Rollup merge of rust-lang#59789 - eddyb:typeck-reverts, r=nikomatsakis

Revert two unapproved changes to rustc_typeck.

There was a breakdown in process (rust-lang#59004 (comment), rust-lang#58894 (comment)) and two changes were made to `rustc_typeck`'s "collect" queries, for rustdoc, that were neither needed *nor* correct.
I'm reverting them here, and will fix up rustdoc *somehow*, if necessary.

cc @rust-lang/compiler How do we ensure this doesn't happen again?

r? @nikomatsakis or @oli-obk

Author: Centril

src/librustc_metadata/cstore_impl.rs

@@ -95,8 +95,8 @@ provide! { <'tcx> tcx, def_id, other, cdata,
     generics_of => {
         tcx.arena.alloc(cdata.get_generics(def_id.index, tcx.sess))
     }
-    predicates_of => { cdata.get_predicates(def_id.index, tcx) }
-    predicates_defined_on => { cdata.get_predicates_defined_on(def_id.index, tcx) }
+    explicit_predicates_of => { cdata.get_explicit_predicates(def_id.index, tcx) }
+    inferred_outlives_of => { cdata.get_inferred_outlives(def_id.index, tcx) }
     super_predicates_of => { cdata.get_super_predicates(def_id.index, tcx) }
     trait_def => {
         tcx.arena.alloc(cdata.get_trait_def(def_id.index, tcx.sess))

src/librustc_metadata/decoder.rs

@@ -658,20 +658,22 @@ impl<'a, 'tcx> CrateMetadata {
         tcx.alloc_adt_def(did, adt_kind, variants, repr)
     }
 
-    crate fn get_predicates(
+    crate fn get_explicit_predicates(
         &self,
         item_id: DefIndex,
         tcx: TyCtxt<'tcx>,
     ) -> ty::GenericPredicates<'tcx> {
-        self.root.per_def.predicates.get(self, item_id).unwrap().decode((self, tcx))
+        self.root.per_def.explicit_predicates.get(self, item_id).unwrap().decode((self, tcx))
     }
 
-    crate fn get_predicates_defined_on(
+    crate fn get_inferred_outlives(
         &self,
         item_id: DefIndex,
         tcx: TyCtxt<'tcx>,
-    ) -> ty::GenericPredicates<'tcx> {
-        self.root.per_def.predicates_defined_on.get(self, item_id).unwrap().decode((self, tcx))
+    ) -> &'tcx [(ty::Predicate<'tcx>, Span)] {
+        self.root.per_def.inferred_outlives.get(self, item_id).map(|predicates| {
+            predicates.decode((self, tcx))
+        }).unwrap_or_default()
     }
 
     crate fn get_super_predicates(

src/librustc_metadata/encoder.rs

@@ -76,8 +76,8 @@ struct PerDefTables<'tcx> {
     inherent_impls: PerDefTable<Lazy<[DefIndex]>>,
     variances: PerDefTable<Lazy<[ty::Variance]>>,
     generics: PerDefTable<Lazy<ty::Generics>>,
-    predicates: PerDefTable<Lazy<ty::GenericPredicates<'tcx>>>,
-    predicates_defined_on: PerDefTable<Lazy<ty::GenericPredicates<'tcx>>>,
+    explicit_predicates: PerDefTable<Lazy<ty::GenericPredicates<'tcx>>>,
+    inferred_outlives: PerDefTable<Lazy<&'tcx [(ty::Predicate<'tcx>, Span)]>>,
     super_predicates: PerDefTable<Lazy<ty::GenericPredicates<'tcx>>>,
 
     mir: PerDefTable<Lazy<mir::Body<'tcx>>>,
@@ -524,8 +524,8 @@ impl<'tcx> EncodeContext<'tcx> {
             inherent_impls: self.per_def.inherent_impls.encode(&mut self.opaque),
             variances: self.per_def.variances.encode(&mut self.opaque),
             generics: self.per_def.generics.encode(&mut self.opaque),
-            predicates: self.per_def.predicates.encode(&mut self.opaque),
-            predicates_defined_on: self.per_def.predicates_defined_on.encode(&mut self.opaque),
+            explicit_predicates: self.per_def.explicit_predicates.encode(&mut self.opaque),
+            inferred_outlives: self.per_def.inferred_outlives.encode(&mut self.opaque),
             super_predicates: self.per_def.super_predicates.encode(&mut self.opaque),
 
