Rollup of 5 pull requests

compiler/rustc_attr/src/builtin.rs

@@ -870,6 +870,23 @@ pub fn find_repr_attrs(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
                         sym::simd => Some(ReprSimd),
                         sym::transparent => Some(ReprTransparent),
                         sym::no_niche => Some(ReprNoNiche),
+                        sym::align => {
+                            let mut err = struct_span_err!(
+                                diagnostic,
+                                item.span(),
+                                E0589,
+                                "invalid `repr(align)` attribute: `align` needs an argument"
+                            );
+                            err.span_suggestion(
+                                item.span(),
+                                "supply an argument here",
+                                "align(...)".to_string(),
+                                Applicability::HasPlaceholders,
+                            );
+                            err.emit();
+                            recognised = true;
+                            None
+                        }
                         name => int_type_of_word(name).map(ReprInt),
                     };
 
@@ -891,53 +908,124 @@ pub fn find_repr_attrs(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
                             Ok(literal) => acc.push(ReprPacked(literal)),
                             Err(message) => literal_error = Some(message),
                         };
+                    } else if matches!(name, sym::C | sym::simd | sym::transparent | sym::no_niche)
+                        || int_type_of_word(name).is_some()
+                    {
+                        recognised = true;
+                        struct_span_err!(
+                                diagnostic,
+                                item.span(),
+                                E0552,
+                                "invalid representation hint: `{}` does not take a parenthesized argument list",
+                                name.to_ident_string(),
+                            ).emit();
                     }
                     if let Some(literal_error) = literal_error {
                         struct_span_err!(
                             diagnostic,
                             item.span(),
                             E0589,
-                            "invalid `repr(align)` attribute: {}",
+                            "invalid `repr({})` attribute: {}",
+                            name.to_ident_string(),
                             literal_error
                         )
                         .emit();
                     }
                 } else if let Some(meta_item) = item.meta_item() {
-                    if meta_item.has_name(sym::align) {
-                        if let MetaItemKind::NameValue(ref value) = meta_item.kind {
+                    if let MetaItemKind::NameValue(ref value) = meta_item.kind {
+                        if meta_item.has_name(sym::align) || meta_item.has_name(sym::packed) {
+                            let name = meta_item.name_or_empty().to_ident_string();
                             recognised = true;
                             let mut err = struct_span_err!(
                                 diagnostic,
                                 item.span(),
                                 E0693,
-                                "incorrect `repr(align)` attribute format"
+                                "incorrect `repr({})` attribute format",
+                                name,
                             );
                             match value.kind {
                                 ast::LitKind::Int(int, ast::LitIntType::Unsuffixed) => {
                                     err.span_suggestion(
                                         item.span(),
                                         "use parentheses instead",
-                                        format!("align({})", int),
+                                        format!("{}({})", name, int),
                                         Applicability::MachineApplicable,
                                     );
                                 }
                                 ast::LitKind::Str(s, _) => {
                                     err.span_suggestion(
                                         item.span(),
                                         "use parentheses instead",
-                                        format!("align({})", s),
+                                        format!("{}({})", name, s),
                                         Applicability::MachineApplicable,
                                     );
                                 }
                                 _ => {}
                             }
                             err.emit();
+                        } else {
+                            if matches!(
+                                meta_item.name_or_empty(),
+                                sym::C | sym::simd | sym::transparent | sym::no_niche
+                            ) || int_type_of_word(meta_item.name_or_empty()).is_some()
+                            {
+                                recognised = true;
+                                struct_span_err!(
+                                    diagnostic,
+                                    meta_item.span,
+                                    E0552,
+                                    "invalid representation hint: `{}` does not take a value",
+                                    meta_item.name_or_empty().to_ident_string(),
+                                )
+                                .emit();
+                            }
+                        }
+                    } else if let MetaItemKind::List(_) = meta_item.kind {
+                        if meta_item.has_name(sym::align) {
+                            recognised = true;
+                            struct_span_err!(
+                                diagnostic,
+                                meta_item.span,
+                                E0693,
+                                "incorrect `repr(align)` attribute format: \
+                                 `align` takes exactly one argument in parentheses"
+                            )
+                            .emit();
+                        } else if meta_item.has_name(sym::packed) {
+                            recognised = true;
+                            struct_span_err!(
+                                diagnostic,
+                                meta_item.span,
+                                E0552,
+                                "incorrect `repr(packed)` attribute format: \
+                                 `packed` takes exactly one parenthesized argument, \
+                                 or no parentheses at all"
+                            )
+                            .emit();
+                        } else if matches!(
+                            meta_item.name_or_empty(),
+                            sym::C | sym::simd | sym::transparent | sym::no_niche
+                        ) || int_type_of_word(meta_item.name_or_empty()).is_some()
+                        {
+                            recognised = true;
+                            struct_span_err!(
+                                diagnostic,
+                                meta_item.span,
+                                E0552,
+                                "invalid representation hint: `{}` does not take a parenthesized argument list",
+                                meta_item.name_or_empty().to_ident_string(),
+                            ).emit();
                         }
                     }
                 }
                 if !recognised {
-                    // Not a word we recognize
-                    diagnostic.delay_span_bug(item.span(), "unrecognized representation hint");
+                    // Not a word we recognize. This will be caught and reported by
+                    // the `check_mod_attrs` pass, but this pass doesn't always run
+                    // (e.g. if we only pretty-print the source), so we have to gate
+                    // the `delay_span_bug` call as follows:
+                    if sess.opts.pretty.map_or(true, |pp| pp.needs_analysis()) {
+                        diagnostic.delay_span_bug(item.span(), "unrecognized representation hint");
+                    }
                 }
             }
         }

