Rollup of 9 pull requests

compiler/rustc_borrowck/src/def_use.rs

@@ -55,7 +55,7 @@ pub fn categorize(context: PlaceContext) -> Option<DefUse> {
         // `PlaceMention` and `AscribeUserType` both evaluate the place, which must not
         // contain dangling references.
         PlaceContext::NonMutatingUse(NonMutatingUseContext::PlaceMention) |
-        PlaceContext::NonUse(NonUseContext::AscribeUserTy) |
+        PlaceContext::NonUse(NonUseContext::AscribeUserTy(_)) |
 
         PlaceContext::MutatingUse(MutatingUseContext::AddressOf) |
         PlaceContext::NonMutatingUse(NonMutatingUseContext::AddressOf) |

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -777,7 +777,7 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
                 Inspect | Copy | Move | PlaceMention | SharedBorrow | ShallowBorrow | UniqueBorrow
                 | AddressOf | Projection,
             ) => ty::Covariant,
-            PlaceContext::NonUse(AscribeUserTy) => ty::Covariant,
+            PlaceContext::NonUse(AscribeUserTy(variance)) => variance,
         }
     }
 

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -745,6 +745,9 @@ LLVMRustOptimize(
         if (InstrProfileOutput) {
           Options.InstrProfileOutput = InstrProfileOutput;
         }
+        // cargo run tests in multhreading mode by default
+        // so use atomics for coverage counters
+        Options.Atomic = true;
         MPM.addPass(InstrProfiling(Options, false));
       }
     );

compiler/rustc_middle/src/mir/visit.rs

@@ -64,7 +64,7 @@
 
 use crate::mir::*;
 use crate::ty::subst::SubstsRef;
-use crate::ty::{CanonicalUserTypeAnnotation, Ty};
+use crate::ty::{self, CanonicalUserTypeAnnotation, Ty};
 use rustc_span::Span;
 
 macro_rules! make_mir_visitor {
@@ -782,12 +782,12 @@ macro_rules! make_mir_visitor {
 
             fn super_ascribe_user_ty(&mut self,
                                      place: & $($mutability)? Place<'tcx>,
-                                     _variance: $(& $mutability)? ty::Variance,
+                                     variance: $(& $mutability)? ty::Variance,
                                      user_ty: & $($mutability)? UserTypeProjection,
                                      location: Location) {
                 self.visit_place(
                     place,
-                    PlaceContext::NonUse(NonUseContext::AscribeUserTy),
+                    PlaceContext::NonUse(NonUseContext::AscribeUserTy($(* &$mutability *)? variance)),
                     location
                 );
                 self.visit_user_type_projection(user_ty);
@@ -1320,7 +1320,7 @@ pub enum NonUseContext {
     /// Ending a storage live range.
     StorageDead,
     /// User type annotation assertions for NLL.
-    AscribeUserTy,
+    AscribeUserTy(ty::Variance),
     /// The data of a user variable, for debug info.
     VarDebugInfo,
 }

compiler/rustc_middle/src/traits/mod.rs

@@ -281,9 +281,6 @@ pub enum ObligationCauseCode<'tcx> {
     /// A type like `Box<Foo<'a> + 'b>` is WF only if `'b: 'a`.
     ObjectTypeBound(Ty<'tcx>, ty::Region<'tcx>),
 
-    /// Obligation incurred due to an object cast.
-    ObjectCastObligation(/* Concrete type */ Ty<'tcx>, /* Object type */ Ty<'tcx>),
-
     /// Obligation incurred due to a coercion.
     Coercion {
         source: Ty<'tcx>,

compiler/rustc_middle/src/ty/util.rs

@@ -1253,7 +1253,7 @@ pub enum ExplicitSelf<'tcx> {
 
 impl<'tcx> ExplicitSelf<'tcx> {
     /// Categorizes an explicit self declaration like `self: SomeType`
-    /// into either `self`, `&self`, `&mut self`, `Box<self>`, or
+    /// into either `self`, `&self`, `&mut self`, `Box<Self>`, or
     /// `Other`.
     /// This is mainly used to require the arbitrary_self_types feature
     /// in the case of `Other`, to improve error messages in the common cases,

