Fix bug

examples/src/ok_tests.rs

@@ -1,5 +1,5 @@
-use std::fmt::Debug;
 use ouroboros::self_referencing;
+use std::fmt::Debug;
 
 // All tests here should compile and run correctly and pass Miri's safety checks.
 
@@ -34,6 +34,14 @@ struct ChainedAndUndocumented {
     ref2: &'this &'this i32,
 }
 
+#[self_referencing]
+struct BoxCheckWithLifetimeParameter<'t> {
+    external_data: Box<&'t ()>,
+    #[borrows(external_data)]
+    #[covariant]
+    self_reference: Box<&'this &'t ()>,
+}
+
 /// This test just makes sure that the macro copes with a ton of template parameters being thrown at
 /// it, specifically checking that the templates work fine even when a generated struct doesn't need
 /// all of them. (E.G. heads will only contain 'd, A, and B.)
@@ -71,7 +79,7 @@ fn box_and_ref() {
 async fn async_new() {
     let bar = BoxAndRefAsyncBuilder {
         data: Box::new(12),
-        dref_builder: |data| Box::pin(async move { data })
+        dref_builder: |data| Box::pin(async move { data }),
     }
     .build()
     .await;
@@ -86,7 +94,7 @@ async fn async_new() {
 async fn async_try_new() {
     let bar = BoxAndRefAsyncTryBuilder {
         data: Box::new(12),
-        dref_builder: |data| Box::pin(async move { Result::<_, ()>::Ok(data) })
+        dref_builder: |data| Box::pin(async move { Result::<_, ()>::Ok(data) }),
     }
     .try_build()
     .await
@@ -102,7 +110,7 @@ async fn async_try_new() {
 async fn async_try_new_err() {
     let result = BoxAndRefAsyncTryBuilder {
         data: Box::new(12),
-        dref_builder: |_data| Box::pin(async move { Err(56u64) })
+        dref_builder: |_data| Box::pin(async move { Err(56u64) }),
     }
     .try_build()
     .await;

ouroboros_macro/src/lib.rs

@@ -1468,6 +1468,11 @@ fn make_type_asserts(
 ) -> TokenStream2 {
     let generic_where = &generic_params.where_clause;
     let mut checks = Vec::new();
+    let fake_lifetime = if let Some(GenericParam::Lifetime(param)) = generic_params.params.first() {
+        param.lifetime.ident.clone()
+    } else {
+        format_ident!("static")
+    };
     for field in field_info {
         let field_type = &field.typ;
         if let Some((std_type, _eltype)) = apparent_std_container_type(field_type) {
@@ -1479,7 +1484,7 @@ fn make_type_asserts(
             };
             let checker_name = format_ident!("{}", checker_name);
             let static_field_type =
-                replace_this_with_lifetime(quote! { #field_type }, format_ident!("static"));
+                replace_this_with_lifetime(quote! { #field_type }, fake_lifetime.clone());
             checks.push(quote! {
                 ::ouroboros::macro_help::CheckIfTypeIsStd::<#static_field_type>::#checker_name();
             });