Normalize opaque types when converting ParamEnv to Reveal::All

Fixes rust-lang#65918

src/librustc_middle/mir/interpret/queries.rs

@@ -18,7 +18,7 @@ impl<'tcx> TyCtxt<'tcx> {
         let substs = InternalSubsts::identity_for_item(self, def_id);
         let instance = ty::Instance::new(def_id, substs);
         let cid = GlobalId { instance, promoted: None };
-        let param_env = self.param_env(def_id).with_reveal_all();
+        let param_env = self.param_env(def_id).with_reveal_all_normalized(self);
         self.const_eval_global_id(param_env, cid, None)
     }
 

src/librustc_middle/mir/interpret/value.rs

@@ -66,7 +66,7 @@ impl<'tcx> ConstValue<'tcx> {
         param_env: ParamEnv<'tcx>,
         ty: Ty<'tcx>,
     ) -> Option<u128> {
-        let size = tcx.layout_of(param_env.with_reveal_all().and(ty)).ok()?.size;
+        let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size;
         self.try_to_bits(size)
     }
 

src/librustc_middle/query/mod.rs

@@ -766,11 +766,17 @@ rustc_queries! {
         /// type-checking etc, and it does not normalize specializable
         /// associated types. This is almost always what you want,
         /// unless you are doing MIR optimizations, in which case you
-        /// might want to use `reveal_all()` method to change modes.
         query param_env(def_id: DefId) -> ty::ParamEnv<'tcx> {
             desc { |tcx| "computing normalized predicates of `{}`", tcx.def_path_str(def_id) }
         }
 
+        /// Like `param_env`, but returns the `ParamEnv in `Reveal::All` mode.
+        /// Prefer this over `tcx.param_env(def_id).with_reveal_all_normalized(tcx)`,
+        /// as this method is more efficient.
+        query param_env_reveal_all_normalized(def_id: DefId) -> ty::ParamEnv<'tcx> {
+            desc { |tcx| "computing revealed normalized predicates of `{}`", tcx.def_path_str(def_id) }
+        }
+
         /// Trait selection queries. These are best used by invoking `ty.is_copy_modulo_regions()`,
         /// `ty.is_copy()`, etc, since that will prune the environment where possible.
         query is_copy_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool {
@@ -1398,5 +1404,9 @@ rustc_queries! {
         ) -> Result<Option<ty::Instance<'tcx>>, ErrorReported> {
             desc { "resolving instance `{}`", ty::Instance::new(key.value.0, key.value.1) }
         }
+
+        query normalize_opaque_types(key: &'tcx ty::List<ty::Predicate<'tcx>>) -> &'tcx ty::List<ty::Predicate<'tcx>> {
+            desc { "normalizing opaque types in {:?}", key }
+        }
     }
 }

src/librustc_middle/ty/layout.rs

@@ -1903,7 +1903,7 @@ impl<'tcx> LayoutOf for LayoutCx<'tcx, TyCtxt<'tcx>> {
     /// Computes the layout of a type. Note that this implicitly
     /// executes in "reveal all" mode.
     fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyAndLayout {
-        let param_env = self.param_env.with_reveal_all();
+        let param_env = self.param_env.with_reveal_all_normalized(self.tcx);
         let ty = self.tcx.normalize_erasing_regions(param_env, ty);
         let layout = self.tcx.layout_raw(param_env.and(ty))?;
         let layout = TyAndLayout { ty, layout };
@@ -1927,7 +1927,7 @@ impl LayoutOf for LayoutCx<'tcx, ty::query::TyCtxtAt<'tcx>> {
     /// Computes the layout of a type. Note that this implicitly
     /// executes in "reveal all" mode.
     fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyAndLayout {
-        let param_env = self.param_env.with_reveal_all();
+        let param_env = self.param_env.with_reveal_all_normalized(*self.tcx);
         let ty = self.tcx.normalize_erasing_regions(param_env, ty);
         let layout = self.tcx.layout_raw(param_env.and(ty))?;
         let layout = TyAndLayout { ty, layout };

src/librustc_middle/ty/mod.rs

@@ -1,4 +1,4 @@
-pub use self::fold::{TypeFoldable, TypeVisitor};
+pub use self::fold::{TypeFoldable, TypeFolder, TypeVisitor};
 pub use self::AssocItemContainer::*;
 pub use self::BorrowKind::*;
 pub use self::IntVarValue::*;
@@ -1605,8 +1605,16 @@ impl<'tcx> ParamEnv<'tcx> {
     /// the desired behavior during codegen and certain other special
     /// contexts; normally though we want to use `Reveal::UserFacing`,
     /// which is the default.
-    pub fn with_reveal_all(self) -> Self {
-        ty::ParamEnv { reveal: Reveal::All, ..self }
+    /// All opaque types in the caller_bounds of the `ParamEnv`
+    /// will be normalized to their underlying types.
+    /// See PR #65989 and issue #65918 for more details
+    pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
+        if self.reveal == Reveal::All {
+            return self;
+        }
+
+        let new_bounds = tcx.normalize_opaque_types(self.caller_bounds);
+        ty::ParamEnv { reveal: Reveal::All, caller_bounds: new_bounds, ..self }
     }
 
