1 files changed, 32 insertions, 16 deletions

diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index d00b26a5a..6231dd9b6 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -5,6 +5,7 @@
 mod chalk;
 pub mod query;
 pub mod select;
+pub mod solve;
 pub mod specialization_graph;
 mod structural_impls;
 pub mod util;
@@ -18,7 +19,8 @@ use crate::ty::{self, AdtKind, Ty, TyCtxt};
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::{Applicability, Diagnostic};
 use rustc_hir as hir;
-use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::def_id::DefId;
+use rustc_span::def_id::{LocalDefId, CRATE_DEF_ID};
 use rustc_span::symbol::Symbol;
 use rustc_span::{Span, DUMMY_SP};
 use smallvec::SmallVec;
@@ -36,7 +38,7 @@ pub use self::chalk::{ChalkEnvironmentAndGoal, RustInterner as ChalkRustInterner
 
 /// Depending on the stage of compilation, we want projection to be
 /// more or less conservative.
-#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, HashStable)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, HashStable, Encodable, Decodable)]
 pub enum Reveal {
     /// At type-checking time, we refuse to project any associated
     /// type that is marked `default`. Non-`default` ("final") types
@@ -89,7 +91,8 @@ pub enum Reveal {
 ///
 /// We do not want to intern this as there are a lot of obligation causes which
 /// only live for a short period of time.
-#[derive(Clone, Debug, PartialEq, Eq, Lift)]
+#[derive(Clone, Debug, PartialEq, Eq, Lift, HashStable, TyEncodable, TyDecodable)]
+#[derive(TypeVisitable, TypeFoldable)]
 pub struct ObligationCause<'tcx> {
     pub span: Span,
 
@@ -99,7 +102,7 @@ pub struct ObligationCause<'tcx> {
     /// (in particular, closures can add new assumptions). See the
     /// field `region_obligations` of the `FulfillmentContext` for more
     /// information.
-    pub body_id: hir::HirId,
+    pub body_id: LocalDefId,
 
     code: InternedObligationCauseCode<'tcx>,
 }
@@ -120,13 +123,13 @@ impl<'tcx> ObligationCause<'tcx> {
     #[inline]
     pub fn new(
         span: Span,
-        body_id: hir::HirId,
+        body_id: LocalDefId,
         code: ObligationCauseCode<'tcx>,
     ) -> ObligationCause<'tcx> {
         ObligationCause { span, body_id, code: code.into() }
     }
 
-    pub fn misc(span: Span, body_id: hir::HirId) -> ObligationCause<'tcx> {
+    pub fn misc(span: Span, body_id: LocalDefId) -> ObligationCause<'tcx> {
         ObligationCause::new(span, body_id, MiscObligation)
     }
 
@@ -137,7 +140,7 @@ impl<'tcx> ObligationCause<'tcx> {
 
     #[inline(always)]
     pub fn dummy_with_span(span: Span) -> ObligationCause<'tcx> {
-        ObligationCause { span, body_id: hir::CRATE_HIR_ID, code: Default::default() }
+        ObligationCause { span, body_id: CRATE_DEF_ID, code: Default::default() }
     }
 
     pub fn span(&self) -> Span {
@@ -196,14 +199,16 @@ impl<'tcx> ObligationCause<'tcx> {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift, HashStable, TyEncodable, TyDecodable)]
+#[derive(TypeVisitable, TypeFoldable)]
 pub struct UnifyReceiverContext<'tcx> {
     pub assoc_item: ty::AssocItem,
     pub param_env: ty::ParamEnv<'tcx>,
     pub substs: SubstsRef<'tcx>,
 }
 
-#[derive(Clone, PartialEq, Eq, Hash, Lift, Default)]
+#[derive(Clone, PartialEq, Eq, Hash, Lift, Default, HashStable)]
+#[derive(TypeVisitable, TypeFoldable, TyEncodable, TyDecodable)]
 pub struct InternedObligationCauseCode<'tcx> {
     /// `None` for `ObligationCauseCode::MiscObligation` (a common case, occurs ~60% of
     /// the time). `Some` otherwise.
@@ -238,7 +243,8 @@ impl<'tcx> std::ops::Deref for InternedObligationCauseCode<'tcx> {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift, HashStable, TyEncodable, TyDecodable)]
+#[derive(TypeVisitable, TypeFoldable)]
 pub enum ObligationCauseCode<'tcx> {
     /// Not well classified or should be obvious from the span.
     MiscObligation,
@@ -446,7 +452,8 @@ pub enum ObligationCauseCode<'tcx> {
 /// This information is used to obtain an `hir::Ty`, which
 /// we can walk in order to obtain precise spans for any
 /// 'nested' types (e.g. `Foo` in `Option<Foo>`).
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, Encodable, Decodable)]
+#[derive(TypeVisitable, TypeFoldable)]
 pub enum WellFormedLoc {
     /// Use the type of the provided definition.
     Ty(LocalDefId),
@@ -463,10 +470,17 @@ pub enum WellFormedLoc {
     },
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift, HashStable, TyEncodable, TyDecodable)]
+#[derive(TypeVisitable, TypeFoldable)]
 pub struct ImplDerivedObligationCause<'tcx> {
     pub derived: DerivedObligationCause<'tcx>,
-    pub impl_def_id: DefId,
+    /// The `DefId` of the `impl` that gave rise to the `derived` obligation.
+    /// If the `derived` obligation arose from a trait alias, which conceptually has a synthetic impl,
+    /// then this will be the `DefId` of that trait alias. Care should therefore be taken to handle
+    /// that exceptional case where appropriate.
+    pub impl_or_alias_def_id: DefId,
+    /// The index of the derived predicate in the parent impl's predicates.
+    pub impl_def_predicate_index: Option<usize>,
     pub span: Span,
 }
 
@@ -517,7 +531,8 @@ impl<'tcx> ty::Lift<'tcx> for StatementAsExpression {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift, HashStable, TyEncodable, TyDecodable)]
+#[derive(TypeVisitable, TypeFoldable)]
 pub struct MatchExpressionArmCause<'tcx> {
     pub arm_block_id: Option<hir::HirId>,
     pub arm_ty: Ty<'tcx>,
@@ -533,7 +548,7 @@ pub struct MatchExpressionArmCause<'tcx> {
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
-#[derive(Lift, TypeFoldable, TypeVisitable)]
+#[derive(Lift, TypeFoldable, TypeVisitable, HashStable, TyEncodable, TyDecodable)]
 pub struct IfExpressionCause<'tcx> {
     pub then_id: hir::HirId,
     pub else_id: hir::HirId,
@@ -543,7 +558,8 @@ pub struct IfExpressionCause<'tcx> {
     pub opt_suggest_box_span: Option<Span>,
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift, HashStable, TyEncodable, TyDecodable)]
+#[derive(TypeVisitable, TypeFoldable)]
 pub struct DerivedObligationCause<'tcx> {
     /// The trait predicate of the parent obligation that led to the
     /// current obligation. Note that only trait obligations lead to