Rollup of 5 pull requests

src/bootstrap/util.rs

@@ -270,9 +270,9 @@ pub enum CiEnv {
 impl CiEnv {
     /// Obtains the current CI environment.
     pub fn current() -> CiEnv {
-        if env::var("TF_BUILD").ok().map_or(false, |e| &*e == "True") {
+        if env::var("TF_BUILD").map_or(false, |e| e == "True") {
             CiEnv::AzurePipelines
-        } else if env::var("GITHUB_ACTIONS").ok().map_or(false, |e| &*e == "true") {
+        } else if env::var("GITHUB_ACTIONS").map_or(false, |e| e == "true") {
             CiEnv::GitHubActions
         } else {
             CiEnv::None

src/libcore/any.rs

@@ -496,7 +496,6 @@ pub const fn type_name<T: ?Sized>() -> &'static str {
 /// ```
 #[unstable(feature = "type_name_of_val", issue = "66359")]
 #[rustc_const_unstable(feature = "const_type_name", issue = "63084")]
-pub const fn type_name_of_val<T: ?Sized>(val: &T) -> &'static str {
-    let _ = val;
+pub const fn type_name_of_val<T: ?Sized>(_val: &T) -> &'static str {
     type_name::<T>()
 }

src/librustc/infer/error_reporting/mod.rs

@@ -1912,6 +1912,7 @@ impl<'tcx> ObligationCause<'tcx> {
         use crate::traits::ObligationCauseCode::*;
         match self.code {
             CompareImplMethodObligation { .. } => Error0308("method not compatible with trait"),
+            CompareImplTypeObligation { .. } => Error0308("type not compatible with trait"),
             MatchExpressionArm(box MatchExpressionArmCause { source, .. }) =>
                 Error0308(match source {
                     hir::MatchSource::IfLetDesugar { .. } =>
@@ -1948,6 +1949,7 @@ impl<'tcx> ObligationCause<'tcx> {
         use crate::traits::ObligationCauseCode::*;
         match self.code {
             CompareImplMethodObligation { .. } => "method type is compatible with trait",
+            CompareImplTypeObligation { .. } => "associated type is compatible with trait",
             ExprAssignable => "expression is assignable",
             MatchExpressionArm(box MatchExpressionArmCause { source, .. }) => match source {
                 hir::MatchSource::IfLetDesugar { .. } => "`if let` arms have compatible types",

src/librustc/traits/error_reporting.rs

@@ -702,6 +702,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             SelectionError::Unimplemented => {
                 if let ObligationCauseCode::CompareImplMethodObligation {
                     item_name, impl_item_def_id, trait_item_def_id,
+                } | ObligationCauseCode::CompareImplTypeObligation {
+                    item_name, impl_item_def_id, trait_item_def_id,
                 } = obligation.cause.code {
                     self.report_extra_impl_obligation(
                         span,
@@ -2631,6 +2633,12 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                               but not on the corresponding trait method",
                              predicate));
             }
+            ObligationCauseCode::CompareImplTypeObligation { .. } => {
+                err.note(&format!(
+                    "the requirement `{}` appears on the associated impl type\
+                     but not on the corresponding associated trait type",
+                     predicate));
+            }
             ObligationCauseCode::ReturnType |
             ObligationCauseCode::ReturnValue(_) |
             ObligationCauseCode::BlockTailExpression(_) => (),

src/librustc/traits/mod.rs

@@ -230,6 +230,13 @@ pub enum ObligationCauseCode<'tcx> {
         trait_item_def_id: DefId,
     },
 
+    /// Error derived when matching traits/impls; see ObligationCause for more details
+    CompareImplTypeObligation {
+        item_name: ast::Name,
+        impl_item_def_id: DefId,
+        trait_item_def_id: DefId,
+    },
+
     /// Checking that this expression can be assigned where it needs to be
     // FIXME(eddyb) #11161 is the original Expr required?
     ExprAssignable,

src/librustc/traits/project.rs

@@ -23,6 +23,7 @@ use crate::ty::subst::{Subst, InternalSubsts};
 use crate::ty::{self, ToPredicate, ToPolyTraitRef, Ty, TyCtxt};
 use crate::ty::fold::{TypeFoldable, TypeFolder};
 use crate::util::common::FN_OUTPUT_NAME;
+use syntax_pos::DUMMY_SP;
 
