Rollup of 9 pull requests

src/liballoc/boxed.rs

@@ -1109,6 +1109,14 @@ impl<T: Clone> Clone for Box<[T]> {
     fn clone(&self) -> Self {
         self.to_vec().into_boxed_slice()
     }
+
+    fn clone_from(&mut self, other: &Self) {
+        if self.len() == other.len() {
+            self.clone_from_slice(&other);
+        } else {
+            *self = other.clone();
+        }
+    }
 }
 
 #[stable(feature = "box_borrow", since = "1.1.0")]

src/liballoc/tests/boxed.rs

@@ -16,3 +16,36 @@ fn unitialized_zero_size_box() {
         NonNull::<MaybeUninit<String>>::dangling().as_ptr(),
     );
 }
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+struct Dummy {
+    _data: u8,
+}
+
+#[test]
+fn box_clone_and_clone_from_equivalence() {
+    for size in (0..8).map(|i| 2usize.pow(i)) {
+        let control = vec![Dummy { _data: 42 }; size].into_boxed_slice();
+        let clone = control.clone();
+        let mut copy = vec![Dummy { _data: 84 }; size].into_boxed_slice();
+        copy.clone_from(&control);
+        assert_eq!(control, clone);
+        assert_eq!(control, copy);
+    }
+}
+
+/// This test might give a false positive in case the box realocates, but the alocator keeps the
+/// original pointer.
+///
+/// On the other hand it won't give a false negative, if it fails than the memory was definitly not
+/// reused
+#[test]
+fn box_clone_from_ptr_stability() {
+    for size in (0..8).map(|i| 2usize.pow(i)) {
+        let control = vec![Dummy { _data: 42 }; size].into_boxed_slice();
+        let mut copy = vec![Dummy { _data: 84 }; size].into_boxed_slice();
+        let copy_raw = copy.as_ptr() as usize;
+        copy.clone_from(&control);
+        assert_eq!(copy.as_ptr() as usize, copy_raw);
+    }
+}

src/libcore/iter/range.rs

@@ -619,15 +619,7 @@ impl<A: Step> Iterator for ops::RangeFrom<A> {
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<A> {
-        // If we would jump over the maximum value, panic immediately.
-        // This is consistent with behavior before the Step redesign,
-        // even though it's inconsistent with n `next` calls.
-        // To get consistent behavior, change it to use `forward` instead.
-        // This change should go through FCP separately to the redesign, so is for now left as a
-        // FIXME: make this consistent
-        let plus_n =
-            Step::forward_checked(self.start.clone(), n).expect("overflow in RangeFrom::nth");
-        // The final step should always be debug-checked.
+        let plus_n = Step::forward(self.start.clone(), n);
         self.start = Step::forward(plus_n.clone(), 1);
         Some(plus_n)
     }

src/libcore/ops/range.rs

@@ -151,10 +151,16 @@ impl<Idx: PartialOrd<Idx>> Range<Idx> {
 ///
 /// The `RangeFrom` `start..` contains all values with `x >= start`.
 ///
-/// *Note*: Currently, no overflow checking is done for the [`Iterator`]
-/// implementation; if you use an integer range and the integer overflows, it
-/// might panic in debug mode or create an endless loop in release mode. **This
-/// overflow behavior might change in the future.**
+/// *Note*: Overflow in the [`Iterator`] implementation (when the contained
+/// data type reaches its numerical limit) is allowed to panic, wrap, or
+/// saturate. This behavior is defined by the implementation of the [`Step`]
+/// trait. For primitive integers, this follows the normal rules, and respects
+/// the overflow checks profile (panic in debug, wrap in release). Note also
+/// that overflow happens earlier than you might assume: the overflow happens
+/// in the call to `next` that yields the maximum value, as the range must be
+/// set to a state to yield the next value.
+///
+/// [`Step`]: crate::iter::Step
 ///
 /// # Examples
 ///

