diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 638ad70..295a43d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,17 +9,16 @@ env:
 jobs:
   check:
     name: 'Build & test'
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     strategy:
       matrix:
         rust-version: ['stable', 'beta', 'nightly', '1.71']
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v7
     - uses: dtolnay/rust-toolchain@master
       with:
         toolchain: stable
         components: rustfmt, clippy
-    - uses: Swatinem/rust-cache@v1
 
     - run: cargo fmt --all -- --check
     - run: cargo clippy --workspace --all-features -- -D warnings
diff --git a/Cargo.toml b/Cargo.toml
index d83b1f8..440ff0c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "auto_impl"
-version = "1.3.0"
+version = "1.4.0"
 authors = [
     "Ashley Mannix <ashleymannix@live.com.au>",
     "Lukas Kalbertodt <lukas.kalbertodt@gmail.com>",
diff --git a/examples/refs.rs b/examples/refs.rs
index 68b2a52..aa3e5e2 100644
--- a/examples/refs.rs
+++ b/examples/refs.rs
@@ -25,8 +25,6 @@ use auto_impl::auto_impl;
 /// ```
 #[auto_impl(&, Box)]
 trait DisplayCollection {
-    /// If the length is statically known, this is `Some(len)`.
-    const LEN: Option<usize>;
     type Out: Display;
     fn display_at(&self, index: usize) -> Option<&Self::Out>;
 }
@@ -34,8 +32,6 @@ trait DisplayCollection {
 impl<T: Display> DisplayCollection for Vec<T> {
     type Out = T;
 
-    const LEN: Option<usize> = None;
-
     fn display_at(&self, index: usize) -> Option<&Self::Out> {
         self.get(index)
     }
diff --git a/tests/compile-fail/fn_generics.stderr b/tests/compile-fail/fn_generics.stderr
index 04221a5..456e733 100644
--- a/tests/compile-fail/fn_generics.stderr
+++ b/tests/compile-fail/fn_generics.stderr
@@ -10,4 +10,4 @@ warning: unused import: `std::fmt::Display`
 1 | use std::fmt::Display;
   |     ^^^^^^^^^^^^^^^^^
   |
-  = note: `#[warn(unused_imports)]` on by default
+  = note: `#[warn(unused_imports)]` (part of `#[warn(unused)]`) on by default
diff --git a/tests/compile-fail/super_trait_not_implemented.stderr b/tests/compile-fail/super_trait_not_implemented.stderr
index 96b16ef..d77f554 100644
--- a/tests/compile-fail/super_trait_not_implemented.stderr
+++ b/tests/compile-fail/super_trait_not_implemented.stderr
@@ -9,9 +9,9 @@ error[E0277]: the trait bound `Box<Dog>: Foo` is not satisfied
 note: required for `Box<Dog>` to implement `Foo`
   --> tests/compile-fail/super_trait_not_implemented.rs:5:1
    |
-5  | #[auto_impl(Box, &)]
+ 5 | #[auto_impl(Box, &)]
    | ^^^^^^^^^^^^^^^^^^^^
-6  | trait Foo: Supi {}
+ 6 | trait Foo: Supi {}
    |       ^^^  ---- unsatisfied trait bound introduced here
 note: required by a bound in `requires_foo`
   --> tests/compile-fail/super_trait_not_implemented.rs:14:20
diff --git a/tests/compile-fail/trait_obj_value_self.stderr b/tests/compile-fail/trait_obj_value_self.stderr
index 1009a79..b15ab8d 100644
--- a/tests/compile-fail/trait_obj_value_self.stderr
+++ b/tests/compile-fail/trait_obj_value_self.stderr
@@ -5,17 +5,21 @@ error[E0277]: the size for values of type `dyn Trait` cannot be known at compila
    |                   ^^^^^^^^^^^^^^ doesn't have a size known at compile-time
    |
    = help: the trait `Sized` is not implemented for `dyn Trait`
-   = help: the trait `Trait` is implemented for `Box<T>`
+help: the trait `Trait` is conditionally implemented for `Box<T>`
+  --> tests/compile-fail/trait_obj_value_self.rs:4:1
+   |
+ 4 | #[auto_impl(Box)]
+   | ^^^^^^^^^^^^^^^^^ unsatisfied requirement introduced here: `_: Sized`
 note: required for `Box<dyn Trait>` to implement `Trait`
   --> tests/compile-fail/trait_obj_value_self.rs:4:1
    |
-4  | #[auto_impl(Box)]
+ 4 | #[auto_impl(Box)]
    | ^^^^^^^^^^^^^^^^^
-5  | trait Trait {
+ 5 | trait Trait {
    |       ^^^^^
 note: required by a bound in `assert_impl`
   --> tests/compile-fail/trait_obj_value_self.rs:9:19
    |
-9  | fn assert_impl<T: Trait>() {}
+ 9 | fn assert_impl<T: Trait>() {}
    |                   ^^^^^ required by this bound in `assert_impl`
    = note: this error originates in the attribute macro `auto_impl` (in Nightly builds, run with -Z macro-backtrace for more info)