             mir: self.per_def.mir.encode(&mut self.opaque),
@@ -675,7 +675,8 @@ impl EncodeContext<'tcx> {
             self.encode_variances_of(def_id);
         }
         self.encode_generics(def_id);
-        self.encode_predicates(def_id);
+        self.encode_explicit_predicates(def_id);
+        self.encode_inferred_outlives(def_id);
         self.encode_optimized_mir(def_id);
         self.encode_promoted_mir(def_id);
     }
@@ -718,7 +719,8 @@ impl EncodeContext<'tcx> {
             self.encode_variances_of(def_id);
         }
         self.encode_generics(def_id);
-        self.encode_predicates(def_id);
+        self.encode_explicit_predicates(def_id);
+        self.encode_inferred_outlives(def_id);
         self.encode_optimized_mir(def_id);
         self.encode_promoted_mir(def_id);
     }
@@ -776,7 +778,8 @@ impl EncodeContext<'tcx> {
         self.encode_deprecation(def_id);
         self.encode_item_type(def_id);
         self.encode_generics(def_id);
-        self.encode_predicates(def_id);
+        self.encode_explicit_predicates(def_id);
+        self.encode_inferred_outlives(def_id);
     }
 
     fn encode_struct_ctor(&mut self, adt_def_id: DefId, def_id: DefId) {
@@ -819,7 +822,8 @@ impl EncodeContext<'tcx> {
             self.encode_variances_of(def_id);
         }
         self.encode_generics(def_id);
-        self.encode_predicates(def_id);
+        self.encode_explicit_predicates(def_id);
+        self.encode_inferred_outlives(def_id);
         self.encode_optimized_mir(def_id);
         self.encode_promoted_mir(def_id);
     }
@@ -829,15 +833,18 @@ impl EncodeContext<'tcx> {
         record!(self.per_def.generics[def_id] <- self.tcx.generics_of(def_id));
     }
 
-    fn encode_predicates(&mut self, def_id: DefId) {
-        debug!("EncodeContext::encode_predicates({:?})", def_id);
-        record!(self.per_def.predicates[def_id] <- self.tcx.predicates_of(def_id));
+    fn encode_explicit_predicates(&mut self, def_id: DefId) {
+        debug!("EncodeContext::encode_explicit_predicates({:?})", def_id);
+        record!(self.per_def.explicit_predicates[def_id] <-
+            self.tcx.explicit_predicates_of(def_id));
     }
 
-    fn encode_predicates_defined_on(&mut self, def_id: DefId) {
-        debug!("EncodeContext::encode_predicates_defined_on({:?})", def_id);
-        record!(self.per_def.predicates_defined_on[def_id] <-
-            self.tcx.predicates_defined_on(def_id))
+    fn encode_inferred_outlives(&mut self, def_id: DefId) {
+        debug!("EncodeContext::encode_inferred_outlives({:?})", def_id);
+        let inferred_outlives = self.tcx.inferred_outlives_of(def_id);
+        if !inferred_outlives.is_empty() {
+            record!(self.per_def.inferred_outlives[def_id] <- inferred_outlives);
+        }
     }
 
     fn encode_super_predicates(&mut self, def_id: DefId) {
@@ -919,7 +926,8 @@ impl EncodeContext<'tcx> {
             self.encode_variances_of(def_id);
         }
         self.encode_generics(def_id);
-        self.encode_predicates(def_id);
+        self.encode_explicit_predicates(def_id);
+        self.encode_inferred_outlives(def_id);
         self.encode_optimized_mir(def_id);
         self.encode_promoted_mir(def_id);
     }
@@ -986,7 +994,8 @@ impl EncodeContext<'tcx> {
             self.encode_variances_of(def_id);
         }
         self.encode_generics(def_id);
-        self.encode_predicates(def_id);
+        self.encode_explicit_predicates(def_id);
+        self.encode_inferred_outlives(def_id);
         let mir = match ast_item.kind {
             hir::ImplItemKind::Const(..) => true,
             hir::ImplItemKind::Method(ref sig, _) => {
@@ -1260,22 +1269,11 @@ impl EncodeContext<'tcx> {
             hir::ItemKind::Trait(..) |
             hir::ItemKind::TraitAlias(..) => {
                 self.encode_generics(def_id);
-                self.encode_predicates(def_id);
+                self.encode_explicit_predicates(def_id);
+                self.encode_inferred_outlives(def_id);
             }
             _ => {}
         }
-        // The only time that `predicates_defined_on` is used (on
-        // an external item) is for traits, during chalk lowering,
-        // so only encode it in that case as an efficiency
-        // hack. (No reason not to expand it in the future if
-        // necessary.)
-        match item.kind {
-            hir::ItemKind::Trait(..) |
-            hir::ItemKind::TraitAlias(..) => {
-                self.encode_predicates_defined_on(def_id);
-            }
-            _ => {} // not *wrong* for other kinds of items, but not needed
-        }
         match item.kind {
             hir::ItemKind::Trait(..) |
             hir::ItemKind::TraitAlias(..) => {
@@ -1377,7 +1375,8 @@ impl EncodeContext<'tcx> {
         record!(self.per_def.span[def_id] <- self.tcx.def_span(def_id));
         self.encode_item_type(def_id);
         self.encode_generics(def_id);
-        self.encode_predicates(def_id);
+        self.encode_explicit_predicates(def_id);
+        self.encode_inferred_outlives(def_id);
         self.encode_optimized_mir(def_id);
         self.encode_promoted_mir(def_id);
     }
@@ -1588,7 +1587,8 @@ impl EncodeContext<'tcx> {
             self.encode_variances_of(def_id);
         }
         self.encode_generics(def_id);
-        self.encode_predicates(def_id);
+        self.encode_explicit_predicates(def_id);
+        self.encode_inferred_outlives(def_id);
     }
 }
 

