Auto merge of rust-lang#94706 - matthiaskrgr:rollup-l5erynr, r=matthiaskrgr

Rollup of 4 pull requests

Successful merges:

 - rust-lang#93350 (libunwind: readd link attrs to _Unwind_Backtrace)
 - rust-lang#93827 (Stabilize const_fn_fn_ptr_basics, const_fn_trait_bound, and const_impl_trait)
 - rust-lang#94696 (Remove whitespaces and use CSS to align line numbers to the right instead)
 - rust-lang#94700 (rustdoc: Update minifier version)

Failed merges:

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

Author: bors

Cargo.lock

@@ -2273,9 +2273,9 @@ dependencies = [
 
 [[package]]
 name = "minifier"
-version = "0.0.42"
+version = "0.0.43"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "55a1388517eda8a68875243b650c26997e055a33d82571b5a0349129faef7d99"
+checksum = "d81352bda6f4d04af1720afaa762054f66e16caffd93c1f86461a1c0ac4e695e"
 dependencies = [
  "macro-utils",
 ]

compiler/rustc_const_eval/src/transform/check_consts/check.rs

@@ -230,8 +230,6 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
                 }
             }
 
-            self.check_item_predicates();
-
             for (idx, local) in body.local_decls.iter_enumerated() {
                 // Handle the return place below.
                 if idx == RETURN_PLACE || local.internal {
@@ -358,83 +356,11 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
 
             match *ty.kind() {
                 ty::Ref(_, _, hir::Mutability::Mut) => self.check_op(ops::ty::MutRef(kind)),
-                ty::Opaque(..) => self.check_op(ops::ty::ImplTrait),
-                ty::FnPtr(..) => self.check_op(ops::ty::FnPtr(kind)),
-
-                ty::Dynamic(preds, _) => {
-                    for pred in preds.iter() {
-                        match pred.skip_binder() {
-                            ty::ExistentialPredicate::AutoTrait(_)
-                            | ty::ExistentialPredicate::Projection(_) => {
-                                self.check_op(ops::ty::DynTrait(kind))
-                            }
-                            ty::ExistentialPredicate::Trait(trait_ref) => {
-                                if Some(trait_ref.def_id) != self.tcx.lang_items().sized_trait() {
-                                    self.check_op(ops::ty::DynTrait(kind))
-                                }
-                            }
-                        }
-                    }
-                }
                 _ => {}
             }
         }
     }
 
-    fn check_item_predicates(&mut self) {
-        let ConstCx { tcx, .. } = *self.ccx;
-
-        let mut current = self.def_id().to_def_id();
-        loop {
-            let predicates = tcx.predicates_of(current);
-            for (predicate, _) in predicates.predicates {
-                match predicate.kind().skip_binder() {
-                    ty::PredicateKind::RegionOutlives(_)
-                    | ty::PredicateKind::TypeOutlives(_)
-                    | ty::PredicateKind::WellFormed(_)
-                    | ty::PredicateKind::Projection(_)
-                    | ty::PredicateKind::ConstEvaluatable(..)
-                    | ty::PredicateKind::ConstEquate(..)
-                    | ty::PredicateKind::TypeWellFormedFromEnv(..) => continue,
-                    ty::PredicateKind::ObjectSafe(_) => {
-                        bug!("object safe predicate on function: {:#?}", predicate)
-                    }
-                    ty::PredicateKind::ClosureKind(..) => {
-                        bug!("closure kind predicate on function: {:#?}", predicate)
-                    }
-                    ty::PredicateKind::Subtype(_) | ty::PredicateKind::Coerce(_) => {
-                        bug!("subtype/coerce predicate on function: {:#?}", predicate)
-                    }
-                    ty::PredicateKind::Trait(pred) => {
-                        if Some(pred.def_id()) == tcx.lang_items().sized_trait() {
-                            continue;
-                        }
-                        match pred.self_ty().kind() {
-                            ty::Param(p) => {
-                                let generics = tcx.generics_of(current);
-                                let def = generics.type_param(p, tcx);
-                                let span = tcx.def_span(def.def_id);
-
-                                // These are part of the function signature, so treat them like
-                                // arguments when determining importance.
-                                let kind = LocalKind::Arg;
-
-                                self.check_op_spanned(ops::ty::TraitBound(kind), span);
-                            }
-                            // other kinds of bounds are either tautologies
-                            // or cause errors in other passes
-                            _ => continue,
-                        }
-                    }
-                }
-            }
-            match predicates.parent {
-                Some(parent) => current = parent,
-                None => break,
-            }
-        }
-    }
-
     fn check_mut_borrow(&mut self, local: Local, kind: hir::BorrowKind) {
         match self.const_kind() {
             // In a const fn all borrows are transient or point to the places given via
@@ -613,7 +539,9 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                 ),
                 _,
                 _,
-            ) => self.check_op(ops::FnPtrCast),
+            ) => {
+                // Nothing to do here. Function pointer casts are allowed now.
+            }
 
             Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), _, _) => {
                 // Nothing to check here (`check_local_or_return_ty` ensures no trait objects occur

compiler/rustc_const_eval/src/transform/check_consts/ops.rs

@@ -355,31 +355,6 @@ impl<'tcx> NonConstOp<'tcx> for FnCallUnstable {
     }
 }
 
-#[derive(Debug)]
-pub struct FnPtrCast;
-impl<'tcx> NonConstOp<'tcx> for FnPtrCast {
-    fn status_in_item(&self, ccx: &ConstCx<'_, 'tcx>) -> Status {
-        if ccx.const_kind() != hir::ConstContext::ConstFn {
-            Status::Allowed
-        } else {
-            Status::Unstable(sym::const_fn_fn_ptr_basics)
-        }
-    }
-
-    fn build_error(
-        &self,
-        ccx: &ConstCx<'_, 'tcx>,
-        span: Span,
-    ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-        feature_err(
-            &ccx.tcx.sess.parse_sess,
-            sym::const_fn_fn_ptr_basics,
-            span,
-            &format!("function pointer casts are not allowed in {}s", ccx.const_kind()),
-        )
-    }
-}
-
 #[derive(Debug)]
 pub struct Generator(pub hir::GeneratorKind);
 impl<'tcx> NonConstOp<'tcx> for Generator {
@@ -820,167 +795,4 @@ pub mod ty {
             )
         }
     }
-
-    #[derive(Debug)]
-    pub struct FnPtr(pub mir::LocalKind);
-    impl<'tcx> NonConstOp<'tcx> for FnPtr {
-        fn importance(&self) -> DiagnosticImportance {
-            match self.0 {
-                mir::LocalKind::Var | mir::LocalKind::Temp => DiagnosticImportance::Secondary,
-                mir::LocalKind::ReturnPointer | mir::LocalKind::Arg => {
-                    DiagnosticImportance::Primary
-                }
-            }
-        }
-
-        fn status_in_item(&self, ccx: &ConstCx<'_, 'tcx>) -> Status {
-            if ccx.const_kind() != hir::ConstContext::ConstFn {
-                Status::Allowed
-            } else {
-                Status::Unstable(sym::const_fn_fn_ptr_basics)
-            }
-        }
-
-        fn build_error(
-            &self,
-            ccx: &ConstCx<'_, 'tcx>,
-            span: Span,
-        ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-            feature_err(
-                &ccx.tcx.sess.parse_sess,
-                sym::const_fn_fn_ptr_basics,
-                span,
-                &format!("function pointers cannot appear in {}s", ccx.const_kind()),
-            )
-        }
-    }
-
-    #[derive(Debug)]
-    pub struct ImplTrait;
-    impl<'tcx> NonConstOp<'tcx> for ImplTrait {
-        fn status_in_item(&self, _: &ConstCx<'_, '_>) -> Status {
-            Status::Unstable(sym::const_impl_trait)
-        }
-
-        fn build_error(
-            &self,
-            ccx: &ConstCx<'_, 'tcx>,
-            span: Span,
-        ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-            feature_err(
-                &ccx.tcx.sess.parse_sess,
-                sym::const_impl_trait,
-                span,
-                &format!("`impl Trait` is not allowed in {}s", ccx.const_kind()),
-            )
-        }
-    }
-
-    #[derive(Debug)]
-    pub struct TraitBound(pub mir::LocalKind);
-    impl<'tcx> NonConstOp<'tcx> for TraitBound {
-        fn importance(&self) -> DiagnosticImportance {
-            match self.0 {
-                mir::LocalKind::Var | mir::LocalKind::Temp => DiagnosticImportance::Secondary,