src/librustc_ast_lowering/expr.rs

@@ -974,20 +974,18 @@ impl<'hir> LoweringContext<'_, 'hir> {
     }
 
     fn lower_expr_asm(&mut self, sp: Span, asm: &InlineAsm) -> hir::ExprKind<'hir> {
-        let asm_arch = if let Some(asm_arch) = self.sess.asm_arch {
-            asm_arch
-        } else {
+        if self.sess.asm_arch.is_none() {
             struct_span_err!(self.sess, sp, E0472, "asm! is unsupported on this target").emit();
-            return hir::ExprKind::Err;
-        };
-        if asm.options.contains(InlineAsmOptions::ATT_SYNTAX) {
-            match asm_arch {
-                asm::InlineAsmArch::X86 | asm::InlineAsmArch::X86_64 => {}
-                _ => self
-                    .sess
-                    .struct_span_err(sp, "the `att_syntax` option is only supported on x86")
-                    .emit(),
-            }
+        }
+        if asm.options.contains(InlineAsmOptions::ATT_SYNTAX)
+            && !matches!(
+                self.sess.asm_arch,
+                Some(asm::InlineAsmArch::X86 | asm::InlineAsmArch::X86_64)
+            )
+        {
+            self.sess
+                .struct_span_err(sp, "the `att_syntax` option is only supported on x86")
+                .emit();
         }
 
         // Lower operands to HIR, filter_map skips any operands with invalid
@@ -1001,10 +999,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     Some(match reg {
                         InlineAsmRegOrRegClass::Reg(s) => asm::InlineAsmRegOrRegClass::Reg(
                             asm::InlineAsmReg::parse(
-                                asm_arch,
-                                |feature| {
-                                    self.sess.target_features.contains(&Symbol::intern(feature))
-                                },
+                                sess.asm_arch?,
+                                |feature| sess.target_features.contains(&Symbol::intern(feature)),
                                 s,
                             )
                             .map_err(|e| {
@@ -1015,7 +1011,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         ),
                         InlineAsmRegOrRegClass::RegClass(s) => {
                             asm::InlineAsmRegOrRegClass::RegClass(
-                                asm::InlineAsmRegClass::parse(asm_arch, s)
+                                asm::InlineAsmRegClass::parse(sess.asm_arch?, s)
                                     .map_err(|e| {
                                         let msg = format!(
                                             "invalid register class `{}`: {}",
@@ -1029,33 +1025,38 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         }
                     })
                 };
-                let op = match op {
-                    InlineAsmOperand::In { reg, expr } => hir::InlineAsmOperand::In {
-                        reg: lower_reg(*reg)?,
+
+                // lower_reg is executed last because we need to lower all
+                // sub-expressions even if we throw them away later.
+                let op = match *op {
+                    InlineAsmOperand::In { reg, ref expr } => hir::InlineAsmOperand::In {
                         expr: self.lower_expr_mut(expr),
+                        reg: lower_reg(reg)?,
                     },
-                    InlineAsmOperand::Out { reg, late, expr } => hir::InlineAsmOperand::Out {
-                        reg: lower_reg(*reg)?,
-                        late: *late,
+                    InlineAsmOperand::Out { reg, late, ref expr } => hir::InlineAsmOperand::Out {
+                        late,
                         expr: expr.as_ref().map(|expr| self.lower_expr_mut(expr)),
+                        reg: lower_reg(reg)?,
                     },
-                    InlineAsmOperand::InOut { reg, late, expr } => hir::InlineAsmOperand::InOut {
-                        reg: lower_reg(*reg)?,
-                        late: *late,
-                        expr: self.lower_expr_mut(expr),
-                    },
-                    InlineAsmOperand::SplitInOut { reg, late, in_expr, out_expr } => {
+                    InlineAsmOperand::InOut { reg, late, ref expr } => {
+                        hir::InlineAsmOperand::InOut {
+                            late,
+                            expr: self.lower_expr_mut(expr),
+                            reg: lower_reg(reg)?,
+                        }
+                    }
+                    InlineAsmOperand::SplitInOut { reg, late, ref in_expr, ref out_expr } => {
                         hir::InlineAsmOperand::SplitInOut {
-                            reg: lower_reg(*reg)?,
-                            late: *late,
+                            late,
                             in_expr: self.lower_expr_mut(in_expr),
                             out_expr: out_expr.as_ref().map(|expr| self.lower_expr_mut(expr)),
+                            reg: lower_reg(reg)?,
                         }
                     }
-                    InlineAsmOperand::Const { expr } => {
+                    InlineAsmOperand::Const { ref expr } => {
                         hir::InlineAsmOperand::Const { expr: self.lower_expr_mut(expr) }
                     }
-                    InlineAsmOperand::Sym { expr } => {
+                    InlineAsmOperand::Sym { ref expr } => {
                         hir::InlineAsmOperand::Sym { expr: self.lower_expr_mut(expr) }
                     }
                 };
@@ -1069,6 +1070,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
 
