Auto merge of #134716 - Zalathar:rollup-1h4q8cc, r=Zalathar

Rollup of 5 pull requests

Successful merges:

 - #134638 (Fix effect predicates from item bounds in old solver)
 - #134662 (Fix safety docs for `dyn Any + Send {+ Sync}`)
 - #134689 (core: fix const ptr::swap_nonoverlapping when there are pointers at odd offsets)
 - #134699 (Belay new reviews for workingjubilee)
 - #134701 (Correctly note item kind in `NonConstFunctionCall` error message)

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

compiler/rustc_const_eval/messages.ftl

@@ -253,7 +253,7 @@ const_eval_non_const_fmt_macro_call =
     cannot call non-const formatting macro in {const_eval_const_context}s
 
 const_eval_non_const_fn_call =
-    cannot call non-const fn `{$def_path_str}` in {const_eval_const_context}s
+    cannot call non-const {$def_descr} `{$def_path_str}` in {const_eval_const_context}s
 
 const_eval_non_const_impl =
     impl defined here, but it is not `const`

compiler/rustc_const_eval/src/check_consts/ops.rs

@@ -304,6 +304,7 @@ impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
             }
             _ => ccx.dcx().create_err(errors::NonConstFnCall {
                 span,
+                def_descr: ccx.tcx.def_descr(callee),
                 def_path_str: ccx.tcx.def_path_str_with_args(callee, args),
                 kind: ccx.const_kind(),
             }),

compiler/rustc_const_eval/src/errors.rs

@@ -192,6 +192,7 @@ pub(crate) struct NonConstFnCall {
     #[primary_span]
     pub span: Span,
     pub def_path_str: String,
+    pub def_descr: &'static str,
     pub kind: ConstContext,
 }
 

