Auto merge of #133818 - matthiaskrgr:rollup-iav1wq7, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #132937 (a release operation synchronizes with an acquire operation)
 - #133681 (improve TagEncoding::Niche docs, sanity check, and UB checks)
 - #133726 (Add `core::arch::breakpoint` and test)
 - #133768 (Remove `generic_associated_types_extended` feature gate)
 - #133811 ([AIX] change AIX default codemodel=large)
 - #133812 (Update wasm-component-ld to 0.5.11)
 - #133813 (compiletest: explain that UI tests are expected not to compile by default)

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

Cargo.lock

@@ -5803,17 +5803,20 @@ checksum = "65fc09f10666a9f147042251e0dda9c18f166ff7de300607007e96bdebc1068d"
 
 [[package]]
 name = "wasm-component-ld"
-version = "0.5.10"
+version = "0.5.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4d4aa6bd7fbe7cffbed29fe3e236fda74419def1bdef6f80f989ec51137edf44"
+checksum = "a2b05c3820968b335f10e703218459e4fd2cc91fdfc8f7936a993f1aacaa0938"
 dependencies = [
  "anyhow",
  "clap",
  "lexopt",
+ "libc",
  "tempfile",
  "wasi-preview1-component-adapter-provider",
  "wasmparser 0.219.1",
  "wat",
+ "windows-sys 0.59.0",
+ "winsplit",
  "wit-component",
  "wit-parser",
 ]
@@ -6185,6 +6188,12 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "winsplit"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3ab703352da6a72f35c39a533526393725640575bb211f61987a2748323ad956"
+
 [[package]]
 name = "wit-component"
 version = "0.219.1"

compiler/rustc_abi/src/lib.rs

@@ -1215,6 +1215,15 @@ impl Scalar {
             Scalar::Union { .. } => true,
         }
     }
+
+    /// Returns `true` if this is a signed integer scalar
+    #[inline]
+    pub fn is_signed(&self) -> bool {
+        match self.primitive() {
+            Primitive::Int(_, signed) => signed,
+            _ => false,
+        }
+    }
 }
 
 // NOTE: This struct is generic over the FieldIdx for rust-analyzer usage.
@@ -1401,10 +1410,7 @@ impl BackendRepr {
     #[inline]
     pub fn is_signed(&self) -> bool {
         match self {
-            BackendRepr::Scalar(scal) => match scal.primitive() {
+            BackendRepr::Scalar(scal) => scal.is_signed(),
-                Primitive::Int(_, signed) => signed,
-                _ => false,
-            },
             _ => panic!("`is_signed` on non-scalar ABI {self:?}"),
         }
     }
@@ -1499,7 +1505,11 @@ impl BackendRepr {
 #[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
 pub enum Variants<FieldIdx: Idx, VariantIdx: Idx> {
     /// Single enum variants, structs/tuples, unions, and all non-ADTs.
-    Single { index: VariantIdx },
+    Single {
+        /// Always 0 for non-enums/generators.
+        /// For enums without a variant, this is an invalid index!
+        index: VariantIdx,
+    },
 
     /// Enum-likes with more than one variant: each variant comes with
     /// a *discriminant* (usually the same as the variant index but the user can
@@ -1528,14 +1538,22 @@ pub enum TagEncoding<VariantIdx: Idx> {
     /// The variant `untagged_variant` contains a niche at an arbitrary
     /// offset (field `tag_field` of the enum), which for a variant with
     /// discriminant `d` is set to
-    /// `(d - niche_variants.start).wrapping_add(niche_start)`.
+    /// `(d - niche_variants.start).wrapping_add(niche_start)`
+    /// (this is wrapping arithmetic using the type of the niche field).
     ///
     /// For example, `Option<(usize, &T)>`  is represented such that
     /// `None` has a null pointer for the second tuple field, and
     /// `Some` is the identity function (with a non-null reference).
+    ///
+    /// Other variants that are not `untagged_variant` and that are outside the `niche_variants`
+    /// range cannot be represented; they must be uninhabited.
     Niche {
         untagged_variant: VariantIdx,
+        /// This range *may* contain `untagged_variant`; that is then just a "dead value" and
+        /// not used to encode anything.
         niche_variants: RangeInclusive<VariantIdx>,
+        /// This is inbounds of the type of the niche field
+        /// (not sign-extended, i.e., all bits beyond the niche field size are 0).
         niche_start: u128,
     },
 }

compiler/rustc_const_eval/src/const_eval/mod.rs

@@ -2,6 +2,7 @@
 
 use rustc_abi::VariantIdx;
 use rustc_middle::query::{Key, TyCtxtAt};
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::{bug, mir};
 use tracing::instrument;
@@ -85,5 +86,6 @@ pub fn tag_for_variant_provider<'tcx>(
         crate::const_eval::DummyMachine,
     );
 
-    ecx.tag_for_variant(ty, variant_index).unwrap().map(|(tag, _tag_field)| tag)
+    let layout = ecx.layout_of(ty).unwrap();
+    ecx.tag_for_variant(layout, variant_index).unwrap().map(|(tag, _tag_field)| tag)
 }

compiler/rustc_const_eval/src/interpret/discriminant.rs

@@ -1,7 +1,7 @@
 //! Functions for reading and writing discriminants of multi-variant layouts (enums and coroutines).
 
