Rollup of 7 pull requests

compiler/rustc_infer/src/infer/canonical/mod.rs

@@ -49,7 +49,6 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
     /// At the end of processing, the substitution S (once
     /// canonicalized) then represents the values that you computed
     /// for each of the canonical inputs to your query.
-
     pub fn instantiate_canonical_with_fresh_inference_vars<T>(
         &self,
         span: Span,

compiler/rustc_infer/src/infer/combine.rs

@@ -27,15 +27,12 @@ use super::glb::Glb;
 use super::lub::Lub;
 use super::sub::Sub;
 use super::type_variable::TypeVariableValue;
-use super::unify_key::replace_if_possible;
-use super::unify_key::{ConstVarValue, ConstVariableValue};
-use super::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
 use super::{InferCtxt, MiscVariable, TypeTrace};
-
 use crate::traits::{Obligation, PredicateObligations};
-
 use rustc_data_structures::sso::SsoHashMap;
 use rustc_hir::def_id::DefId;
+use rustc_middle::infer::unify_key::{ConstVarValue, ConstVariableValue};
+use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
@@ -140,8 +137,8 @@ impl<'infcx, 'tcx> InferCtxt<'infcx, 'tcx> {
             return Ok(a);
         }
 
-        let a = replace_if_possible(&mut self.inner.borrow_mut().const_unification_table(), a);
-        let b = replace_if_possible(&mut self.inner.borrow_mut().const_unification_table(), b);
+        let a = self.shallow_resolve(a);
+        let b = self.shallow_resolve(b);
 
         let a_is_expected = relation.a_is_expected();
 

compiler/rustc_infer/src/infer/freshen.rs

@@ -30,17 +30,13 @@
 //! solving a set of constraints. In contrast, the type inferencer assigns a value to each type
 //! variable only once, and it does so as soon as it can, so it is reasonable to ask what the type
 //! inferencer knows "so far".
-
+use super::InferCtxt;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_middle::infer::unify_key::ToType;
 use rustc_middle::ty::fold::TypeFolder;
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
-
-use rustc_data_structures::fx::FxHashMap;
-
 use std::collections::hash_map::Entry;
 
-use super::unify_key::ToType;
-use super::InferCtxt;
-
 pub struct TypeFreshener<'a, 'tcx> {
     infcx: &'a InferCtxt<'a, 'tcx>,
     ty_freshen_count: u32,

compiler/rustc_infer/src/infer/mod.rs

@@ -70,8 +70,6 @@ mod sub;
 pub mod type_variable;
 mod undo_log;
 
-pub use rustc_middle::infer::unify_key;
-
 #[must_use]
 #[derive(Debug)]
 pub struct InferOk<'tcx, T> {
@@ -558,9 +556,9 @@ impl<'tcx> fmt::Display for FixupError<'tcx> {
     }
 }
 
-/// Helper type of a temporary returned by `tcx.infer_ctxt()`.
-/// Necessary because we can't write the following bound:
-/// `F: for<'b, 'tcx> where 'tcx FnOnce(InferCtxt<'b, 'tcx>)`.
+/// A temporary returned by `tcx.infer_ctxt()`. This is necessary
+/// for multiple `InferCtxt` to share the same `in_progress_typeck_results`
+/// without using `Rc` or something similar.
 pub struct InferCtxtBuilder<'tcx> {
     tcx: TyCtxt<'tcx>,
     fresh_typeck_results: Option<RefCell<ty::TypeckResults<'tcx>>>,

