Rollup of 20 pull requests

.github/workflows/ci.yml

@@ -58,8 +58,8 @@ jobs:
           COMMIT_MESSAGE: ${{ github.event.head_commit.message }}
         run: |
           cd src/ci/citool
-          cargo test
-          cargo run calculate-job-matrix >> $GITHUB_OUTPUT
+          CARGO_INCREMENTAL=0 cargo test
+          CARGO_INCREMENTAL=0 cargo run calculate-job-matrix >> $GITHUB_OUTPUT
         id: jobs
   job:
     name: ${{ matrix.full_name }}
@@ -183,11 +183,11 @@ jobs:
         run: src/ci/scripts/dump-environment.sh
 
       # Pre-build citool before the following step uninstalls rustup
-      # Build is into the build directory, to avoid modifying sources
+      # Build it into the build directory, to avoid modifying sources
       - name: build citool
         run: |
           cd src/ci/citool
-          CARGO_TARGET_DIR=../../../build/citool cargo build
+          CARGO_INCREMENTAL=0 CARGO_TARGET_DIR=../../../build/citool cargo build
 
       - name: run the build
         # Redirect stderr to stdout to avoid reordering the two streams in the GHA logs.
@@ -238,13 +238,9 @@ jobs:
       - name: upload job metrics to DataDog
         if: needs.calculate_matrix.outputs.run_type != 'pr'
         env:
-          DATADOG_SITE: datadoghq.com
           DATADOG_API_KEY: ${{ secrets.DATADOG_API_KEY }}
           DD_GITHUB_JOB_NAME: ${{ matrix.full_name }}
-        run: |
-          cd src/ci
-          npm ci
-          python3 scripts/upload-build-metrics.py ../../build/cpu-usage.csv
+        run: ./build/citool/debug/citool upload-build-metrics build/cpu-usage.csv
 
   # This job isused to tell bors the final status of the build, as there is no practical way to detect
   # when a workflow is successful listening to webhooks only in our current bors implementation (homu).

compiler/rustc_abi/src/extern_abi.rs

@@ -191,6 +191,17 @@ impl StableOrd for ExternAbi {
 }
 
 impl ExternAbi {
+    /// An ABI "like Rust"
+    ///
+    /// These ABIs are fully controlled by the Rust compiler, which means they
+    /// - support unwinding with `-Cpanic=unwind`, unlike `extern "C"`
+    /// - often diverge from the C ABI
+    /// - are subject to change between compiler versions
+    pub fn is_rustic_abi(self) -> bool {
+        use ExternAbi::*;
+        matches!(self, Rust | RustCall | RustIntrinsic | RustCold)
+    }
+
     pub fn supports_varargs(self) -> bool {
         // * C and Cdecl obviously support varargs.
         // * C can be based on Aapcs, SysV64 or Win64, so they must support varargs.

compiler/rustc_error_codes/src/error_codes/E0804.md

@@ -0,0 +1,41 @@
+An auto trait cannot be added to the bounds of a `dyn Trait` type via
+a pointer cast.
+
+Erroneous code example:
+
+```rust,edition2021,compile_fail,E0804
+let ptr: *const dyn core::any::Any = &();
+_ = ptr as *const (dyn core::any::Any + Send);
+```
+
+Adding an auto trait can make the vtable invalid, potentially causing
+UB in safe code afterwards. For example:
+
+```rust,edition2021,no_run
+use core::{mem::transmute, ptr::NonNull};
+
+trait Trait {
+    fn f(&self)
+    where
+        Self: Send;
+}
+
+impl Trait for NonNull<()> {
+    fn f(&self) {
+        unreachable!()
+    }
+}
+
+fn main() {
+    let unsend: &dyn Trait = &NonNull::dangling();
+    let bad: &(dyn Trait + Send) = unsafe { transmute(unsend) };
+    // This crashes, since the vtable for `NonNull as dyn Trait` does
+    // not have an entry for `Trait::f`.
+    bad.f();
+}
+```
+
+To fix this error, you can use `transmute` rather than pointer casts,
+but you must ensure that the vtable is valid for the pointer's type
+before calling a method on the trait object or allowing other code to
+do so.

