Auto merge of #109019 - matthiaskrgr:rollup-ihjntil, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - #104363 (Make `unused_allocation` lint against `Box::new` too)
 - #106633 (Stabilize `nonzero_min_max`)
 - #106844 (allow negative numeric literals in `concat!`)
 - #108071 (Implement goal caching with the new solver)
 - #108542 (Force parentheses around `match` expression in binary expression)
 - #108690 (Place size limits on query keys and values)
 - #108708 (Prevent overflow through Arc::downgrade)
 - #108739 (Prevent the `start_bx` basic block in codegen from having two `Builder`s at the same time)
 - #108806 (Querify register_tools and post-expansion early lints)

Failed merges:

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

compiler/rustc_ast_lowering/src/lib.rs

@@ -436,6 +436,7 @@ fn compute_hir_hash(
 pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> hir::Crate<'_> {
     let sess = tcx.sess;
     tcx.ensure().output_filenames(());
+    let _ = tcx.early_lint_checks(()); // Borrows `resolver_for_lowering`.
     let (mut resolver, krate) = tcx.resolver_for_lowering(()).steal();
 
     let ast_index = index_crate(&resolver.node_id_to_def_id, &krate);

compiler/rustc_ast_pretty/src/pprust/state/expr.rs

@@ -244,6 +244,10 @@ impl<'a> State<'a> {
             (&ast::ExprKind::Let { .. }, _) if !parser::needs_par_as_let_scrutinee(prec) => {
                 parser::PREC_FORCE_PAREN
             }
+            // For a binary expression like `(match () { _ => a }) OP b`, the parens are required
+            // otherwise the parser would interpret `match () { _ => a }` as a statement,
+            // with the remaining `OP b` not making sense. So we force parens.
+            (&ast::ExprKind::Match(..), _) => parser::PREC_FORCE_PAREN,
             _ => left_prec,
         };
 

compiler/rustc_builtin_macros/src/concat.rs

@@ -42,6 +42,18 @@ pub fn expand_concat(
                     has_errors = true;
                 }
             },
+            // We also want to allow negative numeric literals.
+            ast::ExprKind::Unary(ast::UnOp::Neg, ref expr) if let ast::ExprKind::Lit(token_lit) = expr.kind => {
+                match ast::LitKind::from_token_lit(token_lit) {
+                    Ok(ast::LitKind::Int(i, _)) => accumulator.push_str(&format!("-{i}")),
+                    Ok(ast::LitKind::Float(f, _)) => accumulator.push_str(&format!("-{f}")),
+                    Err(err) => {
+                        report_lit_error(&cx.sess.parse_sess, err, token_lit, e.span);
+                        has_errors = true;
+                    }
+                    _ => missing_literal.push(e.span),
+                }
+            }
             ast::ExprKind::IncludedBytes(..) => {
                 cx.span_err(e.span, "cannot concatenate a byte string literal")
             }
@@ -53,9 +65,10 @@ pub fn expand_concat(
             }
         }
     }
+
     if !missing_literal.is_empty() {
         let mut err = cx.struct_span_err(missing_literal, "expected a literal");
-        err.note("only literals (like `\"foo\"`, `42` and `3.14`) can be passed to `concat!()`");
+        err.note("only literals (like `\"foo\"`, `-42` and `3.14`) can be passed to `concat!()`");
         err.emit();
         return DummyResult::any(sp);
     } else if has_errors {

compiler/rustc_codegen_ssa/src/mir/mod.rs

@@ -258,6 +258,10 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     // Apply debuginfo to the newly allocated locals.
     fx.debug_introduce_locals(&mut start_bx);
 
+    // The builders will be created separately for each basic block at `codegen_block`.
+    // So drop the builder of `start_llbb` to avoid having two at the same time.
+    drop(start_bx);
+
     // Codegen the body of each block using reverse postorder
     for (bb, _) in traversal::reverse_postorder(&mir) {
         fx.codegen_block(bb);

compiler/rustc_driver_impl/src/lib.rs

@@ -331,6 +331,7 @@ fn run_compiler(
             if let Some(ppm) = &sess.opts.pretty {
                 if ppm.needs_ast_map() {
                     queries.global_ctxt()?.enter(|tcx| {
+                        tcx.ensure().early_lint_checks(());
                         pretty::print_after_hir_lowering(tcx, *ppm);
                         Ok(())
                     })?;

compiler/rustc_expand/src/base.rs

@@ -12,13 +12,13 @@ use rustc_ast::tokenstream::TokenStream;
 use rustc_ast::visit::{AssocCtxt, Visitor};
 use rustc_ast::{self as ast, AttrVec, Attribute, HasAttrs, Item, NodeId, PatKind};
 use rustc_attr::{self as attr, Deprecation, Stability};
-use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::sync::{self, Lrc};
 use rustc_errors::{
     Applicability, DiagnosticBuilder, ErrorGuaranteed, IntoDiagnostic, MultiSpan, PResult,
 };
 use rustc_lint_defs::builtin::PROC_MACRO_BACK_COMPAT;
-use rustc_lint_defs::{BufferedEarlyLint, BuiltinLintDiagnostics};
+use rustc_lint_defs::{BufferedEarlyLint, BuiltinLintDiagnostics, RegisteredTools};
 use rustc_parse::{self, parser, MACRO_ARGUMENTS};
 use rustc_session::errors::report_lit_error;
 use rustc_session::{parse::ParseSess, Limit, Session};
@@ -947,14 +947,14 @@ pub trait ResolverExpand {
     fn declare_proc_macro(&mut self, id: NodeId);
 
     /// Tools registered with `#![register_tool]` and used by tool attributes and lints.
-    fn registered_tools(&self) -> &FxHashSet<Ident>;
+    fn registered_tools(&self) -> &RegisteredTools;
 }
 
 pub trait LintStoreExpand {
     fn pre_expansion_lint(
         &self,
         sess: &Session,
-        registered_tools: &FxHashSet<Ident>,
+        registered_tools: &RegisteredTools,
         node_id: NodeId,
         attrs: &[Attribute],
         items: &[P<Item>],

compiler/rustc_infer/src/traits/mod.rs

@@ -53,6 +53,12 @@ pub struct Obligation<'tcx, T> {
     pub recursion_depth: usize,
 }
 
+impl<'tcx, P> From<Obligation<'tcx, P>> for solve::Goal<'tcx, P> {
+    fn from(value: Obligation<'tcx, P>) -> Self {
+        solve::Goal { param_env: value.param_env, predicate: value.predicate }
+    }
+}
+
 pub type PredicateObligation<'tcx> = Obligation<'tcx, ty::Predicate<'tcx>>;
 pub type TraitObligation<'tcx> = Obligation<'tcx, ty::PolyTraitPredicate<'tcx>>;
 

compiler/rustc_interface/src/passes.rs

@@ -11,7 +11,7 @@ use rustc_data_structures::parallel;
 use rustc_data_structures::steal::Steal;
 use rustc_data_structures::sync::{Lrc, OnceCell, WorkerLocal};
 use rustc_errors::PResult;
-use rustc_expand::base::{ExtCtxt, LintStoreExpand, ResolverExpand};
+use rustc_expand::base::{ExtCtxt, LintStoreExpand};
 use rustc_hir::def_id::{StableCrateId, LOCAL_CRATE};
 use rustc_lint::{unerased_lint_store, BufferedEarlyLint, EarlyCheckNode, LintStore};
 use rustc_metadata::creader::CStore;
@@ -178,7 +178,7 @@ fn configure_and_expand(mut krate: ast::Crate, resolver: &mut Resolver<'_, '_>)
     let sess = tcx.sess;
     let lint_store = unerased_lint_store(tcx);
     let crate_name = tcx.crate_name(LOCAL_CRATE);
-    pre_expansion_lint(sess, lint_store, resolver.registered_tools(), &krate, crate_name);
+    pre_expansion_lint(sess, lint_store, tcx.registered_tools(()), &krate, crate_name);
     rustc_builtin_macros::register_builtin_macros(resolver);
 
     krate = sess.time("crate_injection", || {
@@ -302,6 +302,16 @@ fn configure_and_expand(mut krate: ast::Crate, resolver: &mut Resolver<'_, '_>)
 
     // Done with macro expansion!
 
