Auto merge of rust-lang#101152 - Dylan-DPC:rollup-v4iw8ux, r=Dylan-DPC

Rollup of 8 pull requests

Successful merges:

 - rust-lang#98304 (Add MaybeUninit memset test)
 - rust-lang#98801 (Add a `File::create_new` constructor)
 - rust-lang#99821 (Remove separate indexing of early-bound regions)
 - rust-lang#100239 (remove an ineffective check in const_prop)
 - rust-lang#100337 (Stabilize `std::io::read_to_string`)
 - rust-lang#100819 (Make use of `[wrapping_]byte_{add,sub}`)
 - rust-lang#100934 (Remove a panicking branch from `fmt::builders::PadAdapter`)
 - rust-lang#101000 (Separate CountIsStar from CountIsParam in rustc_parse_format.)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_arena/src/lib.rs

@@ -16,6 +16,7 @@
 #![feature(maybe_uninit_slice)]
 #![feature(min_specialization)]
 #![feature(decl_macro)]
+#![feature(pointer_byte_offsets)]
 #![feature(rustc_attrs)]
 #![cfg_attr(test, feature(test))]
 #![feature(strict_provenance)]
@@ -211,7 +212,7 @@ impl<T> TypedArena<T> {
 
         unsafe {
             if mem::size_of::<T>() == 0 {
-                self.ptr.set((self.ptr.get() as *mut u8).wrapping_offset(1) as *mut T);
+                self.ptr.set(self.ptr.get().wrapping_byte_add(1));
                 let ptr = ptr::NonNull::<T>::dangling().as_ptr();
                 // Don't drop the object. This `write` is equivalent to `forget`.
                 ptr::write(ptr, object);

compiler/rustc_builtin_macros/src/format.rs

@@ -541,7 +541,7 @@ impl<'a, 'b> Context<'a, 'b> {
     ) {
         match c {
             parse::CountImplied | parse::CountIs(..) => {}
-            parse::CountIsParam(i) => {
+            parse::CountIsParam(i) | parse::CountIsStar(i) => {
                 self.unused_names_lint.maybe_add_positional_named_arg(
                     self.args.get(i),
                     named_arg_type,
@@ -589,7 +589,7 @@ impl<'a, 'b> Context<'a, 'b> {
             + self
                 .arg_with_formatting
                 .iter()
-                .filter(|fmt| matches!(fmt.precision, parse::CountIsParam(_)))
+                .filter(|fmt| matches!(fmt.precision, parse::CountIsStar(_)))
                 .count();
         if self.names.is_empty() && !numbered_position_args && count != self.num_args() {
             e = self.ecx.struct_span_err(
@@ -639,7 +639,7 @@ impl<'a, 'b> Context<'a, 'b> {
             if let Some(span) = fmt.precision_span {
                 let span = self.fmtsp.from_inner(InnerSpan::new(span.start, span.end));
                 match fmt.precision {
-                    parse::CountIsParam(pos) if pos > self.num_args() => {
+                    parse::CountIsParam(pos) if pos >= self.num_args() => {
                         e.span_label(
                             span,
                             &format!(
@@ -651,12 +651,12 @@ impl<'a, 'b> Context<'a, 'b> {
                         );
                         zero_based_note = true;
                     }
-                    parse::CountIsParam(pos) => {
+                    parse::CountIsStar(pos) => {
                         let count = self.pieces.len()
                             + self
                                 .arg_with_formatting
                                 .iter()
-                                .filter(|fmt| matches!(fmt.precision, parse::CountIsParam(_)))
+                                .filter(|fmt| matches!(fmt.precision, parse::CountIsStar(_)))
                                 .count();
                         e.span_label(
                             span,
@@ -837,7 +837,7 @@ impl<'a, 'b> Context<'a, 'b> {
         };
         match c {
             parse::CountIs(i) => count(sym::Is, Some(self.ecx.expr_usize(sp, i))),
-            parse::CountIsParam(i) => {
+            parse::CountIsParam(i) | parse::CountIsStar(i) => {
                 // This needs mapping too, as `i` is referring to a macro
                 // argument. If `i` is not found in `count_positions` then
                 // the error had already been emitted elsewhere.

