diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index eef1ba6..8fc6f6c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -96,5 +96,6 @@ jobs:
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
       - uses: dtolnay/install@cargo-outdated
       - run: cargo outdated --workspace --exit-code 1
diff --git a/Cargo.toml b/Cargo.toml
index a1a0339..6a34bdc 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "async-trait"
-version = "0.1.77"
+version = "0.1.80"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 categories = ["asynchronous", "no-std"]
 description = "Type erasure for async trait methods"
diff --git a/build.rs b/build.rs
deleted file mode 100644
index db7c5f0..0000000
--- a/build.rs
+++ /dev/null
@@ -1,31 +0,0 @@
-use std::env;
-use std::process::Command;
-use std::str;
-
-fn main() {
-    println!("cargo:rerun-if-env-changed=DOCS_RS");
-
-    let compiler = match rustc_minor_version() {
-        Some(compiler) => compiler,
-        None => return,
-    };
-
-    if compiler < 45 {
-        println!("cargo:rustc-cfg=no_span_mixed_site");
-    }
-
-    if compiler < 47 {
-        println!("cargo:rustc-cfg=self_span_hack");
-    }
-}
-
-fn rustc_minor_version() -> Option<u32> {
-    let rustc = env::var_os("RUSTC")?;
-    let output = Command::new(rustc).arg("--version").output().ok()?;
-    let version = str::from_utf8(&output.stdout).ok()?;
-    let mut pieces = version.split('.');
-    if pieces.next() != Some("rustc 1") {
-        return None;
-    }
-    pieces.next()?.parse().ok()
-}
diff --git a/src/bound.rs b/src/bound.rs
index 50182f6..1210517 100644
--- a/src/bound.rs
+++ b/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);
     }
 }
 
diff --git a/src/expand.rs b/src/expand.rs
index 2a8b3c2..793e084 100644
--- a/src/expand.rs
+++ b/src/expand.rs
@@ -166,11 +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)),
     };
 
@@ -232,12 +231,12 @@ 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 let Some(receiver) = sig.receiver() {
+        let bounds: &[InferredBound] = if is_local {
+            &[]
+        } else if let Some(receiver) = sig.receiver() {
             match receiver.ty.as_ref() {
                 // self: &Self
                 Type::Reference(ty) if ty.mutability.is_none() => &[InferredBound::Sync],
@@ -268,21 +267,14 @@ fn transform_sig(
             &[InferredBound::Send]
         };
 
-        let bounds = bounds.iter().filter_map(|bound| {
-            let assume_bound = match context {
-                Context::Trait { supertraits, .. } => !has_default || has_bound(supertraits, bound),
-                Context::Impl { .. } => true,
-            };
-            if assume_bound || is_local {
-                None
-            } else {
-                Some(bound.spanned_path(default_span))
-            }
+        let bounds = bounds.iter().filter(|bound| match context {
+            Context::Trait { supertraits, .. } => has_default && !has_bound(supertraits, bound),
+            Context::Impl { .. } => false,
         });
 
         where_clause_or_default(&mut sig.generics.where_clause)
             .predicates
-            .push(parse_quote_spanned! {default_span=>
+            .push(parse_quote! {
                 Self: #(#bounds +)* 'async_trait
             });
     }
@@ -314,11 +306,11 @@ 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
         >>
@@ -343,7 +335,7 @@ fn transform_sig(
 //         ___ret
 //     })
 fn transform_block(context: Context, sig: &mut Signature, block: &mut Block) {
-    let mut self_span = None;
+    let mut replace_self = false;
     let decls = sig
         .inputs
         .iter()
@@ -354,8 +346,8 @@ fn transform_block(context: Context, sig: &mut Signature, block: &mut Block) {
                 mutability,
                 ..
             }) => {
+                replace_self = true;
                 let ident = Ident::new("__self", self_token.span);
-                self_span = Some(self_token.span);
                 quote!(let #mutability #ident = #self_token;)
             }
             FnArg::Typed(arg) => {
@@ -397,9 +389,8 @@ fn transform_block(context: Context, sig: &mut Signature, block: &mut Block) {
         })
         .collect::<Vec<_>>();
 