compiler/rustc_error_codes/src/error_codes/E0015.md

@@ -7,7 +7,7 @@ fn create_some() -> Option<u8> {
     Some(1)
 }
 
-// error: cannot call non-const fn `create_some` in constants
+// error: cannot call non-const function `create_some` in constants
 const FOO: Option<u8> = create_some();
 ```
 

compiler/rustc_trait_selection/src/traits/effects.rs

@@ -1,13 +1,15 @@
 use rustc_hir as hir;
-use rustc_infer::infer::{BoundRegionConversionTime, DefineOpaqueTypes, InferCtxt};
+use rustc_infer::infer::{BoundRegionConversionTime, DefineOpaqueTypes};
 use rustc_infer::traits::{ImplSource, Obligation, PredicateObligation};
 use rustc_middle::span_bug;
 use rustc_middle::ty::fast_reject::DeepRejectCtxt;
 use rustc_middle::ty::{self, TypingMode};
+use rustc_type_ir::elaborate::elaborate;
 use rustc_type_ir::solve::NoSolution;
-use thin_vec::ThinVec;
+use thin_vec::{ThinVec, thin_vec};
 
 use super::SelectionContext;
+use super::normalize::normalize_with_depth_to;
 
 pub type HostEffectObligation<'tcx> = Obligation<'tcx, ty::HostEffectPredicate<'tcx>>;
 
@@ -38,6 +40,12 @@ pub fn evaluate_host_effect_obligation<'tcx>(
         Err(EvaluationFailure::NoSolution) => {}
     }
 
+    match evaluate_host_effect_from_item_bounds(selcx, obligation) {
+        Ok(result) => return Ok(result),
+        Err(EvaluationFailure::Ambiguous) => return Err(EvaluationFailure::Ambiguous),
+        Err(EvaluationFailure::NoSolution) => {}
+    }
+
     match evaluate_host_effect_from_selection_candiate(selcx, obligation) {
         Ok(result) => return Ok(result),
         Err(EvaluationFailure::Ambiguous) => return Err(EvaluationFailure::Ambiguous),
@@ -48,24 +56,45 @@ pub fn evaluate_host_effect_obligation<'tcx>(
 }
 
 fn match_candidate<'tcx>(
-    infcx: &InferCtxt<'tcx>,
+    selcx: &mut SelectionContext<'_, 'tcx>,
     obligation: &HostEffectObligation<'tcx>,
     candidate: ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>,
+    candidate_is_unnormalized: bool,
+    more_nested: impl FnOnce(&mut SelectionContext<'_, 'tcx>, &mut ThinVec<PredicateObligation<'tcx>>),
 ) -> Result<ThinVec<PredicateObligation<'tcx>>, NoSolution> {
     if !candidate.skip_binder().constness.satisfies(obligation.predicate.constness) {
         return Err(NoSolution);
     }
 
-    let candidate = infcx.instantiate_binder_with_fresh_vars(
+    let mut candidate = selcx.infcx.instantiate_binder_with_fresh_vars(
         obligation.cause.span,
         BoundRegionConversionTime::HigherRankedType,
         candidate,
     );
 
-    let mut nested = infcx
-        .at(&obligation.cause, obligation.param_env)
-        .eq(DefineOpaqueTypes::Yes, obligation.predicate.trait_ref, candidate.trait_ref)?
-        .into_obligations();
+    let mut nested = thin_vec![];
+
+    // Unlike param-env bounds, item bounds may not be normalized.
+    if candidate_is_unnormalized {
+        candidate = normalize_with_depth_to(
+            selcx,
+            obligation.param_env,
+            obligation.cause.clone(),
+            obligation.recursion_depth,
+            candidate,
+            &mut nested,
+        );
+    }
+
+    nested.extend(
+        selcx
+            .infcx
+            .at(&obligation.cause, obligation.param_env)
+            .eq(DefineOpaqueTypes::Yes, obligation.predicate.trait_ref, candidate.trait_ref)?
+            .into_obligations(),
+    );
+
+    more_nested(selcx, &mut nested);
 
     for nested in &mut nested {
         nested.set_depth_from_parent(obligation.recursion_depth);
@@ -82,36 +111,116 @@ fn evaluate_host_effect_from_bounds<'tcx>(
     let drcx = DeepRejectCtxt::relate_rigid_rigid(selcx.tcx());
     let mut candidate = None;
 
-    for predicate in obligation.param_env.caller_bounds() {
-        let bound_predicate = predicate.kind();
-        if let ty::ClauseKind::HostEffect(data) = predicate.kind().skip_binder() {
-            let data = bound_predicate.rebind(data);
-            if data.skip_binder().trait_ref.def_id != obligation.predicate.trait_ref.def_id {
-                continue;
+    for clause in obligation.param_env.caller_bounds() {
+        let bound_clause = clause.kind();
+        let ty::ClauseKind::HostEffect(data) = bound_clause.skip_binder() else {
+            continue;
+        };
+        let data = bound_clause.rebind(data);
+        if data.skip_binder().trait_ref.def_id != obligation.predicate.trait_ref.def_id {
+            continue;
+        }
+
+        if !drcx