 use rustc_abi::{self as abi, TagEncoding, VariantIdx, Variants};
-use rustc_middle::ty::layout::{LayoutOf, PrimitiveExt};
+use rustc_middle::ty::layout::{LayoutOf, PrimitiveExt, TyAndLayout};
 use rustc_middle::ty::{self, CoroutineArgsExt, ScalarInt, Ty};
 use rustc_middle::{mir, span_bug};
 use tracing::{instrument, trace};
@@ -21,17 +21,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         variant_index: VariantIdx,
         dest: &impl Writeable<'tcx, M::Provenance>,
     ) -> InterpResult<'tcx> {
-        // Layout computation excludes uninhabited variants from consideration
+        match self.tag_for_variant(dest.layout(), variant_index)? {
-        // therefore there's no way to represent those variants in the given layout.
-        // Essentially, uninhabited variants do not have a tag that corresponds to their
-        // discriminant, so we cannot do anything here.
-        // When evaluating we will always error before even getting here, but ConstProp 'executes'
-        // dead code, so we cannot ICE here.
-        if dest.layout().for_variant(self, variant_index).is_uninhabited() {
-            throw_ub!(UninhabitedEnumVariantWritten(variant_index))
-        }
-
-        match self.tag_for_variant(dest.layout().ty, variant_index)? {
             Some((tag, tag_field)) => {
                 // No need to validate that the discriminant here because the
                 // `TyAndLayout::for_variant()` call earlier already checks the
@@ -80,7 +70,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 if ty.is_enum() {
                     // Hilariously, `Single` is used even for 0-variant enums.
                     // (See https://github.com/rust-lang/rust/issues/89765).
-                    if matches!(ty.kind(), ty::Adt(def, ..) if def.variants().is_empty()) {
+                    if ty.ty_adt_def().unwrap().variants().is_empty() {
                         throw_ub!(UninhabitedEnumVariantRead(index))
                     }
                     // For consistency with `write_discriminant`, and to make sure that
@@ -188,6 +178,11 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                             let variants =
                                 ty.ty_adt_def().expect("tagged layout for non adt").variants();
                             assert!(variant_index < variants.next_index());
+                            if variant_index == untagged_variant {
+                                // The untagged variant can be in the niche range, but even then it
+                                // is not a valid encoding.
+                                throw_ub!(InvalidTag(Scalar::from_uint(tag_bits, tag_layout.size)))
+                            }
                             variant_index
                         } else {
                             untagged_variant
@@ -236,10 +231,18 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
     ///   given field index.
     pub(crate) fn tag_for_variant(
         &self,
-        ty: Ty<'tcx>,
+        layout: TyAndLayout<'tcx>,
         variant_index: VariantIdx,
     ) -> InterpResult<'tcx, Option<(ScalarInt, usize)>> {
-        match self.layout_of(ty)?.variants {
+        // Layout computation excludes uninhabited variants from consideration.
+        // Therefore, there's no way to represent those variants in the given layout.
+        // Essentially, uninhabited variants do not have a tag that corresponds to their
+        // discriminant, so we have to bail out here.
+        if layout.for_variant(self, variant_index).is_uninhabited() {
+            throw_ub!(UninhabitedEnumVariantWritten(variant_index))
+        }
+
+        match layout.variants {
             abi::Variants::Single { .. } => {
                 // The tag of a `Single` enum is like the tag of the niched
                 // variant: there's no tag as the discriminant is encoded
@@ -260,7 +263,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 // raw discriminants for enums are isize or bigger during
                 // their computation, but the in-memory tag is the smallest possible
                 // representation
-                let discr = self.discriminant_for_variant(ty, variant_index)?;
+                let discr = self.discriminant_for_variant(layout.ty, variant_index)?;
                 let discr_size = discr.layout.size;
                 let discr_val = discr.to_scalar().to_bits(discr_size)?;
                 let tag_size = tag_layout.size(self);
@@ -286,11 +289,13 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 ..
             } => {
                 assert!(variant_index != untagged_variant);
+                // We checked that this variant is inhabited, so it must be in the niche range.
+                assert!(
+                    niche_variants.contains(&variant_index),
+                    "invalid variant index for this enum"
+                );
                 let variants_start = niche_variants.start().as_u32();
-                let variant_index_relative = variant_index
+                let variant_index_relative = variant_index.as_u32().strict_sub(variants_start);
-                    .as_u32()
-                    .checked_sub(variants_start)
-                    .expect("overflow computing relative variant idx");
                 // We need to use machine arithmetic when taking into account `niche_start`:
                 // tag_val = variant_index_relative + niche_start_val
                 let tag_layout = self.layout_of(tag_layout.primitive().to_int_ty(*self.tcx))?;

compiler/rustc_const_eval/src/lib.rs

@@ -10,6 +10,7 @@
 #![feature(never_type)]
 #![feature(rustdoc_internals)]
 #![feature(slice_ptr_get)]
+#![feature(strict_overflow_ops)]
 #![feature(trait_alias)]
 #![feature(try_blocks)]
 #![feature(unqualified_local_imports)]

compiler/rustc_error_codes/src/error_codes/E0622.md

@@ -7,10 +7,11 @@ Erroneous code example:
 #![allow(internal_features)]
 
 extern "rust-intrinsic" {
-    pub static breakpoint: fn(); // error: intrinsic must be a function
+    pub static atomic_singlethreadfence_seqcst: fn();
+    // error: intrinsic must be a function
 }
 
-fn main() { unsafe { breakpoint(); } }
+fn main() { unsafe { atomic_singlethreadfence_seqcst(); } }
 ```
 
 An intrinsic is a function available for use in a given programming language
@@ -22,8 +23,8 @@ error, just declare a function. Example:
 #![allow(internal_features)]
 
 extern "rust-intrinsic" {
-    pub fn breakpoint(); // ok!
+    pub fn atomic_singlethreadfence_seqcst(); // ok!
 }
 
-fn main() { unsafe { breakpoint(); } }
+fn main() { unsafe { atomic_singlethreadfence_seqcst(); } }
 ```

compiler/rustc_feature/src/removed.rs

@@ -119,6 +119,13 @@ declare_features! (
     (removed, generator_clone, "1.65.0", Some(95360), Some("renamed to `coroutine_clone`")),
     /// Allows defining generators.
     (removed, generators, "1.21.0", Some(43122), Some("renamed to `coroutines`")),
+    /// An extension to the `generic_associated_types` feature, allowing incomplete features.
+    (removed, generic_associated_types_extended, "CURRENT_RUSTC_VERSION", Some(95451),
+        Some(
+            "feature needs overhaul and reimplementation pending \
+            better implied higher-ranked implied bounds support"
+        )
+    ),
     /// Allows `impl Trait` in bindings (`let`, `const`, `static`).
     (removed, impl_trait_in_bindings, "1.55.0", Some(63065),
      Some("the implementation was not maintainable, the feature may get reintroduced once the current refactorings are done")),

compiler/rustc_feature/src/unstable.rs

@@ -499,8 +499,6 @@ declare_features! (
     (unstable, gen_blocks, "1.75.0", Some(117078)),
     /// Infer generic args for both consts and types.
     (unstable, generic_arg_infer, "1.55.0", Some(85077)),
-    /// An extension to the `generic_associated_types` feature, allowing incomplete features.
-    (incomplete, generic_associated_types_extended, "1.61.0", Some(95451)),
     /// Allows non-trivial generic constants which have to have wfness manually propagated to callers
     (incomplete, generic_const_exprs, "1.56.0", Some(76560)),
     /// Allows generic parameters and where-clauses on free & associated const items.