src/librustc_metadata/schema.rs

@@ -244,8 +244,13 @@ crate struct LazyPerDefTables<'tcx> {
     pub inherent_impls: Lazy!(PerDefTable<Lazy<[DefIndex]>>),
     pub variances: Lazy!(PerDefTable<Lazy<[ty::Variance]>>),
     pub generics: Lazy!(PerDefTable<Lazy<ty::Generics>>),
-    pub predicates: Lazy!(PerDefTable<Lazy!(ty::GenericPredicates<'tcx>)>),
-    pub predicates_defined_on: Lazy!(PerDefTable<Lazy!(ty::GenericPredicates<'tcx>)>),
+    pub explicit_predicates: Lazy!(PerDefTable<Lazy!(ty::GenericPredicates<'tcx>)>),
+    // FIXME(eddyb) this would ideally be `Lazy<[...]>` but `ty::Predicate`
+    // doesn't handle shorthands in its own (de)serialization impls,
+    // as it's an `enum` for which we want to derive (de)serialization,
+    // so the `ty::codec` APIs handle the whole `&'tcx [...]` at once.
+    // Also, as an optimization, a missing entry indicates an empty `&[]`.
+    pub inferred_outlives: Lazy!(PerDefTable<Lazy!(&'tcx [(ty::Predicate<'tcx>, Span)])>),
     pub super_predicates: Lazy!(PerDefTable<Lazy!(ty::GenericPredicates<'tcx>)>),
 
     pub mir: Lazy!(PerDefTable<Lazy!(mir::Body<'tcx>)>),

src/librustc_typeck/collect.rs

@@ -1146,10 +1146,6 @@ fn report_assoc_ty_on_inherent_impl(tcx: TyCtxt<'_>, span: Span) {
     );
 }
 
-fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
-    checked_type_of(tcx, def_id, true).unwrap()
-}
-
 fn infer_placeholder_type(
     tcx: TyCtxt<'_>,
     def_id: DefId,
@@ -1193,26 +1189,14 @@ fn infer_placeholder_type(
     ty
 }
 
-/// Same as [`type_of`] but returns [`Option`] instead of failing.
-///
-/// If you want to fail anyway, you can set the `fail` parameter to true, but in this case,
-/// you'd better just call [`type_of`] directly.
-pub fn checked_type_of(tcx: TyCtxt<'_>, def_id: DefId, fail: bool) -> Option<Ty<'_>> {
+fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
     use rustc::hir::*;
 
-    let hir_id = match tcx.hir().as_local_hir_id(def_id) {
-        Some(hir_id) => hir_id,
-        None => {
-            if !fail {
-                return None;
-            }
-            bug!("invalid node");
-        }
-    };
+    let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
 
     let icx = ItemCtxt::new(tcx, def_id);
 