     /// Returns this same environment but with no caller bounds.
@@ -2859,6 +2867,7 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
     context::provide(providers);
     erase_regions::provide(providers);
     layout::provide(providers);
+    util::provide(providers);
     super::util::bug::provide(providers);
     *providers = ty::query::Providers {
         trait_impls_of: trait_def::trait_impls_of_provider,

src/librustc_middle/ty/query/keys.rs

@@ -237,6 +237,17 @@ impl<'tcx> Key for Ty<'tcx> {
     }
 }
 
+impl<'tcx> Key for &'tcx ty::List<ty::Predicate<'tcx>> {
+    type CacheSelector = DefaultCacheSelector;
+
+    fn query_crate(&self) -> CrateNum {
+        LOCAL_CRATE
+    }
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
 impl<'tcx> Key for ty::ParamEnv<'tcx> {
     type CacheSelector = DefaultCacheSelector;
 

src/librustc_middle/ty/sty.rs

@@ -2330,7 +2330,7 @@ impl<'tcx> Const<'tcx> {
         ty: Ty<'tcx>,
     ) -> Option<u128> {
         assert_eq!(self.ty, ty);
-        let size = tcx.layout_of(param_env.with_reveal_all().and(ty)).ok()?.size;
+        let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size;
         // if `ty` does not depend on generic parameters, use an empty param_env
         self.eval(tcx, param_env).val.try_to_bits(size)
     }
@@ -2342,12 +2342,16 @@ impl<'tcx> Const<'tcx> {
         if let ConstKind::Unevaluated(did, substs, promoted) = self.val {
             use crate::mir::interpret::ErrorHandled;
 
-            let param_env_and_substs = param_env.with_reveal_all().and(substs);
-
             // HACK(eddyb) this erases lifetimes even though `const_eval_resolve`
             // also does later, but we want to do it before checking for
             // inference variables.
-            let param_env_and_substs = tcx.erase_regions(&param_env_and_substs);
+            // Note that we erase regions *before* calling `with_reveal_all_normalized`,
+            // so that we don't try to invoke this query with
+            // any region variables.
+            let param_env_and_substs = tcx
+                .erase_regions(&param_env)
+                .with_reveal_all_normalized(tcx)
+                .and(tcx.erase_regions(&substs));
 
             // HACK(eddyb) when the query key would contain inference variables,
             // attempt using identity substs and `ParamEnv` instead, that will succeed

