brace.span => {
// Should not trigger `empty_line_after_outer_attr`
#[crate_type = "lib"]
#sig #block
Vec::new()
});
*block = parse_quote!(#my_block);
}
}
}
TokenStream::from(quote!(#item))
}
#[proc_macro_attribute]
pub fn rename_my_lifetimes(_args: TokenStream, input: TokenStream) -> TokenStream {
fn make_name(count: usize) -> String {
format!("'life{}", count)
}
fn mut_receiver_of(sig: &mut Signature) -> Option<&mut FnArg> {
let arg = sig.inputs.first_mut()?;
if let FnArg::Typed(PatType { pat, .. }) = arg {
if let Pat::Ident(PatIdent { ident, .. }) = &**pat {
if ident == "self" {
return Some(arg);
}
}
}
None
}
let mut elided = 0;
let mut item = parse_macro_input!(input as ItemImpl);
// Look for methods having arbitrary self type taken by &mut ref
for inner in &mut item.items {
if let ImplItem::Method(method) = inner {
if let Some(FnArg::Typed(pat_type)) = mut_receiver_of(&mut method.sig) {
if let box Type::Reference(reference) = &mut pat_type.ty {
// Target only unnamed lifetimes
let name = match &reference.lifetime {
Some(lt) if lt.ident == "_" => make_name(elided),
None => make_name(elided),
_ => continue,
};
elided += 1;
// HACK: Syn uses `Span` from the proc_macro2 crate, and does not seem to reexport it.
// In order to avoid adding the dependency, get a default span from a non-existent token.
// A default span is needed to mark the code as coming from expansion.
let span = Star::default().span();
// Replace old lifetime with the named one
let lifetime = Lifetime::new(&name, span);
reference.lifetime = Some(parse_quote!(#lifetime));
// Add lifetime to the generics of the method
method.sig.generics.params.push(parse_quote!(#lifetime));
}
}
}
}
TokenStream::from(quote!(#item))
}
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