Rollup merge of #137764 - compiler-errors:always-applicable-negative-impl, r=lcnr

Ensure that negative auto impls are always applicable

r? lcnr (or reassign if you dont want to review)

https://github.com/rust-lang/rust/issues/68318#issuecomment-2689265030

compiler/rustc_middle/src/traits/mod.rs

@@ -397,9 +397,9 @@ pub enum ObligationCauseCode<'tcx> {
 
     RustCall,
 
-    /// Obligations to prove that a `std::ops::Drop` impl is not stronger than
+    /// Obligations to prove that a `Drop` or negative auto trait impl is not stronger than
     /// the ADT it's being implemented for.
-    DropImpl,
+    AlwaysApplicableImpl,
 
     /// Requirement for a `const N: Ty` to implement `Ty: ConstParamTy`
     ConstParam(Ty<'tcx>),