Rollup of 7 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_codegen_llvm/src/callee.rs

@@ -94,11 +94,11 @@ pub fn get_fn<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, instance: Instance<'tcx>) ->
             // LLVM will prefix the name with `__imp_`. Ideally, we'd like the
             // existing logic below to set the Storage Class, but it has an
             // exemption for MinGW for backwards compatability.
-            let llfn = cx.declare_fn(&common::i686_decorated_name(&dllimport, common::is_mingw_gnu_toolchain(&tcx.sess.target), true), fn_abi);
+            let llfn = cx.declare_fn(&common::i686_decorated_name(&dllimport, common::is_mingw_gnu_toolchain(&tcx.sess.target), true), fn_abi, Some(instance));
             unsafe { llvm::LLVMSetDLLStorageClass(llfn, llvm::DLLStorageClass::DllImport); }
             llfn
         } else {
-            cx.declare_fn(sym, fn_abi)
+            cx.declare_fn(sym, fn_abi, Some(instance))
         };
         debug!("get_fn: not casting pointer!");
 

compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs

@@ -207,6 +207,7 @@ fn declare_unused_fn<'tcx>(cx: &CodegenCx<'_, 'tcx>, def_id: DefId) -> Instance<
             )),
             ty::List::empty(),
         ),
+        None,
     );
 
     llvm::set_linkage(llfn, llvm::Linkage::PrivateLinkage);

compiler/rustc_codegen_llvm/src/declare.rs

@@ -19,8 +19,11 @@ use crate::llvm::AttributePlace::Function;
 use crate::type_::Type;
 use crate::value::Value;
 use rustc_codegen_ssa::traits::TypeMembershipMethods;
-use rustc_middle::ty::Ty;
-use rustc_symbol_mangling::typeid::{kcfi_typeid_for_fnabi, typeid_for_fnabi, TypeIdOptions};
+use rustc_middle::ty::{Instance, Ty};
+use rustc_symbol_mangling::typeid::{
+    kcfi_typeid_for_fnabi, kcfi_typeid_for_instance, typeid_for_fnabi, typeid_for_instance,
+    TypeIdOptions,
+};
 use smallvec::SmallVec;
 
 /// Declare a function.
@@ -116,7 +119,12 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
     ///
     /// If there’s a value with the same name already declared, the function will
     /// update the declaration and return existing Value instead.
-    pub fn declare_fn(&self, name: &str, fn_abi: &FnAbi<'tcx, Ty<'tcx>>) -> &'ll Value {
+    pub fn declare_fn(
+        &self,
+        name: &str,
+        fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
+        instance: Option<Instance<'tcx>>,
+    ) -> &'ll Value {
         debug!("declare_rust_fn(name={:?}, fn_abi={:?})", name, fn_abi);
 
         // Function addresses in Rust are never significant, allowing functions to
@@ -132,18 +140,35 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
         fn_abi.apply_attrs_llfn(self, llfn);
 
         if self.tcx.sess.is_sanitizer_cfi_enabled() {
-            let typeid = typeid_for_fnabi(self.tcx, fn_abi, TypeIdOptions::empty());
-            self.set_type_metadata(llfn, typeid);
-            let typeid = typeid_for_fnabi(self.tcx, fn_abi, TypeIdOptions::GENERALIZE_POINTERS);
-            self.add_type_metadata(llfn, typeid);
-            let typeid = typeid_for_fnabi(self.tcx, fn_abi, TypeIdOptions::NORMALIZE_INTEGERS);
-            self.add_type_metadata(llfn, typeid);
-            let typeid = typeid_for_fnabi(
-                self.tcx,
-                fn_abi,
-                TypeIdOptions::GENERALIZE_POINTERS | TypeIdOptions::NORMALIZE_INTEGERS,
-            );
-            self.add_type_metadata(llfn, typeid);
+            if let Some(instance) = instance {
+                let typeid = typeid_for_instance(self.tcx, &instance, TypeIdOptions::empty());
+                self.set_type_metadata(llfn, typeid);
+                let typeid =
+                    typeid_for_instance(self.tcx, &instance, TypeIdOptions::GENERALIZE_POINTERS);
+                self.add_type_metadata(llfn, typeid);
+                let typeid =
+                    typeid_for_instance(self.tcx, &instance, TypeIdOptions::NORMALIZE_INTEGERS);
+                self.add_type_metadata(llfn, typeid);
+                let typeid = typeid_for_instance(
+                    self.tcx,
+                    &instance,
+                    TypeIdOptions::GENERALIZE_POINTERS | TypeIdOptions::NORMALIZE_INTEGERS,
+                );
+                self.add_type_metadata(llfn, typeid);
+            } else {
+                let typeid = typeid_for_fnabi(self.tcx, fn_abi, TypeIdOptions::empty());
+                self.set_type_metadata(llfn, typeid);
+                let typeid = typeid_for_fnabi(self.tcx, fn_abi, TypeIdOptions::GENERALIZE_POINTERS);
+                self.add_type_metadata(llfn, typeid);
+                let typeid = typeid_for_fnabi(self.tcx, fn_abi, TypeIdOptions::NORMALIZE_INTEGERS);
+                self.add_type_metadata(llfn, typeid);
+                let typeid = typeid_for_fnabi(
+                    self.tcx,
+                    fn_abi,
+                    TypeIdOptions::GENERALIZE_POINTERS | TypeIdOptions::NORMALIZE_INTEGERS,
+                );
+                self.add_type_metadata(llfn, typeid);
+            }
         }
 
         if self.tcx.sess.is_sanitizer_kcfi_enabled() {
@@ -156,8 +181,13 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
                 options.insert(TypeIdOptions::NORMALIZE_INTEGERS);
             }
 
