Rollup of 9 pull requests

CONTRIBUTING.md

@@ -10,7 +10,7 @@ the Zulip stream is the best place to *ask* for help.
 
 Documentation for contributing to the compiler or tooling is located in the [Guide to Rustc
 Development][rustc-dev-guide], commonly known as the [rustc-dev-guide]. Documentation for the
-standard library in the [Standard library developers Guide][std-dev-guide], commonly known as the [std-dev-guide].
+standard library is in the [Standard library developers Guide][std-dev-guide], commonly known as the [std-dev-guide].
 
 ## Making changes to subtrees and submodules
 

Cargo.lock

@@ -4492,6 +4492,7 @@ name = "rustc_query_impl"
 version = "0.0.0"
 dependencies = [
  "measureme",
+ "rustc_abi",
  "rustc_data_structures",
  "rustc_errors",
  "rustc_hashes",
@@ -4501,7 +4502,9 @@ dependencies = [
  "rustc_middle",
  "rustc_query_system",
  "rustc_serialize",
+ "rustc_session",
  "rustc_span",
+ "rustc_thread_pool",
  "tracing",
 ]
 

INSTALL.md

@@ -233,7 +233,7 @@ itself back on after some time).
 
 ### MSVC
 
-MSVC builds of Rust additionally requires an installation of:
+MSVC builds of Rust additionally require an installation of:
 
 - Visual Studio 2022 (or later) build tools so `rustc` can use its linker. Older
   Visual Studio versions such as 2019 *may* work but aren't actively tested.

RELEASES.md

@@ -1546,7 +1546,7 @@ Compatibility Notes
 - [Check well-formedness of the source type's signature in fn pointer casts.](https://github.com/rust-lang/rust/pull/129021) This partly closes a soundness hole that comes when casting a function item to function pointer
 - [Use equality instead of subtyping when resolving type dependent paths.](https://github.com/rust-lang/rust/pull/129073)
 - Linking on macOS now correctly includes Rust's default deployment target. Due to a linker bug, you might have to pass `MACOSX_DEPLOYMENT_TARGET` or fix your `#[link]` attributes to point to the correct frameworks. See <https://github.com/rust-lang/rust/pull/129369>.
-- [Rust will now correctly raise an error for `repr(Rust)` written on non-`struct`/`enum`/`union` items, since it previous did not have any effect.](https://github.com/rust-lang/rust/pull/129422)
+- [Rust will now correctly raise an error for `repr(Rust)` written on non-`struct`/`enum`/`union` items, since it previously did not have any effect.](https://github.com/rust-lang/rust/pull/129422)
 - The future incompatibility lint `deprecated_cfg_attr_crate_type_name` [has been made into a hard error](https://github.com/rust-lang/rust/pull/129670). It was used to deny usage of `#![crate_type]` and `#![crate_name]` attributes in `#![cfg_attr]`, which required a hack in the compiler to be able to change the used crate type and crate name after cfg expansion.
   Users can use `--crate-type` instead of `#![cfg_attr(..., crate_type = "...")]` and `--crate-name` instead of `#![cfg_attr(..., crate_name = "...")]` when running `rustc`/`cargo rustc` on the command line.
   Use of those two attributes outside of `#![cfg_attr]` continue to be fully supported.
@@ -1722,7 +1722,7 @@ Cargo
 Compatibility Notes
 -------------------
  - We now [disallow setting some built-in cfgs via the command-line](https://github.com/rust-lang/rust/pull/126158) with the newly added [`explicit_builtin_cfgs_in_flags`](https://doc.rust-lang.org/rustc/lints/listing/deny-by-default.html#explicit-builtin-cfgs-in-flags) lint in order to prevent incoherent state, eg. `windows` cfg active but target is Linux based. The appropriate [`rustc` flag](https://doc.rust-lang.org/rustc/command-line-arguments.html) should be used instead.
-- The standard library has a new implementation of `binary_search` which is significantly improves performance ([#128254](https://github.com/rust-lang/rust/pull/128254)). However when a sorted slice has multiple values which compare equal, the new implementation may select a different value among the equal ones than the old implementation.
+- The standard library has a new implementation of `binary_search` which significantly improves performance ([#128254](https://github.com/rust-lang/rust/pull/128254)). However when a sorted slice has multiple values which compare equal, the new implementation may select a different value among the equal ones than the old implementation.
 - [illumos/Solaris now sets `MSG_NOSIGNAL` when writing to sockets](https://github.com/rust-lang/rust/pull/128259). This avoids killing the process with SIGPIPE when writing to a closed socket, which matches the existing behavior on other UNIX targets.
 - [Removes a problematic hack that always passed the --whole-archive linker flag for tests, which may cause linker errors for code accidentally relying on it.](https://github.com/rust-lang/rust/pull/128400)
 - The WebAssembly target features `multivalue` and `reference-types` are now
@@ -1872,7 +1872,7 @@ These changes do not affect any public interfaces of Rust, but they represent
 significant improvements to the performance or internals of rustc and related
 tools.
 