compiler/rustc_lint/src/builtin.rs

@@ -2548,7 +2548,7 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
         /// Return `Some` only if we are sure this type does *not*
         /// allow zero initialization.
         fn ty_find_init_error<'tcx>(
-            tcx: TyCtxt<'tcx>,
+            cx: &LateContext<'tcx>,
             ty: Ty<'tcx>,
             init: InitKind,
         ) -> Option<InitError> {
@@ -2575,7 +2575,7 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
                 Adt(adt_def, substs) if !adt_def.is_union() => {
                     // First check if this ADT has a layout attribute (like `NonNull` and friends).
                     use std::ops::Bound;
-                    match tcx.layout_scalar_valid_range(adt_def.did()) {
+                    match cx.tcx.layout_scalar_valid_range(adt_def.did()) {
                         // We exploit here that `layout_scalar_valid_range` will never
                         // return `Bound::Excluded`.  (And we have tests checking that we
                         // handle the attribute correctly.)
@@ -2603,12 +2603,12 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
                             // Proceed recursively, check all fields.
                             let variant = &adt_def.variant(VariantIdx::from_u32(0));
                             variant.fields.iter().find_map(|field| {
-                                ty_find_init_error(tcx, field.ty(tcx, substs), init).map(
+                                ty_find_init_error(cx, field.ty(cx.tcx, substs), init).map(
                                     |(mut msg, span)| {
                                         if span.is_none() {
                                             // Point to this field, should be helpful for figuring
                                             // out where the source of the error is.
-                                            let span = tcx.def_span(field.did);
+                                            let span = cx.tcx.def_span(field.did);
                                             write!(
                                                 &mut msg,
                                                 " (in this {} field)",
@@ -2627,7 +2627,7 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
                         // Multi-variant enum.
                         _ => {
                             if init == InitKind::Uninit && is_multi_variant(*adt_def) {
-                                let span = tcx.def_span(adt_def.did());
+                                let span = cx.tcx.def_span(adt_def.did());
                                 Some((
                                     "enums have to be initialized to a variant".to_string(),
                                     Some(span),
@@ -2642,7 +2642,16 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
                 }
                 Tuple(..) => {
                     // Proceed recursively, check all fields.
-                    ty.tuple_fields().iter().find_map(|field| ty_find_init_error(tcx, field, init))
+                    ty.tuple_fields().iter().find_map(|field| ty_find_init_error(cx, field, init))
+                }
+                Array(ty, len) => {
+                    if matches!(len.try_eval_usize(cx.tcx, cx.param_env), Some(v) if v > 0) {
+                        // Array length known at array non-empty -- recurse.
+                        ty_find_init_error(cx, *ty, init)
+                    } else {
+                        // Empty array or size unknown.
+                        None
+                    }
                 }
                 // Conservative fallback.
                 _ => None,
@@ -2655,7 +2664,7 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
             // We are extremely conservative with what we warn about.
             let conjured_ty = cx.typeck_results().expr_ty(expr);
             if let Some((msg, span)) =
-                with_no_trimmed_paths!(ty_find_init_error(cx.tcx, conjured_ty, init))
+                with_no_trimmed_paths!(ty_find_init_error(cx, conjured_ty, init))
             {
                 cx.struct_span_lint(INVALID_VALUE, expr.span, |lint| {
                     let mut err = lint.build(&format!(

compiler/rustc_middle/src/infer/unify_key.rs

@@ -1,13 +1,8 @@
-use crate::ty::{self, InferConst, Ty, TyCtxt};
-use rustc_data_structures::snapshot_vec;
-use rustc_data_structures::undo_log::UndoLogs;
-use rustc_data_structures::unify::{
-    self, EqUnifyValue, InPlace, NoError, UnificationTable, UnifyKey, UnifyValue,
-};
+use crate::ty::{self, Ty, TyCtxt};
+use rustc_data_structures::unify::{NoError, UnifyKey, UnifyValue};
 use rustc_span::def_id::DefId;
 use rustc_span::symbol::Symbol;
 use rustc_span::Span;
-
 use std::cmp;
 use std::marker::PhantomData;
 
@@ -165,23 +160,3 @@ impl<'tcx> UnifyValue for ConstVarValue<'tcx> {
         })
     }
 }
-
-impl<'tcx> EqUnifyValue for ty::Const<'tcx> {}
-
-pub fn replace_if_possible<'tcx, V, L>(
-    table: &mut UnificationTable<InPlace<ty::ConstVid<'tcx>, V, L>>,
-    c: ty::Const<'tcx>,
-) -> ty::Const<'tcx>
-where
-    V: snapshot_vec::VecLike<unify::Delegate<ty::ConstVid<'tcx>>>,
-    L: UndoLogs<snapshot_vec::UndoLog<unify::Delegate<ty::ConstVid<'tcx>>>>,
-{
-    if let ty::ConstKind::Infer(InferConst::Var(vid)) = c.val() {
-        match table.probe_value(vid).val.known() {
-            Some(c) => c,
-            None => c,
-        }
-    } else {
-        c
-    }
-}

compiler/rustc_passes/src/lib_features.rs

@@ -29,10 +29,11 @@ impl<'tcx> LibFeatureCollector<'tcx> {
     }
 
     fn extract(&self, attr: &Attribute) -> Option<(Symbol, Option<Symbol>, Span)> {
-        let stab_attrs = [sym::stable, sym::unstable, sym::rustc_const_unstable];
+        let stab_attrs =
+            [sym::stable, sym::unstable, sym::rustc_const_stable, sym::rustc_const_unstable];
 