+    resolver.resolve_crate(&krate);
+
+    krate
+}
+
+fn early_lint_checks(tcx: TyCtxt<'_>, (): ()) {
+    let sess = tcx.sess;
+    let (resolver, krate) = &*tcx.resolver_for_lowering(()).borrow();
+    let mut lint_buffer = resolver.lint_buffer.steal();
+
     if sess.opts.unstable_opts.input_stats {
         eprintln!("Post-expansion node count: {}", count_nodes(&krate));
     }
@@ -310,8 +320,6 @@ fn configure_and_expand(mut krate: ast::Crate, resolver: &mut Resolver<'_, '_>)
         hir_stats::print_ast_stats(&krate, "POST EXPANSION AST STATS", "ast-stats-2");
     }
 
-    resolver.resolve_crate(&krate);
-
     // Needs to go *after* expansion to be able to check the results of macro expansion.
     sess.time("complete_gated_feature_checking", || {
         rustc_ast_passes::feature_gate::check_crate(&krate, sess);
@@ -321,7 +329,7 @@ fn configure_and_expand(mut krate: ast::Crate, resolver: &mut Resolver<'_, '_>)
     sess.parse_sess.buffered_lints.with_lock(|buffered_lints| {
         info!("{} parse sess buffered_lints", buffered_lints.len());
         for early_lint in buffered_lints.drain(..) {
-            resolver.lint_buffer().add_early_lint(early_lint);
+            lint_buffer.add_early_lint(early_lint);
         }
     });
 
@@ -340,20 +348,16 @@ fn configure_and_expand(mut krate: ast::Crate, resolver: &mut Resolver<'_, '_>)
         }
     });
 
-    sess.time("early_lint_checks", || {
+    let lint_store = unerased_lint_store(tcx);
-        let lint_buffer = Some(std::mem::take(resolver.lint_buffer()));
+    rustc_lint::check_ast_node(
-        rustc_lint::check_ast_node(
+        sess,
-            sess,
+        false,
-            false,
+        lint_store,
-            lint_store,
+        tcx.registered_tools(()),
-            resolver.registered_tools(),
+        Some(lint_buffer),
-            lint_buffer,
+        rustc_lint::BuiltinCombinedEarlyLintPass::new(),
-            rustc_lint::BuiltinCombinedEarlyLintPass::new(),
+        &**krate,
-            &krate,
+    )
-        )
-    });
-
-    krate
 }
 
 // Returns all the paths that correspond to generated files.
@@ -557,6 +561,7 @@ fn resolver_for_lowering<'tcx>(
     (): (),
 ) -> &'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)> {
     let arenas = Resolver::arenas();
+    let _ = tcx.registered_tools(()); // Uses `crate_for_resolver`.
     let krate = tcx.crate_for_resolver(()).steal();
     let mut resolver = Resolver::new(tcx, &krate, &arenas);
     let krate = configure_and_expand(krate, &mut resolver);
@@ -629,6 +634,7 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
     providers.hir_crate = rustc_ast_lowering::lower_to_hir;
     providers.output_filenames = output_filenames;
     providers.resolver_for_lowering = resolver_for_lowering;
+    providers.early_lint_checks = early_lint_checks;
     proc_macro_decls::provide(providers);
     rustc_const_eval::provide(providers);
     rustc_middle::hir::provide(providers);
@@ -637,6 +643,7 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
     rustc_mir_transform::provide(providers);
     rustc_monomorphize::provide(providers);
     rustc_privacy::provide(providers);
+    rustc_resolve::provide(providers);
     rustc_hir_analysis::provide(providers);
     rustc_hir_typeck::provide(providers);
     ty::provide(providers);

compiler/rustc_lint/src/levels.rs

@@ -128,7 +128,7 @@ fn lint_expectations(tcx: TyCtxt<'_>, (): ()) -> Vec<(LintExpectationId, LintExp
         },
         warn_about_weird_lints: false,
         store,
-        registered_tools: &tcx.resolutions(()).registered_tools,
+        registered_tools: &tcx.registered_tools(()),
     };
 
     builder.add_command_line();
@@ -156,7 +156,7 @@ fn shallow_lint_levels_on(tcx: TyCtxt<'_>, owner: hir::OwnerId) -> ShallowLintLe
         },
         warn_about_weird_lints: false,
         store,
-        registered_tools: &tcx.resolutions(()).registered_tools,
+        registered_tools: &tcx.registered_tools(()),
     };
 
     if owner == hir::CRATE_OWNER_ID {

compiler/rustc_lint/src/unused.rs

@@ -1349,9 +1349,8 @@ declare_lint! {
     /// ### Example
     ///
     /// ```rust
-    /// #![feature(box_syntax)]
     /// fn main() {
-    ///     let a = (box [1, 2, 3]).len();
+    ///     let a = Box::new([1, 2, 3]).len();
     /// }
     /// ```
     ///
@@ -1373,6 +1372,11 @@ impl<'tcx> LateLintPass<'tcx> for UnusedAllocation {
     fn check_expr(&mut self, cx: &LateContext<'_>, e: &hir::Expr<'_>) {
         match e.kind {
             hir::ExprKind::Box(_) => {}
+            hir::ExprKind::Call(path_expr, [_])
+                if let hir::ExprKind::Path(qpath) = &path_expr.kind
+                && let Some(did) = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()
+                && cx.tcx.is_diagnostic_item(sym::box_new, did)
+                => {}
             _ => return,
         }
 

compiler/rustc_lint_defs/src/lib.rs

@@ -8,7 +8,7 @@ extern crate rustc_macros;
 pub use self::Level::*;
 use rustc_ast::node_id::NodeId;
 use rustc_ast::{AttrId, Attribute};
-use rustc_data_structures::fx::FxIndexMap;
+use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
 use rustc_error_messages::{DiagnosticMessage, MultiSpan};
 use rustc_hir::HashStableContext;
@@ -533,6 +533,7 @@ pub enum BuiltinLintDiagnostics {
 
 /// Lints that are buffered up early on in the `Session` before the
 /// `LintLevels` is calculated.
+#[derive(Debug)]
 pub struct BufferedEarlyLint {
     /// The span of code that we are linting on.
     pub span: MultiSpan,
@@ -551,7 +552,7 @@ pub struct BufferedEarlyLint {
     pub diagnostic: BuiltinLintDiagnostics,
 }
 
-#[derive(Default)]
+#[derive(Default, Debug)]
 pub struct LintBuffer {
     pub map: FxIndexMap<NodeId, Vec<BufferedEarlyLint>>,
 }
@@ -601,6 +602,8 @@ impl LintBuffer {
     }
 }
 
+pub type RegisteredTools = FxIndexSet<Ident>;
+
 /// Declares a static item of type `&'static Lint`.
 ///
 /// See <https://rustc-dev-guide.rust-lang.org/diagnostics.html> for

compiler/rustc_middle/src/arena.rs

@@ -108,6 +108,7 @@ macro_rules! arena_types {
             // (during lowering) and the `librustc_middle` arena (for decoding MIR)
             [decode] asm_template: rustc_ast::InlineAsmTemplatePiece,
             [decode] used_trait_imports: rustc_data_structures::unord::UnordSet<rustc_hir::def_id::LocalDefId>,
+            [decode] registered_tools: rustc_middle::ty::RegisteredTools,
             [decode] is_late_bound_map: rustc_data_structures::fx::FxIndexSet<rustc_hir::ItemLocalId>,
             [decode] impl_source: rustc_middle::traits::ImplSource<'tcx, ()>,
 

compiler/rustc_middle/src/query/mod.rs

@@ -26,6 +26,15 @@ rustc_queries! {
         desc { "triggering a delay span bug" }
     }
 
+    query registered_tools(_: ()) -> &'tcx ty::RegisteredTools {
+        arena_cache
+        desc { "compute registered tools for crate" }
+    }
+
+    query early_lint_checks(_: ()) -> () {
+        desc { "perform lints prior to macro expansion" }
+    }
+
     query resolutions(_: ()) -> &'tcx ty::ResolverGlobalCtxt {
         feedable
         no_hash

compiler/rustc_middle/src/traits/solve.rs

@@ -1,12 +1,104 @@
 use std::ops::ControlFlow;
 
 use rustc_data_structures::intern::Interned;
+use rustc_query_system::cache::Cache;
 
