Stabilize const_panic

compiler/rustc_const_eval/src/transform/check_consts/check.rs

@@ -887,8 +887,6 @@ impl Visitor<'tcx> for Checker<'mir, 'tcx> {
 
                 // At this point, we are calling a function, `callee`, whose `DefId` is known...
                 if is_lang_panic_fn(tcx, callee) {
-                    self.check_op(ops::Panic);
-
                     // `begin_panic` and `panic_display` are generic functions that accept
                     // types other than str. Check to enforce that only str can be used in
                     // const-eval.

compiler/rustc_const_eval/src/transform/check_consts/ops.rs

@@ -368,23 +368,6 @@ impl NonConstOp for MutDeref {
     }
 }
 
-#[derive(Debug)]
-pub struct Panic;
-impl NonConstOp for Panic {
-    fn status_in_item(&self, _: &ConstCx<'_, '_>) -> Status {
-        Status::Unstable(sym::const_panic)
-    }
-
-    fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> DiagnosticBuilder<'tcx> {
-        feature_err(
-            &ccx.tcx.sess.parse_sess,
-            sym::const_panic,
-            span,
-            &format!("panicking in {}s is unstable", ccx.const_kind()),
-        )
-    }
-}
-
 /// A call to a `panic()` lang item where the first argument is _not_ a `&str`.
 #[derive(Debug)]
 pub struct PanicNonStr;