Rollup of 9 pull requests

compiler/rustc_ast/src/util/parser.rs

@@ -259,7 +259,6 @@ pub enum ExprPrecedence {
     Assign,
     AssignOp,
 
-    Box,
     AddrOf,
     Let,
     Unary,
@@ -319,8 +318,7 @@ impl ExprPrecedence {
             ExprPrecedence::AssignOp => AssocOp::Assign.precedence() as i8,
 
             // Unary, prefix
-            ExprPrecedence::Box
-            | ExprPrecedence::AddrOf
+            ExprPrecedence::AddrOf
             // Here `let pats = expr` has `let pats =` as a "unary" prefix of `expr`.
             // However, this is not exactly right. When `let _ = a` is the LHS of a binop we
             // need parens sometimes. E.g. we can print `(let _ = a) && b` as `let _ = a && b`

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -255,7 +255,7 @@ fn sccs_info<'cx, 'tcx>(
     let var_to_origin = infcx.reg_var_to_origin.borrow();
 
     let mut var_to_origin_sorted = var_to_origin.clone().into_iter().collect::<Vec<_>>();
-    var_to_origin_sorted.sort_by(|a, b| a.0.cmp(&b.0));
+    var_to_origin_sorted.sort_by_key(|vto| vto.0);
     let mut debug_str = "region variables to origins:\n".to_string();
     for (reg_var, origin) in var_to_origin_sorted.into_iter() {
         debug_str.push_str(&format!("{:?}: {:?}\n", reg_var, origin));
@@ -2216,7 +2216,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         // is in the same SCC or something. In that case, find what
         // appears to be the most interesting point to report to the
         // user via an even more ad-hoc guess.
-        categorized_path.sort_by(|p0, p1| p0.category.cmp(&p1.category));
+        categorized_path.sort_by_key(|p| p.category);
         debug!("sorted_path={:#?}", categorized_path);
 
         (categorized_path.remove(0), extra_info)

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1199,15 +1199,17 @@ pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
                     .and_then(|(lhs, rhs)| rhs.chars().all(char::is_numeric).then_some(lhs))
                     .unwrap_or(stem);
 
-                // GCC can have an optional target prefix.
+                // GCC/Clang can have an optional target prefix.
                 let flavor = if stem == "emcc" {
                     LinkerFlavor::EmCc
                 } else if stem == "gcc"
                     || stem.ends_with("-gcc")
                     || stem == "g++"
                     || stem.ends_with("-g++")
                     || stem == "clang"
+                    || stem.ends_with("-clang")
                     || stem == "clang++"
+                    || stem.ends_with("-clang++")
                 {
                     LinkerFlavor::from_cli(LinkerFlavorCli::Gcc, &sess.target)
                 } else if stem == "wasm-ld" || stem.ends_with("-wasm-ld") {

compiler/rustc_hir/src/hir.rs

@@ -1673,7 +1673,6 @@ pub struct Expr<'hir> {
 impl Expr<'_> {
     pub fn precedence(&self) -> ExprPrecedence {
         match self.kind {
-            ExprKind::Box(_) => ExprPrecedence::Box,
             ExprKind::ConstBlock(_) => ExprPrecedence::ConstBlock,
             ExprKind::Array(_) => ExprPrecedence::Array,
             ExprKind::Call(..) => ExprPrecedence::Call,
@@ -1763,7 +1762,6 @@ impl Expr<'_> {
             | ExprKind::Lit(_)
             | ExprKind::ConstBlock(..)
             | ExprKind::Unary(..)
-            | ExprKind::Box(..)
             | ExprKind::AddrOf(..)
             | ExprKind::Binary(..)
             | ExprKind::Yield(..)
@@ -1851,7 +1849,6 @@ impl Expr<'_> {
             | ExprKind::InlineAsm(..)
             | ExprKind::AssignOp(..)
             | ExprKind::ConstBlock(..)
-            | ExprKind::Box(..)
             | ExprKind::Binary(..)
             | ExprKind::Yield(..)
             | ExprKind::DropTemps(..)
@@ -1862,8 +1859,7 @@ impl Expr<'_> {
     /// To a first-order approximation, is this a pattern?
     pub fn is_approximately_pattern(&self) -> bool {
         match &self.kind {
-            ExprKind::Box(_)
-            | ExprKind::Array(_)
+            ExprKind::Array(_)
             | ExprKind::Call(..)
             | ExprKind::Tup(_)
             | ExprKind::Lit(_)
@@ -1910,8 +1906,6 @@ pub fn is_range_literal(expr: &Expr<'_>) -> bool {
 