compiler/rustc_mir_transform/src/ref_prop.rs

@@ -85,7 +85,9 @@ fn propagate_ssa<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
     let ssa = SsaLocals::new(body);
 
     let mut replacer = compute_replacement(tcx, body, &ssa);
-    debug!(?replacer.targets, ?replacer.allowed_replacements, ?replacer.storage_to_remove);
+    debug!(?replacer.targets);
+    debug!(?replacer.allowed_replacements);
+    debug!(?replacer.storage_to_remove);
 
     replacer.visit_body_preserves_cfg(body);
 
@@ -190,8 +192,11 @@ fn compute_replacement<'tcx>(
             continue;
         }
 
+        // Whether the current local is subject to the uniqueness rule.
+        let needs_unique = ty.is_mutable_ptr();
+
         // If this a mutable reference that we cannot fully replace, mark it as unknown.
-        if ty.is_mutable_ptr() && !fully_replacable_locals.contains(local) {
+        if needs_unique && !fully_replacable_locals.contains(local) {
             debug!("not fully replaceable");
             continue;
         }
@@ -203,32 +208,33 @@ fn compute_replacement<'tcx>(
             // have been visited before.
             Rvalue::Use(Operand::Copy(place) | Operand::Move(place))
             | Rvalue::CopyForDeref(place) => {
-                if let Some(rhs) = place.as_local() {
+                if let Some(rhs) = place.as_local() && ssa.is_ssa(rhs) {
                     let target = targets[rhs];
-                    if matches!(target, Value::Pointer(..)) {
+                    // Only see through immutable reference and pointers, as we do not know yet if
+                    // mutable references are fully replaced.
+                    if !needs_unique && matches!(target, Value::Pointer(..)) {
                         targets[local] = target;
-                    } else if ssa.is_ssa(rhs) {
-                        let refmut = body.local_decls[rhs].ty.is_mutable_ptr();
-                        targets[local] = Value::Pointer(tcx.mk_place_deref(rhs.into()), refmut);
+                    } else {
+                        targets[local] = Value::Pointer(tcx.mk_place_deref(rhs.into()), needs_unique);
                     }
                 }
             }
             Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
                 let mut place = *place;
                 // Try to see through `place` in order to collapse reborrow chains.
                 if place.projection.first() == Some(&PlaceElem::Deref)
-                    && let Value::Pointer(target, refmut) = targets[place.local]
+                    && let Value::Pointer(target, inner_needs_unique) = targets[place.local]
                     // Only see through immutable reference and pointers, as we do not know yet if
                     // mutable references are fully replaced.
-                    && !refmut
+                    && !inner_needs_unique
                     // Only collapse chain if the pointee is definitely live.
                     && can_perform_opt(target, location)
                 {
                     place = target.project_deeper(&place.projection[1..], tcx);
                 }
                 assert_ne!(place.local, local);
                 if is_constant_place(place) {
-                    targets[local] = Value::Pointer(place, ty.is_mutable_ptr());
+                    targets[local] = Value::Pointer(place, needs_unique);
                 }
             }
             // We do not know what to do, so keep as not-a-pointer.
@@ -276,16 +282,35 @@ fn compute_replacement<'tcx>(
                 return;
             }
 