-            let kcfi_typeid = kcfi_typeid_for_fnabi(self.tcx, fn_abi, options);
-            self.set_kcfi_type_metadata(llfn, kcfi_typeid);
+            if let Some(instance) = instance {
+                let kcfi_typeid = kcfi_typeid_for_instance(self.tcx, &instance, options);
+                self.set_kcfi_type_metadata(llfn, kcfi_typeid);
+            } else {
+                let kcfi_typeid = kcfi_typeid_for_fnabi(self.tcx, fn_abi, options);
+                self.set_kcfi_type_metadata(llfn, kcfi_typeid);
+            }
         }
 
         llfn

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -772,7 +772,7 @@ fn gen_fn<'ll, 'tcx>(
 ) -> (&'ll Type, &'ll Value) {
     let fn_abi = cx.fn_abi_of_fn_ptr(rust_fn_sig, ty::List::empty());
     let llty = fn_abi.llvm_type(cx);
-    let llfn = cx.declare_fn(name, fn_abi);
+    let llfn = cx.declare_fn(name, fn_abi, None);
     cx.set_frame_pointer_type(llfn);
     cx.apply_target_cpu_attr(llfn);
     // FIXME(eddyb) find a nicer way to do this.

compiler/rustc_codegen_llvm/src/mono_item.rs

@@ -51,7 +51,7 @@ impl<'tcx> PreDefineMethods<'tcx> for CodegenCx<'_, 'tcx> {
         assert!(!instance.substs.has_infer());
 
         let fn_abi = self.fn_abi_of_instance(instance, ty::List::empty());
-        let lldecl = self.declare_fn(symbol_name, fn_abi);
+        let lldecl = self.declare_fn(symbol_name, fn_abi, Some(instance));
         unsafe { llvm::LLVMRustSetLinkage(lldecl, base::linkage_to_llvm(linkage)) };
         let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
         base::set_link_section(lldecl, attrs);

compiler/rustc_hir_analysis/src/check/check.rs

@@ -31,6 +31,7 @@ use rustc_target::abi::FieldIdx;
 use rustc_target::spec::abi::Abi;
 use rustc_trait_selection::traits::error_reporting::on_unimplemented::OnUnimplementedDirective;
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
+use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
 use rustc_trait_selection::traits::{self, ObligationCtxt, TraitEngine, TraitEngineExt as _};
 
 use std::ops::ControlFlow;
@@ -222,7 +223,7 @@ fn check_opaque(tcx: TyCtxt<'_>, id: hir::ItemId) {
     if check_opaque_for_cycles(tcx, item.owner_id.def_id, substs, span, &origin).is_err() {
         return;
     }
-    check_opaque_meets_bounds(tcx, item.owner_id.def_id, substs, span, &origin);
+    check_opaque_meets_bounds(tcx, item.owner_id.def_id, span, &origin);
 }
 
 /// Checks that an opaque type does not use `Self` or `T::Foo` projections that would result
@@ -391,7 +392,6 @@ pub(super) fn check_opaque_for_cycles<'tcx>(
 fn check_opaque_meets_bounds<'tcx>(
     tcx: TyCtxt<'tcx>,
     def_id: LocalDefId,
-    substs: SubstsRef<'tcx>,
     span: Span,
     origin: &hir::OpaqueTyOrigin,
 ) {
@@ -406,6 +406,8 @@ fn check_opaque_meets_bounds<'tcx>(
         .with_opaque_type_inference(DefiningAnchor::Bind(defining_use_anchor))
         .build();
     let ocx = ObligationCtxt::new(&infcx);
+
+    let substs = InternalSubsts::identity_for_item(tcx, def_id.to_def_id());
     let opaque_ty = tcx.mk_opaque(def_id.to_def_id(), substs);
 
     // `ReErased` regions appear in the "parent_substs" of closures/generators.
@@ -448,9 +450,18 @@ fn check_opaque_meets_bounds<'tcx>(
     match origin {
         // Checked when type checking the function containing them.
         hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..) => {}
+        // Nested opaque types occur only in associated types:
+        // ` type Opaque<T> = impl Trait<&'static T, AssocTy = impl Nested>; `
+        // They can only be referenced as `<Opaque<T> as Trait<&'static T>>::AssocTy`.
+        // We don't have to check them here because their well-formedness follows from the WF of
+        // the projection input types in the defining- and use-sites.
+        hir::OpaqueTyOrigin::TyAlias
+            if tcx.def_kind(tcx.parent(def_id.to_def_id())) == DefKind::OpaqueTy => {}
         // Can have different predicates to their defining use
         hir::OpaqueTyOrigin::TyAlias => {
-            let outlives_env = OutlivesEnvironment::new(param_env);
+            let wf_tys = ocx.assumed_wf_types(param_env, span, def_id);
+            let implied_bounds = infcx.implied_bounds_tys(param_env, def_id, wf_tys);
+            let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
             let _ = ocx.resolve_regions_and_report_errors(defining_use_anchor, &outlives_env);
         }
     }

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/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_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> {