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -187,9 +187,6 @@ pub enum LocalValue<Prov: Provenance = AllocId> {
 
 impl<'tcx, Prov: Provenance + 'static> LocalState<'tcx, Prov> {
     /// Read the local's value or error if the local is not yet live or not live anymore.
-    ///
-    /// Note: This may only be invoked from the `Machine::access_local` hook and not from
-    /// anywhere else. You may be invalidating machine invariants if you do!
     #[inline]
     pub fn access(&self) -> InterpResult<'tcx, &Operand<Prov>> {
         match &self.value {

compiler/rustc_const_eval/src/interpret/machine.rs

@@ -215,23 +215,12 @@ pub trait Machine<'mir, 'tcx>: Sized {
         right: &ImmTy<'tcx, Self::Provenance>,
     ) -> InterpResult<'tcx, (Scalar<Self::Provenance>, bool, Ty<'tcx>)>;
 
-    /// Called to read the specified `local` from the `frame`.
-    /// Since reading a ZST is not actually accessing memory or locals, this is never invoked
-    /// for ZST reads.
-    #[inline]
-    fn access_local<'a>(
-        frame: &'a Frame<'mir, 'tcx, Self::Provenance, Self::FrameExtra>,
-        local: mir::Local,
-    ) -> InterpResult<'tcx, &'a Operand<Self::Provenance>>
-    where
-        'tcx: 'mir,
-    {
-        frame.locals[local].access()
-    }
-
     /// Called to write the specified `local` from the `frame`.
     /// Since writing a ZST is not actually accessing memory or locals, this is never invoked
     /// for ZST reads.
+    ///
+    /// Due to borrow checker trouble, we indicate the `frame` as an index rather than an `&mut
+    /// Frame`.
     #[inline]
     fn access_local_mut<'a>(
         ecx: &'a mut InterpCx<'mir, 'tcx, Self>,

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -444,7 +444,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         }
     }
 
-    /// Read from a local. Will not actually access the local if reading from a ZST.
+    /// Read from a local.
     /// Will not access memory, instead an indirect `Operand` is returned.
     ///
     /// This is public because it is used by [priroda](https://github.com/oli-obk/priroda) to get an
@@ -456,12 +456,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         layout: Option<TyAndLayout<'tcx>>,
     ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> {
         let layout = self.layout_of_local(frame, local, layout)?;
-        let op = if layout.is_zst() {
-            // Bypass `access_local` (helps in ConstProp)
-            Operand::Immediate(Immediate::Uninit)
-        } else {
-            *M::access_local(frame, local)?
-        };
+        let op = *frame.locals[local].access()?;
         Ok(OpTy { op, layout, align: Some(layout.align.abi) })
     }
 

compiler/rustc_const_eval/src/interpret/place.rs

@@ -642,7 +642,7 @@ where
         // avoid force_allocation.
         let src = match self.read_immediate_raw(src)? {
             Ok(src_val) => {
-                assert!(!src.layout.is_unsized(), "cannot have unsized immediates");
+                assert!(!src.layout.is_unsized(), "cannot copy unsized immediates");
                 assert!(
                     !dest.layout.is_unsized(),
                     "the src is sized, so the dest must also be sized"

compiler/rustc_const_eval/src/interpret/projection.rs

@@ -100,6 +100,8 @@ where
         // This makes several assumptions about what layouts we will encounter; we match what
         // codegen does as good as we can (see `extract_field` in `rustc_codegen_ssa/src/mir/operand.rs`).
         let field_val: Immediate<_> = match (*base, base.layout.abi) {
+            // if the entire value is uninit, then so is the field (can happen in ConstProp)
+            (Immediate::Uninit, _) => Immediate::Uninit,
             // the field contains no information, can be left uninit
             _ if field_layout.is_zst() => Immediate::Uninit,
             // the field covers the entire type
@@ -124,6 +126,7 @@ where
                     b_val
                 })
             }
+            // everything else is a bug
             _ => span_bug!(
                 self.cur_span(),
                 "invalid field access on immediate {}, layout {:#?}",