         // Validate template modifiers against the register classes for the operands
+        let asm_arch = sess.asm_arch.unwrap();
         for p in &asm.template {
             if let InlineAsmTemplatePiece::Placeholder {
                 operand_idx,

src/librustc_codegen_ssa/mir/block.rs

@@ -908,13 +908,12 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 mir::InlineAsmOperand::SymFn { ref value } => {
                     let literal = self.monomorphize(&value.literal);
                     if let ty::FnDef(def_id, substs) = literal.ty.kind {
-                        let instance = ty::Instance::resolve(
+                        let instance = ty::Instance::resolve_for_fn_ptr(
                             bx.tcx(),
                             ty::ParamEnv::reveal_all(),
                             def_id,
                             substs,
                         )
-                        .unwrap()
                         .unwrap();
                         InlineAsmOperandRef::SymFn { instance }
                     } else {

src/librustc_error_codes/error_codes/E0055.md

@@ -6,7 +6,7 @@ recursion limit (which can be set via the `recursion_limit` attribute).
 For a somewhat artificial example:
 
 ```compile_fail,E0055
-#![recursion_limit="5"]
+#![recursion_limit="4"]
 
 struct Foo;
 

src/librustc_expand/base.rs

@@ -12,7 +12,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::{self, Lrc};
 use rustc_errors::{DiagnosticBuilder, ErrorReported};
 use rustc_parse::{self, parser, MACRO_ARGUMENTS};
-use rustc_session::parse::ParseSess;
+use rustc_session::{parse::ParseSess, Limit};
 use rustc_span::def_id::DefId;
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::{AstPass, ExpnData, ExpnId, ExpnKind};
@@ -941,7 +941,7 @@ pub struct ExpansionData {
 pub struct ExtCtxt<'a> {
     pub parse_sess: &'a ParseSess,
     pub ecfg: expand::ExpansionConfig<'a>,
-    pub reduced_recursion_limit: Option<usize>,
+    pub reduced_recursion_limit: Option<Limit>,
     pub root_path: PathBuf,
     pub resolver: &'a mut dyn Resolver,
     pub current_expansion: ExpansionData,

src/librustc_expand/expand.rs

@@ -24,6 +24,7 @@ use rustc_parse::validate_attr;
 use rustc_session::lint::builtin::UNUSED_DOC_COMMENTS;
 use rustc_session::lint::BuiltinLintDiagnostics;
 use rustc_session::parse::{feature_err, ParseSess};
+use rustc_session::Limit;
 use rustc_span::source_map::respan;
 use rustc_span::symbol::{sym, Ident, Symbol};
 use rustc_span::{FileName, Span, DUMMY_SP};
@@ -664,7 +665,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
     ) -> ExpandResult<AstFragment, Invocation> {
         let recursion_limit =
             self.cx.reduced_recursion_limit.unwrap_or(self.cx.ecfg.recursion_limit);
-        if self.cx.current_expansion.depth > recursion_limit {
+        if !recursion_limit.value_within_limit(self.cx.current_expansion.depth) {
             if self.cx.reduced_recursion_limit.is_none() {
                 self.error_recursion_limit_reached();
             }
@@ -1784,7 +1785,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
 pub struct ExpansionConfig<'feat> {
     pub crate_name: String,
     pub features: Option<&'feat Features>,
-    pub recursion_limit: usize,
+    pub recursion_limit: Limit,
     pub trace_mac: bool,
     pub should_test: bool, // If false, strip `#[test]` nodes
     pub keep_macs: bool,
@@ -1795,7 +1796,7 @@ impl<'feat> ExpansionConfig<'feat> {
         ExpansionConfig {
             crate_name,
             features: None,
-            recursion_limit: 1024,
+            recursion_limit: Limit::new(1024),
             trace_mac: false,
             should_test: false,
             keep_macs: false,

src/librustc_interface/passes.rs

@@ -838,7 +838,7 @@ fn analysis(tcx: TyCtxt<'_>, cnum: CrateNum) -> Result<()> {
 
     sess.time("MIR_effect_checking", || {
         for def_id in tcx.body_owners() {
-            mir::transform::check_unsafety::check_unsafety(tcx, def_id.to_def_id())
+            mir::transform::check_unsafety::check_unsafety(tcx, def_id)
         }