compiler/rustc_error_codes/src/lib.rs

@@ -547,6 +547,7 @@ E0800: 0800,
 E0801: 0801,
 E0802: 0802,
 E0803: 0803,
+E0804: 0804,
         );
     )
 }

compiler/rustc_feature/src/removed.rs

@@ -244,6 +244,8 @@ declare_features! (
     /// Allows unnamed fields of struct and union type
     (removed, unnamed_fields, "1.83.0", Some(49804), Some("feature needs redesign")),
     (removed, unsafe_no_drop_flag, "1.0.0", None, None),
+    (removed, unsized_tuple_coercion, "CURRENT_RUSTC_VERSION", Some(42877),
+     Some("The feature restricts possible layouts for tuples, and this restriction is not worth it.")),
     /// Allows `union` fields that don't implement `Copy` as long as they don't have any drop glue.
     (removed, untagged_unions, "1.13.0", Some(55149),
      Some("unions with `Copy` and `ManuallyDrop` fields are stable; there is no intent to stabilize more")),

compiler/rustc_feature/src/unstable.rs

@@ -659,8 +659,6 @@ declare_features! (
     (internal, unsized_fn_params, "1.49.0", Some(48055)),
     /// Allows unsized rvalues at arguments and parameters.
     (incomplete, unsized_locals, "1.30.0", Some(48055)),
-    /// Allows unsized tuple coercion.
-    (unstable, unsized_tuple_coercion, "1.20.0", Some(42877)),
     /// Allows using the `#[used(linker)]` (or `#[used(compiler)]`) attribute.
     (unstable, used_with_arg, "1.60.0", Some(93798)),
     /// Allows use of attributes in `where` clauses.

compiler/rustc_hir_analysis/src/check/check.rs

@@ -745,14 +745,10 @@ fn check_static_linkage(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) {
     match tcx.def_kind(def_id) {
         DefKind::Static { .. } => {
-            tcx.ensure_ok().typeck(def_id);
-            maybe_check_static_with_link_section(tcx, def_id);
             check_static_inhabited(tcx, def_id);
             check_static_linkage(tcx, def_id);
         }
-        DefKind::Const => {
-            tcx.ensure_ok().typeck(def_id);
-        }
+        DefKind::Const => {}
         DefKind::Enum => {
             check_enum(tcx, def_id);
         }
@@ -766,7 +762,6 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) {
                     ExternAbi::Rust,
                 )
             }
-            // Everything else is checked entirely within check_item_body
         }
         DefKind::Impl { of_trait } => {
             if of_trait && let Some(impl_trait_header) = tcx.impl_trait_header(def_id) {

compiler/rustc_hir_analysis/src/check/mod.rs

@@ -145,7 +145,7 @@ pub fn forbid_intrinsic_abi(tcx: TyCtxt<'_>, sp: Span, abi: ExternAbi) {
     }
 }
 
-fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDefId) {
+pub(super) fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDefId) {
     // Only restricted on wasm target for now
     if !tcx.sess.target.is_like_wasm {
         return;

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -126,13 +126,14 @@ where
 
     let infcx_compat = infcx.fork();
 
-    // We specifically want to call the non-compat version of `implied_bounds_tys`; we do this always.
+    // We specifically want to *disable* the implied bounds hack, first,
+    // so we can detect when failures are due to bevy's implied bounds.
     let outlives_env = OutlivesEnvironment::new_with_implied_bounds_compat(
         &infcx,
         body_def_id,
         param_env,
         assumed_wf_types.iter().copied(),
-        false,
+        true,
     );
 
     lint_redundant_lifetimes(tcx, body_def_id, &outlives_env);
@@ -142,53 +143,22 @@ where
         return Ok(());
     }
 
