Fix const qualifs under mgca

Author: BoxyUwU

compiler/rustc_const_eval/src/check_consts/qualifs.rs

@@ -6,7 +6,9 @@
 // having basically only two use-cases that act in different ways.
 
 use rustc_errors::ErrorGuaranteed;
-use rustc_hir::LangItem;
+use rustc_hir::attrs::AttributeKind;
+use rustc_hir::def::DefKind;
+use rustc_hir::{LangItem, find_attr};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, AdtDef, Ty};
@@ -366,8 +368,14 @@ 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_assoc(def).is_none() {
+        // Avoid looking at attrs of anon consts as that will ICE
+        let is_type_const_item =
+            matches!(cx.tcx.def_kind(def), DefKind::Const | DefKind::AssocConst)
+                && find_attr!(cx.tcx.get_all_attrs(def), AttributeKind::TypeConst(_));
+
+        // Don't peak inside trait associated consatnts, also `#[type_const] const` items
+        // don't have bodies so there's nothing to look at
+        if promoted.is_none() && cx.tcx.trait_of_assoc(def).is_none() && !is_type_const_item {
             let qualifs = cx.tcx.at(constant.span).mir_const_qualif(def);
 
             if !Q::in_qualifs(&qualifs) {