Fix panic with reported const_eval promoted error

Author: bjorn3

src/base.rs

@@ -1134,7 +1134,7 @@ pub fn trans_place<'a, 'tcx: 'a>(
     match place {
         Place::Base(base) => match base {
             PlaceBase::Local(local) => fx.get_local_place(*local),
-            PlaceBase::Promoted(promoted) => crate::constant::trans_promoted(fx, promoted.0),
+            PlaceBase::Promoted(data) => crate::constant::trans_promoted(fx, data.0, data.1),
             PlaceBase::Static(static_) => crate::constant::codegen_static_ref(fx, static_),
         }
         Place::Projection(projection) => {

src/constant.rs

@@ -53,16 +53,22 @@ pub fn codegen_static_ref<'a, 'tcx: 'a>(
 pub fn trans_promoted<'a, 'tcx: 'a>(
     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
     promoted: Promoted,
+    dest_ty: Ty<'tcx>,
 ) -> CPlace<'tcx> {
-    let const_ = fx
+    match fx
         .tcx
         .const_eval(ParamEnv::reveal_all().and(GlobalId {
             instance: fx.instance,
             promoted: Some(promoted),
         }))
-        .unwrap();
-
-    trans_const_place(fx, const_)
+    {
+        Ok(const_) => {
+            let cplace = trans_const_place(fx, const_);
+            debug_assert_eq!(cplace.layout(), fx.layout_of(dest_ty));
+            cplace
+        }
+        Err(_) => crate::trap::trap_unreachable_ret_place(fx, fx.layout_of(dest_ty)),
+    }
 }
 
 pub fn trans_constant<'a, 'tcx: 'a>(

src/trap.rs

@@ -16,3 +16,10 @@ pub fn trap_unreachable_ret_value<'tcx>(fx: &mut FunctionCx<'_, 'tcx, impl crane
     let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
     CValue::ByRef(zero, dest_layout)
 }
+
+pub fn trap_unreachable_ret_place<'tcx>(fx: &mut FunctionCx<'_, 'tcx, impl cranelift_module::Backend>, dest_layout: TyLayout<'tcx>) -> CPlace<'tcx> {
+    let true_ = fx.bcx.ins().iconst(types::I32, 1);
+    fx.bcx.ins().trapnz(true_, TrapCode::User(!0));
+    let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
+    CPlace::Addr(zero, None, dest_layout)
+}