Rollup of 6 pull requests

src/libarena/lib.rs

@@ -5,8 +5,7 @@
 //! of individual objects while the arena itself is still alive. The benefit
 //! of an arena is very fast allocation; just a pointer bump.
 //!
-//! This crate implements `TypedArena`, a simple arena that can only hold
-//! objects of a single type.
+//! This crate implements several kinds of arena.
 
 #![doc(
     html_root_url = "https://doc.rust-lang.org/nightly/",
@@ -98,7 +97,13 @@ impl<T> TypedArenaChunk<T> {
     }
 }
 
+// The arenas start with PAGE-sized chunks, and then each new chunk is twice as
+// big as its predecessor, up until we reach HUGE_PAGE-sized chunks, whereupon
+// we stop growing. This scales well, from arenas that are barely used up to
+// arenas that are used for 100s of MiBs. Note also that the chosen sizes match
+// the usual sizes of pages and huge pages on Linux.
 const PAGE: usize = 4096;
+const HUGE_PAGE: usize = 2 * 1024 * 1024;
 
 impl<T> Default for TypedArena<T> {
     /// Creates a new `TypedArena`.
@@ -211,6 +216,9 @@ impl<T> TypedArena<T> {
     #[cold]
     fn grow(&self, n: usize) {
         unsafe {
+            // We need the element size in to convert chunk sizes (ranging from
+            // PAGE to HUGE_PAGE bytes) to element counts.
+            let elem_size = cmp::max(1, mem::size_of::<T>());
             let mut chunks = self.chunks.borrow_mut();
             let (chunk, mut new_capacity);
             if let Some(last_chunk) = chunks.last_mut() {
@@ -221,18 +229,20 @@ impl<T> TypedArena<T> {
                     self.end.set(last_chunk.end());
                     return;
                 } else {
+                    // If the previous chunk's capacity is less than HUGE_PAGE
+                    // bytes, then this chunk will be least double the previous
+                    // chunk's size.
                     new_capacity = last_chunk.storage.capacity();
-                    loop {
+                    if new_capacity < HUGE_PAGE / elem_size {
                         new_capacity = new_capacity.checked_mul(2).unwrap();
-                        if new_capacity >= currently_used_cap + n {
-                            break;
-                        }
                     }
                 }
             } else {
-                let elem_size = cmp::max(1, mem::size_of::<T>());
-                new_capacity = cmp::max(n, PAGE / elem_size);
+                new_capacity = PAGE / elem_size;
             }
+            // Also ensure that this chunk can fit `n`.
+            new_capacity = cmp::max(n, new_capacity);
+
             chunk = TypedArenaChunk::<T>::new(new_capacity);
             self.ptr.set(chunk.start());
             self.end.set(chunk.end());
@@ -347,17 +357,20 @@ impl DroplessArena {
                     self.end.set(last_chunk.end());
                     return;
                 } else {
+                    // If the previous chunk's capacity is less than HUGE_PAGE
+                    // bytes, then this chunk will be least double the previous
+                    // chunk's size.
                     new_capacity = last_chunk.storage.capacity();
-                    loop {
+                    if new_capacity < HUGE_PAGE {
                         new_capacity = new_capacity.checked_mul(2).unwrap();
-                        if new_capacity >= used_bytes + needed_bytes {
-                            break;
-                        }
                     }
                 }
             } else {
-                new_capacity = cmp::max(needed_bytes, PAGE);
+                new_capacity = PAGE;
             }
+            // Also ensure that this chunk can fit `needed_bytes`.
+            new_capacity = cmp::max(needed_bytes, new_capacity);
+
             chunk = TypedArenaChunk::<u8>::new(new_capacity);
             self.ptr.set(chunk.start());
             self.end.set(chunk.end());

src/libcore/num/mod.rs

@@ -1448,8 +1448,8 @@ any high-order bits of `rhs` that would cause the shift to exceed the bitwidth o
 
 Note that this is *not* the same as a rotate-left; the RHS of a wrapping shift-left is restricted to
 the range of the type, rather than the bits shifted out of the LHS being returned to the other end.
-The primitive integer types all implement a `rotate_left` function, which may be what you want
-instead.
+The primitive integer types all implement a `[`rotate_left`](#method.rotate_left) function,
+which may be what you want instead.
 