-    let is_bevy = assumed_wf_types.visit_with(&mut ContainsBevyParamSet { tcx }).is_break();
-
-    // If we have set `no_implied_bounds_compat`, then do not attempt compatibility.
-    // We could also just always enter if `is_bevy`, and call `implied_bounds_tys`,
-    // but that does result in slightly more work when this option is set and
-    // just obscures what we mean here anyways. Let's just be explicit.
-    if is_bevy && !infcx.tcx.sess.opts.unstable_opts.no_implied_bounds_compat {
-        let outlives_env = OutlivesEnvironment::new_with_implied_bounds_compat(
-            &infcx,
-            body_def_id,
-            param_env,
-            assumed_wf_types,
-            true,
-        );
-        let errors_compat = infcx_compat.resolve_regions_with_outlives_env(&outlives_env);
-        if errors_compat.is_empty() {
-            Ok(())
-        } else {
-            Err(infcx_compat.err_ctxt().report_region_errors(body_def_id, &errors_compat))
-        }
+    let outlives_env = OutlivesEnvironment::new_with_implied_bounds_compat(
+        &infcx_compat,
+        body_def_id,
+        param_env,
+        assumed_wf_types,
+        // Don't *disable* the implied bounds hack; though this will only apply
+        // the implied bounds hack if this contains `bevy_ecs`'s `ParamSet` type.
+        false,
+    );
+    let errors_compat = infcx_compat.resolve_regions_with_outlives_env(&outlives_env);
+    if errors_compat.is_empty() {
+        // FIXME: Once we fix bevy, this would be the place to insert a warning
+        // to upgrade bevy.
+        Ok(())
     } else {
-        Err(infcx.err_ctxt().report_region_errors(body_def_id, &errors))
-    }
-}
-
-struct ContainsBevyParamSet<'tcx> {
-    tcx: TyCtxt<'tcx>,
-}
-
-impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ContainsBevyParamSet<'tcx> {
-    type Result = ControlFlow<()>;
-
-    fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
-        // We only care to match `ParamSet<T>` or `&ParamSet<T>`.
-        match t.kind() {
-            ty::Adt(def, _) => {
-                if self.tcx.item_name(def.did()) == sym::ParamSet
-                    && self.tcx.crate_name(def.did().krate) == sym::bevy_ecs
-                {
-                    return ControlFlow::Break(());
-                }
-            }
-            ty::Ref(_, ty, _) => ty.visit_with(self)?,
-            _ => {}
-        }
-
-        ControlFlow::Continue(())
+        Err(infcx_compat.err_ctxt().report_region_errors(body_def_id, &errors_compat))
     }
 }
 
@@ -201,7 +171,7 @@ fn check_well_formed(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(), ErrorGua
         hir::Node::ImplItem(item) => check_impl_item(tcx, item),
         hir::Node::ForeignItem(item) => check_foreign_item(tcx, item),
         hir::Node::OpaqueTy(_) => Ok(crate::check::check::check_item_type(tcx, def_id)),
-        _ => unreachable!(),
+        _ => unreachable!("{node:?}"),
     };
 
     if let Some(generics) = node.generics() {
@@ -1108,7 +1078,13 @@ fn check_associated_item(
                 let ty = tcx.type_of(item.def_id).instantiate_identity();
                 let ty = wfcx.normalize(span, Some(WellFormedLoc::Ty(item_id)), ty);
                 wfcx.register_wf_obligation(span, loc, ty.into());
-                check_sized_if_body(wfcx, item.def_id.expect_local(), ty, Some(span));
+                check_sized_if_body(
+                    wfcx,
+                    item.def_id.expect_local(),
+                    ty,
+                    Some(span),
+                    ObligationCauseCode::SizedConstOrStatic,
+                );
                 Ok(())
             }
             ty::AssocKind::Fn => {
@@ -1354,7 +1330,7 @@ fn check_item_type(
                 traits::ObligationCause::new(
                     ty_span,
                     wfcx.body_def_id,
-                    ObligationCauseCode::WellFormed(None),
+                    ObligationCauseCode::SizedConstOrStatic,
                 ),
                 wfcx.param_env,
                 item_ty,
@@ -1698,6 +1674,7 @@ fn check_fn_or_method<'tcx>(
             hir::FnRetTy::Return(ty) => Some(ty.span),
             hir::FnRetTy::DefaultReturn(_) => None,
         },
+        ObligationCauseCode::SizedReturnType,
     );
 }
 