-use crate::infer::canonical::QueryRegionConstraints;
+use crate::infer::canonical::{CanonicalVarValues, QueryRegionConstraints};
+use crate::traits::query::NoSolution;
+use crate::traits::Canonical;
 use crate::ty::{
-    FallibleTypeFolder, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeVisitable, TypeVisitor,
+    self, FallibleTypeFolder, ToPredicate, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeVisitable,
+    TypeVisitor,
 };
 
+pub type EvaluationCache<'tcx> = Cache<CanonicalGoal<'tcx>, QueryResult<'tcx>>;
+
+/// A goal is a statement, i.e. `predicate`, we want to prove
+/// given some assumptions, i.e. `param_env`.
+///
+/// Most of the time the `param_env` contains the `where`-bounds of the function
+/// we're currently typechecking while the `predicate` is some trait bound.
+#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, TypeFoldable, TypeVisitable)]
+pub struct Goal<'tcx, P> {
+    pub param_env: ty::ParamEnv<'tcx>,
+    pub predicate: P,
+}
+
+impl<'tcx, P> Goal<'tcx, P> {
+    pub fn new(
+        tcx: TyCtxt<'tcx>,
+        param_env: ty::ParamEnv<'tcx>,
+        predicate: impl ToPredicate<'tcx, P>,
+    ) -> Goal<'tcx, P> {
+        Goal { param_env, predicate: predicate.to_predicate(tcx) }
+    }
+
+    /// Updates the goal to one with a different `predicate` but the same `param_env`.
+    pub fn with<Q>(self, tcx: TyCtxt<'tcx>, predicate: impl ToPredicate<'tcx, Q>) -> Goal<'tcx, Q> {
+        Goal { param_env: self.param_env, predicate: predicate.to_predicate(tcx) }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, TypeFoldable, TypeVisitable)]
+pub struct Response<'tcx> {
+    pub var_values: CanonicalVarValues<'tcx>,
+    /// Additional constraints returned by this query.
+    pub external_constraints: ExternalConstraints<'tcx>,
+    pub certainty: Certainty,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, TypeFoldable, TypeVisitable)]
+pub enum Certainty {
+    Yes,
+    Maybe(MaybeCause),
+}
+
+impl Certainty {
+    pub const AMBIGUOUS: Certainty = Certainty::Maybe(MaybeCause::Ambiguity);
+
+    /// When proving multiple goals using **AND**, e.g. nested obligations for an impl,
+    /// use this function to unify the certainty of these goals
+    pub fn unify_and(self, other: Certainty) -> Certainty {
+        match (self, other) {
+            (Certainty::Yes, Certainty::Yes) => Certainty::Yes,
+            (Certainty::Yes, Certainty::Maybe(_)) => other,
+            (Certainty::Maybe(_), Certainty::Yes) => self,
+            (Certainty::Maybe(MaybeCause::Overflow), Certainty::Maybe(MaybeCause::Overflow)) => {
+                Certainty::Maybe(MaybeCause::Overflow)
+            }
+            // If at least one of the goals is ambiguous, hide the overflow as the ambiguous goal
+            // may still result in failure.
+            (Certainty::Maybe(MaybeCause::Ambiguity), Certainty::Maybe(_))
+            | (Certainty::Maybe(_), Certainty::Maybe(MaybeCause::Ambiguity)) => {
+                Certainty::Maybe(MaybeCause::Ambiguity)
+            }
+        }
+    }
+}
+
+/// Why we failed to evaluate a goal.
+#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, TypeFoldable, TypeVisitable)]
+pub enum MaybeCause {
+    /// We failed due to ambiguity. This ambiguity can either
+    /// be a true ambiguity, i.e. there are multiple different answers,
+    /// or we hit a case where we just don't bother, e.g. `?x: Trait` goals.
+    Ambiguity,
+    /// We gave up due to an overflow, most often by hitting the recursion limit.
+    Overflow,
+}
+
+pub type CanonicalGoal<'tcx, T = ty::Predicate<'tcx>> = Canonical<'tcx, Goal<'tcx, T>>;
+
+pub type CanonicalResponse<'tcx> = Canonical<'tcx, Response<'tcx>>;
+
+/// The result of evaluating a canonical query.
+///
+/// FIXME: We use a different type than the existing canonical queries. This is because
+/// we need to add a `Certainty` for `overflow` and may want to restructure this code without
+/// having to worry about changes to currently used code. Once we've made progress on this
+/// solver, merge the two responses again.
+pub type QueryResult<'tcx> = Result<CanonicalResponse<'tcx>, NoSolution>;
+
 #[derive(Debug, PartialEq, Eq, Copy, Clone, Hash)]
 pub struct ExternalConstraints<'tcx>(pub(crate) Interned<'tcx, ExternalConstraintsData<'tcx>>);
 

compiler/rustc_middle/src/ty/context.rs

@@ -17,6 +17,7 @@ use crate::mir::{
 };
 use crate::thir::Thir;
 use crate::traits;
+use crate::traits::solve;
 use crate::traits::solve::{ExternalConstraints, ExternalConstraintsData};
 use crate::ty::query::{self, TyCtxtAt};
 use crate::ty::{
@@ -537,6 +538,9 @@ pub struct GlobalCtxt<'tcx> {
     /// Merge this with `selection_cache`?
     pub evaluation_cache: traits::EvaluationCache<'tcx>,
 
+    /// Caches the results of goal evaluation in the new solver.
+    pub new_solver_evaluation_cache: solve::EvaluationCache<'tcx>,
+
     /// Data layout specification for the current target.
     pub data_layout: TargetDataLayout,
 
@@ -712,6 +716,7 @@ impl<'tcx> TyCtxt<'tcx> {
             pred_rcache: Default::default(),
             selection_cache: Default::default(),
             evaluation_cache: Default::default(),
+            new_solver_evaluation_cache: Default::default(),
             data_layout,
             alloc_map: Lock::new(interpret::AllocMap::new()),
         }

compiler/rustc_middle/src/ty/mod.rs

@@ -34,6 +34,7 @@ use rustc_attr as attr;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_data_structures::intern::Interned;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_data_structures::steal::Steal;
 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
@@ -44,6 +45,8 @@ use rustc_index::vec::IndexVec;
 use rustc_macros::HashStable;
 use rustc_query_system::ich::StableHashingContext;
 use rustc_serialize::{Decodable, Encodable};
+use rustc_session::lint::LintBuffer;
+pub use rustc_session::lint::RegisteredTools;
 use rustc_span::hygiene::MacroKind;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{ExpnId, ExpnKind, Span};
@@ -148,8 +151,6 @@ mod typeck_results;
 
 // Data types
 
-pub type RegisteredTools = FxHashSet<Ident>;
-
 pub struct ResolverOutputs {
     pub global_ctxt: ResolverGlobalCtxt,
     pub ast_lowering: ResolverAstLowering,
@@ -175,7 +176,6 @@ pub struct ResolverGlobalCtxt {
     /// Mapping from ident span to path span for paths that don't exist as written, but that
     /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
     pub confused_type_with_std_module: FxHashMap<Span, Span>,
-    pub registered_tools: RegisteredTools,
     pub doc_link_resolutions: FxHashMap<LocalDefId, DocLinkResMap>,
     pub doc_link_traits_in_scope: FxHashMap<LocalDefId, Vec<DefId>>,
     pub all_macro_rules: FxHashMap<Symbol, Res<ast::NodeId>>,
@@ -209,6 +209,9 @@ pub struct ResolverAstLowering {
     pub builtin_macro_kinds: FxHashMap<LocalDefId, MacroKind>,
     /// List functions and methods for which lifetime elision was successful.
     pub lifetime_elision_allowed: FxHashSet<ast::NodeId>,
+
+    /// Lints that were emitted by the resolver and early lints.
+    pub lint_buffer: Steal<LintBuffer>,
 }
 