 # Examples
 
@@ -1480,8 +1480,8 @@ removes any high-order bits of `rhs` that would cause the shift to exceed the bi
 
 Note that this is *not* the same as a rotate-right; the RHS of a wrapping shift-right is restricted
 to the range of the type, rather than the bits shifted out of the LHS being returned to the other
-end. The primitive integer types all implement a `rotate_right` function, which may be what you want
-instead.
+end. The primitive integer types all implement a [`rotate_right`](#method.rotate_right) function,
+which may be what you want instead.
 
 # Examples
 
@@ -3508,8 +3508,8 @@ Note that this is *not* the same as a rotate-left; the
 RHS of a wrapping shift-left is restricted to the range
 of the type, rather than the bits shifted out of the LHS
 being returned to the other end. The primitive integer
-types all implement a `rotate_left` function, which may
-be what you want instead.
+types all implement a [`rotate_left`](#method.rotate_left) function,
+which may be what you want instead.
 
 # Examples
 
@@ -3542,8 +3542,8 @@ Note that this is *not* the same as a rotate-right; the
 RHS of a wrapping shift-right is restricted to the range
 of the type, rather than the bits shifted out of the LHS
 being returned to the other end. The primitive integer
-types all implement a `rotate_right` function, which may
-be what you want instead.
+types all implement a [`rotate_right`](#method.rotate_right) function,
+which may be what you want instead.
 
 # Examples
 

src/librustc_driver/lib.rs

@@ -1138,6 +1138,16 @@ pub fn catch_fatal_errors<F: FnOnce() -> R, R>(f: F) -> Result<R, ErrorReported>
     })
 }
 
+/// Variant of `catch_fatal_errors` for the `interface::Result` return type
+/// that also computes the exit code.
+pub fn catch_with_exit_code(f: impl FnOnce() -> interface::Result<()>) -> i32 {
+    let result = catch_fatal_errors(f).and_then(|result| result);
+    match result {
+        Ok(()) => EXIT_SUCCESS,
+        Err(_) => EXIT_FAILURE,
+    }
+}
+
 lazy_static! {
     static ref DEFAULT_HOOK: Box<dyn Fn(&panic::PanicInfo<'_>) + Sync + Send + 'static> = {
         let hook = panic::take_hook();
@@ -1228,12 +1238,12 @@ pub fn init_rustc_env_logger() {
     env_logger::init_from_env("RUSTC_LOG");
 }
 
-pub fn main() {
+pub fn main() -> ! {
     let start = Instant::now();
     init_rustc_env_logger();
     let mut callbacks = TimePassesCallbacks::default();
     install_ice_hook();
-    let result = catch_fatal_errors(|| {
+    let exit_code = catch_with_exit_code(|| {
         let args = env::args_os()
             .enumerate()
             .map(|(i, arg)| {
@@ -1246,13 +1256,8 @@ pub fn main() {
             })
             .collect::<Vec<_>>();
         run_compiler(&args, &mut callbacks, None, None)
-    })
-    .and_then(|result| result);
-    let exit_code = match result {
-        Ok(_) => EXIT_SUCCESS,
-        Err(_) => EXIT_FAILURE,
-    };
+    });
     // The extra `\t` is necessary to align this label with the others.
     print_time_passes_entry(callbacks.time_passes, "\ttotal", start.elapsed());
-    process::exit(exit_code);
+    process::exit(exit_code)
 }

src/librustc_mir/monomorphize/mod.rs

@@ -2,6 +2,8 @@ use rustc_middle::traits;
 use rustc_middle::ty::adjustment::CustomCoerceUnsized;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 
+use rustc_hir::lang_items::CoerceUnsizedTraitLangItem;
+
 pub mod collector;
 pub mod partitioning;
 