compiler/rustc_feature/src/active.rs

@@ -416,9 +416,6 @@ declare_features! (
     /// Allows accessing fields of unions inside `const` functions.
     (active, const_fn_union, "1.27.0", Some(51909), None),
 
-    /// Allows casting raw pointers to `usize` during const eval.
-    (active, const_raw_ptr_to_usize_cast, "1.27.0", Some(51910), None),
-
     /// Allows dereferencing raw pointers during const eval.
     (active, const_raw_ptr_deref, "1.27.0", Some(51911), None),
 

compiler/rustc_feature/src/removed.rs

@@ -144,6 +144,10 @@ declare_features! (
     (removed, external_doc, "1.54.0", Some(44732), None,
      Some("use #[doc = include_str!(\"filename\")] instead, which handles macro invocations")),
 
+     /// Allows casting raw pointers to `usize` during const eval.
+    (removed, const_raw_ptr_to_usize_cast, "1.55.0", Some(51910), None,
+     Some("at compile-time, pointers do not have an integer value, so these casts cannot be properly supported")),
+
     // -------------------------------------------------------------------------
     // feature-group-end: removed features
     // -------------------------------------------------------------------------

compiler/rustc_middle/src/traits/mod.rs

@@ -426,10 +426,10 @@ pub type SelectionResult<'tcx, T> = Result<Option<T>, SelectionError<'tcx>>;
 /// impl Clone for i32 { ... }                   // Impl_3
 ///
 /// fn foo<T: Clone>(concrete: Option<Box<i32>>, param: T, mixed: Option<T>) {
-///     // Case A: Vtable points at a specific impl. Only possible when
+///     // Case A: ImplSource points at a specific impl. Only possible when
 ///     // type is concretely known. If the impl itself has bounded
-///     // type parameters, Vtable will carry resolutions for those as well:
-///     concrete.clone(); // Vtable(Impl_1, [Vtable(Impl_2, [Vtable(Impl_3)])])
+///     // type parameters, ImplSource will carry resolutions for those as well:
+///     concrete.clone(); // ImpleSource(Impl_1, [ImplSource(Impl_2, [ImplSource(Impl_3)])])
 ///
 ///     // Case A: ImplSource points at a specific impl. Only possible when
 ///     // type is concretely known. If the impl itself has bounded

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

@@ -397,6 +397,9 @@ impl NonConstOp for PanicNonStr {
     }
 }
 
+/// Comparing raw pointers for equality.
+/// Not currently intended to ever be allowed, even behind a feature gate: operation depends on
+/// allocation base addresses that are not known at compile-time.
 #[derive(Debug)]
 pub struct RawPtrComparison;
 impl NonConstOp for RawPtrComparison {
@@ -430,20 +433,22 @@ impl NonConstOp for RawPtrDeref {
     }
 }
 