@@ -1706,13 +1683,14 @@ fn check_sized_if_body<'tcx>(
     def_id: LocalDefId,
     ty: Ty<'tcx>,
     maybe_span: Option<Span>,
+    code: ObligationCauseCode<'tcx>,
 ) {
     let tcx = wfcx.tcx();
     if let Some(body) = tcx.hir_maybe_body_owned_by(def_id) {
         let span = maybe_span.unwrap_or(body.value.span);
 
         wfcx.register_bound(
-            ObligationCause::new(span, def_id, traits::ObligationCauseCode::SizedReturnType),
+            ObligationCause::new(span, def_id, code),
             wfcx.param_env,
             ty,
             tcx.require_lang_item(LangItem::Sized, Some(span)),

compiler/rustc_hir_analysis/src/lib.rs

@@ -212,7 +212,10 @@ pub fn check_crate(tcx: TyCtxt<'_>) {
     tcx.par_hir_body_owners(|item_def_id| {
         let def_kind = tcx.def_kind(item_def_id);
         match def_kind {
-            DefKind::Static { .. } => tcx.ensure_ok().eval_static_initializer(item_def_id),
+            DefKind::Static { .. } => {
+                tcx.ensure_ok().eval_static_initializer(item_def_id);
+                check::maybe_check_static_with_link_section(tcx, item_def_id);
+            }
             DefKind::Const if tcx.generics_of(item_def_id).is_empty() => {
                 let instance = ty::Instance::new(item_def_id.into(), ty::GenericArgs::empty());
                 let cid = GlobalId { instance, promoted: None };
@@ -223,12 +226,9 @@ pub fn check_crate(tcx: TyCtxt<'_>) {
         }
     });
 
-    // FIXME: Remove this when we implement creating `DefId`s
-    // for anon constants during their parents' typeck.
-    // Typeck all body owners in parallel will produce queries
-    // cycle errors because it may typeck on anon constants directly.
     tcx.par_hir_body_owners(|item_def_id| {
         let def_kind = tcx.def_kind(item_def_id);
+        // Skip `AnonConst`s because we feed their `type_of`.
         if !matches!(def_kind, DefKind::AnonConst) {
             tcx.ensure_ok().typeck(item_def_id);
         }

compiler/rustc_hir_typeck/messages.ftl

@@ -171,10 +171,13 @@ hir_typeck_pass_to_variadic_function = can't pass `{$ty}` to variadic function
     .suggestion = cast the value to `{$cast_ty}`
     .teach_help = certain types, like `{$ty}`, must be casted before passing them to a variadic function, because of arcane ABI rules dictated by the C standard
 
-hir_typeck_ptr_cast_add_auto_to_object = adding {$traits_len ->
-    [1] an auto trait {$traits}
+hir_typeck_ptr_cast_add_auto_to_object = cannot add {$traits_len ->
+    [1] auto trait {$traits}
     *[other] auto traits {$traits}
-} to a trait object in a pointer cast may cause UB later on
+} to dyn bound via pointer cast
+    .note = this could allow UB elsewhere
+    .help = use `transmute` if you're sure this is sound
+    .label = unsupported cast
 
 hir_typeck_remove_semi_for_coerce = you might have meant to return the `match` expression
 hir_typeck_remove_semi_for_coerce_expr = this could be implicitly returned but it is a statement, not a tail expression

compiler/rustc_hir_typeck/src/cast.rs

@@ -940,23 +940,19 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                             .collect::<Vec<_>>();
 
                         if !added.is_empty() {
-                            tcx.emit_node_span_lint(
-                                lint::builtin::PTR_CAST_ADD_AUTO_TO_OBJECT,
-                                self.expr.hir_id,
-                                self.span,
-                                errors::PtrCastAddAutoToObject {
-                                    traits_len: added.len(),
-                                    traits: {
-                                        let mut traits: Vec<_> = added
-                                            .into_iter()
-                                            .map(|trait_did| tcx.def_path_str(trait_did))
-                                            .collect();
-
-                                        traits.sort();
-                                        traits.into()
-                                    },
+                            tcx.dcx().emit_err(errors::PtrCastAddAutoToObject {
+                                span: self.span,
+                                traits_len: added.len(),
+                                traits: {
+                                    let mut traits: Vec<_> = added
+                                        .into_iter()
+                                        .map(|trait_did| tcx.def_path_str(trait_did))
+                                        .collect();
+
+                                    traits.sort();
+                                    traits.into()
                                 },
-                            )
+                            });
                         }
 
                         Ok(CastKind::PtrPtrCast)