-- [Add a Rust-for Linux `auto` CI job to check kernel builds.](https://github.com/rust-lang/rust/pull/125209/)
+- [Add a Rust-for-Linux `auto` CI job to check kernel builds.](https://github.com/rust-lang/rust/pull/125209/)
 
 Version 1.80.1 (2024-08-08)
 ===========================
@@ -4510,7 +4510,7 @@ Compatibility Notes
   saturating to `0` instead][89926]. In the real world the panic happened mostly
   on platforms with buggy monotonic clock implementations rather than catching
   programming errors like reversing the start and end times. Such programming
-  errors will now results in `0` rather than a panic.
+  errors will now result in `0` rather than a panic.
 - In a future release we're planning to increase the baseline requirements for
   the Linux kernel to version 3.2, and for glibc to version 2.17. We'd love
   your feedback in [PR #95026][95026].

compiler/rustc_attr_parsing/src/attributes/stability.rs

@@ -244,7 +244,20 @@ impl<S: Stage> AttributeParser<S> for ConstStabilityParser {
             this.promotable = true;
         }),
     ];
-    const ALLOWED_TARGETS: AllowedTargets = ALLOWED_TARGETS;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Impl { of_trait: false }),
+        Allow(Target::Impl { of_trait: true }),
+        Allow(Target::Use), // FIXME I don't think this does anything?
+        Allow(Target::Const),
+        Allow(Target::AssocConst),
+        Allow(Target::Trait),
+        Allow(Target::Static),
+        Allow(Target::Crate),
+    ]);
 
     fn finalize(mut self, cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         if self.promotable {

compiler/rustc_expand/src/base.rs

@@ -962,15 +962,6 @@ impl SyntaxExtension {
 
         let stability = find_attr!(attrs, AttributeKind::Stability { stability, .. } => *stability);
 
-        // FIXME(jdonszelmann): make it impossible to miss the or_else in the typesystem
-        if let Some(sp) =
-            find_attr!(attrs, AttributeKind::RustcConstStability { span, .. } => *span)
-        {
-            sess.dcx().emit_err(errors::MacroConstStability {
-                span: sp,
-                head_span: sess.source_map().guess_head_span(span),
-            });
-        }
         if let Some(sp) = find_attr!(attrs, AttributeKind::RustcBodyStability{ span, .. } => *span)
         {
             sess.dcx().emit_err(errors::MacroBodyStability {

compiler/rustc_expand/src/errors.rs

@@ -80,16 +80,6 @@ pub(crate) struct ResolveRelativePath {
     pub path: String,
 }
 
-#[derive(Diagnostic)]
-#[diag("macros cannot have const stability attributes")]
-pub(crate) struct MacroConstStability {
-    #[primary_span]
-    #[label("invalid const stability attribute")]
-    pub span: Span,
-    #[label("const stability attribute affects this macro")]
-    pub head_span: Span,
-}
-
 #[derive(Diagnostic)]
 #[diag("macros cannot have body stability attributes")]
 pub(crate) struct MacroBodyStability {

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1569,11 +1569,40 @@ pub(super) fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, def_id:
 
     let predicates = predicates.instantiate_identity(tcx);
 