 #[derive(Clone, Copy, Debug)]

compiler/rustc_middle/src/ty/query.rs

@@ -252,6 +252,36 @@ macro_rules! define_callbacks {
             )*
         }
 
+        $(
+            // Ensure that keys grow no larger than 64 bytes
+            #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
+            const _: () = {
+                if mem::size_of::<query_keys::$name<'static>>() > 64 {
+                    panic!("{}", concat!(
+                        "the query `",
+                        stringify!($name),
+                        "` has a key type `",
+                        stringify!($($K)*),
+                        "` that is too large"
+                    ));
+                }
+            };
+
+            // Ensure that values grow no larger than 64 bytes
+            #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
+            const _: () = {
+                if mem::size_of::<query_values::$name<'static>>() > 64 {
+                    panic!("{}", concat!(
+                        "the query `",
+                        stringify!($name),
+                        "` has a value type `",
+                        stringify!($V),
+                        "` that is too large"
+                    ));
+                }
+            };
+        )*
+
         pub struct QueryArenas<'tcx> {
             $($(#[$attr])* pub $name: query_if_arena!([$($modifiers)*]
                 (WorkerLocal<TypedArena<<$V as Deref>::Target>>)

compiler/rustc_resolve/src/lib.rs

@@ -27,6 +27,7 @@ use rustc_ast::{self as ast, NodeId, CRATE_NODE_ID};
 use rustc_ast::{AngleBracketedArg, Crate, Expr, ExprKind, GenericArg, GenericArgs, LitKind, Path};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_data_structures::intern::Interned;
+use rustc_data_structures::steal::Steal;
 use rustc_data_structures::sync::{Lrc, MappedReadGuard};
 use rustc_errors::{
     Applicability, DiagnosticBuilder, DiagnosticMessage, ErrorGuaranteed, SubdiagnosticMessage,
@@ -965,7 +966,7 @@ pub struct Resolver<'a, 'tcx> {
     /// A small map keeping true kinds of built-in macros that appear to be fn-like on
     /// the surface (`macro` items in libcore), but are actually attributes or derives.
     builtin_macro_kinds: FxHashMap<LocalDefId, MacroKind>,
-    registered_tools: RegisteredTools,
+    registered_tools: &'tcx RegisteredTools,
     macro_use_prelude: FxHashMap<Symbol, &'a NameBinding<'a>>,
     macro_map: FxHashMap<DefId, MacroData>,
     dummy_ext_bang: Lrc<SyntaxExtension>,
@@ -1233,7 +1234,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             }
         }
 
-        let registered_tools = macros::registered_tools(tcx.sess, &krate.attrs);
+        let registered_tools = tcx.registered_tools(());
 
         let features = tcx.sess.features_untracked();
 
@@ -1408,7 +1409,6 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             trait_impls: self.trait_impls,
             proc_macros,
             confused_type_with_std_module,
-            registered_tools: self.registered_tools,
             doc_link_resolutions: self.doc_link_resolutions,
             doc_link_traits_in_scope: self.doc_link_traits_in_scope,
             all_macro_rules: self.all_macro_rules,
@@ -1426,6 +1426,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             trait_map: self.trait_map,
             builtin_macro_kinds: self.builtin_macro_kinds,
             lifetime_elision_allowed: self.lifetime_elision_allowed,
+            lint_buffer: Steal::new(self.lint_buffer),
         };
         ResolverOutputs { global_ctxt, ast_lowering }
     }
@@ -2032,3 +2033,7 @@ impl Finalize {
         Finalize { node_id, path_span, root_span, report_private: true }
     }
 }
+
+pub fn provide(providers: &mut ty::query::Providers) {
+    providers.registered_tools = macros::registered_tools;
+}

compiler/rustc_resolve/src/macros.rs

@@ -8,7 +8,6 @@ use crate::{ModuleKind, ModuleOrUniformRoot, NameBinding, PathResult, Segment};
 use rustc_ast::{self as ast, Inline, ItemKind, ModKind, NodeId};
 use rustc_ast_pretty::pprust;
 use rustc_attr::StabilityLevel;
-use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::intern::Interned;
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::{struct_span_err, Applicability};
@@ -20,11 +19,11 @@ use rustc_hir::def::{self, DefKind, NonMacroAttrKind};
 use rustc_hir::def_id::{CrateNum, LocalDefId};
 use rustc_middle::middle::stability;
 use rustc_middle::ty::RegisteredTools;
+use rustc_middle::ty::TyCtxt;
 use rustc_session::lint::builtin::{LEGACY_DERIVE_HELPERS, SOFT_UNSTABLE};
 use rustc_session::lint::builtin::{UNUSED_MACROS, UNUSED_MACRO_RULES};
 use rustc_session::lint::BuiltinLintDiagnostics;
 use rustc_session::parse::feature_err;
-use rustc_session::Session;
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::{self, ExpnData, ExpnKind, LocalExpnId};
 use rustc_span::hygiene::{AstPass, MacroKind};
@@ -111,15 +110,17 @@ fn fast_print_path(path: &ast::Path) -> Symbol {
     }
 }
 
-pub(crate) fn registered_tools(sess: &Session, attrs: &[ast::Attribute]) -> FxHashSet<Ident> {
+pub(crate) fn registered_tools(tcx: TyCtxt<'_>, (): ()) -> RegisteredTools {
-    let mut registered_tools = FxHashSet::default();
+    let mut registered_tools = RegisteredTools::default();
-    for attr in sess.filter_by_name(attrs, sym::register_tool) {
+    let krate = tcx.crate_for_resolver(()).borrow();
+    for attr in tcx.sess.filter_by_name(&krate.attrs, sym::register_tool) {
         for nested_meta in attr.meta_item_list().unwrap_or_default() {
             match nested_meta.ident() {
                 Some(ident) => {
                     if let Some(old_ident) = registered_tools.replace(ident) {
                         let msg = format!("{} `{}` was already registered", "tool", ident);
-                        sess.struct_span_err(ident.span, &msg)
+                        tcx.sess
+                            .struct_span_err(ident.span, &msg)
                             .span_label(old_ident.span, "already registered here")
                             .emit();
                     }
@@ -127,7 +128,10 @@ pub(crate) fn registered_tools(sess: &Session, attrs: &[ast::Attribute]) -> FxHa
                 None => {
                     let msg = format!("`{}` only accepts identifiers", sym::register_tool);
                     let span = nested_meta.span();
-                    sess.struct_span_err(span, &msg).span_label(span, "not an identifier").emit();
+                    tcx.sess
+                        .struct_span_err(span, &msg)
+                        .span_label(span, "not an identifier")
+                        .emit();
                 }
             }
         }

compiler/rustc_span/src/symbol.rs

@@ -429,6 +429,7 @@ symbols! {
         borrowck_graphviz_format,
         borrowck_graphviz_postflow,
         box_free,
+        box_new,
         box_patterns,
         box_syntax,
         bpf_target_feature,

compiler/rustc_trait_selection/src/solve/assembly.rs

@@ -2,11 +2,12 @@
 
 #[cfg(doc)]
 use super::trait_goals::structural_traits::*;
-use super::{CanonicalResponse, Certainty, EvalCtxt, Goal, MaybeCause, QueryResult};
+use super::EvalCtxt;
 use itertools::Itertools;
 use rustc_hir::def_id::DefId;
 use rustc_infer::traits::query::NoSolution;
 use rustc_infer::traits::util::elaborate_predicates;
+use rustc_middle::traits::solve::{CanonicalResponse, Certainty, Goal, MaybeCause, QueryResult};
 use rustc_middle::ty::TypeFoldable;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use std::fmt::Debug;

compiler/rustc_trait_selection/src/solve/mod.rs

@@ -21,11 +21,13 @@ use rustc_hir::def_id::DefId;
 use rustc_infer::infer::canonical::{Canonical, CanonicalVarValues};
 use rustc_infer::infer::{InferCtxt, InferOk, TyCtxtInferExt};
 use rustc_infer::traits::query::NoSolution;
-use rustc_infer::traits::Obligation;
+use rustc_middle::traits::solve::{
-use rustc_middle::traits::solve::{ExternalConstraints, ExternalConstraintsData};
+    CanonicalGoal, CanonicalResponse, Certainty, ExternalConstraints, ExternalConstraintsData,
+    Goal, MaybeCause, QueryResult, Response,
+};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::ty::{
-    CoercePredicate, RegionOutlivesPredicate, SubtypePredicate, ToPredicate, TypeOutlivesPredicate,
+    CoercePredicate, RegionOutlivesPredicate, SubtypePredicate, TypeOutlivesPredicate,
 };
 use rustc_span::DUMMY_SP;
 
@@ -43,45 +45,6 @@ mod trait_goals;
 pub use eval_ctxt::EvalCtxt;
 pub use fulfill::FulfillmentCtxt;
 
