Auto merge of rust-lang#108070 - Dylan-DPC:rollup-v6xw7vk, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - rust-lang#105300 (rework min_choice algorithm of member constraints)
 - rust-lang#107163 (Remove some superfluous type parameters from layout.rs.)
 - rust-lang#107173 (Suggest the correct array length on mismatch)
 - rust-lang#107411 (Handle discriminant in DataflowConstProp)
 - rust-lang#107968 (Enable `#[thread_local]` on armv6k-nintendo-3ds)
 - rust-lang#108032 (Un📦ing the Resolver)
 - rust-lang#108060 (Revert to using `RtlGenRandom` as a fallback)

Failed merges:

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

Author: bors

compiler/rustc_abi/src/layout.rs

@@ -8,6 +8,7 @@ use std::ops::{Add, AddAssign, Mul, RangeInclusive, Sub};
 use std::str::FromStr;
 
 use bitflags::bitflags;
+use rustc_data_structures::intern::Interned;
 #[cfg(feature = "nightly")]
 use rustc_data_structures::stable_hasher::StableOrd;
 use rustc_index::vec::{Idx, IndexVec};
@@ -1250,9 +1251,9 @@ impl Abi {
 
 #[derive(PartialEq, Eq, Hash, Clone, Debug)]
 #[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
-pub enum Variants<V: Idx> {
+pub enum Variants {
     /// Single enum variants, structs/tuples, unions, and all non-ADTs.
-    Single { index: V },
+    Single { index: VariantIdx },
 
     /// Enum-likes with more than one inhabited variant: each variant comes with
     /// a *discriminant* (usually the same as the variant index but the user can
@@ -1262,15 +1263,15 @@ pub enum Variants<V: Idx> {
     /// For enums, the tag is the sole field of the layout.
     Multiple {
         tag: Scalar,
-        tag_encoding: TagEncoding<V>,
+        tag_encoding: TagEncoding,
         tag_field: usize,
-        variants: IndexVec<V, LayoutS<V>>,
+        variants: IndexVec<VariantIdx, LayoutS>,
     },
 }
 
 #[derive(PartialEq, Eq, Hash, Clone, Debug)]
 #[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
-pub enum TagEncoding<V: Idx> {
+pub enum TagEncoding {
     /// The tag directly stores the discriminant, but possibly with a smaller layout
     /// (so converting the tag to the discriminant can require sign extension).
     Direct,
@@ -1285,7 +1286,11 @@ pub enum TagEncoding<V: Idx> {
     /// For example, `Option<(usize, &T)>`  is represented such that
     /// `None` has a null pointer for the second tuple field, and
     /// `Some` is the identity function (with a non-null reference).
-    Niche { untagged_variant: V, niche_variants: RangeInclusive<V>, niche_start: u128 },
+    Niche {
+        untagged_variant: VariantIdx,
+        niche_variants: RangeInclusive<VariantIdx>,
+        niche_start: u128,
+    },
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
@@ -1372,9 +1377,14 @@ impl Niche {
     }
 }
 
+rustc_index::newtype_index! {
+    #[derive(HashStable_Generic)]
+    pub struct VariantIdx {}
+}
+
 #[derive(PartialEq, Eq, Hash, Clone)]
 #[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
-pub struct LayoutS<V: Idx> {
+pub struct LayoutS {
     /// Says where the fields are located within the layout.
     pub fields: FieldsShape,
 
@@ -1385,7 +1395,7 @@ pub struct LayoutS<V: Idx> {
     ///
     /// To access all fields of this layout, both `fields` and the fields of the active variant
     /// must be taken into account.
-    pub variants: Variants<V>,
+    pub variants: Variants,
 
     /// The `abi` defines how this data is passed between functions, and it defines
     /// value restrictions via `valid_range`.
@@ -1404,13 +1414,13 @@ pub struct LayoutS<V: Idx> {
     pub size: Size,
 }
 
