1 // compile-flags: --emit=link
2 // no-prefer-dynamic
3
4 #![crate_type = "proc-macro"]
5 #![feature(repr128, proc_macro_hygiene, proc_macro_quote, box_patterns)]
6 #![allow(incomplete_features)]
7 #![allow(clippy::useless_conversion)]
8
9 extern crate proc_macro;
10 extern crate quote;
11 extern crate syn;
12
13 use proc_macro::TokenStream;
14 use quote::{quote, quote_spanned};
15 use syn::parse_macro_input;
16 use syn::spanned::Spanned;
17 use syn::token::Star;
18 use syn::{
19 parse_quote, FnArg, ImplItem, ItemImpl, ItemTrait, Lifetime, Pat, PatIdent, PatType, Signature, TraitItem, Type,
20 };
21
22 #[proc_macro_attribute]
fake_async_trait(_args: TokenStream, input: TokenStream) -> TokenStream23 pub fn fake_async_trait(_args: TokenStream, input: TokenStream) -> TokenStream {
24 let mut item = parse_macro_input!(input as ItemTrait);
25 for inner in &mut item.items {
26 if let TraitItem::Method(method) = inner {
27 let sig = &method.sig;
28 let block = &mut method.default;
29 if let Some(block) = block {
30 let brace = block.brace_token;
31
32 let my_block = quote_spanned!( brace.span => {
33 // Should not trigger `empty_line_after_outer_attr`
34 #[crate_type = "lib"]
35 #sig #block
36 Vec::new()
37 });
38 *block = parse_quote!(#my_block);
39 }
40 }
41 }
42 TokenStream::from(quote!(#item))
43 }
44
45 #[proc_macro_attribute]
rename_my_lifetimes(_args: TokenStream, input: TokenStream) -> TokenStream46 pub fn rename_my_lifetimes(_args: TokenStream, input: TokenStream) -> TokenStream {
47 fn make_name(count: usize) -> String {
48 format!("'life{}", count)
49 }
50
51 fn mut_receiver_of(sig: &mut Signature) -> Option<&mut FnArg> {
52 let arg = sig.inputs.first_mut()?;
53 if let FnArg::Typed(PatType { pat, .. }) = arg {
54 if let Pat::Ident(PatIdent { ident, .. }) = &**pat {
55 if ident == "self" {
56 return Some(arg);
57 }
58 }
59 }
60 None
61 }
62
63 let mut elided = 0;
64 let mut item = parse_macro_input!(input as ItemImpl);
65
66 // Look for methods having arbitrary self type taken by &mut ref
67 for inner in &mut item.items {
68 if let ImplItem::Method(method) = inner {
69 if let Some(FnArg::Typed(pat_type)) = mut_receiver_of(&mut method.sig) {
70 if let box Type::Reference(reference) = &mut pat_type.ty {
71 // Target only unnamed lifetimes
72 let name = match &reference.lifetime {
73 Some(lt) if lt.ident == "_" => make_name(elided),
74 None => make_name(elided),
75 _ => continue,
76 };
77 elided += 1;
78
79 // HACK: Syn uses `Span` from the proc_macro2 crate, and does not seem to reexport it.
80 // In order to avoid adding the dependency, get a default span from a non-existent token.
81 // A default span is needed to mark the code as coming from expansion.
82 let span = Star::default().span();
83
84 // Replace old lifetime with the named one
85 let lifetime = Lifetime::new(&name, span);
86 reference.lifetime = Some(parse_quote!(#lifetime));
87
88 // Add lifetime to the generics of the method
89 method.sig.generics.params.push(parse_quote!(#lifetime));
90 }
91 }
92 }
93 }
94
95 TokenStream::from(quote!(#item))
96 }
97