-                mir::LocalKind::ReturnPointer | mir::LocalKind::Arg => {
-                    DiagnosticImportance::Primary
-                }
-            }
-        }
-
-        fn status_in_item(&self, ccx: &ConstCx<'_, 'tcx>) -> Status {
-            if ccx.const_kind() != hir::ConstContext::ConstFn {
-                Status::Allowed
-            } else {
-                Status::Unstable(sym::const_fn_trait_bound)
-            }
-        }
-
-        fn build_error(
-            &self,
-            ccx: &ConstCx<'_, 'tcx>,
-            span: Span,
-        ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-            let mut err = feature_err(
-                &ccx.tcx.sess.parse_sess,
-                sym::const_fn_trait_bound,
-                span,
-                "trait bounds other than `Sized` on const fn parameters are unstable",
-            );
-
-            match ccx.fn_sig() {
-                Some(fn_sig) if !fn_sig.span.contains(span) => {
-                    err.span_label(fn_sig.span, "function declared as const here");
-                }
-                _ => {}
-            }
-
-            err
-        }
-    }
-
-    #[derive(Debug)]
-    pub struct DynTrait(pub mir::LocalKind);
-    impl<'tcx> NonConstOp<'tcx> for DynTrait {
-        fn importance(&self) -> DiagnosticImportance {
-            match self.0 {
-                mir::LocalKind::Var | mir::LocalKind::Temp => DiagnosticImportance::Secondary,
-                mir::LocalKind::ReturnPointer | mir::LocalKind::Arg => {
-                    DiagnosticImportance::Primary
-                }
-            }
-        }
-
-        fn status_in_item(&self, ccx: &ConstCx<'_, 'tcx>) -> Status {
-            if ccx.const_kind() != hir::ConstContext::ConstFn {
-                Status::Allowed
-            } else {
-                Status::Unstable(sym::const_fn_trait_bound)
-            }
-        }
-
-        fn build_error(
-            &self,
-            ccx: &ConstCx<'_, 'tcx>,
-            span: Span,
-        ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-            let mut err = feature_err(
-                &ccx.tcx.sess.parse_sess,
-                sym::const_fn_trait_bound,
-                span,
-                "trait objects in const fn are unstable",
-            );
-
-            match ccx.fn_sig() {
-                Some(fn_sig) if !fn_sig.span.contains(span) => {
-                    err.span_label(fn_sig.span, "function declared as const here");
-                }
-                _ => {}
-            }
-
-            err
-        }
-    }
-
-    /// A trait bound with the `?const Trait` opt-out
-    #[derive(Debug)]
-    pub struct TraitBoundNotConst;
-    impl<'tcx> NonConstOp<'tcx> for TraitBoundNotConst {
-        fn status_in_item(&self, _: &ConstCx<'_, 'tcx>) -> Status {
-            Status::Unstable(sym::const_trait_bound_opt_out)
-        }
-
-        fn build_error(
-            &self,
-            ccx: &ConstCx<'_, 'tcx>,
-            span: Span,
-        ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-            feature_err(
-                &ccx.tcx.sess.parse_sess,
-                sym::const_trait_bound_opt_out,
-                span,
-                "`?const Trait` syntax is unstable",
-            )
-        }
-    }
 }