-impl<V: Idx> LayoutS<V> {
+impl LayoutS {
     pub fn scalar<C: HasDataLayout>(cx: &C, scalar: Scalar) -> Self {
         let largest_niche = Niche::from_scalar(cx, Size::ZERO, scalar);
         let size = scalar.size(cx);
         let align = scalar.align(cx);
         LayoutS {
-            variants: Variants::Single { index: V::new(0) },
+            variants: Variants::Single { index: VariantIdx::new(0) },
             fields: FieldsShape::Primitive,
             abi: Abi::Scalar(scalar),
             largest_niche,
@@ -1420,7 +1430,7 @@ impl<V: Idx> LayoutS<V> {
     }
 }
 
-impl<V: Idx> fmt::Debug for LayoutS<V> {
+impl fmt::Debug for LayoutS {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // This is how `Layout` used to print before it become
         // `Interned<LayoutS>`. We print it like this to avoid having to update
@@ -1437,6 +1447,43 @@ impl<V: Idx> fmt::Debug for LayoutS<V> {
     }
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable_Generic)]
+#[rustc_pass_by_value]
+pub struct Layout<'a>(pub Interned<'a, LayoutS>);
+
+impl<'a> fmt::Debug for Layout<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // See comment on `<LayoutS as Debug>::fmt` above.
+        self.0.0.fmt(f)
+    }
+}
+
+impl<'a> Layout<'a> {
+    pub fn fields(self) -> &'a FieldsShape {
+        &self.0.0.fields
+    }
+
+    pub fn variants(self) -> &'a Variants {
+        &self.0.0.variants
+    }
+
+    pub fn abi(self) -> Abi {
+        self.0.0.abi
+    }
+
+    pub fn largest_niche(self) -> Option<Niche> {
+        self.0.0.largest_niche
+    }
+
+    pub fn align(self) -> AbiAndPrefAlign {
+        self.0.0.align
+    }
+
+    pub fn size(self) -> Size {
+        self.0.0.size
+    }
+}
+
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum PointerKind {
     /// Shared reference. `frozen` indicates the absence of any `UnsafeCell`.
@@ -1464,7 +1511,7 @@ pub enum InitKind {
     UninitMitigated0x01Fill,
 }
 
-impl<V: Idx> LayoutS<V> {
+impl LayoutS {
     /// Returns `true` if the layout corresponds to an unsized type.
     pub fn is_unsized(&self) -> bool {
         self.abi.is_unsized()

compiler/rustc_abi/src/lib.rs

@@ -746,20 +746,33 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         }
         debug!(?choice_regions, "after ub");
 
-        // If we ruled everything out, we're done.
-        if choice_regions.is_empty() {
-            return false;
-        }
-
-        // Otherwise, we need to find the minimum remaining choice, if
-        // any, and take that.
-        debug!("choice_regions remaining are {:#?}", choice_regions);
-        let Some(&min_choice) = choice_regions.iter().find(|&r1| {
+        // At this point we can pick any member of `choice_regions`, but to avoid potential
+        // non-determinism we will pick the *unique minimum* choice.
+        //
+        // Because universal regions are only partially ordered (i.e, not every two regions are
+        // comparable), we will ignore any region that doesn't compare to all others when picking
+        // the minimum choice.
+        // For example, consider `choice_regions = ['static, 'a, 'b, 'c, 'd, 'e]`, where
+        // `'static: 'a, 'static: 'b, 'a: 'c, 'b: 'c, 'c: 'd, 'c: 'e`.
+        // `['d, 'e]` are ignored because they do not compare - the same goes for `['a, 'b]`.
+        let totally_ordered_subset = choice_regions.iter().copied().filter(|&r1| {
             choice_regions.iter().all(|&r2| {
-                self.universal_region_relations.outlives(r2, *r1)
+                self.universal_region_relations.outlives(r1, r2)
+                    || self.universal_region_relations.outlives(r2, r1)
             })
+        });
+        // Now we're left with `['static, 'c]`. Pick `'c` as the minimum!
+        let Some(min_choice) = totally_ordered_subset.reduce(|r1, r2| {
+            let r1_outlives_r2 = self.universal_region_relations.outlives(r1, r2);
+            let r2_outlives_r1 = self.universal_region_relations.outlives(r2, r1);
+            match (r1_outlives_r2, r2_outlives_r1) {
+                (true, true) => r1.min(r2),
+                (true, false) => r2,
+                (false, true) => r1,
+                (false, false) => bug!("incomparable regions in total order"),
+            }
         }) else {
-            debug!("no choice region outlived by all others");
+            debug!("no unique minimum choice");
             return false;
         };
 