-    if let Some(span) = self_span {
-        let mut replace_self = ReplaceSelf(span);
-        replace_self.visit_block_mut(block);
+    if replace_self {
+        ReplaceSelf.visit_block_mut(block);
     }
 
     let stmts = &block.stmts;
@@ -416,8 +407,9 @@ 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> {
+                        #[allow(unreachable_code)]
                         return __ret;
                     }
                     #(#decls)*
@@ -435,9 +427,7 @@ fn transform_block(context: Context, sig: &mut Signature, block: &mut Block) {
 }
 
 fn positional_arg(i: usize, pat: &Pat) -> Ident {
-    let span: Span = syn::spanned::Spanned::span(pat);
-    #[cfg(not(no_span_mixed_site))]
-    let span = span.resolved_at(Span::mixed_site());
+    let span = syn::spanned::Spanned::span(pat).resolved_at(Span::mixed_site());
     format_ident!("__arg{}", i, span = span)
 }
 
diff --git a/src/lib.rs b/src/lib.rs
index 7a48574..cc8b628 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -316,7 +316,7 @@
 //! let object = &value as &dyn ObjectSafe;
 //! ```
 
-#![doc(html_root_url = "https://docs.rs/async-trait/0.1.77")]
+#![doc(html_root_url = "https://docs.rs/async-trait/0.1.80")]
 #![allow(
     clippy::default_trait_access,
     clippy::doc_markdown,
diff --git a/src/receiver.rs b/src/receiver.rs
index f5791bf..e4627f1 100644
--- a/src/receiver.rs
+++ b/src/receiver.rs
@@ -1,4 +1,4 @@
-use proc_macro2::{Group, Span, TokenStream, TokenTree};
+use proc_macro2::{Group, TokenStream, TokenTree};
 use syn::visit_mut::{self, VisitMut};
 use syn::{
     Block, ExprPath, Ident, Item, Macro, Pat, PatIdent, Path, Receiver, Signature, Token, TypePath,
@@ -78,20 +78,17 @@ impl VisitMut for HasSelf {
     }
 }
 
-pub struct ReplaceSelf(pub Span);
+pub struct ReplaceSelf;
 
-impl ReplaceSelf {
-    #[cfg_attr(not(self_span_hack), allow(clippy::unused_self))]
-    fn prepend_underscore_to_self(&self, ident: &mut Ident) -> bool {
-        let modified = ident == "self";
-        if modified {
-            *ident = Ident::new("__self", ident.span());
-            #[cfg(self_span_hack)]
-            ident.set_span(self.0);
-        }
-        modified
+fn prepend_underscore_to_self(ident: &mut Ident) -> bool {
+    let modified = ident == "self";
+    if modified {
+        *ident = Ident::new("__self", ident.span());
     }
+    modified
+}
 
+impl ReplaceSelf {
     fn visit_token_stream(&mut self, tokens: &mut TokenStream) -> bool {
         let mut out = Vec::new();
         let mut modified = false;
@@ -110,7 +107,7 @@ impl ReplaceSelf {
             for tt in tokens {
                 match tt {
                     TokenTree::Ident(mut ident) => {
-                        *modified |= visitor.prepend_underscore_to_self(&mut ident);
+                        *modified |= prepend_underscore_to_self(&mut ident);
                         out.push(TokenTree::Ident(ident));
                     }
                     TokenTree::Group(group) => {
@@ -129,7 +126,7 @@ impl ReplaceSelf {
 
 impl VisitMut for ReplaceSelf {
     fn visit_ident_mut(&mut self, i: &mut Ident) {
-        self.prepend_underscore_to_self(i);
+        prepend_underscore_to_self(i);
     }
 