 #[derive(Debug, HashStable_Generic)]
 pub enum ExprKind<'hir> {
-    /// A `box x` expression.
-    Box(&'hir Expr<'hir>),
     /// Allow anonymous constants from an inline `const` block
     ConstBlock(AnonConst),
     /// An array (e.g., `[a, b, c, d]`).

compiler/rustc_hir/src/intravisit.rs

@@ -682,7 +682,6 @@ pub fn walk_anon_const<'v, V: Visitor<'v>>(visitor: &mut V, constant: &'v AnonCo
 pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>) {
     visitor.visit_id(expression.hir_id);
     match expression.kind {
-        ExprKind::Box(ref subexpression) => visitor.visit_expr(subexpression),
         ExprKind::Array(subexpressions) => {
             walk_list!(visitor, visit_expr, subexpressions);
         }

compiler/rustc_hir_analysis/src/check/check.rs

@@ -557,7 +557,7 @@ fn check_item_type(tcx: TyCtxt<'_>, id: hir::ItemId) {
             check_opaque(tcx, id);
         }
         DefKind::ImplTraitPlaceholder => {
-            let parent = tcx.impl_trait_in_trait_parent(id.owner_id.to_def_id());
+            let parent = tcx.impl_trait_in_trait_parent_fn(id.owner_id.to_def_id());
             // Only check the validity of this opaque type if the function has a default body
             if let hir::Node::TraitItem(hir::TraitItem {
                 kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(_)),

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -1205,6 +1205,17 @@ fn compare_number_of_generics<'tcx>(
         return Ok(());
     }
 
+    // We never need to emit a separate error for RPITITs, since if an RPITIT
+    // has mismatched type or const generic arguments, then the method that it's
+    // inheriting the generics from will also have mismatched arguments, and
+    // we'll report an error for that instead. Delay a bug for safety, though.
+    if tcx.opt_rpitit_info(trait_.def_id).is_some() {
+        return Err(tcx.sess.delay_span_bug(
+            rustc_span::DUMMY_SP,
+            "errors comparing numbers of generics of trait/impl functions were not emitted",
+        ));
+    }
+
     let matchings = [
         ("type", trait_own_counts.types, impl_own_counts.types),
         ("const", trait_own_counts.consts, impl_own_counts.consts),

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1,7 +1,6 @@
 use crate::autoderef::Autoderef;
 use crate::constrained_generic_params::{identify_constrained_generic_params, Parameter};
 