+/// Casting raw pointer or function pointer to an integer.
+/// Not currently intended to ever be allowed, even behind a feature gate: operation depends on
+/// allocation base addresses that are not known at compile-time.
 #[derive(Debug)]
 pub struct RawPtrToIntCast;
 impl NonConstOp for RawPtrToIntCast {
-    fn status_in_item(&self, _: &ConstCx<'_, '_>) -> Status {
-        Status::Unstable(sym::const_raw_ptr_to_usize_cast)
-    }
-
     fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> DiagnosticBuilder<'tcx> {
-        feature_err(
-            &ccx.tcx.sess.parse_sess,
-            sym::const_raw_ptr_to_usize_cast,
-            span,
-            &format!("casting pointers to integers in {}s is unstable", ccx.const_kind(),),
-        )
+        let mut err = ccx
+            .tcx
+            .sess
+            .struct_span_err(span, "pointers cannot be cast to integers during const eval.");
+        err.note("at compile-time, pointers do not have an integer value");
+        err.note(
+            "avoiding this restriction via `transmute`, `union`, or raw pointers leads to compile-time undefined behavior",
+        );
+        err
     }
 }
 

compiler/rustc_mir/src/transform/check_unsafety.rs

@@ -7,7 +7,6 @@ use rustc_hir::intravisit;
 use rustc_hir::Node;
 use rustc_middle::mir::visit::{MutatingUseContext, PlaceContext, Visitor};
 use rustc_middle::mir::*;
-use rustc_middle::ty::cast::CastTy;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_session::lint::builtin::{UNSAFE_OP_IN_UNSAFE_FN, UNUSED_UNSAFE};
@@ -18,7 +17,6 @@ use std::ops::Bound;
 pub struct UnsafetyChecker<'a, 'tcx> {
     body: &'a Body<'tcx>,
     body_did: LocalDefId,
-    const_context: bool,
     violations: Vec<UnsafetyViolation>,
     source_info: SourceInfo,
     tcx: TyCtxt<'tcx>,
@@ -30,7 +28,6 @@ pub struct UnsafetyChecker<'a, 'tcx> {
 
 impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
     fn new(
-        const_context: bool,
         body: &'a Body<'tcx>,
         body_did: LocalDefId,
         tcx: TyCtxt<'tcx>,
@@ -39,7 +36,6 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
         Self {
             body,
             body_did,
-            const_context,
             violations: vec![],
             source_info: SourceInfo::outermost(body.span),
             tcx,
@@ -136,25 +132,6 @@ impl<'a, 'tcx> Visitor<'tcx> for UnsafetyChecker<'a, 'tcx> {
                     self.register_violations(&violations, &unsafe_blocks);
                 }
             },
-            // casting pointers to ints is unsafe in const fn because the const evaluator cannot
-            // possibly know what the result of various operations like `address / 2` would be
-            // pointers during const evaluation have no integral address, only an abstract one
-            Rvalue::Cast(CastKind::Misc, ref operand, cast_ty)
-                if self.const_context && self.tcx.features().const_raw_ptr_to_usize_cast =>
-            {
-                let operand_ty = operand.ty(self.body, self.tcx);
-                let cast_in = CastTy::from_ty(operand_ty).expect("bad input type for cast");
-                let cast_out = CastTy::from_ty(cast_ty).expect("bad output type for cast");
-                match (cast_in, cast_out) {
-                    (CastTy::Ptr(_) | CastTy::FnPtr, CastTy::Int(_)) => {
-                        self.require_unsafe(
-                            UnsafetyViolationKind::General,
-                            UnsafetyViolationDetails::CastOfPointerToInt,
-                        );
-                    }
-                    _ => {}
-                }
-            }
             _ => {}
         }
         self.super_rvalue(rvalue, location);
@@ -469,13 +446,7 @@ fn unsafety_check_result<'tcx>(
 
     let param_env = tcx.param_env(def.did);
 