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/find_anon_type.rs

@@ -103,7 +103,7 @@ impl<'tcx> Visitor<'tcx> for FindNestedTypeVisitor<'tcx> {
                     // Find the index of the named region that was part of the
                     // error. We will then search the function parameters for a bound
                     // region at the right depth with the same index
-                    (Some(rl::Region::EarlyBound(_, id)), ty::BrNamed(def_id, _)) => {
+                    (Some(rl::Region::EarlyBound(id)), ty::BrNamed(def_id, _)) => {
                         debug!("EarlyBound id={:?} def_id={:?}", id, def_id);
                         if id == def_id {
                             self.found_type = Some(arg);
@@ -133,7 +133,7 @@ impl<'tcx> Visitor<'tcx> for FindNestedTypeVisitor<'tcx> {
                         Some(
                             rl::Region::Static
                             | rl::Region::Free(_, _)
-                            | rl::Region::EarlyBound(_, _)
+                            | rl::Region::EarlyBound(_)
                             | rl::Region::LateBound(_, _, _),
                         )
                         | None,
@@ -188,7 +188,7 @@ impl<'tcx> Visitor<'tcx> for TyPathVisitor<'tcx> {
     fn visit_lifetime(&mut self, lifetime: &hir::Lifetime) {
         match (self.tcx.named_region(lifetime.hir_id), self.bound_region) {
             // the lifetime of the TyPath!
-            (Some(rl::Region::EarlyBound(_, id)), ty::BrNamed(def_id, _)) => {
+            (Some(rl::Region::EarlyBound(id)), ty::BrNamed(def_id, _)) => {
                 debug!("EarlyBound id={:?} def_id={:?}", id, def_id);
                 if id == def_id {
                     self.found_it = true;
@@ -209,7 +209,7 @@ impl<'tcx> Visitor<'tcx> for TyPathVisitor<'tcx> {
             (
                 Some(
                     rl::Region::Static
-                    | rl::Region::EarlyBound(_, _)
+                    | rl::Region::EarlyBound(_)
                     | rl::Region::LateBound(_, _, _)
                     | rl::Region::Free(_, _),
                 )