-use hir::def::DefKind;
 use rustc_ast as ast;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
 use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed};
@@ -1548,16 +1547,27 @@ fn check_return_position_impl_trait_in_trait_bounds<'tcx>(
     if let Some(assoc_item) = tcx.opt_associated_item(fn_def_id.to_def_id())
         && assoc_item.container == ty::AssocItemContainer::TraitContainer
     {
+        // FIXME(-Zlower-impl-trait-in-trait-to-assoc-ty): Even with the new lowering
+        // strategy, we can't just call `check_associated_item` on the new RPITITs,
+        // because tests like `tests/ui/async-await/in-trait/implied-bounds.rs` will fail.
+        // That's because we need to check that the bounds of the RPITIT hold using
+        // the special substs that we create during opaque type lowering, otherwise we're
+        // getting a bunch of early bound and free regions mixed up... Haven't looked too
+        // deep into this, though.
         for arg in fn_output.walk() {
             if let ty::GenericArgKind::Type(ty) = arg.unpack()
-                && let ty::Alias(ty::Opaque, proj) = ty.kind()
-                && tcx.def_kind(proj.def_id) == DefKind::ImplTraitPlaceholder
-                && tcx.impl_trait_in_trait_parent(proj.def_id) == fn_def_id.to_def_id()
+                // RPITITs are always eagerly normalized into opaques, so always look for an
+                // opaque here.
+                && let ty::Alias(ty::Opaque, opaque_ty) = ty.kind()
+                && let Some(opaque_def_id) = opaque_ty.def_id.as_local()
+                && let opaque = tcx.hir().expect_item(opaque_def_id).expect_opaque_ty()
+                && let hir::OpaqueTyOrigin::FnReturn(source) | hir::OpaqueTyOrigin::AsyncFn(source) = opaque.origin
+                && source == fn_def_id
             {
-                let span = tcx.def_span(proj.def_id);
-                let bounds = wfcx.tcx().explicit_item_bounds(proj.def_id);
+                let span = tcx.def_span(opaque_ty.def_id);
+                let bounds = wfcx.tcx().explicit_item_bounds(opaque_ty.def_id);
                 let wf_obligations = bounds.iter().flat_map(|&(bound, bound_span)| {
-                    let bound = ty::EarlyBinder(bound).subst(tcx, proj.substs);
+                    let bound = ty::EarlyBinder(bound).subst(tcx, opaque_ty.substs);
                     let normalized_bound = wfcx.normalize(span, None, bound);
                     traits::wf::predicate_obligations(
                         wfcx.infcx,

compiler/rustc_hir_analysis/src/collect/item_bounds.rs

@@ -3,7 +3,7 @@ use crate::astconv::AstConv;
 use rustc_hir as hir;
 use rustc_infer::traits::util;
 use rustc_middle::ty::subst::InternalSubsts;
-use rustc_middle::ty::{self, ImplTraitInTraitData, Ty, TyCtxt};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::def_id::DefId;
 use rustc_span::Span;
 
@@ -76,18 +76,26 @@ pub(super) fn explicit_item_bounds(
     tcx: TyCtxt<'_>,
     def_id: DefId,
 ) -> &'_ [(ty::Predicate<'_>, Span)] {
-    // If the def_id is about an RPITIT, delegate explicit_item_bounds to the opaque_def_id that
-    // generated the synthesized associate type.
-    let rpitit_info = if let Some(ImplTraitInTraitData::Trait { opaque_def_id, .. }) =
-        tcx.opt_rpitit_info(def_id)
-    {
-        Some(opaque_def_id)
-    } else {
-        None
-    };
+    match tcx.opt_rpitit_info(def_id) {
+        // RPITIT's bounds are the same as opaque type bounds, but with
+        // a projection self type.
+        Some(ty::ImplTraitInTraitData::Trait { opaque_def_id, .. }) => {
+            let item = tcx.hir().get_by_def_id(opaque_def_id.expect_local()).expect_item();
+            let opaque_ty = item.expect_opaque_ty();
+            return opaque_type_bounds(
+                tcx,
+                opaque_def_id,
+                opaque_ty.bounds,
+                tcx.mk_projection(def_id, ty::InternalSubsts::identity_for_item(tcx, def_id)),
+                item.span,
+            );
+        }
+        // These should have been fed!
+        Some(ty::ImplTraitInTraitData::Impl { .. }) => unreachable!(),
+        None => {}
+    }
 
