Rollup of 7 pull requests

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -1770,7 +1770,7 @@ extern "C" {
 
     pub fn LLVMDisposeMessage(message: *mut c_char);
 
-    pub fn LLVMStartMultithreaded() -> Bool;
+    pub fn LLVMIsMultithreaded() -> Bool;
 
     /// Returns a string describing the last error caused by an LLVMRust* call.
     pub fn LLVMRustGetLastError() -> *const c_char;

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -17,35 +17,25 @@ use std::path::Path;
 use std::ptr;
 use std::slice;
 use std::str;
-use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Once;
 
-static POISONED: AtomicBool = AtomicBool::new(false);
 static INIT: Once = Once::new();
 
 pub(crate) fn init(sess: &Session) {
     unsafe {
         // Before we touch LLVM, make sure that multithreading is enabled.
+        if llvm::LLVMIsMultithreaded() != 1 {
+            bug!("LLVM compiled without support for threads");
+        }
         INIT.call_once(|| {
-            if llvm::LLVMStartMultithreaded() != 1 {
-                // use an extra bool to make sure that all future usage of LLVM
-                // cannot proceed despite the Once not running more than once.
-                POISONED.store(true, Ordering::SeqCst);
-            }
-
             configure_llvm(sess);
         });
-
-        if POISONED.load(Ordering::SeqCst) {
-            bug!("couldn't enable multi-threaded LLVM");
-        }
     }
 }
 
 fn require_inited() {
-    INIT.call_once(|| bug!("llvm is not initialized"));
-    if POISONED.load(Ordering::SeqCst) {
-        bug!("couldn't enable multi-threaded LLVM");
+    if !INIT.is_completed() {
+        bug!("LLVM is not initialized");
     }
 }
 

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -72,9 +72,7 @@ impl<'mir, 'tcx> InterpCx<'mir, 'tcx, CompileTimeInterpreter<'mir, 'tcx>> {
             let span = self.find_closest_untracked_caller_location();
             let (file, line, col) = self.location_triple_for_span(span);
             return Err(ConstEvalErrKind::Panic { msg, file, line, col }.into());
-        } else if Some(def_id) == self.tcx.lang_items().panic_fmt()
-            || Some(def_id) == self.tcx.lang_items().begin_panic_fmt()
-        {
+        } else if Some(def_id) == self.tcx.lang_items().panic_fmt() {
             // For panic_fmt, call const_panic_fmt instead.
             if let Some(const_panic_fmt) = self.tcx.lang_items().const_panic_fmt() {
                 return Ok(Some(

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

@@ -79,7 +79,6 @@ pub fn is_lang_panic_fn(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool {
         || Some(def_id) == tcx.lang_items().panic_display()
         || Some(def_id) == tcx.lang_items().begin_panic_fn()
         || Some(def_id) == tcx.lang_items().panic_fmt()
-        || Some(def_id) == tcx.lang_items().begin_panic_fmt()
 }
 
 /// Returns `true` if this `DefId` points to one of the lang items that will be handled differently

compiler/rustc_hir/src/lang_items.rs

@@ -292,7 +292,6 @@ language_item_table! {
     PanicImpl,               sym::panic_impl,          panic_impl,                 Target::Fn,             GenericRequirement::None;
     /// libstd panic entry point. Necessary for const eval to be able to catch it
     BeginPanic,              sym::begin_panic,         begin_panic_fn,             Target::Fn,             GenericRequirement::None;
-    BeginPanicFmt,           sym::begin_panic_fmt,     begin_panic_fmt,            Target::Fn,             GenericRequirement::None;
 