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -87,6 +87,7 @@ pub fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -
         | sym::assert_inhabited
         | sym::assert_zero_valid
         | sym::assert_mem_uninitialized_valid
+        | sym::breakpoint
         | sym::size_of
         | sym::min_align_of
         | sym::needs_drop

compiler/rustc_middle/src/query/mod.rs

@@ -1081,6 +1081,8 @@ rustc_queries! {
     }
 
     /// Computes the tag (if any) for a given type and variant.
+    /// `None` means that the variant doesn't need a tag (because it is niched).
+    /// Will panic for uninhabited variants.
     query tag_for_variant(
         key: (Ty<'tcx>, abi::VariantIdx)
     ) -> Option<ty::ScalarInt> {

compiler/rustc_target/src/spec/base/aix.rs

@@ -4,7 +4,7 @@ use crate::spec::{Cc, CodeModel, LinkOutputKind, LinkerFlavor, TargetOptions, cr
 pub(crate) fn opts() -> TargetOptions {
     TargetOptions {
         abi: "vec-extabi".into(),
-        code_model: Some(CodeModel::Small),
+        code_model: Some(CodeModel::Large),
         cpu: "pwr7".into(),
         os: "aix".into(),
         vendor: "ibm".into(),

compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs

@@ -328,10 +328,7 @@ pub fn dyn_compatibility_violations_for_assoc_item(
             .collect(),
         // Associated types can only be dyn-compatible if they have `Self: Sized` bounds.
         ty::AssocKind::Type => {
-            if !tcx.features().generic_associated_types_extended()
+            if !tcx.generics_of(item.def_id).is_own_empty() && !item.is_impl_trait_in_trait() {
-                && !tcx.generics_of(item.def_id).is_own_empty()
-                && !item.is_impl_trait_in_trait()
-            {
                 vec![DynCompatibilityViolation::GAT(item.name, item.ident(tcx).span)]
             } else {
                 // We will permit associated types if they are explicitly mentioned in the trait object.

compiler/rustc_trait_selection/src/traits/project.rs

@@ -14,7 +14,7 @@ use rustc_middle::traits::select::OverflowError;
 use rustc_middle::traits::{BuiltinImplSource, ImplSource, ImplSourceUserDefinedData};
 use rustc_middle::ty::fast_reject::DeepRejectCtxt;
 use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::visit::{MaxUniverse, TypeVisitable, TypeVisitableExt};
+use rustc_middle::ty::visit::TypeVisitableExt;
 use rustc_middle::ty::{self, Term, Ty, TyCtxt, TypingMode, Upcast};
 use rustc_middle::{bug, span_bug};
 use rustc_span::symbol::sym;
@@ -179,35 +179,11 @@ pub(super) fn poly_project_and_unify_term<'cx, 'tcx>(
 ) -> ProjectAndUnifyResult<'tcx> {
     let infcx = selcx.infcx;
     let r = infcx.commit_if_ok(|_snapshot| {
-        let old_universe = infcx.universe();
         let placeholder_predicate = infcx.enter_forall_and_leak_universe(obligation.predicate);
-        let new_universe = infcx.universe();
 
         let placeholder_obligation = obligation.with(infcx.tcx, placeholder_predicate);
         match project_and_unify_term(selcx, &placeholder_obligation) {
             ProjectAndUnifyResult::MismatchedProjectionTypes(e) => Err(e),
-            ProjectAndUnifyResult::Holds(obligations)
-                if old_universe != new_universe
-                    && selcx.tcx().features().generic_associated_types_extended() =>
-            {
-                // If the `generic_associated_types_extended` feature is active, then we ignore any
-                // obligations references lifetimes from any universe greater than or equal to the
-                // universe just created. Otherwise, we can end up with something like `for<'a> I: 'a`,
-                // which isn't quite what we want. Ideally, we want either an implied
-                // `for<'a where I: 'a> I: 'a` or we want to "lazily" check these hold when we
-                // instantiate concrete regions. There is design work to be done here; until then,
-                // however, this allows experimenting potential GAT features without running into
-                // well-formedness issues.
-                let new_obligations = obligations
-                    .into_iter()
-                    .filter(|obligation| {
-                        let mut visitor = MaxUniverse::new();
-                        obligation.predicate.visit_with(&mut visitor);
-                        visitor.max_universe() < new_universe
-                    })
-                    .collect();
-                Ok(ProjectAndUnifyResult::Holds(new_obligations))
-            }
             other => Ok(other),
         }
     });

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -626,7 +626,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         for assoc_type in assoc_types {
             let defs: &ty::Generics = tcx.generics_of(assoc_type);
 
-            if !defs.own_params.is_empty() && !tcx.features().generic_associated_types_extended() {
+            if !defs.own_params.is_empty() {
                 tcx.dcx().span_delayed_bug(
                     obligation.cause.span,
                     "GATs in trait object shouldn't have been considered",

compiler/rustc_transmute/src/layout/tree.rs

@@ -319,11 +319,15 @@ pub(crate) mod rustc {
         ) -> Result<Self, Err> {
             assert!(def.is_enum());
 
-            // Computes the variant of a given index.
+            // Computes the layout of a variant.
-            let layout_of_variant = |index, encoding: Option<TagEncoding<VariantIdx>>| {
+            let layout_of_variant =
+                |index, encoding: Option<TagEncoding<VariantIdx>>| -> Result<Self, Err> {
+                    let variant_layout = ty_variant(cx, (ty, layout), index);
+                    if variant_layout.is_uninhabited() {
+                        return Ok(Self::uninhabited());
+                    }
                     let tag = cx.tcx().tag_for_variant((cx.tcx().erase_regions(ty), index));
                     let variant_def = Def::Variant(def.variant(index));
-                let variant_layout = ty_variant(cx, (ty, layout), index);
                     Self::from_variant(
                         variant_def,
                         tag.map(|tag| (tag, index, encoding.unwrap())),
@@ -333,25 +337,18 @@ pub(crate) mod rustc {
                     )
                 };
 
-            // We consider three kinds of enums, each demanding a different
-            // treatment of their layout computation:
-            // 1. enums that are uninhabited ZSTs
-            // 2. enums that delegate their layout to a variant
-            // 3. enums with multiple variants
             match layout.variants() {
-                Variants::Single { .. } if layout.is_uninhabited() && layout.size == Size::ZERO => {
-                    // The layout representation of uninhabited, ZST enums is
-                    // defined to be like that of the `!` type, as opposed of a
-                    // typical enum. Consequently, they cannot be descended into
-                    // as if they typical enums. We therefore special-case this
-                    // scenario and simply return an uninhabited `Tree`.
-                    Ok(Self::uninhabited())
-                }
                 Variants::Single { index } => {
+                    // Hilariously, `Single` is used even for 0-variant enums;
+                    // `index` is just junk in that case.
+                    if ty.ty_adt_def().unwrap().variants().is_empty() {
+                        Ok(Self::uninhabited())
+                    } else {
                         // `Variants::Single` on enums with variants denotes that
                         // the enum delegates its layout to the variant at `index`.
                         layout_of_variant(*index, None)
                     }
+                }
                 Variants::Multiple { tag, tag_encoding, tag_field, .. } => {
                     // `Variants::Multiple` denotes an enum with multiple
                     // variants. The layout of such an enum is the disjunction
@@ -369,7 +366,7 @@ pub(crate) mod rustc {
                         },
                     )?;
 