-/// A goal is a statement, i.e. `predicate`, we want to prove
-/// given some assumptions, i.e. `param_env`.
-///
-/// Most of the time the `param_env` contains the `where`-bounds of the function
-/// we're currently typechecking while the `predicate` is some trait bound.
-#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, TypeFoldable, TypeVisitable)]
-pub struct Goal<'tcx, P> {
-    param_env: ty::ParamEnv<'tcx>,
-    predicate: P,
-}
-
-impl<'tcx, P> Goal<'tcx, P> {
-    pub fn new(
-        tcx: TyCtxt<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
-        predicate: impl ToPredicate<'tcx, P>,
-    ) -> Goal<'tcx, P> {
-        Goal { param_env, predicate: predicate.to_predicate(tcx) }
-    }
-
-    /// Updates the goal to one with a different `predicate` but the same `param_env`.
-    fn with<Q>(self, tcx: TyCtxt<'tcx>, predicate: impl ToPredicate<'tcx, Q>) -> Goal<'tcx, Q> {
-        Goal { param_env: self.param_env, predicate: predicate.to_predicate(tcx) }
-    }
-}
-
-impl<'tcx, P> From<Obligation<'tcx, P>> for Goal<'tcx, P> {
-    fn from(obligation: Obligation<'tcx, P>) -> Goal<'tcx, P> {
-        Goal { param_env: obligation.param_env, predicate: obligation.predicate }
-    }
-}
-#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, TypeFoldable, TypeVisitable)]
-pub struct Response<'tcx> {
-    pub var_values: CanonicalVarValues<'tcx>,
-    /// Additional constraints returned by this query.
-    pub external_constraints: ExternalConstraints<'tcx>,
-    pub certainty: Certainty,
-}
-
 trait CanonicalResponseExt {
     fn has_no_inference_or_external_constraints(&self) -> bool;
 }
@@ -94,56 +57,6 @@ impl<'tcx> CanonicalResponseExt for Canonical<'tcx, Response<'tcx>> {
     }
 }
 
-#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, TypeFoldable, TypeVisitable)]
-pub enum Certainty {
-    Yes,
-    Maybe(MaybeCause),
-}
-
-impl Certainty {
-    pub const AMBIGUOUS: Certainty = Certainty::Maybe(MaybeCause::Ambiguity);
-
-    /// When proving multiple goals using **AND**, e.g. nested obligations for an impl,
-    /// use this function to unify the certainty of these goals
-    pub fn unify_and(self, other: Certainty) -> Certainty {
-        match (self, other) {
-            (Certainty::Yes, Certainty::Yes) => Certainty::Yes,
-            (Certainty::Yes, Certainty::Maybe(_)) => other,
-            (Certainty::Maybe(_), Certainty::Yes) => self,
-            (Certainty::Maybe(MaybeCause::Overflow), Certainty::Maybe(MaybeCause::Overflow)) => {
-                Certainty::Maybe(MaybeCause::Overflow)
-            }
-            // If at least one of the goals is ambiguous, hide the overflow as the ambiguous goal
-            // may still result in failure.
-            (Certainty::Maybe(MaybeCause::Ambiguity), Certainty::Maybe(_))
-            | (Certainty::Maybe(_), Certainty::Maybe(MaybeCause::Ambiguity)) => {
-                Certainty::Maybe(MaybeCause::Ambiguity)
-            }
-        }
-    }
-}
-
-/// Why we failed to evaluate a goal.
-#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, TypeFoldable, TypeVisitable)]
-pub enum MaybeCause {
-    /// We failed due to ambiguity. This ambiguity can either
-    /// be a true ambiguity, i.e. there are multiple different answers,
-    /// or we hit a case where we just don't bother, e.g. `?x: Trait` goals.
-    Ambiguity,
-    /// We gave up due to an overflow, most often by hitting the recursion limit.
-    Overflow,
-}
-
-type CanonicalGoal<'tcx, T = ty::Predicate<'tcx>> = Canonical<'tcx, Goal<'tcx, T>>;
-type CanonicalResponse<'tcx> = Canonical<'tcx, Response<'tcx>>;
-/// The result of evaluating a canonical query.
-///
-/// FIXME: We use a different type than the existing canonical queries. This is because
-/// we need to add a `Certainty` for `overflow` and may want to restructure this code without
-/// having to worry about changes to currently used code. Once we've made progress on this
-/// solver, merge the two responses again.
-pub type QueryResult<'tcx> = Result<CanonicalResponse<'tcx>, NoSolution>;
-
 pub trait InferCtxtEvalExt<'tcx> {
     /// Evaluates a goal from **outside** of the trait solver.
     ///

compiler/rustc_trait_selection/src/solve/project_goals.rs

@@ -2,7 +2,7 @@ use crate::traits::{specialization_graph, translate_substs};
 
 use super::assembly;
 use super::trait_goals::structural_traits;
-use super::{Certainty, EvalCtxt, Goal, QueryResult};
+use super::EvalCtxt;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;
@@ -11,6 +11,7 @@ use rustc_infer::infer::InferCtxt;
 use rustc_infer::traits::query::NoSolution;
 use rustc_infer::traits::specialization_graph::LeafDef;
 use rustc_infer::traits::Reveal;
+use rustc_middle::traits::solve::{CanonicalResponse, Certainty, Goal, QueryResult};
 use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
 use rustc_middle::ty::ProjectionPredicate;
 use rustc_middle::ty::{self, Ty, TyCtxt};
@@ -512,7 +513,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
     fn consider_builtin_dyn_upcast_candidates(
         _ecx: &mut EvalCtxt<'_, 'tcx>,
         goal: Goal<'tcx, Self>,
-    ) -> Vec<super::CanonicalResponse<'tcx>> {
+    ) -> Vec<CanonicalResponse<'tcx>> {
         bug!("`Unsize` does not have an associated type: {:?}", goal);
     }
 

compiler/rustc_trait_selection/src/solve/search_graph/cache.rs

@@ -8,12 +8,10 @@
 //!
 //! FIXME(@lcnr): Write that section, feel free to ping me if you need help here
 //! before then or if I still haven't done that before January 2023.
-use super::overflow::OverflowData;
 use super::StackDepth;
-use crate::solve::{CanonicalGoal, QueryResult};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_index::vec::IndexVec;
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::traits::solve::{CanonicalGoal, QueryResult};
 
 rustc_index::newtype_index! {
     pub struct EntryIndex {}
@@ -98,26 +96,3 @@ impl<'tcx> ProvisionalCache<'tcx> {
         self.entries[entry_index].response
     }
 }
-
-pub(super) fn try_move_finished_goal_to_global_cache<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    overflow_data: &mut OverflowData,
-    stack: &IndexVec<super::StackDepth, super::StackElem<'tcx>>,
-    goal: CanonicalGoal<'tcx>,
-    response: QueryResult<'tcx>,
-) {
-    // We move goals to the global cache if we either did not hit an overflow or if it's
-    // the root goal as that will now always hit the same overflow limit.
-    //
-    // NOTE: We cannot move any non-root goals to the global cache even if their final result
-    // isn't impacted by the overflow as that goal still has unstable query dependencies
-    // because it didn't go its full depth.
-    //
-    // FIXME(@lcnr): We could still cache subtrees which are not impacted by overflow though.
-    // Tracking that info correctly isn't trivial, so I haven't implemented it for now.
-    let should_cache_globally = !overflow_data.did_overflow() || stack.is_empty();
-    if should_cache_globally {
-        // FIXME: move the provisional entry to the global cache.
-        let _ = (tcx, goal, response);
-    }
-}

compiler/rustc_trait_selection/src/solve/search_graph/mod.rs

@@ -2,11 +2,12 @@ mod cache;
 mod overflow;
 
 use self::cache::ProvisionalEntry;
-use super::{CanonicalGoal, Certainty, MaybeCause, QueryResult};
 pub(super) use crate::solve::search_graph::overflow::OverflowHandler;
 use cache::ProvisionalCache;
 use overflow::OverflowData;
 use rustc_index::vec::IndexVec;
+use rustc_middle::dep_graph::DepKind;
+use rustc_middle::traits::solve::{CanonicalGoal, Certainty, MaybeCause, QueryResult};
 use rustc_middle::ty::TyCtxt;
 use std::{collections::hash_map::Entry, mem};
 