+    let assoc_const_obligations: Vec<_> = predicates
+        .predicates
+        .iter()
+        .copied()
+        .zip(predicates.spans.iter().copied())
+        .filter_map(|(clause, sp)| {
+            let proj = clause.as_projection_clause()?;
+            let pred_binder = proj
+                .map_bound(|pred| {
+                    pred.term.as_const().map(|ct| {
+                        let assoc_const_ty = tcx
+                            .type_of(pred.projection_term.def_id)
+                            .instantiate(tcx, pred.projection_term.args);
+                        ty::ClauseKind::ConstArgHasType(ct, assoc_const_ty)
+                    })
+                })
+                .transpose();
+            pred_binder.map(|pred_binder| {
+                let cause = traits::ObligationCause::new(
+                    sp,
+                    wfcx.body_def_id,
+                    ObligationCauseCode::WhereClause(def_id.to_def_id(), sp),
+                );
+                Obligation::new(tcx, cause, wfcx.param_env, pred_binder)
+            })
+        })
+        .collect();
+
     assert_eq!(predicates.predicates.len(), predicates.spans.len());
     let wf_obligations = predicates.into_iter().flat_map(|(p, sp)| {
         traits::wf::clause_obligations(infcx, wfcx.param_env, wfcx.body_def_id, p, sp)
     });
-    let obligations: Vec<_> = wf_obligations.chain(default_obligations).collect();
+    let obligations: Vec<_> =
+        wf_obligations.chain(default_obligations).chain(assoc_const_obligations).collect();
     wfcx.register_obligations(obligations);
 }
 

compiler/rustc_interface/src/interface.rs

@@ -16,8 +16,7 @@ use rustc_parse::lexer::StripTokens;
 use rustc_parse::new_parser_from_source_str;
 use rustc_parse::parser::Recovery;
 use rustc_parse::parser::attr::AllowLeadingUnsafe;
-use rustc_query_impl::QueryCtxt;
-use rustc_query_system::query::print_query_stack;
+use rustc_query_impl::{QueryCtxt, print_query_stack};
 use rustc_session::config::{self, Cfg, CheckCfg, ExpectedValues, Input, OutFileName};
 use rustc_session::parse::ParseSess;
 use rustc_session::{CompilerIO, EarlyDiagCtxt, Session, lint};

compiler/rustc_interface/src/util.rs

@@ -184,8 +184,7 @@ pub(crate) fn run_in_thread_pool_with_globals<
     use rustc_data_structures::defer;
     use rustc_data_structures::sync::FromDyn;
     use rustc_middle::ty::tls;
-    use rustc_query_impl::QueryCtxt;
-    use rustc_query_system::query::{QueryContext, break_query_cycles};
+    use rustc_query_impl::{QueryCtxt, break_query_cycles};
 
     let thread_stack_size = init_stack_size(thread_builder_diag);
 

compiler/rustc_middle/src/query/mod.rs

@@ -13,7 +13,6 @@ mod keys;
 pub mod on_disk_cache;
 #[macro_use]
 pub mod plumbing;
-pub mod values;
 
 pub fn describe_as_module(def_id: impl Into<LocalDefId>, tcx: TyCtxt<'_>) -> String {
     let def_id = def_id.into();

compiler/rustc_next_trait_solver/src/solve/trait_goals.rs

@@ -687,6 +687,9 @@ where
     ///
     /// because these impls overlap, and I'd rather not build a coherence hack for
     /// this harmless overlap.
+    ///
+    /// This trait is indirectly exposed on stable, so do *not* extend the set of types that
+    /// implement the trait without FCP!
     fn consider_builtin_bikeshed_guaranteed_no_drop_candidate(
         ecx: &mut EvalCtxt<'_, D>,
         goal: Goal<I, Self>,

compiler/rustc_query_impl/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2024"
 [dependencies]
 # tidy-alphabetical-start
 measureme = "12.0.1"
+rustc_abi = { path = "../rustc_abi" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_hashes = { path = "../rustc_hashes" }
@@ -15,6 +16,8 @@ rustc_macros = { path = "../rustc_macros" }
 rustc_middle = { path = "../rustc_middle" }
 rustc_query_system = { path = "../rustc_query_system" }
 rustc_serialize = { path = "../rustc_serialize" }
+rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
+rustc_thread_pool = { path = "../rustc_thread_pool" }
 tracing = "0.1"
 # tidy-alphabetical-end