+            .args_may_unify(obligation.predicate.trait_ref.args, data.skip_binder().trait_ref.args)
+        {
+            continue;
+        }
+
+        let is_match =
+            infcx.probe(|_| match_candidate(selcx, obligation, data, false, |_, _| {}).is_ok());
+
+        if is_match {
+            if candidate.is_some() {
+                return Err(EvaluationFailure::Ambiguous);
+            } else {
+                candidate = Some(data);
             }
+        }
+    }
 
-            if !drcx.args_may_unify(
-                obligation.predicate.trait_ref.args,
-                data.skip_binder().trait_ref.args,
+    if let Some(data) = candidate {
+        Ok(match_candidate(selcx, obligation, data, false, |_, _| {})
+            .expect("candidate matched before, so it should match again"))
+    } else {
+        Err(EvaluationFailure::NoSolution)
+    }
+}
+
+fn evaluate_host_effect_from_item_bounds<'tcx>(
+    selcx: &mut SelectionContext<'_, 'tcx>,
+    obligation: &HostEffectObligation<'tcx>,
+) -> Result<ThinVec<PredicateObligation<'tcx>>, EvaluationFailure> {
+    let infcx = selcx.infcx;
+    let tcx = infcx.tcx;
+    let drcx = DeepRejectCtxt::relate_rigid_rigid(selcx.tcx());
+    let mut candidate = None;
+
+    let mut consider_ty = obligation.predicate.self_ty();
+    while let ty::Alias(kind @ (ty::Projection | ty::Opaque), alias_ty) = *consider_ty.kind() {
+        if tcx.is_conditionally_const(alias_ty.def_id) {
+            for clause in elaborate(
+                tcx,
+                tcx.explicit_implied_const_bounds(alias_ty.def_id)
+                    .iter_instantiated_copied(tcx, alias_ty.args)
+                    .map(|(trait_ref, _)| {
+                        trait_ref.to_host_effect_clause(tcx, obligation.predicate.constness)
+                    }),
             ) {
-                continue;
-            }
+                let bound_clause = clause.kind();
+                let ty::ClauseKind::HostEffect(data) = bound_clause.skip_binder() else {
+                    unreachable!("should not elaborate non-HostEffect from HostEffect")
+                };
+                let data = bound_clause.rebind(data);
+                if data.skip_binder().trait_ref.def_id != obligation.predicate.trait_ref.def_id {
+                    continue;
+                }
 
-            let is_match = infcx.probe(|_| match_candidate(infcx, obligation, data).is_ok());
+                if !drcx.args_may_unify(
+                    obligation.predicate.trait_ref.args,
+                    data.skip_binder().trait_ref.args,
+                ) {
+                    continue;
+                }
 
-            if is_match {
-                if candidate.is_some() {
-                    return Err(EvaluationFailure::Ambiguous);
-                } else {
-                    candidate = Some(data);
+                let is_match = infcx
+                    .probe(|_| match_candidate(selcx, obligation, data, true, |_, _| {}).is_ok());
+
+                if is_match {
+                    if candidate.is_some() {
+                        return Err(EvaluationFailure::Ambiguous);
+                    } else {
+                        candidate = Some((data, alias_ty));
+                    }
                 }
             }
         }
+
+        if kind != ty::Projection {
+            break;
+        }
+
+        consider_ty = alias_ty.self_ty();
     }
 
-    if let Some(data) = candidate {
-        Ok(match_candidate(infcx, obligation, data)
-            .expect("candidate matched before, so it should match again"))
+    if let Some((data, alias_ty)) = candidate {
+        Ok(match_candidate(selcx, obligation, data, true, |selcx, nested| {
+            // An alias bound only holds if we also check the const conditions
+            // of the alias, so we need to register those, too.
+            let const_conditions = normalize_with_depth_to(
+                selcx,
+                obligation.param_env,
+                obligation.cause.clone(),
+                obligation.recursion_depth,
+                tcx.const_conditions(alias_ty.def_id).instantiate(tcx, alias_ty.args),
+                nested,
+            );
+            nested.extend(const_conditions.into_iter().map(|(trait_ref, _)| {
+                obligation
+                    .with(tcx, trait_ref.to_host_effect_clause(tcx, obligation.predicate.constness))
+            }));
+        })
+        .expect("candidate matched before, so it should match again"))