@@ -139,10 +140,9 @@ impl<'tcx> SearchGraph<'tcx> {
     /// updated the provisional cache and we have to recompute the current goal.
     ///
     /// FIXME: Refer to the rustc-dev-guide entry once it exists.
-    #[instrument(level = "debug", skip(self, tcx, actual_goal), ret)]
+    #[instrument(level = "debug", skip(self, actual_goal), ret)]
     fn try_finalize_goal(
         &mut self,
-        tcx: TyCtxt<'tcx>,
         actual_goal: CanonicalGoal<'tcx>,
         response: QueryResult<'tcx>,
     ) -> bool {
@@ -176,72 +176,87 @@ impl<'tcx> SearchGraph<'tcx> {
             self.stack.push(StackElem { goal, has_been_used: false });
             false
         } else {
-            self.try_move_finished_goal_to_global_cache(tcx, stack_elem);
             true
         }
     }
 
-    fn try_move_finished_goal_to_global_cache(
-        &mut self,
-        tcx: TyCtxt<'tcx>,
-        stack_elem: StackElem<'tcx>,
-    ) {
-        let StackElem { goal, .. } = stack_elem;
-        let cache = &mut self.provisional_cache;
-        let provisional_entry_index = *cache.lookup_table.get(&goal).unwrap();
-        let provisional_entry = &mut cache.entries[provisional_entry_index];
-        let depth = provisional_entry.depth;
-
-        // If not, we're done with this goal.
-        //
-        // Check whether that this goal doesn't depend on a goal deeper on the stack
-        // and if so, move it and all nested goals to the global cache.
-        //
-        // Note that if any nested goal were to depend on something deeper on the stack,
-        // this would have also updated the depth of the current goal.
-        if depth == self.stack.next_index() {
-            for (i, entry) in cache.entries.drain_enumerated(provisional_entry_index.index()..) {
-                let actual_index = cache.lookup_table.remove(&entry.goal);
-                debug_assert_eq!(Some(i), actual_index);
-                debug_assert!(entry.depth == depth);
-                cache::try_move_finished_goal_to_global_cache(
-                    tcx,
-                    &mut self.overflow_data,
-                    &self.stack,
-                    entry.goal,
-                    entry.response,
-                );
-            }
-        }
-    }
-
     pub(super) fn with_new_goal(
         &mut self,
         tcx: TyCtxt<'tcx>,
         canonical_goal: CanonicalGoal<'tcx>,
         mut loop_body: impl FnMut(&mut Self) -> QueryResult<'tcx>,
     ) -> QueryResult<'tcx> {
+        if let Some(result) = tcx.new_solver_evaluation_cache.get(&canonical_goal, tcx) {
+            return result;
+        }
+
         match self.try_push_stack(tcx, canonical_goal) {
             Ok(()) => {}
             // Our goal is already on the stack, eager return.
             Err(response) => return response,
         }
 
-        self.repeat_while_none(
+        // This is for global caching, so we properly track query dependencies.
-            |this| {
+        // Everything that affects the `Result` should be performed within this
-                let result = this.deal_with_overflow(tcx, canonical_goal);
+        // `with_anon_task` closure.
-                let stack_elem = this.stack.pop().unwrap();
+        let (result, dep_node) = tcx.dep_graph.with_anon_task(tcx, DepKind::TraitSelect, || {
-                this.try_move_finished_goal_to_global_cache(tcx, stack_elem);
+            self.repeat_while_none(
-                result
+                |this| {
-            },
+                    let result = this.deal_with_overflow(tcx, canonical_goal);
-            |this| {
+                    let _ = this.stack.pop().unwrap();
-                let result = loop_body(this);
+                    result
-                if this.try_finalize_goal(tcx, canonical_goal, result) {
+                },
-                    Some(result)
+                |this| {
-                } else {
+                    let result = loop_body(this);
-                    None
+                    this.try_finalize_goal(canonical_goal, result).then(|| result)
-                }
+                },
-            },
+            )
-        )
+        });
+
+        let cache = &mut self.provisional_cache;
+        let provisional_entry_index = *cache.lookup_table.get(&canonical_goal).unwrap();
+        let provisional_entry = &mut cache.entries[provisional_entry_index];
+        let depth = provisional_entry.depth;
+
+        // If not, we're done with this goal.
+        //
+        // Check whether that this goal doesn't depend on a goal deeper on the stack
+        // and if so, move it to the global cache.
+        //
+        // Note that if any nested goal were to depend on something deeper on the stack,
+        // this would have also updated the depth of the current goal.
+        if depth == self.stack.next_index() {
+            // If the current goal is the head of a cycle, we drop all other
+            // cycle participants without moving them to the global cache.
+            let other_cycle_participants = provisional_entry_index.index() + 1;
+            for (i, entry) in cache.entries.drain_enumerated(other_cycle_participants..) {
+                let actual_index = cache.lookup_table.remove(&entry.goal);
+                debug_assert_eq!(Some(i), actual_index);
+                debug_assert!(entry.depth == depth);
+            }
+
+            let current_goal = cache.entries.pop().unwrap();
+            let actual_index = cache.lookup_table.remove(&current_goal.goal);
+            debug_assert_eq!(Some(provisional_entry_index), actual_index);
+            debug_assert!(current_goal.depth == depth);
+
+            // We move the root goal to the global cache if we either did not hit an overflow or if it's
+            // the root goal as that will now always hit the same overflow limit.
+            //
+            // NOTE: We cannot move any non-root goals to the global cache. When replaying the root goal's
+            // dependencies, our non-root goal may no longer appear as child of the root goal.
+            //
+            // See https://github.com/rust-lang/rust/pull/108071 for some additional context.
+            let should_cache_globally = !self.overflow_data.did_overflow() || self.stack.is_empty();
+            if should_cache_globally {
+                tcx.new_solver_evaluation_cache.insert(
+                    current_goal.goal,
+                    dep_node,
+                    current_goal.response,
+                );
+            }
+        }
+
+        result
     }
 }

compiler/rustc_trait_selection/src/solve/search_graph/overflow.rs

@@ -1,10 +1,11 @@
 use rustc_infer::infer::canonical::Canonical;
 use rustc_infer::traits::query::NoSolution;
+use rustc_middle::traits::solve::{Certainty, MaybeCause, QueryResult};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Limit;
 
 use super::SearchGraph;
-use crate::solve::{response_no_constraints, Certainty, EvalCtxt, MaybeCause, QueryResult};
+use crate::solve::{response_no_constraints, EvalCtxt};
 
 /// When detecting a solver overflow, we return ambiguity. Overflow can be
 /// *hidden* by either a fatal error in an **AND** or a trivial success in an **OR**.

compiler/rustc_trait_selection/src/solve/trait_goals.rs

@@ -2,12 +2,12 @@
 
 use std::iter;
 
-use super::assembly;
+use super::{assembly, EvalCtxt};
-use super::{CanonicalResponse, Certainty, EvalCtxt, Goal, QueryResult};
 use rustc_hir::def_id::DefId;
 use rustc_hir::LangItem;
 use rustc_infer::traits::query::NoSolution;
 use rustc_infer::traits::util::supertraits;
+use rustc_middle::traits::solve::{CanonicalResponse, Certainty, Goal, QueryResult};
 use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
 use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt};
 use rustc_middle::ty::{TraitPredicate, TypeVisitableExt};

compiler/rustc_trait_selection/src/traits/query/evaluate_obligation.rs

@@ -1,9 +1,10 @@
+use rustc_middle::traits::solve::{Certainty, Goal, MaybeCause};
 use rustc_middle::ty;
 use rustc_session::config::TraitSolver;
 
 use crate::infer::canonical::OriginalQueryValues;
 use crate::infer::InferCtxt;
-use crate::solve::{Certainty, Goal, InferCtxtEvalExt, MaybeCause};
+use crate::solve::InferCtxtEvalExt;
 use crate::traits::{EvaluationResult, OverflowError, PredicateObligation, SelectionContext};
 
 pub trait InferCtxtExt<'tcx> {

library/alloc/src/boxed.rs

@@ -214,6 +214,7 @@ impl<T> Box<T> {
     #[inline(always)]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
+    #[rustc_diagnostic_item = "box_new"]
     pub fn new(x: T) -> Self {
         #[rustc_box]
         Box::new(x)

library/alloc/src/sync.rs

@@ -51,8 +51,16 @@ mod tests;
 ///
 /// Going above this limit will abort your program (although not
 /// necessarily) at _exactly_ `MAX_REFCOUNT + 1` references.
+/// Trying to go above it might call a `panic` (if not actually going above it).
+///
+/// This is a global invariant, and also applies when using a compare-exchange loop.
+///
+/// See comment in `Arc::clone`.
 const MAX_REFCOUNT: usize = (isize::MAX) as usize;
 