-                    return Ok(Self::def(Def::Adt(def)).then(variants));
+                    Ok(Self::def(Def::Adt(def)).then(variants))
                 }
             }
         }

compiler/rustc_ty_utils/src/layout.rs

@@ -81,7 +81,7 @@ fn layout_of<'tcx>(
         record_layout_for_printing(&cx, layout);
     }
 
-    invariant::partially_check_layout(&cx, &layout);
+    invariant::layout_sanity_check(&cx, &layout);
 
     Ok(layout)
 }

compiler/rustc_ty_utils/src/layout/invariant.rs

@@ -1,11 +1,11 @@
 use std::assert_matches::assert_matches;
 
-use rustc_abi::{BackendRepr, FieldsShape, Scalar, Size, Variants};
+use rustc_abi::{BackendRepr, FieldsShape, Scalar, Size, TagEncoding, Variants};
 use rustc_middle::bug;
 use rustc_middle::ty::layout::{HasTyCtxt, LayoutCx, TyAndLayout};
 
 /// Enforce some basic invariants on layouts.
-pub(super) fn partially_check_layout<'tcx>(cx: &LayoutCx<'tcx>, layout: &TyAndLayout<'tcx>) {
+pub(super) fn layout_sanity_check<'tcx>(cx: &LayoutCx<'tcx>, layout: &TyAndLayout<'tcx>) {
     let tcx = cx.tcx();
 
     // Type-level uninhabitedness should always imply ABI uninhabitedness.
@@ -241,7 +241,17 @@ pub(super) fn partially_check_layout<'tcx>(cx: &LayoutCx<'tcx>, layout: &TyAndLa
 
     check_layout_abi(cx, layout);
 
-    if let Variants::Multiple { variants, .. } = &layout.variants {
+    if let Variants::Multiple { variants, tag, tag_encoding, .. } = &layout.variants {
+        if let TagEncoding::Niche { niche_start, untagged_variant, niche_variants } = tag_encoding {
+            let niche_size = tag.size(cx);
+            assert!(*niche_start <= niche_size.unsigned_int_max());
+            for (idx, variant) in variants.iter_enumerated() {
+                // Ensure all inhabited variants are accounted for.
+                if !variant.is_uninhabited() {
+                    assert!(idx == *untagged_variant || niche_variants.contains(&idx));
+                }
+            }
+        }
         for variant in variants.iter() {
             // No nested "multiple".
             assert_matches!(variant.variants, Variants::Single { .. });

library/core/src/arch.rs

@@ -42,3 +42,30 @@ pub macro naked_asm("assembly template", $(operands,)* $(options($(option),*))?)
 pub macro global_asm("assembly template", $(operands,)* $(options($(option),*))?) {
     /* compiler built-in */
 }
+
+/// Compiles to a target-specific software breakpoint instruction or equivalent.
+///
+/// This will typically abort the program. It may result in a core dump, and/or the system logging
+/// debug information. Additional target-specific capabilities may be possible depending on
+/// debuggers or other tooling; in particular, a debugger may be able to resume execution.
+///
+/// If possible, this will produce an instruction sequence that allows a debugger to resume *after*
+/// the breakpoint, rather than resuming *at* the breakpoint; however, the exact behavior is
+/// target-specific and debugger-specific, and not guaranteed.
+///
+/// If the target platform does not have any kind of debug breakpoint instruction, this may compile
+/// to a trapping instruction (e.g. an undefined instruction) instead, or to some other form of
+/// target-specific abort that may or may not support convenient resumption.
+///
+/// The precise behavior and the precise instruction generated are not guaranteed, except that in
+/// normal execution with no debug tooling involved this will not continue executing.
+///
+/// - On x86 targets, this produces an `int3` instruction.
+/// - On aarch64 targets, this produces a `brk #0xf000` instruction.
+// When stabilizing this, update the comment on `core::intrinsics::breakpoint`.
+#[unstable(feature = "breakpoint", issue = "133724")]
+#[inline(always)]
+#[cfg(not(bootstrap))]
+pub fn breakpoint() {
+    core::intrinsics::breakpoint();
+}

library/core/src/intrinsics/mod.rs

@@ -1381,6 +1381,18 @@ pub unsafe fn prefetch_write_instruction<T>(_data: *const T, _locality: i32) {
 #[rustc_intrinsic]
 #[rustc_intrinsic_must_be_overridden]
 #[rustc_nounwind]
+#[cfg(not(bootstrap))]
+pub fn breakpoint() {
+    unreachable!()
+}
+
+/// Executes a breakpoint trap, for inspection by a debugger.
+///
+/// This intrinsic does not have a stable counterpart.
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+#[rustc_nounwind]
+#[cfg(bootstrap)]
 pub unsafe fn breakpoint() {
     unreachable!()
 }

library/std/src/thread/mod.rs

@@ -1021,11 +1021,11 @@ impl Drop for PanicGuard {
 ///
 /// # Memory Ordering
 ///
-/// Calls to `park` _synchronize-with_ calls to `unpark`, meaning that memory
+/// Calls to `unpark` _synchronize-with_ calls to `park`, meaning that memory
 /// operations performed before a call to `unpark` are made visible to the thread that
 /// consumes the token and returns from `park`. Note that all `park` and `unpark`
-/// operations for a given thread form a total order and `park` synchronizes-with
+/// operations for a given thread form a total order and _all_ prior `unpark` operations
-/// _all_ prior `unpark` operations.
+/// synchronize-with `park`.
 ///
 /// In atomic ordering terms, `unpark` performs a `Release` operation and `park`
 /// performs the corresponding `Acquire` operation. Calls to `unpark` for the same

src/tools/compiletest/src/runtest.rs

@@ -350,10 +350,13 @@ impl<'test> TestCx<'test> {
             }
         } else {
             if proc_res.status.success() {
-                self.fatal_proc_rec(
+                {
-                    &format!("{} test compiled successfully!", self.config.mode)[..],
+                    self.error(&format!("{} test did not emit an error", self.config.mode));
-                    proc_res,
+                    if self.config.mode == crate::common::Mode::Ui {
-                );
+                        println!("note: by default, ui tests are expected not to compile");
+                    }
+                    proc_res.fatal(None, || ());
+                };
             }
 
             if !self.props.dont_check_failure_status {

src/tools/miri/tests/fail/breakpoint.rs

@@ -1,7 +1,5 @@
 #![feature(core_intrinsics)]
 