@@ -10,7 +12,7 @@ pub fn custom_coerce_unsize_info<'tcx>(
     source_ty: Ty<'tcx>,
     target_ty: Ty<'tcx>,
 ) -> CustomCoerceUnsized {
-    let def_id = tcx.lang_items().coerce_unsized_trait().unwrap();
+    let def_id = tcx.require_lang_item(CoerceUnsizedTraitLangItem, None);
 
     let trait_ref = ty::Binder::bind(ty::TraitRef {
         def_id,

src/librustc_mir_build/hair/pattern/const_to_pat.rs

@@ -141,7 +141,8 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 // code at the moment, because types like `for <'a> fn(&'a ())` do
                 // not *yet* implement `PartialEq`. So for now we leave this here.
                 let ty_is_partial_eq: bool = {
-                    let partial_eq_trait_id = self.tcx().require_lang_item(EqTraitLangItem, None);
+                    let partial_eq_trait_id =
+                        self.tcx().require_lang_item(EqTraitLangItem, Some(self.span));
                     let obligation: PredicateObligation<'_> = predicate_for_trait_def(
                         self.tcx(),
                         self.param_env,

src/librustc_trait_selection/traits/structural_match.rs

@@ -4,6 +4,7 @@ use crate::traits::{self, ConstPatternStructural, TraitEngine};
 
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
+use rustc_hir::lang_items::{StructuralPeqTraitLangItem, StructuralTeqTraitLangItem};
 use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt, TypeFoldable, TypeVisitor};
 use rustc_span::Span;
 
@@ -69,7 +70,7 @@ pub fn type_marked_structural(
     let mut fulfillment_cx = traits::FulfillmentContext::new();
     let cause = ObligationCause::new(span, id, ConstPatternStructural);
     // require `#[derive(PartialEq)]`
-    let structural_peq_def_id = infcx.tcx.lang_items().structural_peq_trait().unwrap();
+    let structural_peq_def_id = infcx.tcx.require_lang_item(StructuralPeqTraitLangItem, Some(span));
     fulfillment_cx.register_bound(
         infcx,
         ty::ParamEnv::empty(),
@@ -80,7 +81,7 @@ pub fn type_marked_structural(
     // for now, require `#[derive(Eq)]`. (Doing so is a hack to work around
     // the type `for<'a> fn(&'a ())` failing to implement `Eq` itself.)
     let cause = ObligationCause::new(span, id, ConstPatternStructural);
-    let structural_teq_def_id = infcx.tcx.lang_items().structural_teq_trait().unwrap();
+    let structural_teq_def_id = infcx.tcx.require_lang_item(StructuralTeqTraitLangItem, Some(span));
     fulfillment_cx.register_bound(
         infcx,
         ty::ParamEnv::empty(),

src/librustc_typeck/check/closure.rs

@@ -6,7 +6,7 @@ use crate::astconv::AstConv;
 use crate::middle::region;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
-use rustc_hir::lang_items;
+use rustc_hir::lang_items::{FutureTraitLangItem, GeneratorTraitLangItem};
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::LateBoundRegionConversionTime;
 use rustc_infer::infer::{InferOk, InferResult};
@@ -245,7 +245,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let trait_ref = projection.to_poly_trait_ref(tcx);
 
