Fix yet more ICEs

Author: camelid

compiler/rustc_const_eval/src/check_consts/qualifs.rs

@@ -7,6 +7,7 @@
 
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::LangItem;
+use rustc_hir::def::DefKind;
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, AdtDef, Ty};
@@ -368,8 +369,12 @@ where
         // check performed after the promotion. Verify that with an assertion.
         assert!(promoted.is_none() || Q::ALLOW_PROMOTED);
 
-        // Don't peek inside trait associated constants.
-        if promoted.is_none() && cx.tcx.trait_of_item(def).is_none() {
+        // Const items don't themselves have bodies -- they will have either a path or an anon const instead.
+        // FIXME(mgca): is this really the right behavior? should we return the qualifs of the anon const body instead?
+        //              (note also that original code ignored trait assoc items)
+        if promoted.is_none()
+            && !matches!(cx.tcx.def_kind(def), DefKind::Const | DefKind::AssocConst)
+        {
             let qualifs = cx.tcx.at(constant.span).mir_const_qualif(def);
 
             if !Q::in_qualifs(&qualifs) {

compiler/rustc_hir/src/hir.rs

@@ -4280,6 +4280,7 @@ pub enum ItemKind<'hir> {
     /// A `static` item.
     Static(Ident, &'hir Ty<'hir>, Mutability, BodyId),
     /// A `const` item.
+    // TODO: make sure we only allow usage of path RHS in generic contexts under mgca, not stable!
     Const(Ident, &'hir Ty<'hir>, &'hir Generics<'hir>, &'hir ConstArg<'hir>),
     /// A function declaration.
     Fn {

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1310,6 +1310,7 @@ fn should_encode_constness(def_kind: DefKind) -> bool {
 
 fn should_encode_const(def_kind: DefKind) -> bool {
     match def_kind {
+        // FIXME(mgca): should we remove Const and AssocConst here?
         DefKind::Const | DefKind::AssocConst | DefKind::AnonConst | DefKind::InlineConst => true,
 
         DefKind::Struct

compiler/rustc_mir_transform/src/lib.rs

@@ -418,11 +418,9 @@ fn mir_promoted(
         {
             tcx.mir_const_qualif(def)
         }
-        DefKind::AssocConst
-        | DefKind::Const
-        | DefKind::Static { .. }
-        | DefKind::InlineConst
-        | DefKind::AnonConst => tcx.mir_const_qualif(def),
+        DefKind::Static { .. } | DefKind::InlineConst | DefKind::AnonConst => {
+            tcx.mir_const_qualif(def)
+        }
         _ => ConstQualifs::default(),
     };