src/librustc_middle/ty/util.rs

@@ -3,11 +3,12 @@
 use crate::ich::NodeIdHashingMode;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::mir::interpret::{sign_extend, truncate};
+use crate::ty::fold::TypeFolder;
 use crate::ty::layout::IntegerExt;
 use crate::ty::query::TyCtxtAt;
 use crate::ty::subst::{GenericArgKind, InternalSubsts, Subst, SubstsRef};
 use crate::ty::TyKind::*;
-use crate::ty::{self, DefIdTree, GenericParamDefKind, Ty, TyCtxt, TypeFoldable};
+use crate::ty::{self, DefIdTree, GenericParamDefKind, List, Ty, TyCtxt, TypeFoldable};
 use rustc_apfloat::Float as _;
 use rustc_ast::ast;
 use rustc_attr::{self as attr, SignedInt, UnsignedInt};
@@ -557,82 +558,84 @@ impl<'tcx> TyCtxt<'tcx> {
         def_id: DefId,
         substs: SubstsRef<'tcx>,
     ) -> Result<Ty<'tcx>, Ty<'tcx>> {
-        use crate::ty::fold::TypeFolder;
-
-        struct OpaqueTypeExpander<'tcx> {
-            // Contains the DefIds of the opaque types that are currently being
-            // expanded. When we expand an opaque type we insert the DefId of
-            // that type, and when we finish expanding that type we remove the
-            // its DefId.
-            seen_opaque_tys: FxHashSet<DefId>,
-            // Cache of all expansions we've seen so far. This is a critical
-            // optimization for some large types produced by async fn trees.
-            expanded_cache: FxHashMap<(DefId, SubstsRef<'tcx>), Ty<'tcx>>,
-            primary_def_id: DefId,
-            found_recursion: bool,
-            tcx: TyCtxt<'tcx>,
-        }
-
-        impl<'tcx> OpaqueTypeExpander<'tcx> {
-            fn expand_opaque_ty(
-                &mut self,
-                def_id: DefId,
-                substs: SubstsRef<'tcx>,
-            ) -> Option<Ty<'tcx>> {
-                if self.found_recursion {
-                    return None;
-                }
-                let substs = substs.fold_with(self);
-                if self.seen_opaque_tys.insert(def_id) {
-                    let expanded_ty = match self.expanded_cache.get(&(def_id, substs)) {
-                        Some(expanded_ty) => expanded_ty,
-                        None => {
-                            let generic_ty = self.tcx.type_of(def_id);
-                            let concrete_ty = generic_ty.subst(self.tcx, substs);
-                            let expanded_ty = self.fold_ty(concrete_ty);
-                            self.expanded_cache.insert((def_id, substs), expanded_ty);
-                            expanded_ty
-                        }
-                    };
-                    self.seen_opaque_tys.remove(&def_id);
-                    Some(expanded_ty)
-                } else {
-                    // If another opaque type that we contain is recursive, then it
-                    // will report the error, so we don't have to.
-                    self.found_recursion = def_id == self.primary_def_id;
-                    None
-                }
-            }
-        }
-
-        impl<'tcx> TypeFolder<'tcx> for OpaqueTypeExpander<'tcx> {
-            fn tcx(&self) -> TyCtxt<'tcx> {
-                self.tcx
-            }
-
-            fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
-                if let ty::Opaque(def_id, substs) = t.kind {
-                    self.expand_opaque_ty(def_id, substs).unwrap_or(t)
-                } else if t.has_opaque_types() {
-                    t.super_fold_with(self)
-                } else {
-                    t
-                }
-            }
-        }
-
         let mut visitor = OpaqueTypeExpander {
             seen_opaque_tys: FxHashSet::default(),
             expanded_cache: FxHashMap::default(),
-            primary_def_id: def_id,
+            primary_def_id: Some(def_id),
             found_recursion: false,
+            check_recursion: true,
             tcx: self,
         };
+
         let expanded_type = visitor.expand_opaque_ty(def_id, substs).unwrap();
         if visitor.found_recursion { Err(expanded_type) } else { Ok(expanded_type) }
     }
 }
 
+struct OpaqueTypeExpander<'tcx> {
+    // Contains the DefIds of the opaque types that are currently being
+    // expanded. When we expand an opaque type we insert the DefId of
+    // that type, and when we finish expanding that type we remove the
+    // its DefId.
+    seen_opaque_tys: FxHashSet<DefId>,
+    // Cache of all expansions we've seen so far. This is a critical
+    // optimization for some large types produced by async fn trees.
+    expanded_cache: FxHashMap<(DefId, SubstsRef<'tcx>), Ty<'tcx>>,
+    primary_def_id: Option<DefId>,
+    found_recursion: bool,
+    /// Whether or not to check for recursive opaque types.
+    /// This is `true` when we're explicitly checking for opaque type
+    /// recursion, and 'false' otherwise to avoid unecessary work.
+    check_recursion: bool,
+    tcx: TyCtxt<'tcx>,
+}
+
+impl<'tcx> OpaqueTypeExpander<'tcx> {
+    fn expand_opaque_ty(&mut self, def_id: DefId, substs: SubstsRef<'tcx>) -> Option<Ty<'tcx>> {
+        if self.found_recursion {
+            return None;
+        }
+        let substs = substs.fold_with(self);
+        if !self.check_recursion || self.seen_opaque_tys.insert(def_id) {
+            let expanded_ty = match self.expanded_cache.get(&(def_id, substs)) {
+                Some(expanded_ty) => expanded_ty,
+                None => {
+                    let generic_ty = self.tcx.type_of(def_id);
+                    let concrete_ty = generic_ty.subst(self.tcx, substs);
+                    let expanded_ty = self.fold_ty(concrete_ty);
+                    self.expanded_cache.insert((def_id, substs), expanded_ty);
+                    expanded_ty
+                }
+            };
+            if self.check_recursion {
+                self.seen_opaque_tys.remove(&def_id);
+            }
+            Some(expanded_ty)
+        } else {
+            // If another opaque type that we contain is recursive, then it
+            // will report the error, so we don't have to.
+            self.found_recursion = def_id == *self.primary_def_id.as_ref().unwrap();
+            None
+        }
+    }
+}
+
+impl<'tcx> TypeFolder<'tcx> for OpaqueTypeExpander<'tcx> {
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+
+    fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
+        if let ty::Opaque(def_id, substs) = t.kind {
+            self.expand_opaque_ty(def_id, substs).unwrap_or(t)
+        } else if t.has_opaque_types() {
+            t.super_fold_with(self)
+        } else {
+            t
+        }
+    }
+}
+
 impl<'tcx> ty::TyS<'tcx> {
     /// Returns the maximum value for the given numeric type (including `char`s)
     /// or returns `None` if the type is not numeric.
@@ -1088,3 +1091,24 @@ pub fn needs_drop_components(
 