 /// Depending on the stage of compilation, we want projection to be
 /// more or less conservative.
@@ -1437,11 +1438,14 @@ fn confirm_impl_candidate<'cx, 'tcx>(
     obligation: &ProjectionTyObligation<'tcx>,
     impl_vtable: VtableImplData<'tcx, PredicateObligation<'tcx>>,
 ) -> Progress<'tcx> {
+    let tcx = selcx.tcx();
+
     let VtableImplData { impl_def_id, substs, nested } = impl_vtable;
+    let assoc_item_id = obligation.predicate.item_def_id;
+    let trait_def_id = tcx.trait_id_of_impl(impl_def_id).unwrap();
 
-    let tcx = selcx.tcx();
     let param_env = obligation.param_env;
-    let assoc_ty = assoc_ty_def(selcx, impl_def_id, obligation.predicate.item_def_id);
+    let assoc_ty = assoc_ty_def(selcx, impl_def_id, assoc_item_id);
 
     if !assoc_ty.item.defaultness.has_value() {
         // This means that the impl is missing a definition for the
@@ -1456,16 +1460,28 @@ fn confirm_impl_candidate<'cx, 'tcx>(
             obligations: nested,
         };
     }
+    let substs = obligation.predicate.substs.rebase_onto(tcx, trait_def_id, substs);
     let substs = translate_substs(selcx.infcx(), param_env, impl_def_id, substs, assoc_ty.node);
     let ty = if let ty::AssocKind::OpaqueTy = assoc_ty.item.kind {
         let item_substs = InternalSubsts::identity_for_item(tcx, assoc_ty.item.def_id);
         tcx.mk_opaque(assoc_ty.item.def_id, item_substs)
     } else {
         tcx.type_of(assoc_ty.item.def_id)
     };
-    Progress {
-        ty: ty.subst(tcx, substs),
-        obligations: nested,
+    if substs.len() != tcx.generics_of(assoc_ty.item.def_id).count() {
+        tcx.sess.delay_span_bug(
+            DUMMY_SP,
+            "impl item and trait item have different parameter counts",
+        );
+        Progress {
+            ty: tcx.types.err,
+            obligations: nested,
+        }
+    } else {
+        Progress {
+            ty: ty.subst(tcx, substs),
+            obligations: nested,
+        }
     }
 }
 

src/librustc/traits/structural_impls.rs

@@ -514,6 +514,15 @@ impl<'a, 'tcx> Lift<'tcx> for traits::ObligationCauseCode<'a> {
                 impl_item_def_id,
                 trait_item_def_id,
             }),
+            super::CompareImplTypeObligation {
+                item_name,
+                impl_item_def_id,
+                trait_item_def_id,
+            } => Some(super::CompareImplTypeObligation {
+                item_name,
+                impl_item_def_id,
+                trait_item_def_id,
+            }),
             super::ExprAssignable => Some(super::ExprAssignable),
             super::MatchExpressionArm(box super::MatchExpressionArmCause {
                 arm_span,

src/librustc/ty/mod.rs

@@ -1305,7 +1305,7 @@ impl<'tcx> PolyProjectionPredicate<'tcx> {
     }
 
     #[inline]
-    pub fn to_poly_trait_ref(&self, tcx: TyCtxt<'_>) -> PolyTraitRef<'tcx> {
+    pub fn to_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
         // Note: unlike with `TraitRef::to_poly_trait_ref()`,
         // `self.0.trait_ref` is permitted to have escaping regions.
         // This is because here `self` has a `Binder` and so does our

