1 files changed, 101 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/auxiliary/proc_macro_attr.rs b/src/tools/clippy/tests/ui/auxiliary/proc_macro_attr.rs
new file mode 100644
index 000000000..ae2cc2492
--- /dev/null
+++ b/src/tools/clippy/tests/ui/auxiliary/proc_macro_attr.rs
@@ -0,0 +1,101 @@
+// 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)]
+
+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))
+}