updated pci argument for fn_abi_of_fn_ptr call, sig does not skip_binder

Author: wilbertbw

compiler/rustc_codegen_llvm/src/builder/autodiff.rs

@@ -26,10 +26,11 @@ pub(crate) fn adjust_activity_to_abi<'tcx>(
 
     // We don't actually pass the types back into the type system.
     // All we do is decide how to handle the arguments.
-    let sig = fn_ptr_ty.fn_sig(tcx).skip_binder();
+    let poly_sig = fn_ptr_ty.fn_sig(tcx);
+    let sig = poly_sig.skip_binder();
 
     // FIXME(Sa4dUs): pass proper varargs once we have support for differentiating variadic functions
-    let pci = PseudoCanonicalInput { typing_env, value: (sig, ty::List::empty()) };
+    let pci = PseudoCanonicalInput { typing_env, value: (poly_sig, ty::List::empty()) };
     let Ok(fn_abi) = tcx.fn_abi_of_fn_ptr(pci) else {
         bug!("failed to get fn_abi of fn_ptr with empty varargs");
     };