         let is_fn = tcx.fn_trait_kind_from_lang_item(trait_ref.def_id()).is_some();
-        let gen_trait = tcx.require_lang_item(lang_items::GeneratorTraitLangItem, cause_span);
+        let gen_trait = tcx.require_lang_item(GeneratorTraitLangItem, cause_span);
         let is_gen = gen_trait == trait_ref.def_id();
         if !is_fn && !is_gen {
             debug!("deduce_sig_from_projection: not fn or generator");
@@ -678,7 +678,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         // Check that this is a projection from the `Future` trait.
         let trait_ref = predicate.projection_ty.trait_ref(self.tcx);
-        let future_trait = self.tcx.lang_items().future_trait().unwrap();
+        let future_trait = self.tcx.require_lang_item(FutureTraitLangItem, Some(cause_span));
         if trait_ref.def_id != future_trait {
             debug!("deduce_future_output_from_projection: not a future");
             return None;

src/librustc_typeck/check/demand.rs

@@ -7,7 +7,7 @@ use rustc_trait_selection::traits::{self, ObligationCause};
 use rustc_ast::util::parser::PREC_POSTFIX;
 use rustc_errors::{Applicability, DiagnosticBuilder};
 use rustc_hir as hir;
-use rustc_hir::lang_items::DerefTraitLangItem;
+use rustc_hir::lang_items::{CloneTraitLangItem, DerefTraitLangItem};
 use rustc_hir::{is_range_literal, Node};
 use rustc_middle::ty::adjustment::AllowTwoPhase;
 use rustc_middle::ty::{self, AssocItem, Ty, TypeAndMut};
@@ -456,8 +456,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 };
                 if self.can_coerce(ref_ty, expected) {
                     let mut sugg_sp = sp;
-                    if let hir::ExprKind::MethodCall(segment, _sp, args) = &expr.kind {
-                        let clone_trait = self.tcx.lang_items().clone_trait().unwrap();
+                    if let hir::ExprKind::MethodCall(ref segment, sp, ref args) = expr.kind {
+                        let clone_trait = self.tcx.require_lang_item(CloneTraitLangItem, Some(sp));
                         if let ([arg], Some(true), sym::clone) = (
                             &args[..],
                             self.tables.borrow().type_dependent_def_id(expr.hir_id).map(|did| {
@@ -635,7 +635,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             _ if sp == expr.span && !is_macro => {
                 // Check for `Deref` implementations by constructing a predicate to
                 // prove: `<T as Deref>::Output == U`
-                let deref_trait = self.tcx.require_lang_item(DerefTraitLangItem, Some(expr.span));
+                let deref_trait = self.tcx.require_lang_item(DerefTraitLangItem, Some(sp));
                 let item_def_id = self
                     .tcx
                     .associated_items(deref_trait)

src/librustc_typeck/check/mod.rs

@@ -100,7 +100,9 @@ use rustc_hir::def::{CtorOf, DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefIdSet, LocalDefId, LOCAL_CRATE};
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
-use rustc_hir::lang_items;
+use rustc_hir::lang_items::{
+    FutureTraitLangItem, PinTypeLangItem, SizedTraitLangItem, VaListTypeLangItem,
+};
 use rustc_hir::{ExprKind, GenericArg, HirIdMap, Item, ItemKind, Node, PatKind, QPath};
 use rustc_index::bit_set::BitSet;
 use rustc_index::vec::Idx;
@@ -1335,10 +1337,8 @@ fn check_fn<'a, 'tcx>(
     // C-variadic fns also have a `VaList` input that's not listed in `fn_sig`
     // (as it's created inside the body itself, not passed in from outside).
     let maybe_va_list = if fn_sig.c_variadic {
-        let va_list_did = tcx.require_lang_item(
-            lang_items::VaListTypeLangItem,
-            Some(body.params.last().unwrap().span),
-        );
+        let va_list_did =
+            tcx.require_lang_item(VaListTypeLangItem, Some(body.params.last().unwrap().span));
         let region = tcx.mk_region(ty::ReScope(region::Scope {
             id: body.value.hir_id.local_id,
             data: region::ScopeData::CallSite,
@@ -3296,7 +3296,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         code: traits::ObligationCauseCode<'tcx>,
     ) {
         if !ty.references_error() {
-            let lang_item = self.tcx.require_lang_item(lang_items::SizedTraitLangItem, None);
+            let lang_item = self.tcx.require_lang_item(SizedTraitLangItem, None);
             self.require_type_meets(ty, span, code, lang_item);
         }
     }
@@ -5135,7 +5135,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             _ => {}
         }
         let boxed_found = self.tcx.mk_box(found);
-        let new_found = self.tcx.mk_lang_item(boxed_found, lang_items::PinTypeLangItem).unwrap();
+        let new_found = self.tcx.mk_lang_item(boxed_found, PinTypeLangItem).unwrap();
         if let (true, Ok(snippet)) = (
             self.can_coerce(new_found, expected),
             self.sess().source_map().span_to_snippet(expr.span),
@@ -5291,7 +5291,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 let sp = expr.span;
                 // Check for `Future` implementations by constructing a predicate to
                 // prove: `<T as Future>::Output == U`
-                let future_trait = self.tcx.lang_items().future_trait().unwrap();
+                let future_trait = self.tcx.require_lang_item(FutureTraitLangItem, Some(sp));
                 let item_def_id = self
                     .tcx
                     .associated_items(future_trait)

