Move late-bound arg type checks to resolve_bound_vars

compiler/rustc_middle/src/middle/resolve_bound_vars.rs

@@ -3,6 +3,7 @@
 use crate::ty;
 
 use rustc_data_structures::fx::FxHashMap;
+use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def_id::DefId;
 use rustc_hir::{ItemLocalId, OwnerId};
 use rustc_macros::HashStable;
@@ -13,6 +14,7 @@ pub enum ResolvedArg {
     EarlyBound(/* decl */ DefId),
     LateBound(ty::DebruijnIndex, /* late-bound index */ u32, /* decl */ DefId),
     Free(DefId, /* lifetime decl */ DefId),
+    Error(ErrorGuaranteed),
 }
 
 /// A set containing, at most, one known element.

compiler/rustc_middle/src/ty/consts.rs

@@ -149,6 +149,9 @@ impl<'tcx> Const<'tcx> {
                         ty::ConstKind::Bound(debruijn, ty::BoundVar::from_u32(index)),
                         ty,
                     )),
+                    Some(rbv::ResolvedArg::Error(guar)) => {
+                        Some(tcx.const_error_with_guaranteed(ty, guar))
+                    }
                     arg => bug!("unexpected bound var resolution for {:?}: {arg:?}", expr.hir_id),
                 }
             }