     fn visit_path_mut(&mut self, p: &mut Path) {
diff --git a/tests/test.rs b/tests/test.rs
index b78c9ff..a42b225 100644
--- a/tests/test.rs
+++ b/tests/test.rs
@@ -1,9 +1,10 @@
 #![cfg_attr(
     async_trait_nightly_testing,
-    feature(impl_trait_in_assoc_type, min_specialization)
+    feature(impl_trait_in_assoc_type, min_specialization, never_type)
 )]
-#![deny(rust_2021_compatibility)]
+#![deny(rust_2021_compatibility, unused_qualifications)]
 #![allow(
+    clippy::incompatible_msrv, // https://github.com/rust-lang/rust-clippy/issues/12257
     clippy::let_underscore_untyped,
     clippy::let_unit_value,
     clippy::missing_panics_doc,
@@ -157,9 +158,11 @@ pub unsafe trait UnsafeTrait {}
 unsafe impl UnsafeTrait for () {}
 
 #[async_trait]
+#[allow(dead_code)]
 pub(crate) unsafe trait UnsafeTraitPubCrate {}
 
 #[async_trait]
+#[allow(dead_code)]
 unsafe trait UnsafeTraitPrivate {}
 
 pub async fn test_can_destruct() {
@@ -177,6 +180,8 @@ pub async fn test_can_destruct() {
             let _d: u8 = d;
         }
     }
+
+    let _ = <Struct as CanDestruct>::f;
 }
 
 pub async fn test_self_in_macro() {
@@ -199,6 +204,10 @@ pub async fn test_self_in_macro() {
             println!("{}", self);
         }
     }
+
+    let _ = <String as Trait>::a;
+    let _ = <String as Trait>::b;
+    let _ = <String as Trait>::c;
 }
 
 pub async fn test_inference() {
@@ -208,6 +217,10 @@ pub async fn test_inference() {
             Box::new(std::iter::empty())
         }
     }
+
+    impl Trait for () {}
+
+    let _ = <() as Trait>::f;
 }
 
 pub async fn test_internal_items() {
@@ -233,6 +246,10 @@ pub async fn test_unimplemented() {
             unimplemented!()
         }
     }
+
+    impl Trait for () {}
+
+    let _ = <() as Trait>::f;
 }
 
 // https://github.com/dtolnay/async-trait/issues/1
@@ -240,7 +257,7 @@ pub mod issue1 {
     use async_trait::async_trait;
 
     #[async_trait]
-    trait Issue1 {
+    pub trait Issue1 {
         async fn f<U>(&self);
     }
 
@@ -284,11 +301,11 @@ pub mod issue11 {
     use std::sync::Arc;
 
     #[async_trait]
-    trait Issue11 {
+    pub trait Issue11 {
         async fn example(self: Arc<Self>);
     }
 
-    struct Struct;
+    pub struct Struct;
 
     #[async_trait]
     impl Issue11 for Struct {
@@ -301,10 +318,10 @@ pub mod issue15 {
     use async_trait::async_trait;
     use std::marker::PhantomData;
 
-    trait Trait {}
+    pub trait Trait {}
 
     #[async_trait]
-    trait Issue15 {
+    pub trait Issue15 {
         async fn myfn(&self, _: PhantomData<dyn Trait + Send>) {}
     }
 }
@@ -314,11 +331,11 @@ pub mod issue17 {
     use async_trait::async_trait;
 
     #[async_trait]
-    trait Issue17 {
+    pub trait Issue17 {
         async fn f(&self);
     }
 
-    struct Struct {
+    pub struct Struct {
         string: String,
     }
 
@@ -346,6 +363,7 @@ pub mod issue23 {
         }
     }
 
+    #[allow(dead_code)]
     struct S {}
 
     #[async_trait]
@@ -409,10 +427,10 @@ pub mod issue25 {
 pub mod issue28 {
     use async_trait::async_trait;
 
-    struct Str<'a>(&'a str);
+    pub struct Str<'a>(&'a str);
 
