Make DefiningAnchor::Bind only store the opaque types that may be constrained, instead of the current infcx root item.

This makes `Bind` almost always be empty, so we can start forwarding it to queries, allowing us to remove `Bubble` entirely

compiler/rustc_middle/src/traits/mod.rs

@@ -12,8 +12,8 @@ pub mod util;
 use crate::infer::canonical::Canonical;
 use crate::mir::ConstraintCategory;
 use crate::ty::abstract_const::NotConstEvaluatable;
-use crate::ty::GenericArgsRef;
 use crate::ty::{self, AdtKind, Ty};
+use crate::ty::{GenericArgsRef, TyCtxt};
 
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::{Applicability, Diag, EmissionGuarantee};
@@ -1001,10 +1001,10 @@ pub enum CodegenObligationError {
 /// opaques are replaced with inference vars eagerly in the old solver (e.g.
 /// in projection, and in the signature during function type-checking).
 #[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, HashStable, TypeFoldable, TypeVisitable)]
-pub enum DefiningAnchor {
-    /// Define opaques which are in-scope of the `LocalDefId`. Also, eagerly
-    /// replace opaque types in `replace_opaque_types_with_inference_vars`.
-    Bind(LocalDefId),
+pub enum DefiningAnchor<'tcx> {
+    /// Define opaques which are in-scope of the current item being analyzed.
+    /// Also, eagerly replace these opaque types in `replace_opaque_types_with_inference_vars`.
+    Bind(&'tcx ty::List<LocalDefId>),
     /// In contexts where we don't currently know what opaques are allowed to be
     /// defined, such as (old solver) canonical queries, we will simply allow
     /// opaques to be defined, but "bubble" them up in the canonical response or
@@ -1018,3 +1018,9 @@ pub enum DefiningAnchor {
     /// otherwise reveal opaques (such as [`Reveal::All`] reveal mode).
     Error,
 }
+
+impl<'tcx> DefiningAnchor<'tcx> {
+    pub fn bind(tcx: TyCtxt<'tcx>, item: LocalDefId) -> Self {
+        Self::Bind(tcx.opaque_types_defined_by(item))
+    }
+}