Addd TraitFlags::COINDUCTIVE

Author: jackh726

crates/hir-def/src/signatures.rs

@@ -395,14 +395,15 @@ impl ImplSignature {
 
 bitflags::bitflags! {
     #[derive(Debug, Clone, Copy, Eq, PartialEq, Default)]
-    pub struct TraitFlags: u8 {
+    pub struct TraitFlags: u16 {
         const RUSTC_HAS_INCOHERENT_INHERENT_IMPLS = 1 << 1;
         const FUNDAMENTAL = 1 << 2;
         const UNSAFE = 1 << 3;
         const AUTO = 1 << 4;
         const SKIP_ARRAY_DURING_METHOD_DISPATCH = 1 << 5;
         const SKIP_BOXED_SLICE_DURING_METHOD_DISPATCH = 1 << 6;
         const RUSTC_PAREN_SUGAR = 1 << 7;
+        const COINDUCTIVE = 1 << 8;
     }
 }
 
@@ -436,6 +437,9 @@ impl TraitSignature {
         if attrs.by_key(sym::rustc_paren_sugar).exists() {
             flags |= TraitFlags::RUSTC_PAREN_SUGAR;
         }
+        if attrs.by_key(sym::rustc_coinductive).exists() {
+            flags |= TraitFlags::COINDUCTIVE;
+        }
         let mut skip_array_during_method_dispatch =
             attrs.by_key(sym::rustc_skip_array_during_method_dispatch).exists();
         let mut skip_boxed_slice_during_method_dispatch = false;

crates/hir-ty/src/next_solver/interner.rs

@@ -1897,7 +1897,7 @@ impl<'db> rustc_type_ir::Interner for DbInterner<'db> {
             SolverDefId::TraitId(id) => id,
             _ => unreachable!(),
         };
-        self.db().trait_signature(id).flags.contains(TraitFlags::AUTO)
+        self.db().trait_signature(id).flags.contains(TraitFlags::COINDUCTIVE)
     }
 
     fn trait_is_unsafe(self, trait_def_id: Self::DefId) -> bool {

crates/intern/src/symbol/symbols.rs

@@ -420,6 +420,7 @@ define_symbols! {
     rustc_allow_incoherent_impl,
     rustc_builtin_macro,
     rustc_coherence_is_core,
+    rustc_coinductive,
     rustc_const_panic_str,
     rustc_deallocator,
     rustc_deprecated_safe_2024,