-            if let Value::Pointer(target, refmut) = self.targets[place.local]
-                && place.projection.first() == Some(&PlaceElem::Deref)
-            {
-                let perform_opt = (self.can_perform_opt)(target, loc);
-                if perform_opt {
-                    self.allowed_replacements.insert((target.local, loc));
-                } else if refmut {
-                    // This mutable reference is not fully replacable, so drop it.
-                    self.targets[place.local] = Value::Unknown;
+            if place.projection.first() != Some(&PlaceElem::Deref) {
+                // This is not a dereference, nothing to do.
+                return;
+            }
+
+            let mut place = place.as_ref();
+            loop {
+                if let Value::Pointer(target, needs_unique) = self.targets[place.local] {
+                    let perform_opt = (self.can_perform_opt)(target, loc);
+                    debug!(?place, ?target, ?needs_unique, ?perform_opt);
+
+                    // This a reborrow chain, recursively allow the replacement.
+                    //
+                    // This also allows to detect cases where `target.local` is not replacable,
+                    // and mark it as such.
+                    if let &[PlaceElem::Deref] = &target.projection[..] {
+                        assert!(perform_opt);
+                        self.allowed_replacements.insert((target.local, loc));
+                        place.local = target.local;
+                        continue;
+                    } else if perform_opt {
+                        self.allowed_replacements.insert((target.local, loc));
+                    } else if needs_unique {
+                        // This mutable reference is not fully replacable, so drop it.
+                        self.targets[place.local] = Value::Unknown;
+                    }
                 }
+
+                break;
             }
         }
     }
@@ -326,18 +351,23 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'tcx> {
     }
 
     fn visit_place(&mut self, place: &mut Place<'tcx>, ctxt: PlaceContext, loc: Location) {
-        if let Value::Pointer(target, _) = self.targets[place.local]
-            && place.projection.first() == Some(&PlaceElem::Deref)
-        {
-            let perform_opt = matches!(ctxt, PlaceContext::NonUse(_))
-                || self.allowed_replacements.contains(&(target.local, loc));
-
-            if perform_opt {
-                *place = target.project_deeper(&place.projection[1..], self.tcx);
-                self.any_replacement = true;
+        if place.projection.first() != Some(&PlaceElem::Deref) {
+            return;
+        }
+
+        loop {
+            if let Value::Pointer(target, _) = self.targets[place.local] {
+                let perform_opt = matches!(ctxt, PlaceContext::NonUse(_))
+                    || self.allowed_replacements.contains(&(target.local, loc));
+
+                if perform_opt {
+                    *place = target.project_deeper(&place.projection[1..], self.tcx);
+                    self.any_replacement = true;
+                    continue;
+                }
             }
-        } else {
-            self.super_place(place, ctxt, loc);
+
+            break;
         }
     }
 

compiler/rustc_resolve/messages.ftl

@@ -199,6 +199,10 @@ resolve_invalid_asm_sym =
     .label = is a local variable
     .help = `sym` operands must refer to either a function or a static
 
+resolve_lowercase_self =
+    attempt to use a non-constant value in a constant
+    .suggestion = try using `Self`
+
 resolve_trait_impl_duplicate =
     duplicate definitions with name `{$name}`:
     .label = duplicate definition

compiler/rustc_resolve/src/diagnostics.rs

@@ -948,6 +948,9 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             ResolutionError::InvalidAsmSym => {
                 self.tcx.sess.create_err(errs::InvalidAsmSym { span })
             }
+            ResolutionError::LowercaseSelf => {
+                self.tcx.sess.create_err(errs::LowercaseSelf { span })
+            }
         }
     }
 

compiler/rustc_resolve/src/errors.rs

@@ -442,6 +442,14 @@ pub(crate) struct InvalidAsmSym {
     pub(crate) span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(resolve_lowercase_self)]
+pub(crate) struct LowercaseSelf {
+    #[primary_span]
+    #[suggestion(code = "Self", applicability = "maybe-incorrect", style = "short")]
+    pub(crate) span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(resolve_trait_impl_duplicate, code = "E0201")]
 pub(crate) struct TraitImplDuplicate {

compiler/rustc_resolve/src/ident.rs

@@ -15,8 +15,7 @@ use std::ptr;
 