-        // Find a stability attribute (i.e., `#[stable (..)]`, `#[unstable (..)]`,
-        // `#[rustc_const_unstable (..)]`).
+        // Find a stability attribute: one of #[stable(…)], #[unstable(…)],
+        // #[rustc_const_stable(…)], or #[rustc_const_unstable(…)].
         if let Some(stab_attr) = stab_attrs.iter().find(|stab_attr| attr.has_name(**stab_attr)) {
             let meta_kind = attr.meta_kind();
             if let Some(MetaItemKind::List(ref metas)) = meta_kind {
@@ -52,7 +53,9 @@ impl<'tcx> LibFeatureCollector<'tcx> {
                     // This additional check for stability is to make sure we
                     // don't emit additional, irrelevant errors for malformed
                     // attributes.
-                    if *stab_attr != sym::stable || since.is_some() {
+                    let is_unstable =
+                        matches!(*stab_attr, sym::unstable | sym::rustc_const_unstable);
+                    if since.is_some() || is_unstable {
                         return Some((feature, since, attr.span));
                     }
                 }

compiler/rustc_passes/src/naked_functions.rs

@@ -1,7 +1,7 @@
 //! Checks validity of naked functions.
 
 use rustc_ast::{Attribute, InlineAsmOptions};
-use rustc_errors::struct_span_err;
+use rustc_errors::{struct_span_err, Applicability};
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::intravisit::{FnKind, Visitor};
@@ -274,12 +274,25 @@ impl<'tcx> CheckInlineAssembly<'tcx> {
         }
 
         if !asm.options.contains(InlineAsmOptions::NORETURN) {
+            let last_span = asm
+                .operands
+                .last()
+                .map_or_else(|| asm.template_strs.last().unwrap().2, |op| op.1)
+                .shrink_to_hi();
+
             struct_span_err!(
                 self.tcx.sess,
                 span,
                 E0787,
                 "asm in naked functions must use `noreturn` option"
             )
+            .span_suggestion(
+                last_span,
+                "consider specifying that the asm block is responsible \
+                for returning from the function",
+                String::from(", options(noreturn)"),
+                Applicability::MachineApplicable,
+            )
             .emit();
         }
     }

compiler/rustc_trait_selection/src/traits/object_safety.rs

@@ -131,16 +131,18 @@ fn object_safety_violations_for_trait(
             }),
     );
 
-    violations.extend(
-        tcx.associated_items(trait_def_id)
-            .in_definition_order()
-            .filter(|item| item.kind == ty::AssocKind::Type)
-            .filter(|item| !tcx.generics_of(item.def_id).params.is_empty())
-            .map(|item| {
-                let ident = item.ident(tcx);
-                ObjectSafetyViolation::GAT(ident.name, ident.span)
-            }),
-    );
+    if !tcx.features().generic_associated_types_extended {
+        violations.extend(
+            tcx.associated_items(trait_def_id)
+                .in_definition_order()
+                .filter(|item| item.kind == ty::AssocKind::Type)
+                .filter(|item| !tcx.generics_of(item.def_id).params.is_empty())
+                .map(|item| {
+                    let ident = item.ident(tcx);
+                    ObjectSafetyViolation::GAT(ident.name, ident.span)
+                }),
+        );
+    }
 
     debug!(
         "object_safety_violations_for_trait(trait_def_id={:?}) = {:?}",

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -11,8 +11,8 @@ use rustc_hir::lang_items::LangItem;
 use rustc_index::bit_set::GrowableBitSet;
 use rustc_infer::infer::InferOk;
 use rustc_infer::infer::LateBoundRegionConversionTime::HigherRankedType;
-use rustc_middle::ty::subst::{GenericArg, GenericArgKind, Subst, SubstsRef};
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, Subst, SubstsRef};
+use rustc_middle::ty::{self, GenericParamDefKind, Ty};
 use rustc_middle::ty::{ToPolyTraitRef, ToPredicate};
 use rustc_span::def_id::DefId;
 