     } else {
         Err(EvaluationFailure::NoSolution)
     }

library/core/src/any.rs

@@ -423,7 +423,8 @@ impl dyn Any + Send {
     ///
     /// # Safety
     ///
-    /// Same as the method on the type `dyn Any`.
+    /// The contained value must be of type `T`. Calling this method
+    /// with the incorrect type is *undefined behavior*.
     #[unstable(feature = "downcast_unchecked", issue = "90850")]
     #[inline]
     pub unsafe fn downcast_ref_unchecked<T: Any>(&self) -> &T {
@@ -451,7 +452,8 @@ impl dyn Any + Send {
     ///
     /// # Safety
     ///
-    /// Same as the method on the type `dyn Any`.
+    /// The contained value must be of type `T`. Calling this method
+    /// with the incorrect type is *undefined behavior*.
     #[unstable(feature = "downcast_unchecked", issue = "90850")]
     #[inline]
     pub unsafe fn downcast_mut_unchecked<T: Any>(&mut self) -> &mut T {
@@ -552,6 +554,10 @@ impl dyn Any + Send + Sync {
     ///     assert_eq!(*x.downcast_ref_unchecked::<usize>(), 1);
     /// }
     /// ```
+    /// # Safety
+    ///
+    /// The contained value must be of type `T`. Calling this method
+    /// with the incorrect type is *undefined behavior*.
     #[unstable(feature = "downcast_unchecked", issue = "90850")]
     #[inline]
     pub unsafe fn downcast_ref_unchecked<T: Any>(&self) -> &T {
@@ -576,6 +582,10 @@ impl dyn Any + Send + Sync {
     ///
     /// assert_eq!(*x.downcast_ref::<usize>().unwrap(), 2);
     /// ```
+    /// # Safety
+    ///
+    /// The contained value must be of type `T`. Calling this method
+    /// with the incorrect type is *undefined behavior*.
     #[unstable(feature = "downcast_unchecked", issue = "90850")]
     #[inline]
     pub unsafe fn downcast_mut_unchecked<T: Any>(&mut self) -> &mut T {

library/core/src/intrinsics/mod.rs

@@ -3795,15 +3795,15 @@ where
 /// See [`const_eval_select()`] for the rules and requirements around that intrinsic.
 pub(crate) macro const_eval_select {
     (
-        @capture { $($arg:ident : $ty:ty = $val:expr),* $(,)? } $( -> $ret:ty )? :
+        @capture$([$($binders:tt)*])? { $($arg:ident : $ty:ty = $val:expr),* $(,)? } $( -> $ret:ty )? :
         if const
             $(#[$compiletime_attr:meta])* $compiletime:block
         else
             $(#[$runtime_attr:meta])* $runtime:block
     ) => {
         // Use the `noinline` arm, after adding explicit `inline` attributes
         $crate::intrinsics::const_eval_select!(
-            @capture { $($arg : $ty = $val),* } $(-> $ret)? :
+            @capture$([$($binders)*])? { $($arg : $ty = $val),* } $(-> $ret)? :
             #[noinline]
             if const
                 #[inline] // prevent codegen on this function
@@ -3817,20 +3817,20 @@ pub(crate) macro const_eval_select {
     },
     // With a leading #[noinline], we don't add inline attributes
     (
-        @capture { $($arg:ident : $ty:ty = $val:expr),* $(,)? } $( -> $ret:ty )? :
+        @capture$([$($binders:tt)*])? { $($arg:ident : $ty:ty = $val:expr),* $(,)? } $( -> $ret:ty )? :
         #[noinline]
         if const
             $(#[$compiletime_attr:meta])* $compiletime:block
         else
             $(#[$runtime_attr:meta])* $runtime:block
     ) => {{
         $(#[$runtime_attr])*
-        fn runtime($($arg: $ty),*) $( -> $ret )? {
+        fn runtime$(<$($binders)*>)?($($arg: $ty),*) $( -> $ret )? {
             $runtime
         }
 
         $(#[$compiletime_attr])*
-        const fn compiletime($($arg: $ty),*) $( -> $ret )? {
+        const fn compiletime$(<$($binders)*>)?($($arg: $ty),*) $( -> $ret )? {
             // Don't warn if one of the arguments is unused.
             $(let _ = $arg;)*
 
@@ -3842,14 +3842,14 @@ pub(crate) macro const_eval_select {
     // We support leaving away the `val` expressions for *all* arguments
     // (but not for *some* arguments, that's too tricky).
     (
-        @capture { $($arg:ident : $ty:ty),* $(,)? } $( -> $ret:ty )? :
+        @capture$([$($binders:tt)*])? { $($arg:ident : $ty:ty),* $(,)? } $( -> $ret:ty )? :
         if const
             $(#[$compiletime_attr:meta])* $compiletime:block
         else
             $(#[$runtime_attr:meta])* $runtime:block
     ) => {
         $crate::intrinsics::const_eval_select!(
-            @capture { $($arg : $ty = $arg),* } $(-> $ret)? :
+            @capture$([$($binders)*])? { $($arg : $ty = $arg),* } $(-> $ret)? :
             if const
                 $(#[$compiletime_attr])* $compiletime
             else