+/// The error in case either counter reaches above `MAX_REFCOUNT`, and we can `panic` safely.
+const INTERNAL_OVERFLOW_ERROR: &str = "Arc counter overflow";
+
 #[cfg(not(sanitize = "thread"))]
 macro_rules! acquire {
     ($x:expr) => {
@@ -1104,6 +1112,9 @@ impl<T: ?Sized> Arc<T> {
                 continue;
             }
 
+            // We can't allow the refcount to increase much past `MAX_REFCOUNT`.
+            assert!(cur <= MAX_REFCOUNT, "{}", INTERNAL_OVERFLOW_ERROR);
+
             // NOTE: this code currently ignores the possibility of overflow
             // into usize::MAX; in general both Rc and Arc need to be adjusted
             // to deal with overflow.
@@ -1519,6 +1530,11 @@ impl<T: ?Sized> Clone for Arc<T> {
         // the worst already happened and we actually do overflow the `usize` counter. However, that
         // requires the counter to grow from `isize::MAX` to `usize::MAX` between the increment
         // above and the `abort` below, which seems exceedingly unlikely.
+        //
+        // This is a global invariant, and also applies when using a compare-exchange loop to increment
+        // counters in other methods.
+        // Otherwise, the counter could be brought to an almost-overflow using a compare-exchange loop,
+        // and then overflow using a few `fetch_add`s.
         if old_size > MAX_REFCOUNT {
             abort();
         }
@@ -2180,9 +2196,7 @@ impl<T: ?Sized> Weak<T> {
                     return None;
                 }
                 // See comments in `Arc::clone` for why we do this (for `mem::forget`).
-                if n > MAX_REFCOUNT {
+                assert!(n <= MAX_REFCOUNT, "{}", INTERNAL_OVERFLOW_ERROR);
-                    abort();
-                }
                 Some(n + 1)
             })
             .ok()

library/alloc/src/tests.rs

@@ -4,7 +4,6 @@ use core::any::Any;
 use core::clone::Clone;
 use core::convert::TryInto;
 use core::ops::Deref;
-use core::result::Result::{Err, Ok};
 
 use std::boxed::Box;
 
@@ -15,7 +14,7 @@ fn test_owned_clone() {
     assert!(a == b);
 }
 
-#[derive(PartialEq, Eq)]
+#[derive(Debug, PartialEq, Eq)]
 struct Test;
 
 #[test]
@@ -23,24 +22,17 @@ fn any_move() {
     let a = Box::new(8) as Box<dyn Any>;
     let b = Box::new(Test) as Box<dyn Any>;
 
-    match a.downcast::<i32>() {
+    let a: Box<i32> = a.downcast::<i32>().unwrap();
-        Ok(a) => {
+    assert_eq!(*a, 8);
-            assert!(a == Box::new(8));
+
-        }
+    let b: Box<Test> = b.downcast::<Test>().unwrap();
-        Err(..) => panic!(),
+    assert_eq!(*b, Test);
-    }
-    match b.downcast::<Test>() {
-        Ok(a) => {
-            assert!(a == Box::new(Test));
-        }
-        Err(..) => panic!(),
-    }
 
     let a = Box::new(8) as Box<dyn Any>;
     let b = Box::new(Test) as Box<dyn Any>;
 
-    assert!(a.downcast::<Box<Test>>().is_err());
+    assert!(a.downcast::<Box<i32>>().is_err());
-    assert!(b.downcast::<Box<i32>>().is_err());
+    assert!(b.downcast::<Box<Test>>().is_err());
 }
 
 #[test]

library/core/src/num/nonzero.rs

@@ -1147,12 +1147,10 @@ macro_rules! nonzero_min_max_unsigned {
                 /// # Examples
                 ///
                 /// ```
-                /// #![feature(nonzero_min_max)]
-                ///
                 #[doc = concat!("# use std::num::", stringify!($Ty), ";")]
                 #[doc = concat!("assert_eq!(", stringify!($Ty), "::MIN.get(), 1", stringify!($Int), ");")]
                 /// ```
-                #[unstable(feature = "nonzero_min_max", issue = "89065")]
+                #[stable(feature = "nonzero_min_max", since = "CURRENT_RUSTC_VERSION")]
                 pub const MIN: Self = Self::new(1).unwrap();
 
                 /// The largest value that can be represented by this non-zero
@@ -1162,12 +1160,10 @@ macro_rules! nonzero_min_max_unsigned {
                 /// # Examples
                 ///
                 /// ```
-                /// #![feature(nonzero_min_max)]
-                ///
                 #[doc = concat!("# use std::num::", stringify!($Ty), ";")]
                 #[doc = concat!("assert_eq!(", stringify!($Ty), "::MAX.get(), ", stringify!($Int), "::MAX);")]
                 /// ```
-                #[unstable(feature = "nonzero_min_max", issue = "89065")]
+                #[stable(feature = "nonzero_min_max", since = "CURRENT_RUSTC_VERSION")]
                 pub const MAX: Self = Self::new(<$Int>::MAX).unwrap();
             }
         )+
@@ -1189,12 +1185,10 @@ macro_rules! nonzero_min_max_signed {
                 /// # Examples
                 ///
                 /// ```
-                /// #![feature(nonzero_min_max)]
-                ///
                 #[doc = concat!("# use std::num::", stringify!($Ty), ";")]
                 #[doc = concat!("assert_eq!(", stringify!($Ty), "::MIN.get(), ", stringify!($Int), "::MIN);")]
                 /// ```
-                #[unstable(feature = "nonzero_min_max", issue = "89065")]
+                #[stable(feature = "nonzero_min_max", since = "CURRENT_RUSTC_VERSION")]
                 pub const MIN: Self = Self::new(<$Int>::MIN).unwrap();
 
                 /// The largest value that can be represented by this non-zero
@@ -1208,12 +1202,10 @@ macro_rules! nonzero_min_max_signed {
                 /// # Examples
                 ///
                 /// ```
-                /// #![feature(nonzero_min_max)]
-                ///
                 #[doc = concat!("# use std::num::", stringify!($Ty), ";")]
                 #[doc = concat!("assert_eq!(", stringify!($Ty), "::MAX.get(), ", stringify!($Int), "::MAX);")]
                 /// ```
-                #[unstable(feature = "nonzero_min_max", issue = "89065")]
+                #[stable(feature = "nonzero_min_max", since = "CURRENT_RUSTC_VERSION")]
                 pub const MAX: Self = Self::new(<$Int>::MAX).unwrap();
             }
         )+

tests/ui/issues/issue-3029.rs

@@ -2,9 +2,7 @@
 // error-pattern:so long
 // ignore-emscripten no processes
 
-#![allow(unused_allocation)]
 #![allow(unreachable_code)]
-#![allow(unused_variables)]
 
 fn main() {
     let mut x = Vec::new();

tests/ui/iterators/into-iter-on-arrays-lint.fixed

@@ -2,7 +2,7 @@
 // run-rustfix
 // rustfix-only-machine-applicable
 
-#[allow(unused_must_use)]
+#[allow(unused_must_use, unused_allocation)]
 fn main() {
     let small = [1, 2];
     let big = [0u8; 33];

tests/ui/iterators/into-iter-on-arrays-lint.rs

@@ -2,7 +2,7 @@
 // run-rustfix
 // rustfix-only-machine-applicable
 
-#[allow(unused_must_use)]
+#[allow(unused_must_use, unused_allocation)]
 fn main() {
     let small = [1, 2];
     let big = [0u8; 33];

tests/ui/lint/unused/unused-allocation.rs

@@ -0,0 +1,7 @@
+#![feature(rustc_attrs, stmt_expr_attributes)]
+#![deny(unused_allocation)]
+
+fn main() {
+    _ = (#[rustc_box] Box::new([1])).len(); //~ error: unnecessary allocation, use `&` instead
+    _ = Box::new([1]).len(); //~ error: unnecessary allocation, use `&` instead
+}