 fn main() {
-    unsafe {
+    core::intrinsics::breakpoint(); //~ ERROR: trace/breakpoint trap
-        core::intrinsics::breakpoint() //~ ERROR: trace/breakpoint trap
-    };
 }

src/tools/miri/tests/fail/breakpoint.stderr

@@ -1,7 +1,7 @@
 error: abnormal termination: trace/breakpoint trap
   --> tests/fail/breakpoint.rs:LL:CC
    |
-LL |         core::intrinsics::breakpoint()
+LL |     core::intrinsics::breakpoint();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ trace/breakpoint trap
    |
    = note: BACKTRACE:

src/tools/miri/tests/fail/enum-untagged-variant-invalid-encoding.rs

@@ -0,0 +1,27 @@
+// Validity makes this fail at the wrong place.
+//@compile-flags: -Zmiri-disable-validation
+use std::mem;
+
+// This enum has untagged variant idx 1, with niche_variants being 0..=2
+// and niche_start being 2.
+// That means the untagged variants is in the niche variant range!
+// However, using the corresponding value (2+1 = 3) is not a valid encoding of this variant.
+#[derive(Copy, Clone, PartialEq)]
+enum Foo {
+    Var1,
+    Var2(bool),
+    Var3,
+}
+
+fn main() {
+    unsafe {
+        assert!(Foo::Var2(false) == mem::transmute(0u8));
+        assert!(Foo::Var2(true) == mem::transmute(1u8));
+        assert!(Foo::Var1 == mem::transmute(2u8));
+        assert!(Foo::Var3 == mem::transmute(4u8));
+
+        let invalid: Foo = mem::transmute(3u8);
+        assert!(matches!(invalid, Foo::Var2(_)));
+        //~^ ERROR: invalid tag
+    }
+}

src/tools/miri/tests/fail/enum-untagged-variant-invalid-encoding.stderr

@@ -0,0 +1,15 @@
+error: Undefined Behavior: enum value has invalid tag: 0x03
+  --> tests/fail/enum-untagged-variant-invalid-encoding.rs:LL:CC
+   |
+LL |         assert!(matches!(invalid, Foo::Var2(_)));
+   |                          ^^^^^^^ enum value has invalid tag: 0x03
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `main` at tests/fail/enum-untagged-variant-invalid-encoding.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+

src/tools/wasm-component-ld/Cargo.toml

@@ -10,4 +10,4 @@ name = "wasm-component-ld"
 path = "src/main.rs"
 
 [dependencies]
-wasm-component-ld = "0.5.10"
+wasm-component-ld = "0.5.11"

tests/assembly/breakpoint.rs

@@ -0,0 +1,14 @@
+//@ revisions: aarch64 x86_64
+//@ assembly-output: emit-asm
+//@[aarch64] only-aarch64
+//@[x86_64] only-x86_64
+
+#![feature(breakpoint)]
+#![crate_type = "lib"]
+
+// CHECK-LABEL: use_bp
+// aarch64: brk #0xf000
+// x86_64: int3
+pub fn use_bp() {
+    core::arch::breakpoint();
+}

tests/crashes/126267.rs

@@ -1,30 +0,0 @@
-//@ known-bug: rust-lang/rust#126267
-
-#![feature(transmutability)]
-#![crate_type = "lib"]
-
-pub enum ApiError {}
-pub struct TokioError {
-    b: bool,
-}
-pub enum Error {
-    Api { source: ApiError },
-    Ethereum,
-    Tokio { source: TokioError },
-}
-
-mod assert {
-    use std::mem::TransmuteFrom;
-
-    pub fn is_transmutable<Src, Dst>()
-    where
-        Dst: TransmuteFrom<Src>, // safety is NOT assumed
-    {
-    }
-}
-
-fn test() {
-    struct Src;
-    type Dst = Error;
-    assert::is_transmutable::<Src, Dst>();
-}

tests/crashes/131538.rs

@@ -1,13 +0,0 @@
-//@ known-bug: #131538
-#![feature(generic_associated_types_extended)]
-#![feature(trivial_bounds)]
-
-trait HealthCheck {
-    async fn check<const N: usize>();
-}
-
-fn do_health_check_par()
-where
-    HealthCheck: HealthCheck,
-{
-}

tests/ui/error-codes/E0622.rs

@@ -1,6 +1,6 @@
 #![feature(intrinsics)]
 extern "rust-intrinsic" {
-    pub static breakpoint : unsafe extern "rust-intrinsic" fn();
+    pub static atomic_singlethreadfence_seqcst : unsafe extern "rust-intrinsic" fn();
     //~^ ERROR intrinsic must be a function [E0622]
 }
-fn main() { unsafe { breakpoint(); } }
+fn main() { unsafe { atomic_singlethreadfence_seqcst(); } }

tests/ui/error-codes/E0622.stderr

@@ -1,8 +1,8 @@
 error[E0622]: intrinsic must be a function
   --> $DIR/E0622.rs:3:5
    |
-LL |     pub static breakpoint : unsafe extern "rust-intrinsic" fn();
+LL |     pub static atomic_singlethreadfence_seqcst : unsafe extern "rust-intrinsic" fn();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected a function
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected a function
 
 error: aborting due to 1 previous error
 

tests/ui/feature-gates/feature-gate-generic_associated_types_extended.rs

@@ -1,4 +0,0 @@
-// This feature doesn't *currently* fire on any specific code; it's just a
-// behavior change. Future changes might.
-#[rustc_error] //~ the
-fn main() {}

tests/ui/feature-gates/feature-gate-generic_associated_types_extended.stderr

@@ -1,12 +0,0 @@
-error[E0658]: the `#[rustc_error]` attribute is just used for rustc unit tests and will never be stable
-  --> $DIR/feature-gate-generic_associated_types_extended.rs:3:1
-   |
-LL | #[rustc_error]
-   | ^^^^^^^^^^^^^^
-   |
-   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0658`.