-    let id = tcx.hir().local_def_id_to_hir_id(def.did);
-    let const_context = match tcx.hir().body_owner_kind(id) {
-        hir::BodyOwnerKind::Closure => false,
-        hir::BodyOwnerKind::Fn => tcx.is_const_fn_raw(def.did.to_def_id()),
-        hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_) => true,
-    };
-    let mut checker = UnsafetyChecker::new(const_context, body, def.did, tcx, param_env);
+    let mut checker = UnsafetyChecker::new(body, def.did, tcx, param_env);
     checker.visit_body(&body);
 
     check_unused_unsafe(tcx, def.did, &checker.used_unsafe, &mut checker.inherited_blocks);

compiler/rustc_mir/src/transform/inline.rs

@@ -284,7 +284,7 @@ impl Inliner<'tcx> {
         &self,
         callsite: &CallSite<'tcx>,
         callee_attrs: &CodegenFnAttrs,
-    ) -> Result<(), &'satic str> {
+    ) -> Result<(), &'static str> {
         if let InlineAttr::Never = callee_attrs.inline {
             return Err("never inline hint");
         }

compiler/rustc_mir_build/src/check_unsafety.rs

@@ -25,7 +25,6 @@ struct UnsafetyVisitor<'a, 'tcx> {
     /// The `#[target_feature]` attributes of the body. Used for checking
     /// calls to functions with `#[target_feature]` (RFC 2396).
     body_target_features: &'tcx Vec<Symbol>,
-    is_const: bool,
     in_possible_lhs_union_assign: bool,
     in_union_destructure: bool,
 }
@@ -315,16 +314,6 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
                 (Bound::Unbounded, Bound::Unbounded) => {}
                 _ => self.requires_unsafe(expr.span, InitializingTypeWith),
             },
-            ExprKind::Cast { source } => {
-                let source = &self.thir[source];
-                if self.tcx.features().const_raw_ptr_to_usize_cast
-                    && self.is_const
-                    && (source.ty.is_unsafe_ptr() || source.ty.is_fn_ptr())
-                    && expr.ty.is_integral()
-                {
-                    self.requires_unsafe(expr.span, CastOfPointerToInt);
-                }
-            }
             ExprKind::Closure {
                 closure_id,
                 substs: _,
@@ -413,7 +402,6 @@ enum UnsafeOpKind {
     CallToUnsafeFunction,
     UseOfInlineAssembly,
     InitializingTypeWith,
-    CastOfPointerToInt,
     UseOfMutableStatic,
     UseOfExternStatic,
     DerefOfRawPointer,
@@ -446,9 +434,6 @@ impl UnsafeOpKind {
                 "initializing a layout restricted type's field with a value outside the valid \
                  range is undefined behavior",
             ),
-            CastOfPointerToInt => {
-                ("cast of pointer to int", "casting pointers to integers in constants")
-            }
             UseOfMutableStatic => (
                 "use of mutable static",
                 "mutable statics can be mutated by multiple threads: aliasing violations or data \
@@ -526,19 +511,13 @@ pub fn check_unsafety<'tcx>(tcx: TyCtxt<'tcx>, def: ty::WithOptConstParam<LocalD
     let body_target_features = &tcx.codegen_fn_attrs(def.did).target_features;
     let safety_context =
         if body_unsafety.is_unsafe() { SafetyContext::UnsafeFn } else { SafetyContext::Safe };
-    let is_const = match tcx.hir().body_owner_kind(hir_id) {
-        hir::BodyOwnerKind::Closure => false,
-        hir::BodyOwnerKind::Fn => tcx.is_const_fn_raw(def.did.to_def_id()),
-        hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_) => true,
-    };
     let mut visitor = UnsafetyVisitor {
         tcx,
         thir,
         safety_context,
         hir_context: hir_id,
         body_unsafety,
         body_target_features,
-        is_const,
         in_possible_lhs_union_assign: false,
         in_union_destructure: false,
     };

library/std/src/thread/mod.rs

@@ -999,11 +999,12 @@ impl ThreadId {
         static mut COUNTER: u64 = 1;
 
         unsafe {
-            let _guard = GUARD.lock();
+            let guard = GUARD.lock();
 
             // If we somehow use up all our bits, panic so that we're not
             // covering up subtle bugs of IDs being reused.
             if COUNTER == u64::MAX {
+                drop(guard); // in case the panic handler ends up calling `ThreadId::new()`, avoid reentrant lock acquire.
                 panic!("failed to generate unique thread ID: bitspace exhausted");
             }