 #[derive(Copy, Clone, Debug, HashStable, RustcEncodable, RustcDecodable)]
 pub struct AlwaysRequiresDrop;
+
+/// Normalizes all opaque types in the given value, replacing them
+/// with their underlying types.
+pub fn normalize_opaque_types(
+    tcx: TyCtxt<'tcx>,
+    val: &'tcx List<ty::Predicate<'tcx>>,
+) -> &'tcx List<ty::Predicate<'tcx>> {
+    let mut visitor = OpaqueTypeExpander {
+        seen_opaque_tys: FxHashSet::default(),
+        expanded_cache: FxHashMap::default(),
+        primary_def_id: None,
+        found_recursion: false,
+        check_recursion: false,
+        tcx,
+    };
+    val.fold_with(&mut visitor)
+}
+
+pub fn provide(providers: &mut ty::query::Providers<'_>) {
+    *providers = ty::query::Providers { normalize_opaque_types, ..*providers }
+}

src/librustc_mir/shim.rs

@@ -203,7 +203,7 @@ fn build_drop_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>)
             );
         }
         let patch = {
-            let param_env = tcx.param_env(def_id).with_reveal_all();
+            let param_env = tcx.param_env_reveal_all_normalized(def_id);
             let mut elaborator =
                 DropShimElaborator { body: &body, patch: MirPatch::new(&body), tcx, param_env };
             let dropee = tcx.mk_place_deref(dropee_ptr);

src/librustc_mir/transform/const_prop.rs

@@ -310,7 +310,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
     ) -> ConstPropagator<'mir, 'tcx> {
         let def_id = source.def_id();
         let substs = &InternalSubsts::identity_for_item(tcx, def_id);
-        let param_env = tcx.param_env(def_id).with_reveal_all();
+        let param_env = tcx.param_env_reveal_all_normalized(def_id);
 
         let span = tcx.def_span(def_id);
         let mut ecx = InterpCx::new(tcx.at(span), param_env, ConstPropMachine::new(), ());

src/librustc_mir/transform/elaborate_drops.rs

@@ -25,7 +25,7 @@ impl<'tcx> MirPass<'tcx> for ElaborateDrops {
         debug!("elaborate_drops({:?} @ {:?})", src, body.span);
 
         let def_id = src.def_id();
-        let param_env = tcx.param_env(src.def_id()).with_reveal_all();
+        let param_env = tcx.param_env_reveal_all_normalized(src.def_id());
         let move_data = match MoveData::gather_moves(body, tcx, param_env) {
             Ok(move_data) => move_data,
             Err((move_data, _)) => {

src/librustc_mir/transform/inline.rs

@@ -66,7 +66,7 @@ impl Inliner<'tcx> {
 
         let mut callsites = VecDeque::new();
 
-        let param_env = self.tcx.param_env(self.source.def_id()).with_reveal_all();
+        let param_env = self.tcx.param_env_reveal_all_normalized(self.source.def_id());
 
         // Only do inlining into fn bodies.
         let id = self.tcx.hir().as_local_hir_id(self.source.def_id().expect_local());

src/librustc_mir_build/hair/pattern/mod.rs

@@ -778,7 +778,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
 
         // Use `Reveal::All` here because patterns are always monomorphic even if their function
         // isn't.
-        let param_env_reveal_all = self.param_env.with_reveal_all();
+        let param_env_reveal_all = self.param_env.with_reveal_all_normalized(self.tcx);
         let substs = self.tables.node_substs(id);
         let instance = match ty::Instance::resolve(self.tcx, param_env_reveal_all, def_id, substs) {
             Ok(Some(i)) => i,

src/librustc_symbol_mangling/v0.rs

@@ -271,7 +271,7 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
         let key = self.tcx.def_key(impl_def_id);
         let parent_def_id = DefId { index: key.parent.unwrap(), ..impl_def_id };
 
-        let mut param_env = self.tcx.param_env(impl_def_id).with_reveal_all();
+        let mut param_env = self.tcx.param_env_reveal_all_normalized(impl_def_id);
         if !substs.is_empty() {
             param_env = param_env.subst(self.tcx, substs);
         }

src/librustc_ty/instance.rs

@@ -102,7 +102,7 @@ fn resolve_associated_item<'tcx>(
                 });
 
             let substs = tcx.infer_ctxt().enter(|infcx| {
-                let param_env = param_env.with_reveal_all();
+                let param_env = param_env.with_reveal_all_normalized(tcx);
                 let substs = rcvr_substs.rebase_onto(tcx, trait_def_id, impl_data.substs);
                 let substs = translate_substs(
                     &infcx,