tests/ui/generic-associated-types/extended/lending_iterator.rs

@@ -1,9 +1,4 @@
-//@ revisions: base extended
+//@ known-bug: #133805
-//@[base] check-fail
-//@[extended] check-pass
-
-#![cfg_attr(extended, feature(generic_associated_types_extended))]
-#![cfg_attr(extended, allow(incomplete_features))]
 
 pub trait FromLendingIterator<A>: Sized {
     fn from_iter<T: for<'x> LendingIterator<Item<'x> = A>>(iter: T) -> Self;
@@ -11,7 +6,6 @@ pub trait FromLendingIterator<A>: Sized {
 
 impl<A> FromLendingIterator<A> for Vec<A> {
     fn from_iter<I: for<'x> LendingIterator<Item<'x> = A>>(mut iter: I) -> Self {
-        //[base]~^ impl has stricter
         let mut v = vec![];
         while let Some(item) = iter.next() {
             v.push(item);
@@ -32,7 +26,6 @@ pub trait LendingIterator {
         Self: for<'q> LendingIterator<Item<'q> = A>,
     {
         <B as FromLendingIterator<A>>::from_iter(self)
-        //[base]~^ ERROR: does not live long enough
     }
 }
 

tests/ui/generic-associated-types/extended/lending_iterator.stderr

@@ -1,5 +1,5 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/lending_iterator.rs:13:45
+  --> $DIR/lending_iterator.rs:8:45
    |
 LL |     fn from_iter<T: for<'x> LendingIterator<Item<'x> = A>>(iter: T) -> Self;
    |     ------------------------------------------------------------------------ definition of `from_iter` from trait
@@ -8,7 +8,7 @@ LL |     fn from_iter<I: for<'x> LendingIterator<Item<'x> = A>>(mut iter: I) ->
    |                                             ^^^^^^^^^^^^ impl has extra requirement `I: 'x`
 
 error: `Self` does not live long enough
-  --> $DIR/lending_iterator.rs:34:9
+  --> $DIR/lending_iterator.rs:28:9
    |
 LL |         <B as FromLendingIterator<A>>::from_iter(self)
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

tests/ui/generic-associated-types/extended/lending_iterator_2.rs

@@ -1,9 +1,4 @@
-//@ revisions: base extended
+//@ known-bug: #133805
-//@[base] check-fail
-//@[extended] check-pass
-
-#![cfg_attr(extended, feature(generic_associated_types_extended))]
-#![cfg_attr(extended, allow(incomplete_features))]
 
 pub trait FromLendingIterator<A>: Sized {
     fn from_iter<T: for<'x> LendingIterator<Item<'x> = A>>(iter: T) -> Self;
@@ -11,7 +6,6 @@ pub trait FromLendingIterator<A>: Sized {
 
 impl<A> FromLendingIterator<A> for Vec<A> {
     fn from_iter<I: for<'x> LendingIterator<Item<'x> = A>>(mut iter: I) -> Self {
-        //[base]~^ impl has stricter
         let mut v = vec![];
         while let Some(item) = iter.next() {
             v.push(item);

tests/ui/generic-associated-types/extended/lending_iterator_2.stderr

@@ -1,5 +1,5 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/lending_iterator_2.rs:13:45
+  --> $DIR/lending_iterator_2.rs:8:45
    |
 LL |     fn from_iter<T: for<'x> LendingIterator<Item<'x> = A>>(iter: T) -> Self;
    |     ------------------------------------------------------------------------ definition of `from_iter` from trait

tests/ui/generic-associated-types/gat-in-trait-path.rs

@@ -1,10 +1,6 @@
-//@ revisions: base extended
+//@ check-fail
-//@[base] check-fail
-//@[extended] check-pass
 
 #![feature(associated_type_defaults)]
-#![cfg_attr(extended, feature(generic_associated_types_extended))]
-#![cfg_attr(extended, allow(incomplete_features))]
 
 trait Foo {
     type A<'a> where Self: 'a;
@@ -24,12 +20,12 @@ impl<T> Foo for Fooer<T> {
 }
 
 fn f(_arg : Box<dyn for<'a> Foo<A<'a> = &'a ()>>) {}
-//[base]~^ the trait `Foo` cannot be made into an object
+//~^ the trait `Foo` cannot be made into an object
 
 
 fn main() {
   let foo = Fooer(5);
   f(Box::new(foo));
-  //[base]~^ the trait `Foo` cannot be made into an object
+  //~^ the trait `Foo` cannot be made into an object
-  //[base]~| the trait `Foo` cannot be made into an object
+  //~| the trait `Foo` cannot be made into an object
 }

tests/ui/generic-associated-types/gat-in-trait-path.stderr

@@ -0,0 +1,58 @@
+error[E0038]: the trait `Foo` cannot be made into an object
+  --> $DIR/gat-in-trait-path.rs:22:17
+   |
+LL | fn f(_arg : Box<dyn for<'a> Foo<A<'a> = &'a ()>>) {}
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Foo` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/gat-in-trait-path.rs:6:10
+   |
+LL | trait Foo {
+   |       --- this trait cannot be made into an object...
+LL |     type A<'a> where Self: 'a;
+   |          ^ ...because it contains the generic associated type `A`
+   = help: consider moving `A` to another trait
+   = help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `Foo` for this new enum and using it instead:
+             Fooy
+             Fooer<T>
+
+error[E0038]: the trait `Foo` cannot be made into an object
+  --> $DIR/gat-in-trait-path.rs:28:5
+   |
+LL |   f(Box::new(foo));
+   |     ^^^^^^^^^^^^^ `Foo` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/gat-in-trait-path.rs:6:10
+   |
+LL | trait Foo {
+   |       --- this trait cannot be made into an object...
+LL |     type A<'a> where Self: 'a;
+   |          ^ ...because it contains the generic associated type `A`
+   = help: consider moving `A` to another trait
+   = help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `Foo` for this new enum and using it instead:
+             Fooy
+             Fooer<T>
+
+error[E0038]: the trait `Foo` cannot be made into an object
+  --> $DIR/gat-in-trait-path.rs:28:5
+   |
+LL |   f(Box::new(foo));
+   |     ^^^^^^^^^^^^^ `Foo` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/gat-in-trait-path.rs:6:10
+   |
+LL | trait Foo {
+   |       --- this trait cannot be made into an object...
+LL |     type A<'a> where Self: 'a;
+   |          ^ ...because it contains the generic associated type `A`
+   = help: consider moving `A` to another trait
+   = help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `Foo` for this new enum and using it instead:
+             Fooy
+             Fooer<T>
+   = note: required for the cast from `Box<Fooer<{integer}>>` to `Box<(dyn Foo<A<'a> = &'a ()> + 'static)>`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0038`.

tests/ui/generic-associated-types/issue-67510-pass.rs

@@ -1,15 +1,10 @@
-//@ revisions: base extended
+//@ check-fail
-//@[base] check-fail
-//@[extended] check-pass
-
-#![cfg_attr(extended, feature(generic_associated_types_extended))]
-#![cfg_attr(extended, allow(incomplete_features))]
 
 trait X {
     type Y<'a>;
 }
 
 fn _func1<'a>(_x: Box<dyn X<Y<'a>=&'a ()>>) {}
-//[base]~^ ERROR the trait `X` cannot be made into an object
+//~^ ERROR the trait `X` cannot be made into an object
 
 fn main() {}

tests/ui/generic-associated-types/issue-67510-pass.stderr

@@ -0,0 +1,18 @@
+error[E0038]: the trait `X` cannot be made into an object
+  --> $DIR/issue-67510-pass.rs:7:23
+   |
+LL | fn _func1<'a>(_x: Box<dyn X<Y<'a>=&'a ()>>) {}
+   |                       ^^^^^^^^^^^^^^^^^^^ `X` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/issue-67510-pass.rs:4:10
+   |
+LL | trait X {
+   |       - this trait cannot be made into an object...
+LL |     type Y<'a>;
+   |          ^ ...because it contains the generic associated type `Y`
+   = help: consider moving `Y` to another trait
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0038`.