compiler/rustc_lint/src/builtin.rs

@@ -2026,13 +2026,13 @@ declare_lint_pass!(ExplicitOutlivesRequirements => [EXPLICIT_OUTLIVES_REQUIREMEN
 impl ExplicitOutlivesRequirements {
     fn lifetimes_outliving_lifetime<'tcx>(
         inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
-        index: u32,
+        def_id: DefId,
     ) -> Vec<ty::Region<'tcx>> {
         inferred_outlives
             .iter()
             .filter_map(|(pred, _)| match pred.kind().skip_binder() {
                 ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(a, b)) => match *a {
-                    ty::ReEarlyBound(ebr) if ebr.index == index => Some(b),
+                    ty::ReEarlyBound(ebr) if ebr.def_id == def_id => Some(b),
                     _ => None,
                 },
                 _ => None,
@@ -2069,8 +2069,12 @@ impl ExplicitOutlivesRequirements {
             .filter_map(|(i, bound)| {
                 if let hir::GenericBound::Outlives(lifetime) = bound {
                     let is_inferred = match tcx.named_region(lifetime.hir_id) {
-                        Some(Region::EarlyBound(index, ..)) => inferred_outlives.iter().any(|r| {
-                            if let ty::ReEarlyBound(ebr) = **r { ebr.index == index } else { false }
+                        Some(Region::EarlyBound(def_id)) => inferred_outlives.iter().any(|r| {
+                            if let ty::ReEarlyBound(ebr) = **r {
+                                ebr.def_id == def_id
+                            } else {
+                                false
+                            }
                         }),
                         _ => false,
                     };
@@ -2164,11 +2168,14 @@ impl<'tcx> LateLintPass<'tcx> for ExplicitOutlivesRequirements {
             for (i, where_predicate) in hir_generics.predicates.iter().enumerate() {
                 let (relevant_lifetimes, bounds, span, in_where_clause) = match where_predicate {
                     hir::WherePredicate::RegionPredicate(predicate) => {
-                        if let Some(Region::EarlyBound(index, ..)) =
+                        if let Some(Region::EarlyBound(region_def_id)) =
                             cx.tcx.named_region(predicate.lifetime.hir_id)
                         {
                             (
-                                Self::lifetimes_outliving_lifetime(inferred_outlives, index),
+                                Self::lifetimes_outliving_lifetime(
+                                    inferred_outlives,
+                                    region_def_id,
+                                ),
                                 &predicate.bounds,
                                 predicate.span,
                                 predicate.in_where_clause,

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -199,6 +199,7 @@ provide! { tcx, def_id, other, cdata,
     codegen_fn_attrs => { table }
     impl_trait_ref => { table }
     const_param_default => { table }
+    object_lifetime_default => { table }
     thir_abstract_const => { table }
     optimized_mir => { table }
     mir_for_ctfe => { table }

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1076,6 +1076,11 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                     record_array!(self.tables.inferred_outlives_of[def_id] <- inferred_outlives);
                 }
             }
+            if let DefKind::TyParam | DefKind::ConstParam = def_kind {
+                if let Some(default) = self.tcx.object_lifetime_default(def_id) {
+                    record!(self.tables.object_lifetime_default[def_id] <- default);
+                }
+            }
             if let DefKind::Trait | DefKind::TraitAlias = def_kind {
                 record!(self.tables.super_predicates_of[def_id] <- self.tcx.super_predicates_of(def_id));
             }

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -16,6 +16,7 @@ use rustc_index::{bit_set::FiniteBitSet, vec::IndexVec};
 use rustc_middle::metadata::ModChild;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
+use rustc_middle::middle::resolve_lifetime::ObjectLifetimeDefault;
 use rustc_middle::mir;
 use rustc_middle::ty::fast_reject::SimplifiedType;
 use rustc_middle::ty::query::Providers;
@@ -358,6 +359,7 @@ define_tables! {
     codegen_fn_attrs: Table<DefIndex, LazyValue<CodegenFnAttrs>>,
     impl_trait_ref: Table<DefIndex, LazyValue<ty::TraitRef<'static>>>,
     const_param_default: Table<DefIndex, LazyValue<rustc_middle::ty::Const<'static>>>,
+    object_lifetime_default: Table<DefIndex, LazyValue<ObjectLifetimeDefault>>,
     optimized_mir: Table<DefIndex, LazyValue<mir::Body<'static>>>,
     mir_for_ctfe: Table<DefIndex, LazyValue<mir::Body<'static>>>,
     promoted_mir: Table<DefIndex, LazyValue<IndexVec<mir::Promoted, mir::Body<'static>>>>,