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -64,6 +64,7 @@ use rustc_errors::{Applicability, DiagnosticBuilder, DiagnosticStyledString};
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::intravisit::Visitor;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::Node;
 use rustc_middle::dep_graph::DepContext;
@@ -1985,6 +1986,70 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                         (ty::Bool, ty::Tuple(list)) => if list.len() == 0 {
                             self.suggest_let_for_letchains(&mut err, &trace.cause, span);
                         }
+                        (ty::Array(_, _), ty::Array(_, _)) => 'block: {
+                            let hir = self.tcx.hir();
+                            let TypeError::FixedArraySize(sz) = terr else {
+                                break 'block;
+                            };
+                            let tykind = match hir.find_by_def_id(trace.cause.body_id) {
+                                Some(hir::Node::Item(hir::Item {
+                                    kind: hir::ItemKind::Fn(_, _, body_id),
+                                    ..
+                                })) => {
+                                    let body = hir.body(*body_id);
+                                    struct LetVisitor<'v> {
+                                        span: Span,
+                                        result: Option<&'v hir::Ty<'v>>,
+                                    }
+                                    impl<'v> Visitor<'v> for LetVisitor<'v> {
+                                        fn visit_stmt(&mut self, s: &'v hir::Stmt<'v>) {
+                                            if self.result.is_some() {
+                                                return;
+                                            }
+                                            // Find a local statement where the initializer has
+                                            // the same span as the error and the type is specified.
+                                            if let hir::Stmt {
+                                                kind: hir::StmtKind::Local(hir::Local {
+                                                    init: Some(hir::Expr {
+                                                        span: init_span,
+                                                        ..
+                                                    }),
+                                                    ty: Some(array_ty),
+                                                    ..
+                                                }),
+                                                ..
+                                            } = s
+                                            && init_span == &self.span {
+                                                self.result = Some(*array_ty);
+                                            }
+                                        }
+                                    }
+                                    let mut visitor = LetVisitor {span, result: None};
+                                    visitor.visit_body(body);
+                                    visitor.result.map(|r| &r.peel_refs().kind)
+                                }
+                                Some(hir::Node::Item(hir::Item {
+                                    kind: hir::ItemKind::Const(ty, _),
+                                    ..
+                                })) => {
+                                    Some(&ty.peel_refs().kind)
+                                }
+                                _ => None
+                            };
+
+                            if let Some(tykind) = tykind
+                                && let hir::TyKind::Array(_, length) = tykind
+                                && let hir::ArrayLen::Body(hir::AnonConst { hir_id, .. }) = length
+                                && let Some(span) = self.tcx.hir().opt_span(*hir_id)
+                            {
+                                err.span_suggestion(
+                                    span,
+                                    "consider specifying the actual array length",
+                                    sz.found,
+                                    Applicability::MaybeIncorrect,
+                                );
+                            }
+                        }
                         _ => {}
                     }
                 }

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

@@ -1,4 +1,3 @@
-pub use crate::passes::BoxedResolver;
 use crate::util;
 
 use rustc_ast::token;

compiler/rustc_interface/src/interface.rs

@@ -23,9 +23,9 @@ use rustc_parse::{parse_crate_from_file, parse_crate_from_source_str, validate_a
 use rustc_passes::{self, hir_stats, layout_test};
 use rustc_plugin_impl as plugin;
 use rustc_query_impl::{OnDiskCache, Queries as TcxQueries};
-use rustc_resolve::{Resolver, ResolverArenas};
+use rustc_resolve::Resolver;
 use rustc_session::config::{CrateType, Input, OutputFilenames, OutputType};
-use rustc_session::cstore::{CrateStoreDyn, MetadataLoader, MetadataLoaderDyn, Untracked};
+use rustc_session::cstore::{CrateStoreDyn, MetadataLoader, Untracked};
 use rustc_session::output::filename_for_input;
 use rustc_session::search_paths::PathKind;
 use rustc_session::{Limit, Session};
@@ -37,9 +37,7 @@ use rustc_trait_selection::traits;
 use std::any::Any;
 use std::ffi::OsString;
 use std::io::{self, BufWriter, Write};
-use std::marker::PhantomPinned;
 use std::path::{Path, PathBuf};
-use std::pin::Pin;
 use std::sync::{Arc, LazyLock};
 use std::{env, fs, iter};
 