tests/ui/generic-associated-types/issue-76535.rs

@@ -1,8 +1,3 @@
-//@ revisions: base extended
-
-#![cfg_attr(extended, feature(generic_associated_types_extended))]
-#![cfg_attr(extended, allow(incomplete_features))]
-
 pub trait SubTrait {}
 
 pub trait SuperTrait {
@@ -38,6 +33,6 @@ impl SuperTrait for SuperStruct {
 fn main() {
     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
       //~^ ERROR missing generics for associated type
-      //[base]~^^ ERROR the trait
+      //~^^ ERROR the trait
-      //[base]~| ERROR the trait
+      //~| ERROR the trait
 }

tests/ui/generic-associated-types/issue-76535.stderr

@@ -0,0 +1,55 @@
+error[E0107]: missing generics for associated type `SuperTrait::SubType`
+  --> $DIR/issue-76535.rs:34:33
+   |
+LL |     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
+   |                                 ^^^^^^^ expected 1 lifetime argument
+   |
+note: associated type defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/issue-76535.rs:4:10
+   |
+LL |     type SubType<'a>: SubTrait where Self: 'a;
+   |          ^^^^^^^ --
+help: add missing lifetime argument
+   |
+LL |     let sub: Box<dyn SuperTrait<SubType<'a> = SubStruct>> = Box::new(SuperStruct::new(0));
+   |                                        ++++
+
+error[E0038]: the trait `SuperTrait` cannot be made into an object
+  --> $DIR/issue-76535.rs:34:14
+   |
+LL |     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/issue-76535.rs:4:10
+   |
+LL | pub trait SuperTrait {
+   |           ---------- this trait cannot be made into an object...
+LL |     type SubType<'a>: SubTrait where Self: 'a;
+   |          ^^^^^^^ ...because it contains the generic associated type `SubType`
+   = help: consider moving `SubType` to another trait
+   = help: only type `SuperStruct` is seen to implement the trait in this crate, consider using it directly instead
+   = note: `SuperTrait` can be implemented in other crates; if you want to support your users passing their own types here, you can't refer to a specific type
+
+error[E0038]: the trait `SuperTrait` cannot be made into an object
+  --> $DIR/issue-76535.rs:34:57
+   |
+LL |     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
+   |                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/issue-76535.rs:4:10
+   |
+LL | pub trait SuperTrait {
+   |           ---------- this trait cannot be made into an object...
+LL |     type SubType<'a>: SubTrait where Self: 'a;
+   |          ^^^^^^^ ...because it contains the generic associated type `SubType`
+   = help: consider moving `SubType` to another trait
+   = help: only type `SuperStruct` is seen to implement the trait in this crate, consider using it directly instead
+   = note: `SuperTrait` can be implemented in other crates; if you want to support your users passing their own types here, you can't refer to a specific type
+   = note: required for the cast from `Box<SuperStruct>` to `Box<dyn SuperTrait<SubType<'_> = SubStruct<'_>>>`
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0038, E0107.
+For more information about an error, try `rustc --explain E0038`.

tests/ui/generic-associated-types/issue-78671.rs

@@ -1,15 +1,10 @@
-//@ revisions: base extended
-
-#![cfg_attr(extended, feature(generic_associated_types_extended))]
-#![cfg_attr(extended, allow(incomplete_features))]
-
 trait CollectionFamily {
     type Member<T>;
 }
 fn floatify() {
     Box::new(Family) as &dyn CollectionFamily<Member=usize>
     //~^ ERROR: missing generics for associated type
-    //[base]~^^ ERROR: the trait `CollectionFamily` cannot be made into an object
+    //~| ERROR: the trait `CollectionFamily` cannot be made into an object
 }
 
 struct Family;

tests/ui/generic-associated-types/issue-78671.stderr

@@ -0,0 +1,35 @@
+error[E0107]: missing generics for associated type `CollectionFamily::Member`
+  --> $DIR/issue-78671.rs:5:47
+   |
+LL |     Box::new(Family) as &dyn CollectionFamily<Member=usize>
+   |                                               ^^^^^^ expected 1 generic argument
+   |
+note: associated type defined here, with 1 generic parameter: `T`
+  --> $DIR/issue-78671.rs:2:10
+   |
+LL |     type Member<T>;
+   |          ^^^^^^ -
+help: add missing generic argument
+   |
+LL |     Box::new(Family) as &dyn CollectionFamily<Member<T>=usize>
+   |                                                     +++
+
+error[E0038]: the trait `CollectionFamily` cannot be made into an object
+  --> $DIR/issue-78671.rs:5:25
+   |
+LL |     Box::new(Family) as &dyn CollectionFamily<Member=usize>
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `CollectionFamily` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/issue-78671.rs:2:10
+   |
+LL | trait CollectionFamily {
+   |       ---------------- this trait cannot be made into an object...
+LL |     type Member<T>;
+   |          ^^^^^^ ...because it contains the generic associated type `Member`
+   = help: consider moving `Member` to another trait
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0038, E0107.
+For more information about an error, try `rustc --explain E0038`.

tests/ui/generic-associated-types/issue-79422.rs

@@ -1,8 +1,3 @@
-//@ revisions: base extended
-
-#![cfg_attr(extended, feature(generic_associated_types_extended))]
-#![cfg_attr(extended, allow(incomplete_features))]
-
 trait RefCont<'a, T> {
     fn t(&'a self) -> &'a T;
 }
@@ -42,9 +37,8 @@ impl<K, V: Default> MapLike<K, V> for Source {
 
 fn main() {
     let m = Box::new(std::collections::BTreeMap::<u8, u8>::new())
-    //[base]~^ ERROR the trait
+    //~^ ERROR the trait
-    //[extended]~^^ type mismatch
         as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
       //~^ ERROR missing generics for associated type
-      //[base]~^^ ERROR the trait
+      //~| ERROR the trait
 }