compiler/rustc_middle/src/hir/map/mod.rs

@@ -486,7 +486,9 @@ impl<'hir> Map<'hir> {
         let def_kind = self.tcx.def_kind(def_id);
         match def_kind {
             DefKind::Trait | DefKind::TraitAlias => def_id,
-            DefKind::TyParam | DefKind::ConstParam => self.tcx.local_parent(def_id),
+            DefKind::LifetimeParam | DefKind::TyParam | DefKind::ConstParam => {
+                self.tcx.local_parent(def_id)
+            }
             _ => bug!("ty_param_owner: {:?} is a {:?} not a type parameter", def_id, def_kind),
         }
     }
@@ -495,7 +497,9 @@ impl<'hir> Map<'hir> {
         let def_kind = self.tcx.def_kind(def_id);
         match def_kind {
             DefKind::Trait | DefKind::TraitAlias => kw::SelfUpper,
-            DefKind::TyParam | DefKind::ConstParam => self.tcx.item_name(def_id.to_def_id()),
+            DefKind::LifetimeParam | DefKind::TyParam | DefKind::ConstParam => {
+                self.tcx.item_name(def_id.to_def_id())
+            }
             _ => bug!("ty_param_name: {:?} is a {:?} not a type parameter", def_id, def_kind),
         }
     }

compiler/rustc_middle/src/middle/resolve_lifetime.rs

@@ -10,7 +10,7 @@ use rustc_macros::HashStable;
 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, HashStable)]
 pub enum Region {
     Static,
-    EarlyBound(/* index */ u32, /* lifetime decl */ DefId),
+    EarlyBound(/* lifetime decl */ DefId),
     LateBound(ty::DebruijnIndex, /* late-bound index */ u32, /* lifetime decl */ DefId),
     Free(DefId, /* lifetime decl */ DefId),
 }
@@ -35,7 +35,13 @@ impl<T: PartialEq> Set1<T> {
     }
 }
 
-pub type ObjectLifetimeDefault = Set1<Region>;
+#[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)]
+pub enum ObjectLifetimeDefault {
+    Empty,
+    Static,
+    Ambiguous,
+    Param(DefId),
+}
 
 /// Maps the id of each lifetime reference to the lifetime decl
 /// that it corresponds to.

compiler/rustc_middle/src/query/mod.rs

@@ -1597,8 +1597,9 @@ rustc_queries! {
     /// for each parameter if a trait object were to be passed for that parameter.
     /// For example, for `struct Foo<'a, T, U>`, this would be `['static, 'static]`.
     /// For `struct Foo<'a, T: 'a, U>`, this would instead be `['a, 'static]`.
-    query object_lifetime_defaults(_: LocalDefId) -> Option<&'tcx [ObjectLifetimeDefault]> {
-        desc { "looking up lifetime defaults for a region on an item" }
+    query object_lifetime_default(key: DefId) -> Option<ObjectLifetimeDefault> {
+        desc { "looking up lifetime defaults for generic parameter `{:?}`", key }
+        separate_provide_extern
     }
     query late_bound_vars_map(_: LocalDefId)
         -> Option<&'tcx FxHashMap<ItemLocalId, Vec<ty::BoundVariableKind>>> {

compiler/rustc_middle/src/ty/generics.rs

@@ -1,4 +1,3 @@
-use crate::middle::resolve_lifetime::ObjectLifetimeDefault;
 use crate::ty;
 use crate::ty::subst::{Subst, SubstsRef};
 use crate::ty::EarlyBinder;
@@ -13,7 +12,7 @@ use super::{EarlyBoundRegion, InstantiatedPredicates, ParamConst, ParamTy, Predi
 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
 pub enum GenericParamDefKind {
     Lifetime,
-    Type { has_default: bool, object_lifetime_default: ObjectLifetimeDefault, synthetic: bool },
+    Type { has_default: bool, synthetic: bool },
     Const { has_default: bool },
 }
 

compiler/rustc_middle/src/ty/parameterized.rs

@@ -53,6 +53,7 @@ trivially_parameterized_over_tcx! {
     crate::metadata::ModChild,
     crate::middle::codegen_fn_attrs::CodegenFnAttrs,
     crate::middle::exported_symbols::SymbolExportInfo,
+    crate::middle::resolve_lifetime::ObjectLifetimeDefault,
     crate::mir::ConstQualifs,
     ty::Generics,
     ty::ImplPolarity,