src/librustc_typeck/coherence/builtin.rs

@@ -4,7 +4,9 @@
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
-use rustc_hir::lang_items::UnsizeTraitLangItem;
+use rustc_hir::lang_items::{
+    CoerceUnsizedTraitLangItem, DispatchFromDynTraitLangItem, UnsizeTraitLangItem,
+};
 use rustc_hir::ItemKind;
 use rustc_infer::infer;
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
@@ -145,11 +147,11 @@ fn visit_implementation_of_coerce_unsized(tcx: TyCtxt<'tcx>, impl_did: LocalDefI
 fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
     debug!("visit_implementation_of_dispatch_from_dyn: impl_did={:?}", impl_did);
 
-    let dispatch_from_dyn_trait = tcx.lang_items().dispatch_from_dyn_trait().unwrap();
-
     let impl_hir_id = tcx.hir().as_local_hir_id(impl_did);
     let span = tcx.hir().span(impl_hir_id);
 
+    let dispatch_from_dyn_trait = tcx.require_lang_item(DispatchFromDynTraitLangItem, Some(span));
+
     let source = tcx.type_of(impl_did);
     assert!(!source.has_escaping_bound_vars());
     let target = {
@@ -314,22 +316,23 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef
 
 pub fn coerce_unsized_info(tcx: TyCtxt<'tcx>, impl_did: DefId) -> CoerceUnsizedInfo {
     debug!("compute_coerce_unsized_info(impl_did={:?})", impl_did);
-    let coerce_unsized_trait = tcx.lang_items().coerce_unsized_trait().unwrap();
+
+    // this provider should only get invoked for local def-ids
+    let impl_hir_id = tcx.hir().as_local_hir_id(impl_did.expect_local());
+    let span = tcx.hir().span(impl_hir_id);
+
+    let coerce_unsized_trait = tcx.require_lang_item(CoerceUnsizedTraitLangItem, Some(span));
 
     let unsize_trait = tcx.lang_items().require(UnsizeTraitLangItem).unwrap_or_else(|err| {
         tcx.sess.fatal(&format!("`CoerceUnsized` implementation {}", err));
     });
 
-    // this provider should only get invoked for local def-ids
-    let impl_hir_id = tcx.hir().as_local_hir_id(impl_did.expect_local());
-
     let source = tcx.type_of(impl_did);
     let trait_ref = tcx.impl_trait_ref(impl_did).unwrap();
     assert_eq!(trait_ref.def_id, coerce_unsized_trait);
     let target = trait_ref.substs.type_at(1);
     debug!("visit_implementation_of_coerce_unsized: {:?} -> {:?} (bound)", source, target);
 
-    let span = tcx.hir().span(impl_hir_id);
     let param_env = tcx.param_env(impl_did);
     assert!(!source.has_escaping_bound_vars());