compiler/rustc_query_impl/src/error.rs

@@ -1,3 +1,4 @@
+use rustc_errors::codes::*;
 use rustc_hir::limit::Limit;
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::{Span, Symbol};
@@ -22,3 +23,59 @@ pub(crate) struct QueryOverflowNote {
     pub desc: String,
     pub depth: usize,
 }
+
+#[derive(Subdiagnostic)]
+#[note("...which requires {$desc}...")]
+pub(crate) struct CycleStack {
+    #[primary_span]
+    pub span: Span,
+    pub desc: String,
+}
+
+#[derive(Subdiagnostic)]
+pub(crate) enum StackCount {
+    #[note("...which immediately requires {$stack_bottom} again")]
+    Single,
+    #[note("...which again requires {$stack_bottom}, completing the cycle")]
+    Multiple,
+}
+
+#[derive(Subdiagnostic)]
+pub(crate) enum Alias {
+    #[note("type aliases cannot be recursive")]
+    #[help("consider using a struct, enum, or union instead to break the cycle")]
+    #[help(
+        "see <https://doc.rust-lang.org/reference/types.html#recursive-types> for more information"
+    )]
+    Ty,
+    #[note("trait aliases cannot be recursive")]
+    Trait,
+}
+
+#[derive(Subdiagnostic)]
+#[note("cycle used when {$usage}")]
+pub(crate) struct CycleUsage {
+    #[primary_span]
+    pub span: Span,
+    pub usage: String,
+}
+
+#[derive(Diagnostic)]
+#[diag("cycle detected when {$stack_bottom}", code = E0391)]
+pub(crate) struct Cycle {
+    #[primary_span]
+    pub span: Span,
+    pub stack_bottom: String,
+    #[subdiagnostic]
+    pub cycle_stack: Vec<CycleStack>,
+    #[subdiagnostic]
+    pub stack_count: StackCount,
+    #[subdiagnostic]
+    pub alias: Option<Alias>,
+    #[subdiagnostic]
+    pub cycle_usage: Option<CycleUsage>,
+    #[note(
+        "see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information"
+    )]
+    pub note_span: (),
+}

compiler/rustc_query_impl/src/execution.rs

@@ -9,13 +9,13 @@ use rustc_middle::dep_graph::DepsType;
 use rustc_middle::ty::TyCtxt;
 use rustc_query_system::dep_graph::{DepGraphData, DepNodeKey, HasDepContext};
 use rustc_query_system::query::{
-    ActiveKeyStatus, CycleError, CycleErrorHandling, QueryCache, QueryContext, QueryJob,
-    QueryJobId, QueryJobInfo, QueryLatch, QueryMap, QueryMode, QueryStackDeferred, QueryStackFrame,
-    QueryState, incremental_verify_ich, report_cycle,
+    ActiveKeyStatus, CycleError, CycleErrorHandling, QueryCache, QueryJob, QueryJobId, QueryLatch,
+    QueryMode, QueryStackDeferred, QueryStackFrame, QueryState, incremental_verify_ich,
 };
 use rustc_span::{DUMMY_SP, Span};
 
 use crate::dep_graph::{DepContext, DepNode, DepNodeIndex};
+use crate::job::{QueryJobInfo, QueryMap, find_cycle_in_stack, report_cycle};
 use crate::{QueryCtxt, QueryFlags, SemiDynamicQueryDispatcher};
 
 #[inline]
@@ -218,7 +218,7 @@ fn cycle_error<'tcx, C: QueryCache, const FLAGS: QueryFlags>(
         .ok()
         .expect("failed to collect active queries");
 
-    let error = try_execute.find_cycle_in_stack(query_map, &qcx.current_query_job(), span);
+    let error = find_cycle_in_stack(try_execute, query_map, &qcx.current_query_job(), span);
     (mk_cycle(query, qcx, error.lift()), None)
 }