     ExchangeMalloc,          sym::exchange_malloc,     exchange_malloc_fn,         Target::Fn,             GenericRequirement::None;
     BoxFree,                 sym::box_free,            box_free_fn,                Target::Fn,             GenericRequirement::Minimum(1);

compiler/rustc_lint_defs/src/builtin.rs

@@ -1957,7 +1957,7 @@ declare_lint! {
     /// [issue #50504]: https://github.com/rust-lang/rust/issues/50504
     /// [future-incompatible]: ../index.md#future-incompatible-lints
     pub PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
-    Warn,
+    Deny,
     "detects proc macro derives using inaccessible names from parent modules",
     @future_incompatible = FutureIncompatibleInfo {
         reference: "issue #83583 <https://github.com/rust-lang/rust/issues/83583>",
@@ -3253,7 +3253,7 @@ declare_lint! {
     /// [issue #83125]: https://github.com/rust-lang/rust/issues/83125
     /// [future-incompatible]: ../index.md#future-incompatible-lints
     pub PROC_MACRO_BACK_COMPAT,
-    Warn,
+    Deny,
     "detects usage of old versions of certain proc-macro crates",
     @future_incompatible = FutureIncompatibleInfo {
         reference: "issue #83125 <https://github.com/rust-lang/rust/issues/83125>",

compiler/rustc_span/src/symbol.rs

@@ -355,7 +355,6 @@ symbols! {
         await_macro,
         bang,
         begin_panic,
-        begin_panic_fmt,
         bench,
         bin,
         bind_by_move_pattern_guards,

compiler/rustc_typeck/src/bounds.rs

@@ -64,16 +64,16 @@ impl<'tcx> Bounds<'tcx> {
             })
         });
 
-        self.region_bounds
-            .iter()
-            .map(|&(region_bound, span)| {
+        sized_predicate
+            .into_iter()
+            .chain(self.region_bounds.iter().map(|&(region_bound, span)| {
                 (
                     region_bound
                         .map_bound(|region_bound| ty::OutlivesPredicate(param_ty, region_bound))
                         .to_predicate(tcx),
                     span,
                 )
-            })
+            }))
             .chain(self.trait_bounds.iter().map(|&(bound_trait_ref, span, constness)| {
                 let predicate = bound_trait_ref.with_constness(constness).to_predicate(tcx);
                 (predicate, span)
@@ -83,7 +83,6 @@ impl<'tcx> Bounds<'tcx> {
                     .iter()
                     .map(|&(projection, span)| (projection.to_predicate(tcx), span)),
             )
-            .chain(sized_predicate.into_iter())
             .collect()
     }
 }

library/core/src/array/mod.rs

@@ -125,7 +125,8 @@ impl TryFromSliceError {
 }
 
 #[stable(feature = "try_from_slice_error", since = "1.36.0")]
-impl From<Infallible> for TryFromSliceError {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl const From<Infallible> for TryFromSliceError {
     fn from(x: Infallible) -> TryFromSliceError {
         match x {}
     }

library/core/src/cell.rs

@@ -308,7 +308,8 @@ impl<T: Ord + Copy> Ord for Cell<T> {
 }
 
 #[stable(feature = "cell_from", since = "1.12.0")]
-impl<T> From<T> for Cell<T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T> const From<T> for Cell<T> {
     fn from(t: T) -> Cell<T> {
         Cell::new(t)
     }
@@ -1236,7 +1237,8 @@ impl<T: ?Sized + Ord> Ord for RefCell<T> {
 }
 
 #[stable(feature = "cell_from", since = "1.12.0")]
-impl<T> From<T> for RefCell<T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T> const From<T> for RefCell<T> {
     fn from(t: T) -> RefCell<T> {
         RefCell::new(t)
     }
@@ -1976,7 +1978,8 @@ impl<T: Default> Default for UnsafeCell<T> {
 }
 
 #[stable(feature = "cell_from", since = "1.12.0")]
-impl<T> From<T> for UnsafeCell<T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T> const From<T> for UnsafeCell<T> {
     fn from(t: T) -> UnsafeCell<T> {
         UnsafeCell::new(t)
     }

library/core/src/char/convert.rs

@@ -97,7 +97,8 @@ pub unsafe fn from_u32_unchecked(i: u32) -> char {
 }
 
 #[stable(feature = "char_convert", since = "1.13.0")]
-impl From<char> for u32 {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl const From<char> for u32 {
     /// Converts a [`char`] into a [`u32`].
     ///
     /// # Examples
@@ -116,7 +117,8 @@ impl From<char> for u32 {
 }
 