@@ -487,18 +487,80 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             .collect();
 
         for assoc_type in assoc_types {
-            if !tcx.generics_of(assoc_type).params.is_empty() {
+            let defs: &ty::Generics = tcx.generics_of(assoc_type);
+
+            if !defs.params.is_empty() && !tcx.features().generic_associated_types_extended {
                 tcx.sess.delay_span_bug(
                     obligation.cause.span,
                     "GATs in trait object shouldn't have been considered",
                 );
                 return Err(SelectionError::Unimplemented);
             }
+
             // This maybe belongs in wf, but that can't (doesn't) handle
             // higher-ranked things.
             // Prevent, e.g., `dyn Iterator<Item = str>`.
             for bound in self.tcx().item_bounds(assoc_type) {
-                let subst_bound = bound.subst(tcx, trait_predicate.trait_ref.substs);
+                let subst_bound =
+                    if defs.count() == 0 {
+                        bound.subst(tcx, trait_predicate.trait_ref.substs)
+                    } else {
+                        let mut substs = smallvec::SmallVec::with_capacity(defs.count());
+                        substs.extend(trait_predicate.trait_ref.substs.iter());
+                        let mut bound_vars: smallvec::SmallVec<[ty::BoundVariableKind; 8]> =
+                            smallvec::SmallVec::with_capacity(
+                                bound.kind().bound_vars().len() + defs.count(),
+                            );
+                        bound_vars.extend(bound.kind().bound_vars().into_iter());
+                        InternalSubsts::fill_single(&mut substs, defs, &mut |param, _| match param
+                            .kind
+                        {
+                            GenericParamDefKind::Type { .. } => {
+                                let kind = ty::BoundTyKind::Param(param.name);
+                                let bound_var = ty::BoundVariableKind::Ty(kind);
+                                bound_vars.push(bound_var);
+                                tcx.mk_ty(ty::Bound(
+                                    ty::INNERMOST,
+                                    ty::BoundTy {
+                                        var: ty::BoundVar::from_usize(bound_vars.len() - 1),
+                                        kind,
+                                    },
+                                ))
+                                .into()
+                            }
+                            GenericParamDefKind::Lifetime => {
+                                let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name);
+                                let bound_var = ty::BoundVariableKind::Region(kind);
+                                bound_vars.push(bound_var);
+                                tcx.mk_region(ty::ReLateBound(
+                                    ty::INNERMOST,
+                                    ty::BoundRegion {
+                                        var: ty::BoundVar::from_usize(bound_vars.len() - 1),
+                                        kind,
+                                    },
+                                ))
+                                .into()
+                            }
+                            GenericParamDefKind::Const { .. } => {
+                                let bound_var = ty::BoundVariableKind::Const;
+                                bound_vars.push(bound_var);
+                                tcx.mk_const(ty::ConstS {
+                                    ty: tcx.type_of(param.def_id),
+                                    val: ty::ConstKind::Bound(
+                                        ty::INNERMOST,
+                                        ty::BoundVar::from_usize(bound_vars.len() - 1),
+                                    ),
+                                })
+                                .into()
+                            }
+                        });
+                        let bound_vars = tcx.mk_bound_variable_kinds(bound_vars.into_iter());
+                        let assoc_ty_substs = tcx.intern_substs(&substs);
+
+                        let bound_vars = tcx.mk_bound_variable_kinds(bound_vars.into_iter());
+                        let bound = bound.kind().skip_binder().subst(tcx, assoc_ty_substs);
+                        tcx.mk_predicate(ty::Binder::bind_with_vars(bound, bound_vars))
+                    };
                 let normalized_bound = normalize_with_depth_to(
                     self,
                     obligation.param_env,

compiler/rustc_typeck/src/check/fn_ctxt/mod.rs

@@ -14,7 +14,7 @@ use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_infer::infer;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use rustc_infer::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
+use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::subst::GenericArgKind;
 use rustc_middle::ty::{self, Const, Ty, TyCtxt};

compiler/rustc_typeck/src/check/inherited.rs

@@ -68,9 +68,9 @@ impl<'a, 'tcx> Deref for Inherited<'a, 'tcx> {
     }
 }
 
-/// Helper type of a temporary returned by `Inherited::build(...)`.
-/// Necessary because we can't write the following bound:
-/// `F: for<'b, 'tcx> where 'tcx FnOnce(Inherited<'b, 'tcx>)`.
+/// A temporary returned by `Inherited::build(...)`. This is necessary
+/// for multiple `InferCtxt` to share the same `in_progress_typeck_results`
+/// without using `Rc` or something similar.
 pub struct InheritedBuilder<'tcx> {
     infcx: infer::InferCtxtBuilder<'tcx>,
     def_id: LocalDefId,