-    Some(match tcx.hir().get(hir_id) {
+    match tcx.hir().get(hir_id) {
         Node::TraitItem(item) => match item.kind {
             TraitItemKind::Method(..) => {
                 let substs = InternalSubsts::identity_for_item(tcx, def_id);
@@ -1229,9 +1213,6 @@ pub fn checked_type_of(tcx: TyCtxt<'_>, def_id: DefId, fail: bool) -> Option<Ty<
             },
             TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
             TraitItemKind::Type(_, None) => {
-                if !fail {
-                    return None;
-                }
                 span_bug!(item.span, "associated type missing default");
             }
         },
@@ -1325,9 +1306,6 @@ pub fn checked_type_of(tcx: TyCtxt<'_>, def_id: DefId, fail: bool) -> Option<Ty<
                 | ItemKind::GlobalAsm(..)
                 | ItemKind::ExternCrate(..)
                 | ItemKind::Use(..) => {
-                    if !fail {
-                        return None;
-                    }
                     span_bug!(
                         item.span,
                         "compute_type_of_item: unexpected item type: {:?}",
@@ -1365,7 +1343,7 @@ pub fn checked_type_of(tcx: TyCtxt<'_>, def_id: DefId, fail: bool) -> Option<Ty<
             ..
         }) => {
             if gen.is_some() {
-                return Some(tcx.typeck_tables_of(def_id).node_type(hir_id));
+                return tcx.typeck_tables_of(def_id).node_type(hir_id);
             }
 
             let substs = InternalSubsts::identity_for_item(tcx, def_id);
@@ -1440,13 +1418,9 @@ pub fn checked_type_of(tcx: TyCtxt<'_>, def_id: DefId, fail: bool) -> Option<Ty<
                                     .map(|(index, _)| index)
                                     .next()
                             })
-                            .or_else(|| {
-                                if !fail {
-                                    None
-                                } else {
-                                    bug!("no arg matching AnonConst in path")
-                                }
-                            })?;
+                            .unwrap_or_else(|| {
+                                bug!("no arg matching AnonConst in path");
+                            });
 
                         // We've encountered an `AnonConst` in some path, so we need to
                         // figure out which generic parameter it corresponds to and return
@@ -1456,8 +1430,7 @@ pub fn checked_type_of(tcx: TyCtxt<'_>, def_id: DefId, fail: bool) -> Option<Ty<
                                 tcx.generics_of(tcx.parent(def_id).unwrap())
                             }
                             Res::Def(_, def_id) => tcx.generics_of(def_id),
-                            Res::Err => return Some(tcx.types.err),
-                            _ if !fail => return None,
+                            Res::Err => return tcx.types.err,
                             res => {
                                 tcx.sess.delay_span_bug(
                                     DUMMY_SP,
@@ -1466,7 +1439,7 @@ pub fn checked_type_of(tcx: TyCtxt<'_>, def_id: DefId, fail: bool) -> Option<Ty<
                                         res,
                                     ),
                                 );
-                                return Some(tcx.types.err);
+                                return tcx.types.err;
                             }
                         };
 
@@ -1484,24 +1457,18 @@ pub fn checked_type_of(tcx: TyCtxt<'_>, def_id: DefId, fail: bool) -> Option<Ty<
                             // probably from an extra arg where one is not needed.
                             .unwrap_or(tcx.types.err)
                     } else {
-                        if !fail {
-                            return None;
-                        }
                         tcx.sess.delay_span_bug(
                             DUMMY_SP,
                             &format!(
                                 "unexpected const parent path {:?}",
                                 parent_node,
                             ),
                         );
-                        return Some(tcx.types.err);
+                        return tcx.types.err;
                     }
                 }
 
                 x => {
-                    if !fail {
-                        return None;
-                    }
                     tcx.sess.delay_span_bug(
                         DUMMY_SP,
                         &format!(
@@ -1551,21 +1518,13 @@ pub fn checked_type_of(tcx: TyCtxt<'_>, def_id: DefId, fail: bool) -> Option<Ty<
                 }
                 ty
             }
-            x => {
-                if !fail {
-                    return None;
-                }
-                bug!("unexpected non-type Node::GenericParam: {:?}", x)
-            },
+            x => bug!("unexpected non-type Node::GenericParam: {:?}", x),
         },
 
         x => {
-            if !fail {
-                return None;
-            }
             bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
         }
-    })
+    }
 }
 
 fn find_opaque_ty_constraints(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
@@ -2075,10 +2034,7 @@ fn explicit_predicates_of(
         }
     }
 
-    let hir_id = match tcx.hir().as_local_hir_id(def_id) {
-        Some(hir_id) => hir_id,
-        None => return tcx.predicates_of(def_id),
-    };
+    let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
     let node = tcx.hir().get(hir_id);
 
     let mut is_trait = None;

src/librustc_typeck/lib.rs

@@ -109,8 +109,6 @@ use util::common::time;
 use std::iter;
 
 use astconv::{AstConv, Bounds};
-pub use collect::checked_type_of;
-
 pub struct TypeAndSubsts<'tcx> {
     substs: SubstsRef<'tcx>,
     ty: Ty<'tcx>,