     #[async_trait]
-    trait Trait1<'a> {
+    pub trait Trait1<'a> {
         async fn f(x: Str<'a>) -> &'a str;
         async fn g(x: Str<'a>) -> &'a str {
             x.0
@@ -427,7 +445,7 @@ pub mod issue28 {
     }
 
     #[async_trait]
-    trait Trait2 {
+    pub trait Trait2 {
         async fn f();
     }
 
@@ -437,7 +455,7 @@ pub mod issue28 {
     }
 
     #[async_trait]
-    trait Trait3<'a, 'b> {
+    pub trait Trait3<'a, 'b> {
         async fn f(_: &'a &'b ()); // chain 'a and 'b
         async fn g(_: &'b ()); // chain 'b only
         async fn h(); // do not chain
@@ -675,7 +693,7 @@ pub mod issue53 {
     use async_trait::async_trait;
 
     pub struct Unit;
-    pub struct Tuple(u8);
+    pub struct Tuple(pub u8);
     pub struct Struct {
         pub x: u8,
     }
@@ -715,7 +733,6 @@ pub mod issue53 {
 }
 
 // https://github.com/dtolnay/async-trait/issues/57
-#[cfg(async_trait_nightly_testing)]
 pub mod issue57 {
     use crate::executor;
     use async_trait::async_trait;
@@ -867,7 +884,7 @@ pub mod issue89 {
     use async_trait::async_trait;
 
     #[async_trait]
-    trait Trait {
+    pub trait Trait {
         async fn f(&self);
     }
 
@@ -1003,7 +1020,7 @@ pub mod issue104 {
     use async_trait::async_trait;
 
     #[async_trait]
-    trait T1 {
+    pub trait T1 {
         async fn id(&self) -> i32;
     }
 
@@ -1018,7 +1035,7 @@ pub mod issue104 {
         };
     }
 
-    struct Foo;
+    pub struct Foo;
 
     impl_t1!(Foo, 1);
 }
@@ -1082,7 +1099,7 @@ pub mod issue120 {
     use async_trait::async_trait;
 
     #[async_trait]
-    trait Trait {
+    pub trait Trait {
         async fn f(&self);
     }
 
@@ -1097,7 +1114,7 @@ pub mod issue123 {
     use async_trait::async_trait;
 
     #[async_trait]
-    trait Trait<T = ()> {
+    pub trait Trait<T = ()> {
         async fn f(&self) -> &str
         where
             T: 'async_trait,
@@ -1132,12 +1149,11 @@ pub mod issue129 {
 }
 
 // https://github.com/dtolnay/async-trait/issues/134
-#[cfg(async_trait_nightly_testing)]
 pub mod issue134 {
     use async_trait::async_trait;
 
     #[async_trait]
-    trait TestTrait {
+    pub trait TestTrait {
         async fn run<const DUMMY: bool>(self)
         where
             Self: Sized,
@@ -1284,13 +1300,13 @@ pub mod issue152 {
     use async_trait::async_trait;
 
     #[async_trait]
-    trait Trait {
+    pub trait Trait {
         type Assoc;
 
         async fn f(&self) -> Self::Assoc;
     }
 
-    struct Struct;
+    pub struct Struct;
 
     #[async_trait]
     impl Trait for Struct {
@@ -1329,6 +1345,7 @@ pub mod issue158 {
     fn f() {}
 
     #[async_trait]
+    #[allow(unused_qualifications)]
     pub trait Trait {
         async fn f(&self) {
             self::f();
@@ -1368,6 +1385,7 @@ pub mod issue169 {
     use async_trait::async_trait;
 
     #[async_trait]
+    #[allow(unused_qualifications)]
     pub trait Trait: ::core::marker::Sync {
         async fn f(&self) {}
     }
@@ -1399,7 +1417,7 @@ pub mod issue183 {
     use async_trait::async_trait;
 
     #[async_trait]
-    trait Foo {
+    pub trait Foo {
         async fn foo(_n: i32) {}
     }
 }
@@ -1474,6 +1492,7 @@ pub mod issue226 {
         async fn cfg_param_tuple(&self, (left, right): (u8, u8));
     }
 