 use crate::errors::{ParamKindInEnumDiscriminant, ParamKindInNonTrivialAnonConst};
 use crate::late::{
-    ConstantHasGenerics, ConstantItemKind, HasGenericParams, NoConstantGenericsReason, PathSource,
-    Rib, RibKind,
+    ConstantHasGenerics, HasGenericParams, NoConstantGenericsReason, PathSource, Rib, RibKind,
 };
 use crate::macros::{sub_namespace_match, MacroRulesScope};
 use crate::{errors, AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, Determinacy, Finalize};
@@ -1127,28 +1126,25 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                         RibKind::ConstantItem(_, item) => {
                             // Still doesn't deal with upvars
                             if let Some(span) = finalize {
-                                let (span, resolution_error) =
-                                    if let Some((ident, constant_item_kind)) = item {
-                                        let kind_str = match constant_item_kind {
-                                            ConstantItemKind::Const => "const",
-                                            ConstantItemKind::Static => "static",
-                                        };
-                                        (
-                                            span,
-                                            AttemptToUseNonConstantValueInConstant(
-                                                ident, "let", kind_str,
-                                            ),
-                                        )
-                                    } else {
-                                        (
-                                            rib_ident.span,
-                                            AttemptToUseNonConstantValueInConstant(
-                                                original_rib_ident_def,
-                                                "const",
-                                                "let",
-                                            ),
-                                        )
-                                    };
+                                let (span, resolution_error) = match item {
+                                    None if rib_ident.as_str() == "self" => (span, LowercaseSelf),
+                                    None => (
+                                        rib_ident.span,
+                                        AttemptToUseNonConstantValueInConstant(
+                                            original_rib_ident_def,
+                                            "const",
+                                            "let",
+                                        ),
+                                    ),
+                                    Some((ident, kind)) => (
+                                        span,
+                                        AttemptToUseNonConstantValueInConstant(
+                                            ident,
+                                            "let",
+                                            kind.as_str(),
+                                        ),
+                                    ),
+                                };
                                 self.report_error(span, resolution_error);
                             }
                             return Res::Err;

compiler/rustc_resolve/src/late.rs

@@ -150,6 +150,15 @@ pub(crate) enum ConstantItemKind {
     Static,
 }
 
+impl ConstantItemKind {
+    pub(crate) fn as_str(&self) -> &'static str {
+        match self {
+            Self::Const => "const",
+            Self::Static => "static",
+        }
+    }
+}
+
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 enum RecordPartialRes {
     Yes,
@@ -1482,7 +1491,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
             if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
                 self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named);
 
-                if let LifetimeRes::Param { param, .. } = res {
+                if let LifetimeRes::Param { param, binder } = res {
                     match self.lifetime_uses.entry(param) {
                         Entry::Vacant(v) => {
                             debug!("First use of {:?} at {:?}", res, ident.span);
@@ -1496,10 +1505,16 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                                     LifetimeRibKind::Item
                                     | LifetimeRibKind::AnonymousReportError
                                     | LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
-                                    // An anonymous lifetime is legal here, go ahead.
-                                    LifetimeRibKind::AnonymousCreateParameter { .. } => {
-                                        Some(LifetimeUseSet::One { use_span: ident.span, use_ctxt })
-                                    }
+                                    // An anonymous lifetime is legal here, and bound to the right
+                                    // place, go ahead.
+                                    LifetimeRibKind::AnonymousCreateParameter {
+                                        binder: anon_binder,
+                                        ..
+                                    } => Some(if binder == anon_binder {
+                                        LifetimeUseSet::One { use_span: ident.span, use_ctxt }
+                                    } else {
+                                        LifetimeUseSet::Many
+                                    }),
                                     // Only report if eliding the lifetime would have the same
                                     // semantics.
                                     LifetimeRibKind::Elided(r) => Some(if res == r {

compiler/rustc_resolve/src/lib.rs

@@ -251,6 +251,8 @@ enum ResolutionError<'a> {
     TraitImplDuplicate { name: Symbol, trait_item_span: Span, old_span: Span },
     /// Inline asm `sym` operand must refer to a `fn` or `static`.
     InvalidAsmSym,
+    /// `self` used instead of `Self` in a generic parameter
+    LowercaseSelf,
 }
 
 enum VisResolutionError<'a> {