 #[stable(feature = "more_char_conversions", since = "1.51.0")]
-impl From<char> for u64 {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl const From<char> for u64 {
     /// Converts a [`char`] into a [`u64`].
     ///
     /// # Examples
@@ -137,7 +139,8 @@ impl From<char> for u64 {
 }
 
 #[stable(feature = "more_char_conversions", since = "1.51.0")]
-impl From<char> for u128 {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl const From<char> for u128 {
     /// Converts a [`char`] into a [`u128`].
     ///
     /// # Examples
@@ -176,7 +179,8 @@ impl From<char> for u128 {
 /// for a superset of Windows-1252 that fills the remaining blanks with corresponding
 /// C0 and C1 control codes.
 #[stable(feature = "char_convert", since = "1.13.0")]
-impl From<u8> for char {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl const From<u8> for char {
     /// Converts a [`u8`] into a [`char`].
     ///
     /// # Examples

library/core/src/convert/mod.rs

@@ -545,7 +545,8 @@ where
 
 // From (and thus Into) is reflexive
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T> From<T> for T {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T> const From<T> for T {
     fn from(t: T) -> T {
         t
     }
@@ -560,7 +561,8 @@ impl<T> From<T> for T {
 #[allow(unused_attributes)] // FIXME(#58633): do a principled fix instead.
 #[rustc_reservation_impl = "permitting this impl would forbid us from adding \
                             `impl<T> From<!> for T` later; see rust-lang/rust#64715 for details"]
-impl<T> From<!> for T {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T> const From<!> for T {
     fn from(t: !) -> T {
         t
     }
@@ -726,7 +728,8 @@ impl Ord for Infallible {
 }
 
 #[stable(feature = "convert_infallible", since = "1.34.0")]
-impl From<!> for Infallible {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl const From<!> for Infallible {
     fn from(x: !) -> Self {
         x
     }

library/core/src/lazy.rs

@@ -74,7 +74,7 @@ impl<T: PartialEq> PartialEq for OnceCell<T> {
 impl<T: Eq> Eq for OnceCell<T> {}
 
 #[unstable(feature = "once_cell", issue = "74465")]
-impl<T> From<T> for OnceCell<T> {
+impl<T> const From<T> for OnceCell<T> {
     fn from(value: T) -> Self {
         OnceCell { inner: UnsafeCell::new(Some(value)) }
     }

library/core/src/num/error.rs

@@ -29,14 +29,15 @@ impl fmt::Display for TryFromIntError {
 }
 
 #[stable(feature = "try_from", since = "1.34.0")]
-impl From<Infallible> for TryFromIntError {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl const From<Infallible> for TryFromIntError {
     fn from(x: Infallible) -> TryFromIntError {
         match x {}
     }
 }
 
 #[unstable(feature = "never_type", issue = "35121")]
-impl From<!> for TryFromIntError {
+impl const From<!> for TryFromIntError {
     fn from(never: !) -> TryFromIntError {
         // Match rather than coerce to make sure that code like
         // `From<Infallible> for TryFromIntError` above will keep working

library/core/src/num/nonzero.rs

@@ -82,7 +82,8 @@ macro_rules! nonzero_integers {
             }
 
             #[stable(feature = "from_nonzero", since = "1.31.0")]
-            impl From<$Ty> for $Int {
+            #[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+            impl const From<$Ty> for $Int {
                 #[doc = concat!("Converts a `", stringify!($Ty), "` into an `", stringify!($Int), "`")]
                 #[inline]
                 fn from(nonzero: $Ty) -> Self {

library/core/src/option.rs

@@ -1723,7 +1723,8 @@ impl<'a, T> IntoIterator for &'a mut Option<T> {
 }
 
 #[stable(since = "1.12.0", feature = "option_from")]
-impl<T> From<T> for Option<T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T> const From<T> for Option<T> {
     /// Moves `val` into a new [`Some`].
     ///
     /// # Examples
@@ -1739,7 +1740,8 @@ impl<T> From<T> for Option<T> {
 }
 
 #[stable(feature = "option_ref_from_ref_option", since = "1.30.0")]
-impl<'a, T> From<&'a Option<T>> for Option<&'a T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<'a, T> const From<&'a Option<T>> for Option<&'a T> {
     /// Converts from `&Option<T>` to `Option<&T>`.
     ///
     /// # Examples
@@ -1766,7 +1768,8 @@ impl<'a, T> From<&'a Option<T>> for Option<&'a T> {
 }
 
