don't normalize wf predicates

[rust.git] / compiler / rustc_middle / src / ty / mod.rs

diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 1978f84c137065c6f1d440caaf5ef0915fdf6140..a7833ab64310fc29513aac6f9c7eb015cc1f29ba 100644 (file)
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -48,7 +48,7 @@
 pub use vtable::*;
 
 use std::fmt::Debug;
-use std::hash::Hash;
+use std::hash::{Hash, Hasher};
 use std::ops::ControlFlow;
 use std::{fmt, str};
 
@@ -124,6 +124,7 @@
 mod generics;
 mod impls_ty;
 mod instance;
+mod layout_sanity_check;
 mod list;
 mod parameterized;
 mod rvalue_scopes;
@@ -177,6 +178,11 @@ pub struct ResolverAstLowering {
     pub label_res_map: NodeMap<ast::NodeId>,
     /// Resolutions for lifetimes.
     pub lifetimes_res_map: NodeMap<LifetimeRes>,
+    /// Mapping from generics `def_id`s to TAIT generics `def_id`s.
+    /// For each captured lifetime (e.g., 'a), we create a new lifetime parameter that is a generic
+    /// defined on the TAIT, so we have type Foo<'a1> = ... and we establish a mapping in this
+    /// field from the original parameter 'a to the new parameter 'a1.
+    pub generics_def_id_map: Vec<FxHashMap<LocalDefId, LocalDefId>>,
     /// Lifetime parameters that lowering will have to introduce.
     pub extra_lifetime_params_map: NodeMap<Vec<(Ident, ast::NodeId, LifetimeRes)>>,
 
@@ -588,6 +594,29 @@ pub fn without_const(mut self, tcx: TyCtxt<'tcx>) -> Self {
         }
         self
     }
+
+    /// Whether this projection can be soundly normalized.
+    ///
+    /// Wf predicates must not be normalized, as normalization
+    /// can remove required bounds which would cause us to
+    /// unsoundly accept some programs. See #91068.
+    #[inline]
+    pub fn allow_normalization(self) -> bool {
+        match self.kind().skip_binder() {
+            PredicateKind::WellFormed(_) => false,
+            PredicateKind::Trait(_)
+            | PredicateKind::RegionOutlives(_)
+            | PredicateKind::TypeOutlives(_)
+            | PredicateKind::Projection(_)
+            | PredicateKind::ObjectSafe(_)
+            | PredicateKind::ClosureKind(_, _, _)
+            | PredicateKind::Subtype(_)
+            | PredicateKind::Coerce(_)
+            | PredicateKind::ConstEvaluatable(_)
+            | PredicateKind::ConstEquate(_, _)
+            | PredicateKind::TypeWellFormedFromEnv(_) => true,
+        }
+    }
 }
 
 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
@@ -1200,7 +1229,7 @@ pub struct BoundConst<'tcx> {
     pub ty: Ty<'tcx>,
 }
 
-pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
+pub type PlaceholderConst<'tcx> = Placeholder<BoundVar>;
 
 /// A `DefId` which, in case it is a const argument, is potentially bundled with
 /// the `DefId` of the generic parameter it instantiates.
@@ -1704,6 +1733,59 @@ pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
     }
 }
 
+impl PartialEq for VariantDef {
+    #[inline]
+    fn eq(&self, other: &Self) -> bool {
+        // There should be only one `VariantDef` for each `def_id`, therefore
+        // it is fine to implement `PartialEq` only based on `def_id`.
+        //
+        // Below, we exhaustively destructure `self` and `other` so that if the
+        // definition of `VariantDef` changes, a compile-error will be produced,
+        // reminding us to revisit this assumption.
+
+        let Self {
+            def_id: lhs_def_id,
+            ctor_def_id: _,
+            name: _,
+            discr: _,
+            fields: _,
+            ctor_kind: _,
+            flags: _,
+        } = &self;
+
+        let Self {
+            def_id: rhs_def_id,
+            ctor_def_id: _,
+            name: _,
+            discr: _,
+            fields: _,
+            ctor_kind: _,
+            flags: _,
+        } = other;
+
+        lhs_def_id == rhs_def_id
+    }
+}
+
+impl Eq for VariantDef {}
+
+impl Hash for VariantDef {
+    #[inline]
+    fn hash<H: Hasher>(&self, s: &mut H) {
+        // There should be only one `VariantDef` for each `def_id`, therefore
+        // it is fine to implement `Hash` only based on `def_id`.
+        //
+        // Below, we exhaustively destructure `self` so that if the definition
+        // of `VariantDef` changes, a compile-error will be produced, reminding
+        // us to revisit this assumption.
+
+        let Self { def_id, ctor_def_id: _, name: _, discr: _, fields: _, ctor_kind: _, flags: _ } =
+            &self;
+
+        def_id.hash(s)
+    }
+}
+
 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
 pub enum VariantDiscr {
     /// Explicit value for this variant, i.e., `X = 123`.
@@ -1724,6 +1806,42 @@ pub struct FieldDef {
     pub vis: Visibility,
 }
 
+impl PartialEq for FieldDef {
+    #[inline]
+    fn eq(&self, other: &Self) -> bool {
+        // There should be only one `FieldDef` for each `did`, therefore it is
+        // fine to implement `PartialEq` only based on `did`.
+        //
+        // Below, we exhaustively destructure `self` so that if the definition
+        // of `FieldDef` changes, a compile-error will be produced, reminding
+        // us to revisit this assumption.
+
+        let Self { did: lhs_did, name: _, vis: _ } = &self;
+
+        let Self { did: rhs_did, name: _, vis: _ } = other;
+
+        lhs_did == rhs_did
+    }
+}
+
+impl Eq for FieldDef {}
+
+impl Hash for FieldDef {
+    #[inline]
+    fn hash<H: Hasher>(&self, s: &mut H) {
+        // There should be only one `FieldDef` for each `did`, therefore it is
+        // fine to implement `Hash` only based on `did`.
+        //
+        // Below, we exhaustively destructure `self` so that if the definition
+        // of `FieldDef` changes, a compile-error will be produced, reminding
+        // us to revisit this assumption.
+
+        let Self { did, name: _, vis: _ } = &self;
+
+        did.hash(s)
+    }
+}
+
 bitflags! {
     #[derive(TyEncodable, TyDecodable, Default, HashStable)]
     pub struct ReprFlags: u8 {