     });
 

src/librustc_middle/middle/limits.rs

@@ -8,7 +8,7 @@
 use crate::bug;
 use rustc_ast::ast;
 use rustc_data_structures::sync::OnceCell;
-use rustc_session::Session;
+use rustc_session::{Limit, Session};
 use rustc_span::symbol::{sym, Symbol};
 
 use std::num::IntErrorKind;
@@ -22,7 +22,7 @@ pub fn update_limits(sess: &Session, krate: &ast::Crate) {
 fn update_limit(
     sess: &Session,
     krate: &ast::Crate,
-    limit: &OnceCell<usize>,
+    limit: &OnceCell<Limit>,
     name: Symbol,
     default: usize,
 ) {
@@ -34,7 +34,7 @@ fn update_limit(
         if let Some(s) = attr.value_str() {
             match s.as_str().parse() {
                 Ok(n) => {
-                    limit.set(n).unwrap();
+                    limit.set(Limit::new(n)).unwrap();
                     return;
                 }
                 Err(e) => {
@@ -62,5 +62,5 @@ fn update_limit(
             }
         }
     }
-    limit.set(default).unwrap();
+    limit.set(Limit::new(default)).unwrap();
 }

src/librustc_middle/mir/mod.rs

@@ -1072,7 +1072,8 @@ pub enum TerminatorKind<'tcx> {
     Abort,
 
     /// Indicates a normal return. The return place should have
-    /// been filled in by now. This should occur at most once.
+    /// been filled in before this executes. This can occur multiple times
+    /// in different basic blocks.
     Return,
 
     /// Indicates a terminator that can never be reached.

src/librustc_middle/query/mod.rs

@@ -386,8 +386,14 @@ rustc_queries! {
             storage(ArenaCacheSelector<'tcx>)
         }
 
-        /// HACK: when evaluated, this reports a "unsafe derive on repr(packed)" error
-        query unsafe_derive_on_repr_packed(_: DefId) -> () {}
+        /// HACK: when evaluated, this reports a "unsafe derive on repr(packed)" error.
+        ///
+        /// Unsafety checking is executed for each method separately, but we only want
+        /// to emit this error once per derive. As there are some impls with multiple
+        /// methods, we use a query for deduplication.
+        query unsafe_derive_on_repr_packed(key: LocalDefId) -> () {
+            desc { |tcx| "processing `{}`", tcx.def_path_str(key.to_def_id()) }
+        }
 
         /// The signature of functions and closures.
         query fn_sig(_: DefId) -> ty::PolyFnSig<'tcx> {}

src/librustc_middle/ty/layout.rs

@@ -187,10 +187,9 @@ fn layout_raw<'tcx>(
     query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
 ) -> Result<&'tcx Layout, LayoutError<'tcx>> {
     ty::tls::with_related_context(tcx, move |icx| {
-        let rec_limit = tcx.sess.recursion_limit.get().copied().unwrap();
         let (param_env, ty) = query.into_parts();
 
-        if icx.layout_depth > rec_limit {
+        if !tcx.sess.recursion_limit().value_within_limit(icx.layout_depth) {
             tcx.sess.fatal(&format!("overflow representing the type `{}`", ty));
         }
 

src/librustc_mir/const_eval/machine.rs

@@ -10,6 +10,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_ast::ast::Mutability;
 use rustc_hir::def_id::DefId;
 use rustc_middle::mir::AssertMessage;
+use rustc_session::Limit;
 use rustc_span::symbol::Symbol;
 
 use crate::interpret::{
@@ -109,8 +110,8 @@ pub struct MemoryExtra {
 }
 
 impl<'mir, 'tcx> CompileTimeInterpreter<'mir, 'tcx> {
-    pub(super) fn new(const_eval_limit: usize) -> Self {
-        CompileTimeInterpreter { steps_remaining: const_eval_limit, stack: Vec::new() }
+    pub(super) fn new(const_eval_limit: Limit) -> Self {
+        CompileTimeInterpreter { steps_remaining: const_eval_limit.0, stack: Vec::new() }
     }
 }
 

src/librustc_mir/interpret/eval_context.rs

@@ -651,7 +651,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         M::after_stack_push(self)?;
         info!("ENTERING({}) {}", self.frame_idx(), self.frame().instance);
 
-        if self.stack().len() > self.tcx.sess.recursion_limit() {
+        if !self.tcx.sess.recursion_limit().value_within_limit(self.stack().len()) {
             throw_exhaust!(StackFrameLimitReached)
         } else {
             Ok(())