Merge pull request #262 from dtolnay/asyncspan

Minimize use of `async` token's span in expanded code

Author: dtolnay

src/bound.rs

@@ -1,5 +1,5 @@
 use proc_macro2::{Ident, Span, TokenStream};
-use quote::quote_spanned;
+use quote::{quote, ToTokens};
 use syn::punctuated::Punctuated;
 use syn::{Token, TypeParamBound};
 
@@ -34,10 +34,12 @@ impl InferredBound {
             InferredBound::Sync => "Sync",
         }
     }
+}
 
-    pub fn spanned_path(&self, span: Span) -> TokenStream {
-        let ident = Ident::new(self.as_str(), span);
-        quote_spanned!(span=> ::core::marker::#ident)
+impl ToTokens for InferredBound {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let ident = Ident::new(self.as_str(), Span::call_site());
+        quote!(::core::marker::#ident).to_tokens(tokens);
     }
 }
 

src/expand.rs

@@ -125,7 +125,6 @@ pub fn expand(input: &mut Item, is_local: bool) {
 fn lint_suppress_with_body() -> Attribute {
     parse_quote! {
         #[allow(
-            unused_qualifications,
             clippy::async_yields_async,
             clippy::diverging_sub_expression,
             clippy::let_unit_value,
@@ -141,7 +140,6 @@ fn lint_suppress_with_body() -> Attribute {
 fn lint_suppress_without_body() -> Attribute {
     parse_quote! {
         #[allow(
-            unused_qualifications,
             clippy::type_complexity,
             clippy::type_repetition_in_bounds
         )]
@@ -168,11 +166,10 @@ fn transform_sig(
     has_default: bool,
     is_local: bool,
 ) {
-    let default_span = sig.asyncness.take().unwrap().span;
-    sig.fn_token.span = default_span;
+    sig.fn_token.span = sig.asyncness.take().unwrap().span;
 
     let (ret_arrow, ret) = match &sig.output {
-        ReturnType::Default => (Token![->](default_span), quote_spanned!(default_span=> ())),
+        ReturnType::Default => (Token![->](Span::call_site()), quote!(())),
         ReturnType::Type(arrow, ret) => (*arrow, quote!(#ret)),
     };
 
@@ -234,9 +231,7 @@ fn transform_sig(
             .push(parse_quote_spanned!(elided.span()=> #elided: 'async_trait));
     }
 
-    sig.generics
-        .params
-        .push(parse_quote_spanned!(default_span=> 'async_trait));
+    sig.generics.params.push(parse_quote!('async_trait));
 
     if has_self {
         let bounds: &[InferredBound] = if is_local {
@@ -272,21 +267,17 @@ fn transform_sig(
             &[InferredBound::Send]
         };
 
-        let bounds = bounds.iter().filter_map(|bound| {
+        let bounds = bounds.iter().filter(|bound| {
             let assume_bound = match context {
                 Context::Trait { supertraits, .. } => !has_default || has_bound(supertraits, bound),
                 Context::Impl { .. } => true,
             };
-            if assume_bound {
-                None
-            } else {
-                Some(bound.spanned_path(default_span))
-            }
+            !assume_bound
         });
 
         where_clause_or_default(&mut sig.generics.where_clause)
             .predicates
-            .push(parse_quote_spanned! {default_span=>
+            .push(parse_quote! {
                 Self: #(#bounds +)* 'async_trait
             });
     }
@@ -318,11 +309,11 @@ fn transform_sig(
     }
 
     let bounds = if is_local {
-        quote_spanned!(default_span=> 'async_trait)
+        quote!('async_trait)
     } else {
-        quote_spanned!(default_span=> ::core::marker::Send + 'async_trait)
+        quote!(::core::marker::Send + 'async_trait)
     };
-    sig.output = parse_quote_spanned! {default_span=>
+    sig.output = parse_quote! {
         #ret_arrow ::core::pin::Pin<Box<
             dyn ::core::future::Future<Output = #ret> + #bounds
         >>
@@ -420,7 +411,7 @@ fn transform_block(context: Context, sig: &mut Signature, block: &mut Block) {
                     quote!(#(#decls)* { #(#stmts)* })
                 }
             } else {
-                quote_spanned! {block.brace_token.span=>
+                quote! {
                     if let ::core::option::Option::Some(__ret) = ::core::option::Option::None::<#ret> {
                         return __ret;
                     }

tests/test.rs

@@ -1345,6 +1345,7 @@ pub mod issue158 {
     fn f() {}
 
     #[async_trait]
+    #[allow(unused_qualifications)]
     pub trait Trait {
         async fn f(&self) {
             self::f();