Fix tests

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -1063,8 +1063,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                         }) => {}
                         // auto trait impl
                         AutoImplCandidate(..) => {}
-                        // FIXME check if this is right, but this would allow Sized impls
-                        // BuiltinCandidate { .. } => {}
+                        // generator, this will raise error in other places
+                        // or ignore error with const_async_blocks feature
+                        GeneratorCandidate => {}
                         _ => {
                             // reject all other types of candidates
                             return Err(Unimplemented);

src/test/ui/consts/const-eval/issue-49296.rs

@@ -1,8 +1,10 @@
 // issue-49296: Unsafe shenigans in constants can result in missing errors
 
 #![feature(const_fn_trait_bound)]
+#![feature(const_trait_bound_opt_out)]
+#![allow(incomplete_features)]
 
-const unsafe fn transmute<T: Copy, U: Copy>(t: T) -> U {
+const unsafe fn transmute<T: ?const Copy, U: ?const Copy>(t: T) -> U {
     #[repr(C)]
     union Transmute<T: Copy, U: Copy> {
         from: T,

src/test/ui/consts/const-eval/issue-49296.stderr

@@ -1,5 +1,5 @@
 error[E0080]: evaluation of constant value failed
-  --> $DIR/issue-49296.rs:18:16
+  --> $DIR/issue-49296.rs:20:16
    |
 LL | const X: u64 = *wat(42);
    |                ^^^^^^^^ pointer to alloc2 was dereferenced after this allocation got freed