compiler/rustc_feature/src/accepted.rs

@@ -86,6 +86,10 @@ declare_features! (
     (accepted, conservative_impl_trait, "1.26.0", Some(34511), None),
     /// Allows calling constructor functions in `const fn`.
     (accepted, const_constructor, "1.40.0", Some(61456), None),
+    /// Allows using and casting function pointers in a `const fn`.
+    (accepted, const_fn_fn_ptr_basics, "1.61.0", Some(57563), None),
+    /// Allows trait bounds in `const fn`.
+    (accepted, const_fn_trait_bound, "1.61.0", Some(93706), None),
     /// Allows calling `transmute` in const fn
     (accepted, const_fn_transmute, "1.56.0", Some(53605), None),
     /// Allows accessing fields of unions inside `const` functions.
@@ -96,6 +100,8 @@ declare_features! (
     (accepted, const_generics_defaults, "1.59.0", Some(44580), None),
     /// Allows the use of `if` and `match` in constants.
     (accepted, const_if_match, "1.46.0", Some(49146), None),
+    /// Allows argument and return position `impl Trait` in a `const fn`.
+    (accepted, const_impl_trait, "1.61.0", Some(77463), None),
     /// Allows indexing into constant arrays.
     (accepted, const_indexing, "1.26.0", Some(29947), None),
     /// Allows let bindings, assignments and destructuring in `const` functions and constants.

compiler/rustc_feature/src/active.rs

@@ -338,14 +338,8 @@ declare_features! (
     (active, const_extern_fn, "1.40.0", Some(64926), None),
     /// Allows basic arithmetic on floating point types in a `const fn`.
     (active, const_fn_floating_point_arithmetic, "1.48.0", Some(57241), None),
-    /// Allows using and casting function pointers in a `const fn`.
-    (active, const_fn_fn_ptr_basics, "1.48.0", Some(57563), None),
-    /// Allows trait bounds in `const fn`.
-    (active, const_fn_trait_bound, "1.53.0", Some(93706), None),
     /// Allows `for _ in _` loops in const contexts.
     (active, const_for, "1.56.0", Some(87575), None),
-    /// Allows argument and return position `impl Trait` in a `const fn`.
-    (active, const_impl_trait, "1.48.0", Some(77463), None),
     /// Allows using `&mut` in constant functions.
     (active, const_mut_refs, "1.41.0", Some(57349), None),
     /// Be more precise when looking for live drops in a const context.

library/alloc/src/lib.rs

@@ -140,7 +140,7 @@
 #![feature(box_syntax)]
 #![feature(cfg_sanitize)]
 #![feature(const_deref)]
-#![feature(const_fn_trait_bound)]
+#![cfg_attr(bootstrap, feature(const_fn_trait_bound))]
 #![feature(const_mut_refs)]
 #![feature(const_ptr_write)]
 #![feature(const_precise_live_drops)]

library/core/src/lib.rs

@@ -158,9 +158,9 @@
 #![feature(cfg_target_has_atomic)]
 #![feature(cfg_target_has_atomic_equal_alignment)]
 #![feature(const_fn_floating_point_arithmetic)]
-#![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
-#![feature(const_impl_trait)]
+#![cfg_attr(bootstrap, feature(const_fn_fn_ptr_basics))]
+#![cfg_attr(bootstrap, feature(const_fn_trait_bound))]
+#![cfg_attr(bootstrap, feature(const_impl_trait))]
 #![feature(const_mut_refs)]
 #![feature(const_precise_live_drops)]
 #![feature(const_refs_to_cell)]

library/proc_macro/src/lib.rs

@@ -20,8 +20,8 @@
 #![feature(rustc_allow_const_fn_unstable)]
 #![feature(nll)]
 #![feature(staged_api)]
-#![feature(const_fn_trait_bound)]
-#![feature(const_fn_fn_ptr_basics)]
+#![cfg_attr(bootstrap, feature(const_fn_trait_bound))]
+#![cfg_attr(bootstrap, feature(const_fn_fn_ptr_basics))]
 #![feature(allow_internal_unstable)]
 #![feature(decl_macro)]
 #![feature(extern_types)]

library/std/src/lib.rs

@@ -242,8 +242,8 @@
 #![feature(char_internals)]
 #![feature(concat_bytes)]
 #![feature(concat_idents)]
-#![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
+#![cfg_attr(bootstrap, feature(const_fn_fn_ptr_basics))]
+#![cfg_attr(bootstrap, feature(const_fn_trait_bound))]
 #![feature(const_format_args)]
 #![feature(const_io_structs)]
 #![feature(const_ip)]