tests/ui/generic-associated-types/issue-79422.stderr

@@ -0,0 +1,57 @@
+error[E0107]: missing generics for associated type `MapLike::VRefCont`
+  --> $DIR/issue-79422.rs:41:36
+   |
+LL |         as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
+   |                                    ^^^^^^^^ expected 1 lifetime argument
+   |
+note: associated type defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/issue-79422.rs:18:10
+   |
+LL |     type VRefCont<'a>: RefCont<'a, V> where Self: 'a;
+   |          ^^^^^^^^ --
+help: add missing lifetime argument
+   |
+LL |         as Box<dyn MapLike<u8, u8, VRefCont<'a> = dyn RefCont<'_, u8>>>;
+   |                                            ++++
+
+error[E0038]: the trait `MapLike` cannot be made into an object
+  --> $DIR/issue-79422.rs:41:12
+   |
+LL |         as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `MapLike` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/issue-79422.rs:18:10
+   |
+LL | trait MapLike<K, V> {
+   |       ------- this trait cannot be made into an object...
+LL |     type VRefCont<'a>: RefCont<'a, V> where Self: 'a;
+   |          ^^^^^^^^ ...because it contains the generic associated type `VRefCont`
+   = help: consider moving `VRefCont` to another trait
+   = help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `MapLike` for this new enum and using it instead:
+             std::collections::BTreeMap<K, V>
+             Source
+
+error[E0038]: the trait `MapLike` cannot be made into an object
+  --> $DIR/issue-79422.rs:39:13
+   |
+LL |     let m = Box::new(std::collections::BTreeMap::<u8, u8>::new())
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `MapLike` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/issue-79422.rs:18:10
+   |
+LL | trait MapLike<K, V> {
+   |       ------- this trait cannot be made into an object...
+LL |     type VRefCont<'a>: RefCont<'a, V> where Self: 'a;
+   |          ^^^^^^^^ ...because it contains the generic associated type `VRefCont`
+   = help: consider moving `VRefCont` to another trait
+   = help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `MapLike` for this new enum and using it instead:
+             std::collections::BTreeMap<K, V>
+             Source
+   = note: required for the cast from `Box<BTreeMap<u8, u8>>` to `Box<dyn MapLike<u8, u8, VRefCont<'_> = (dyn RefCont<'_, u8> + 'static)>>`
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0038, E0107.
+For more information about an error, try `rustc --explain E0038`.

tests/ui/generic-associated-types/trait-objects.rs

@@ -1,8 +1,3 @@
-//@ revisions: base extended
-
-#![cfg_attr(extended, feature(generic_associated_types_extended))]
-#![cfg_attr(extended, allow(incomplete_features))]
-
 trait StreamingIterator {
     type Item<'a> where Self: 'a;
     fn size_hint(&self) -> (usize, Option<usize>);
@@ -11,11 +6,10 @@ trait StreamingIterator {
 }
 
 fn min_size(x: &mut dyn for<'a> StreamingIterator<Item<'a> = &'a i32>) -> usize {
-    //[base]~^ the trait `StreamingIterator` cannot be made into an object
+    //~^ the trait `StreamingIterator` cannot be made into an object
     x.size_hint().0
-    //[extended]~^ borrowed data escapes
+    //~^ the trait `StreamingIterator` cannot be made into an object
-    //[base]~^^ the trait `StreamingIterator` cannot be made into an object
+    //~| the trait `StreamingIterator` cannot be made into an object
-    //[base]~| the trait `StreamingIterator` cannot be made into an object
 }
 
 fn main() {}

tests/ui/generic-associated-types/trait-objects.stderr

@@ -0,0 +1,48 @@
+error[E0038]: the trait `StreamingIterator` cannot be made into an object
+  --> $DIR/trait-objects.rs:8:21
+   |
+LL | fn min_size(x: &mut dyn for<'a> StreamingIterator<Item<'a> = &'a i32>) -> usize {
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `StreamingIterator` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/trait-objects.rs:2:10
+   |
+LL | trait StreamingIterator {
+   |       ----------------- this trait cannot be made into an object...
+LL |     type Item<'a> where Self: 'a;
+   |          ^^^^ ...because it contains the generic associated type `Item`
+   = help: consider moving `Item` to another trait
+
+error[E0038]: the trait `StreamingIterator` cannot be made into an object
+  --> $DIR/trait-objects.rs:10:7
+   |
+LL |     x.size_hint().0
+   |       ^^^^^^^^^ `StreamingIterator` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/trait-objects.rs:2:10
+   |
+LL | trait StreamingIterator {
+   |       ----------------- this trait cannot be made into an object...
+LL |     type Item<'a> where Self: 'a;
+   |          ^^^^ ...because it contains the generic associated type `Item`
+   = help: consider moving `Item` to another trait
+
+error[E0038]: the trait `StreamingIterator` cannot be made into an object
+  --> $DIR/trait-objects.rs:10:5
+   |
+LL |     x.size_hint().0
+   |     ^^^^^^^^^^^^^ `StreamingIterator` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/trait-objects.rs:2:10
+   |
+LL | trait StreamingIterator {
+   |       ----------------- this trait cannot be made into an object...
+LL |     type Item<'a> where Self: 'a;
+   |          ^^^^ ...because it contains the generic associated type `Item`
+   = help: consider moving `Item` to another trait
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0038`.

tests/ui/transmutability/uninhabited.rs

@@ -91,3 +91,19 @@ fn distant_void() {
     assert::is_maybe_transmutable::<DistantVoid, &'static Void>();
     assert::is_maybe_transmutable::<u128, DistantVoid>(); //~ ERROR: cannot be safely transmuted
 }
+
+fn issue_126267() {
+    pub enum ApiError {}
+    pub struct TokioError {
+        b: bool,
+    }
+    pub enum Error {
+        Api { source: ApiError }, // this variant is uninhabited
+        Ethereum,
+        Tokio { source: TokioError },
+    }
+
+    struct Src;
+    type Dst = Error;
+    assert::is_maybe_transmutable::<Src, Dst>(); //~ERROR: cannot be safely transmuted
+}

tests/ui/transmutability/uninhabited.stderr

@@ -110,7 +110,29 @@ LL | |             }
 LL | |         }>
    | |__________^ required by this bound in `is_maybe_transmutable`
 
-error: aborting due to 7 previous errors
+error[E0277]: `Src` cannot be safely transmuted into `issue_126267::Error`
+  --> $DIR/uninhabited.rs:108:42
+   |
+LL |     assert::is_maybe_transmutable::<Src, Dst>();
+   |                                          ^^^ the size of `Src` is smaller than the size of `issue_126267::Error`
+   |
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/uninhabited.rs:10:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this function
+LL |       where
+LL |           Dst: TransmuteFrom<Src, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error: aborting due to 8 previous errors
 
 Some errors have detailed explanations: E0080, E0277.
 For more information about an error, try `rustc --explain E0080`.