tests/ui/lint/unused/unused-allocation.stderr

@@ -0,0 +1,20 @@
+error: unnecessary allocation, use `&` instead
+  --> $DIR/unused-allocation.rs:5:9
+   |
+LL |     _ = (#[rustc_box] Box::new([1])).len();
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/unused-allocation.rs:2:9
+   |
+LL | #![deny(unused_allocation)]
+   |         ^^^^^^^^^^^^^^^^^
+
+error: unnecessary allocation, use `&` instead
+  --> $DIR/unused-allocation.rs:6:9
+   |
+LL |     _ = Box::new([1]).len();
+   |         ^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+

tests/ui/macros/bad-concat.stderr

@@ -4,7 +4,7 @@ error: expected a literal
 LL |     let _ = concat!(x, y, z, "bar");
    |                     ^  ^  ^
    |
-   = note: only literals (like `"foo"`, `42` and `3.14`) can be passed to `concat!()`
+   = note: only literals (like `"foo"`, `-42` and `3.14`) can be passed to `concat!()`
 
 error: aborting due to previous error
 

tests/ui/macros/concat.stderr

@@ -16,7 +16,7 @@ error: expected a literal
 LL |     concat!(foo);
    |             ^^^
    |
-   = note: only literals (like `"foo"`, `42` and `3.14`) can be passed to `concat!()`
+   = note: only literals (like `"foo"`, `-42` and `3.14`) can be passed to `concat!()`
 
 error: expected a literal
   --> $DIR/concat.rs:5:13
@@ -24,7 +24,7 @@ error: expected a literal
 LL |     concat!(foo());
    |             ^^^^^
    |
-   = note: only literals (like `"foo"`, `42` and `3.14`) can be passed to `concat!()`
+   = note: only literals (like `"foo"`, `-42` and `3.14`) can be passed to `concat!()`
 
 error: aborting due to 4 previous errors
 

tests/ui/macros/issue-106837.rs

@@ -0,0 +1,10 @@
+fn main() {
+    concat!(-42);
+    concat!(-3.14);
+
+    concat!(-"hello");
+    //~^ ERROR expected a literal
+
+    concat!(--1);
+    //~^ ERROR expected a literal
+}

tests/ui/macros/issue-106837.stderr

@@ -0,0 +1,18 @@
+error: expected a literal
+  --> $DIR/issue-106837.rs:5:13
+   |
+LL |     concat!(-"hello");
+   |             ^^^^^^^^
+   |
+   = note: only literals (like `"foo"`, `-42` and `3.14`) can be passed to `concat!()`
+
+error: expected a literal
+  --> $DIR/issue-106837.rs:8:13
+   |
+LL |     concat!(--1);
+   |             ^^^
+   |
+   = note: only literals (like `"foo"`, `-42` and `3.14`) can be passed to `concat!()`
+
+error: aborting due to 2 previous errors
+

tests/ui/macros/issue-98790.rs

@@ -0,0 +1,24 @@
+// run-pass
+
+macro_rules! stringify_item {
+    ($item:item) => {
+        stringify!($item)
+    };
+}
+
+macro_rules! repro {
+    ($expr:expr) => {
+        stringify_item! {
+            pub fn repro() -> bool {
+                $expr
+            }
+        }
+    };
+}
+
+fn main() {
+    assert_eq!(
+        repro!(match () { () => true } | true),
+        "pub fn repro() -> bool { (match () { () => true, }) | true }"
+    );
+}

tests/ui/macros/rfc-2011-nicer-assert-messages/all-expr-kinds.rs

@@ -164,7 +164,7 @@ fn main() {
     // mac call
 
     // match
-    [ match elem { _ => elem } == 3 ] => "Assertion failed: match elem { _ => elem, } == 3"
+    [ match elem { _ => elem } == 3 ] => "Assertion failed: (match elem { _ => elem, }) == 3"
 
     // ret
     [ (|| { return elem; })() == 3 ] => "Assertion failed: (|| { return elem; })() == 3"

tests/ui/self/arbitrary_self_types_trait.rs

@@ -1,4 +1,5 @@
 // run-pass
+#![allow(unused_allocation)]
 
 use std::rc::Rc;
 
@@ -13,7 +14,7 @@ impl Trait for Vec<i32> {
 }
 
 fn main() {
-    let v = vec![1,2,3];
+    let v = vec![1, 2, 3];
 
-    assert_eq!(&[1,2,3], Box::new(Rc::new(v)).trait_method());
+    assert_eq!(&[1, 2, 3], Box::new(Rc::new(v)).trait_method());
 }

tests/ui/structs-enums/align-struct.rs

@@ -1,5 +1,5 @@
 // run-pass
-#![allow(dead_code)]
+#![allow(dead_code, unused_allocation)]
 
 use std::mem;
 
@@ -20,7 +20,6 @@ struct AlignMany(i32);
 
 // Raising alignment may not alter size.
 #[repr(align(8))]
-#[allow(dead_code)]
 struct Align8Many {
     a: i32,
     b: i32,
@@ -29,9 +28,8 @@ struct Align8Many {
 }
 
 enum Enum {
-    #[allow(dead_code)]
     A(i32),
-    B(Align16)
+    B(Align16),
 }
 
 // Nested alignment - use `#[repr(C)]` to suppress field reordering for sizeof test
@@ -73,7 +71,7 @@ struct AlignLarge {
 
 union UnionContainsAlign {
     a: Align16,
-    b: f32
+    b: f32,
 }
 
 impl Align16 {
@@ -158,7 +156,7 @@ pub fn main() {
     // Note that the size of Nested may change if struct field re-ordering is enabled
     assert_eq!(mem::align_of::<Nested>(), 16);
     assert_eq!(mem::size_of::<Nested>(), 48);
-    let a = Nested{ a: 1, b: 2, c: Align16(3), d: 4};
+    let a = Nested { a: 1, b: 2, c: Align16(3), d: 4 };
     assert_eq!(mem::align_of_val(&a), 16);
     assert_eq!(mem::align_of_val(&a.b), 4);
     assert_eq!(mem::align_of_val(&a.c), 16);
@@ -179,8 +177,8 @@ pub fn main() {
             assert_eq!(a.0, 15);
             assert_eq!(mem::align_of_val(a), 16);
             assert_eq!(mem::size_of_val(a), 16);
-        },
+        }
-        _ => ()
+        _ => (),
     }
     assert!(is_aligned_to(&e, 16));
 
@@ -197,8 +195,8 @@ pub fn main() {
     }
 
     // arrays of aligned elements should also be aligned
-    assert_eq!(mem::align_of::<[Align16;2]>(), 16);
+    assert_eq!(mem::align_of::<[Align16; 2]>(), 16);
-    assert_eq!(mem::size_of::<[Align16;2]>(), 32);
+    assert_eq!(mem::size_of::<[Align16; 2]>(), 32);
 
     let a = [Align16(0), Align16(1)];
     assert_eq!(mem::align_of_val(&a[0]), 16);
@@ -209,7 +207,7 @@ pub fn main() {
     assert_eq!(mem::align_of_val(Box::new(Align16(0)).as_ref()), 16);
 
     // check heap array is aligned
-    let a = vec!(Align16(0), Align16(1));
+    let a = vec![Align16(0), Align16(1)];
     assert_eq!(mem::align_of_val(&a[0]), 16);
     assert_eq!(mem::align_of_val(&a[1]), 16);
 
@@ -224,16 +222,14 @@ pub fn main() {
 
     assert_eq!(mem::align_of::<AlignContainsPacked4C>(), 16);
     assert_eq!(mem::size_of::<AlignContainsPacked4C>(), 32);
-    let a = AlignContainsPacked4C { a: Packed4C{ a: 1, b: 2 }, b: 3 };
+    let a = AlignContainsPacked4C { a: Packed4C { a: 1, b: 2 }, b: 3 };
     assert_eq!(mem::align_of_val(&a), 16);
     assert_eq!(mem::align_of_val(&a.a), 4);
     assert_eq!(mem::align_of_val(&a.b), mem::align_of::<u64>());
     assert_eq!(mem::size_of_val(&a), 32);
     assert!(is_aligned_to(&a, 16));
 
-    let mut large = Box::new(AlignLarge {
+    let mut large = Box::new(AlignLarge { stuff: [0; 0x10000] });
-        stuff: [0; 0x10000],
-    });
     large.stuff[0] = 132;
     *large.stuff.last_mut().unwrap() = 102;
     assert_eq!(large.stuff[0], 132);