-    let bounds_def_id = rpitit_info.unwrap_or(def_id);
-    let hir_id = tcx.hir().local_def_id_to_hir_id(bounds_def_id.expect_local());
+    let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
     match tcx.hir().get(hir_id) {
         hir::Node::TraitItem(hir::TraitItem {
             kind: hir::TraitItemKind::Type(bounds, _),
@@ -100,12 +108,12 @@ pub(super) fn explicit_item_bounds(
             ..
         }) => {
             let substs = InternalSubsts::identity_for_item(tcx, def_id);
-            let item_ty = if *in_trait || rpitit_info.is_some() {
+            let item_ty = if *in_trait && !tcx.lower_impl_trait_in_trait_to_assoc_ty() {
                 tcx.mk_projection(def_id, substs)
             } else {
                 tcx.mk_opaque(def_id, substs)
             };
-            opaque_type_bounds(tcx, bounds_def_id, bounds, item_ty, *span)
+            opaque_type_bounds(tcx, def_id, bounds, item_ty, *span)
         }
         _ => bug!("item_bounds called on {:?}", def_id),
     }

compiler/rustc_hir_analysis/src/variance/mod.rs

@@ -112,10 +112,14 @@ fn variance_of_opaque(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Varianc
         fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
             match t.kind() {
                 ty::Alias(_, ty::AliasTy { def_id, substs, .. })
-                    if matches!(
-                        self.tcx.def_kind(*def_id),
-                        DefKind::OpaqueTy | DefKind::ImplTraitPlaceholder
-                    ) =>
+                    if matches!(self.tcx.def_kind(*def_id), DefKind::OpaqueTy) =>
+                {
+                    self.visit_opaque(*def_id, substs)
+                }
+                // FIXME(-Zlower-impl-trait-in-trait-to-assoc-ty) check whether this is necessary
+                // at all for RPITITs.
+                ty::Alias(_, ty::AliasTy { def_id, substs, .. })
+                    if self.tcx.is_impl_trait_in_trait(*def_id) =>
                 {
                     self.visit_opaque(*def_id, substs)
                 }

compiler/rustc_hir_pretty/src/lib.rs

@@ -1366,10 +1366,6 @@ impl<'a> State<'a> {
         self.ibox(INDENT_UNIT);
         self.ann.pre(self, AnnNode::Expr(expr));
         match expr.kind {
-            hir::ExprKind::Box(expr) => {
-                self.word_space("Box::new");
-                self.print_call_post(std::slice::from_ref(expr));
-            }
             hir::ExprKind::Array(exprs) => {
                 self.print_expr_vec(exprs);
             }

compiler/rustc_hir_typeck/src/closure.rs

@@ -2,7 +2,6 @@
 
 use super::{check_fn, Expectation, FnCtxt, GeneratorTypes};
 
-use hir::def::DefKind;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::lang_items::LangItem;
@@ -715,14 +714,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 .subst_iter_copied(self.tcx, substs)
                 .find_map(|(p, s)| get_future_output(p, s))?,
             ty::Error(_) => return None,
-            ty::Alias(ty::Projection, proj)
-                if self.tcx.def_kind(proj.def_id) == DefKind::ImplTraitPlaceholder =>
-            {
-                self.tcx
-                    .bound_explicit_item_bounds(proj.def_id)
-                    .subst_iter_copied(self.tcx, proj.substs)
-                    .find_map(|(p, s)| get_future_output(p, s))?
-            }
+            ty::Alias(ty::Projection, proj) if self.tcx.is_impl_trait_in_trait(proj.def_id) => self
+                .tcx
+                .bound_explicit_item_bounds(proj.def_id)
+                .subst_iter_copied(self.tcx, proj.substs)
+                .find_map(|(p, s)| get_future_output(p, s))?,
             _ => span_bug!(
                 self.tcx.def_span(expr_def_id),
                 "async fn generator return type not an inference variable: {ret_ty}"

