add ConstArgKind::Error

Author: BoxyUwU

compiler/rustc_hir/src/hir.rs

@@ -474,6 +474,7 @@ impl<'hir, Unambig> ConstArg<'hir, Unambig> {
         match self.kind {
             ConstArgKind::Path(path) => path.span(),
             ConstArgKind::Anon(anon) => anon.span,
+            ConstArgKind::Error(span, _) => span,
             ConstArgKind::Infer(span, _) => span,
         }
     }
@@ -490,6 +491,8 @@ pub enum ConstArgKind<'hir, Unambig = ()> {
     /// However, in the future, we'll be using it for all of those.
     Path(QPath<'hir>),
     Anon(&'hir AnonConst),
+    /// Error const
+    Error(Span, ErrorGuaranteed),
     /// This variant is not always used to represent inference consts, sometimes
     /// [`GenericArg::Infer`] is used instead.
     Infer(Span, Unambig),

compiler/rustc_hir/src/intravisit.rs

@@ -1058,6 +1058,7 @@ pub fn walk_const_arg<'v, V: Visitor<'v>>(
     match kind {
         ConstArgKind::Path(qpath) => visitor.visit_qpath(qpath, *hir_id, qpath.span()),
         ConstArgKind::Anon(anon) => visitor.visit_anon_const(*anon),
+        ConstArgKind::Error(_, _) => V::Result::output(), // errors and spans are not important
     }
 }
 

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -2242,6 +2242,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             }
             hir::ConstArgKind::Anon(anon) => self.lower_anon_const(anon),
             hir::ConstArgKind::Infer(span, ()) => self.ct_infer(None, span),
+            hir::ConstArgKind::Error(_, e) => ty::Const::new_error(tcx, e),
         }
     }
 

compiler/rustc_hir_pretty/src/lib.rs

@@ -1131,6 +1131,7 @@ impl<'a> State<'a> {
         match &const_arg.kind {
             ConstArgKind::Path(qpath) => self.print_qpath(qpath, true),
             ConstArgKind::Anon(anon) => self.print_anon_const(anon),
+            ConstArgKind::Error(_, _) => self.word("/*ERROR*/"),
             ConstArgKind::Infer(..) => self.word("_"),
         }
     }

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1428,7 +1428,9 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 && match tcx.hir_node_by_def_id(local_id) {
                     hir::Node::ConstArg(hir::ConstArg { kind, .. }) => match kind {
                         // Skip encoding defs for these as they should not have had a `DefId` created
-                        hir::ConstArgKind::Path(..) | hir::ConstArgKind::Infer(..) => true,
+                        hir::ConstArgKind::Error(..)
+                        | hir::ConstArgKind::Path(..)
+                        | hir::ConstArgKind::Infer(..) => true,
                         hir::ConstArgKind::Anon(..) => false,
                     },
                     _ => false,