src/librustc/ty/sty.rs

@@ -1026,11 +1026,11 @@ impl<'tcx> ProjectionTy<'tcx> {
     /// Extracts the underlying trait reference from this projection.
     /// For example, if this is a projection of `<T as Iterator>::Item`,
     /// then this function would return a `T: Iterator` trait reference.
-    pub fn trait_ref(&self, tcx: TyCtxt<'_>) -> ty::TraitRef<'tcx> {
+    pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
         let def_id = tcx.associated_item(self.item_def_id).container.id();
         ty::TraitRef {
             def_id,
-            substs: self.substs,
+            substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)),
         }
     }
 

src/librustc/ty/subst.rs

@@ -234,7 +234,7 @@ impl<'a, 'tcx> InternalSubsts<'tcx> {
                 ty::GenericParamDefKind::Const => {
                     tcx.mk_const(ty::Const {
                         val: ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from(param.index)),
-                        ty: tcx.type_of(def_id),
+                        ty: tcx.type_of(param.def_id),
                     }).into()
                 }
             }
@@ -533,8 +533,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for SubstFolder<'a, 'tcx> {
                             data.name,
                             self.root_ty,
                             data.index);
-                        self.tcx.sess.delay_span_bug(span, &msg);
-                        r
+                        span_bug!(span, "{}", msg);
                     }
                 }
             }

src/librustc_mir/transform/inline.rs

@@ -663,9 +663,9 @@ impl<'a, 'tcx> Integrator<'a, 'tcx> {
 
     fn make_integrate_local(&self, local: &Local) -> Local {
         if *local == RETURN_PLACE {
-            match self.destination.as_local() {
-                Some(l) => return l,
-                ref place => bug!("Return place is {:?}, not local", place),
+            match self.destination.base {
+                PlaceBase::Local(l) => return l,
+                PlaceBase::Static(ref s) => bug!("Return place is {:?}, not local", s),
             }
         }
 
@@ -695,14 +695,24 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
     fn visit_place(
         &mut self,
         place: &mut Place<'tcx>,
-        context: PlaceContext,
-        location: Location,
+        _context: PlaceContext,
+        _location: Location,
     ) {
-        if let Some(RETURN_PLACE) = place.as_local() {
-            // Return pointer; update the place itself
-            *place = self.destination.clone();
-        } else {
-            self.super_place(place, context, location);
+        match &mut place.base {
+            PlaceBase::Static(_) => {},
+            PlaceBase::Local(l) => {
+                // If this is the `RETURN_PLACE`, we need to rebase any projections onto it.
+                let dest_proj_len = self.destination.projection.len();
+                if *l == RETURN_PLACE && dest_proj_len > 0 {
+                    let mut projs = Vec::with_capacity(dest_proj_len + place.projection.len());
+                    projs.extend(self.destination.projection);
+                    projs.extend(place.projection);
+
+                    place.projection = self.tcx.intern_place_elems(&*projs);
+                }
+
+                *l = self.make_integrate_local(l);
+            }
         }
     }
 

src/librustc_resolve/late.rs

@@ -1119,17 +1119,16 @@ impl<'a, 'b> LateResolutionVisitor<'a, '_> {
 
                                                 visit::walk_impl_item(this, impl_item);
                                             }
-                                            AssocItemKind::TyAlias(_, Some(ref ty)) => {
+                                            AssocItemKind::TyAlias(_, _) => {
                                                 // If this is a trait impl, ensure the type
                                                 // exists in trait
                                                 this.check_trait_item(impl_item.ident,
                                                                       TypeNS,
                                                                       impl_item.span,
                                                     |n, s| TypeNotMemberOfTrait(n, s));
 
-                                                this.visit_ty(ty);
+                                                visit::walk_impl_item(this, impl_item);
                                             }
-                                            AssocItemKind::TyAlias(_, None) => {}
                                             AssocItemKind::Macro(_) =>
                                                 panic!("unexpanded macro in resolve!"),
                                         }