compiler/rustc_hir_typeck/src/expr.rs

@@ -284,7 +284,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         let tcx = self.tcx;
         match expr.kind {
-            ExprKind::Box(subexpr) => self.check_expr_box(subexpr, expected),
             ExprKind::Lit(ref lit) => self.check_lit(&lit, expected),
             ExprKind::Binary(op, lhs, rhs) => self.check_binop(expr, op, lhs, rhs, expected),
             ExprKind::Assign(lhs, rhs, span) => {
@@ -359,16 +358,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
-    fn check_expr_box(&self, expr: &'tcx hir::Expr<'tcx>, expected: Expectation<'tcx>) -> Ty<'tcx> {
-        let expected_inner = expected.to_option(self).map_or(NoExpectation, |ty| match ty.kind() {
-            ty::Adt(def, _) if def.is_box() => Expectation::rvalue_hint(self, ty.boxed_ty()),
-            _ => NoExpectation,
-        });
-        let referent_ty = self.check_expr_with_expectation(expr, expected_inner);
-        self.require_type_is_sized(referent_ty, expr.span, traits::SizedBoxType);
-        self.tcx.mk_box(referent_ty)
-    }
-
     fn check_expr_unary(
         &self,
         unop: hir::UnOp,

compiler/rustc_hir_typeck/src/expr_use_visitor.rs

@@ -356,10 +356,6 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                 self.walk_captures(closure);
             }
 
-            hir::ExprKind::Box(ref base) => {
-                self.consume_expr(base);
-            }
-
             hir::ExprKind::Yield(value, _) => {
                 self.consume_expr(value);
             }

compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_build.rs

@@ -190,7 +190,6 @@ impl<'a, 'tcx> DropRangeVisitor<'a, 'tcx> {
             //
             // Some of these may be interesting in the future
             ExprKind::Path(..)
-            | ExprKind::Box(..)
             | ExprKind::ConstBlock(..)
             | ExprKind::Array(..)
             | ExprKind::Call(..)
@@ -478,7 +477,6 @@ impl<'a, 'tcx> Visitor<'tcx> for DropRangeVisitor<'a, 'tcx> {
             | ExprKind::AssignOp(..)
             | ExprKind::Binary(..)
             | ExprKind::Block(..)
-            | ExprKind::Box(..)
             | ExprKind::Cast(..)
             | ExprKind::Closure { .. }
             | ExprKind::ConstBlock(..)

compiler/rustc_hir_typeck/src/mem_categorization.rs

@@ -382,7 +382,6 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
             | hir::ExprKind::Struct(..)
             | hir::ExprKind::Repeat(..)
             | hir::ExprKind::InlineAsm(..)
-            | hir::ExprKind::Box(..)
             | hir::ExprKind::Err(_) => Ok(self.cat_rvalue(expr.hir_id, expr.span, expr_ty)),
         }
     }

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

@@ -359,10 +359,12 @@ impl<'tcx> InferCtxt<'tcx> {
     pub fn get_impl_future_output_ty(&self, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
         let (def_id, substs) = match *ty.kind() {
             ty::Alias(_, ty::AliasTy { def_id, substs, .. })
-                if matches!(
-                    self.tcx.def_kind(def_id),
-                    DefKind::OpaqueTy | DefKind::ImplTraitPlaceholder
-                ) =>
+                if matches!(self.tcx.def_kind(def_id), DefKind::OpaqueTy) =>
+            {
+                (def_id, substs)
+            }
+            ty::Alias(_, ty::AliasTy { def_id, substs, .. })
+                if self.tcx.is_impl_trait_in_trait(def_id) =>
             {
                 (def_id, substs)
             }
@@ -1757,8 +1759,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                                 )
                             }
                             (true, ty::Alias(ty::Projection, proj))
-                                if self.tcx.def_kind(proj.def_id)
-                                    == DefKind::ImplTraitPlaceholder =>
+                                if self.tcx.is_impl_trait_in_trait(proj.def_id) =>
                             {
                                 let sm = self.tcx.sess.source_map();
                                 let pos = sm.lookup_char_pos(self.tcx.def_span(proj.def_id).lo());