 #[stable(feature = "option_ref_from_ref_option", since = "1.30.0")]
-impl<'a, T> From<&'a mut Option<T>> for Option<&'a mut T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<'a, T> const From<&'a mut Option<T>> for Option<&'a mut T> {
     /// Converts from `&mut Option<T>` to `Option<&mut T>`
     ///
     /// # Examples
@@ -2052,7 +2055,7 @@ impl<T> ops::Try for Option<T> {
 }
 
 #[unstable(feature = "try_trait_v2", issue = "84277")]
-impl<T> ops::FromResidual for Option<T> {
+impl<T> const ops::FromResidual for Option<T> {
     #[inline]
     fn from_residual(residual: Option<convert::Infallible>) -> Self {
         match residual {

library/core/src/panic/panic_info.rs

@@ -121,7 +121,7 @@ impl<'a> PanicInfo<'a> {
     #[stable(feature = "panic_hooks", since = "1.10.0")]
     pub fn location(&self) -> Option<&Location<'_>> {
         // NOTE: If this is changed to sometimes return None,
-        // deal with that case in std::panicking::default_hook and std::panicking::begin_panic_fmt.
+        // deal with that case in std::panicking::default_hook and core::panicking::panic_fmt.
         Some(&self.location)
     }
 }

library/core/src/panicking.rs

@@ -76,8 +76,15 @@ fn panic_bounds_check(index: usize, len: usize) -> ! {
     panic!("index out of bounds: the len is {} but the index is {}", len, index)
 }
 
-/// The underlying implementation of libcore's `panic!` macro when formatting is used.
+/// The entry point for panicking with a formatted message.
+///
+/// This is designed to reduce the amount of code required at the call
+/// site as much as possible (so that `panic!()` has as low an impact
+/// on (e.g.) the inlining of other functions as possible), by moving
+/// the actual formatting into this shared place.
 #[cold]
+// If panic_immediate_abort, inline the abort call,
+// otherwise avoid inlining because of it is cold path.
 #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
 #[cfg_attr(feature = "panic_immediate_abort", inline)]
 #[track_caller]

library/core/src/ptr/non_null.rs

@@ -698,7 +698,8 @@ impl<T: ?Sized> hash::Hash for NonNull<T> {
 }
 
 #[unstable(feature = "ptr_internals", issue = "none")]
-impl<T: ?Sized> From<Unique<T>> for NonNull<T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T: ?Sized> const From<Unique<T>> for NonNull<T> {
     #[inline]
     fn from(unique: Unique<T>) -> Self {
         // SAFETY: A Unique pointer cannot be null, so the conditions for
@@ -708,7 +709,8 @@ impl<T: ?Sized> From<Unique<T>> for NonNull<T> {
 }
 
 #[stable(feature = "nonnull", since = "1.25.0")]
-impl<T: ?Sized> From<&mut T> for NonNull<T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T: ?Sized> const From<&mut T> for NonNull<T> {
     #[inline]
     fn from(reference: &mut T) -> Self {
         // SAFETY: A mutable reference cannot be null.
@@ -717,7 +719,8 @@ impl<T: ?Sized> From<&mut T> for NonNull<T> {
 }
 
 #[stable(feature = "nonnull", since = "1.25.0")]
-impl<T: ?Sized> From<&T> for NonNull<T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T: ?Sized> const From<&T> for NonNull<T> {
     #[inline]
     fn from(reference: &T) -> Self {
         // SAFETY: A reference cannot be null, so the conditions for

library/core/src/ptr/unique.rs

@@ -176,7 +176,7 @@ impl<T: ?Sized> fmt::Pointer for Unique<T> {
 }
 
 #[unstable(feature = "ptr_internals", issue = "none")]
-impl<T: ?Sized> From<&mut T> for Unique<T> {
+impl<T: ?Sized> const From<&mut T> for Unique<T> {
     #[inline]
     fn from(reference: &mut T) -> Self {
         // SAFETY: A mutable reference cannot be null