+    #[allow(dead_code)]
     struct Struct;
 
     #[async_trait]
@@ -1603,3 +1622,23 @@ pub mod issue238 {
         async fn f() {}
     }
 }
+
+// https://github.com/dtolnay/async-trait/issues/266
+#[cfg(async_trait_nightly_testing)]
+pub mod issue266 {
+    use async_trait::async_trait;
+
+    #[async_trait]
+    pub trait Trait {
+        async fn f() -> !;
+    }
+
+    #[async_trait]
+    impl Trait for () {
+        async fn f() -> ! {
+            loop {
+                std::thread::sleep(std::time::Duration::from_millis(1));
+            }
+        }
+    }
+}
diff --git a/tests/ui/lifetime-span.stderr b/tests/ui/lifetime-span.stderr
index fa16ac7..aa7d57e 100644
--- a/tests/ui/lifetime-span.stderr
+++ b/tests/ui/lifetime-span.stderr
@@ -9,6 +9,15 @@ help: indicate the anonymous lifetime
 12 | impl Trait<'_> for A {
    |           ++++
 
+error[E0195]: lifetime parameters or bounds on method `method` do not match the trait declaration
+  --> tests/ui/lifetime-span.rs:18:14
+   |
+8  |     async fn method(&'r self);
+   |              ---------------- lifetimes in impl do not match this method in trait
+...
+18 |     async fn method(&self) {}
+   |              ^^^^^^^^^^^^^ lifetimes do not match method in trait
+
 error[E0107]: trait takes 0 lifetime arguments but 1 lifetime argument was supplied
   --> tests/ui/lifetime-span.rs:32:10
    |
@@ -22,3 +31,12 @@ note: trait defined here, with 0 lifetime parameters
    |
 22 | pub trait Trait2 {
    |           ^^^^^^
+
+error[E0195]: lifetime parameters or bounds on method `method` do not match the trait declaration
+  --> tests/ui/lifetime-span.rs:33:14
+   |
+23 |     async fn method<'r>(&'r self);
+   |                    ---- lifetimes in impl do not match this method in trait
+...
+33 |     async fn method(&'r self) {}
+   |              ^^^^^^^^^^^^^^^^ lifetimes do not match method in trait
diff --git a/tests/ui/send-not-implemented.stderr b/tests/ui/send-not-implemented.stderr
index 7152b98..5171b7c 100644
--- a/tests/ui/send-not-implemented.stderr
+++ b/tests/ui/send-not-implemented.stderr
@@ -9,7 +9,7 @@ error: future cannot be sent between threads safely
 12 | |     }
    | |_____^ future created by async block is not `Send`
    |
-   = help: within `{async block@$DIR/tests/ui/send-not-implemented.rs:8:26: 12:6}`, the trait `Send` is not implemented for `MutexGuard<'_, ()>`
+   = help: within `{async block@$DIR/tests/ui/send-not-implemented.rs:8:26: 12:6}`, the trait `Send` is not implemented for `MutexGuard<'_, ()>`, which is required by `{async block@$DIR/tests/ui/send-not-implemented.rs:8:26: 12:6}: Send`
 note: future is not `Send` as this value is used across an await
   --> tests/ui/send-not-implemented.rs:11:13
    |
@@ -31,7 +31,7 @@ error: future cannot be sent between threads safely
 19 | |     }
    | |_____^ future created by async block is not `Send`
    |
-   = help: within `{async block@$DIR/tests/ui/send-not-implemented.rs:14:38: 19:6}`, the trait `Send` is not implemented for `MutexGuard<'_, ()>`
+   = help: within `{async block@$DIR/tests/ui/send-not-implemented.rs:14:38: 19:6}`, the trait `Send` is not implemented for `MutexGuard<'_, ()>`, which is required by `{async block@$DIR/tests/ui/send-not-implemented.rs:14:38: 19:6}: Send`
 note: future is not `Send` as this value is used across an await
   --> tests/ui/send-not-implemented.rs:17:13
    |

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