@@ -73,84 +71,6 @@ fn count_nodes(krate: &ast::Crate) -> usize {
     counter.count
 }
 
-pub use boxed_resolver::BoxedResolver;
-mod boxed_resolver {
-    use super::*;
-
-    pub struct BoxedResolver(Pin<Box<BoxedResolverInner>>);
-
-    struct BoxedResolverInner {
-        session: Lrc<Session>,
-        resolver_arenas: Option<ResolverArenas<'static>>,
-        resolver: Option<Resolver<'static>>,
-        _pin: PhantomPinned,
-    }
-
-    // Note: Drop order is important to prevent dangling references. Resolver must be dropped first,
-    // then resolver_arenas and session.
-    impl Drop for BoxedResolverInner {
-        fn drop(&mut self) {
-            self.resolver.take();
-            self.resolver_arenas.take();
-        }
-    }
-
-    impl BoxedResolver {
-        pub(super) fn new(
-            session: Lrc<Session>,
-            make_resolver: impl for<'a> FnOnce(&'a Session, &'a ResolverArenas<'a>) -> Resolver<'a>,
-        ) -> BoxedResolver {
-            let mut boxed_resolver = Box::new(BoxedResolverInner {
-                session,
-                resolver_arenas: Some(Resolver::arenas()),
-                resolver: None,
-                _pin: PhantomPinned,
-            });
-            // SAFETY: `make_resolver` takes a resolver arena with an arbitrary lifetime and
-            // returns a resolver with the same lifetime as the arena. We ensure that the arena
-            // outlives the resolver in the drop impl and elsewhere so these transmutes are sound.
-            unsafe {
-                let resolver = make_resolver(
-                    std::mem::transmute::<&Session, &Session>(&boxed_resolver.session),
-                    std::mem::transmute::<&ResolverArenas<'_>, &ResolverArenas<'_>>(
-                        boxed_resolver.resolver_arenas.as_ref().unwrap(),
-                    ),
-                );
-                boxed_resolver.resolver = Some(resolver);
-                BoxedResolver(Pin::new_unchecked(boxed_resolver))
-            }
-        }
-
-        pub fn access<F: for<'a> FnOnce(&mut Resolver<'a>) -> R, R>(&mut self, f: F) -> R {
-            // SAFETY: The resolver doesn't need to be pinned.
-            let mut resolver = unsafe {
-                self.0.as_mut().map_unchecked_mut(|boxed_resolver| &mut boxed_resolver.resolver)
-            };
-            f((&mut *resolver).as_mut().unwrap())
-        }
-
-        pub fn into_outputs(mut self) -> ty::ResolverOutputs {
-            // SAFETY: The resolver doesn't need to be pinned.
-            let mut resolver = unsafe {
-                self.0.as_mut().map_unchecked_mut(|boxed_resolver| &mut boxed_resolver.resolver)
-            };
-            resolver.take().unwrap().into_outputs()
-        }
-    }
-}
-
-pub fn create_resolver(
-    sess: Lrc<Session>,
-    metadata_loader: Box<MetadataLoaderDyn>,
-    krate: &ast::Crate,
-    crate_name: Symbol,
-) -> BoxedResolver {
-    trace!("create_resolver");
-    BoxedResolver::new(sess, move |sess, resolver_arenas| {
-        Resolver::new(sess, krate, crate_name, metadata_loader, resolver_arenas)
-    })
-}
-
 pub fn register_plugins<'a>(
     sess: &'a Session,
     metadata_loader: &'a dyn MetadataLoader,
@@ -256,7 +176,7 @@ pub fn configure_and_expand(
     lint_store: &LintStore,
     mut krate: ast::Crate,
     crate_name: Symbol,
-    resolver: &mut Resolver<'_>,
+    resolver: &mut Resolver<'_, '_>,
 ) -> Result<ast::Crate> {
     trace!("configure_and_expand");
     pre_expansion_lint(sess, lint_store, resolver.registered_tools(), &krate, crate_name);