Add more from the std

crates/std/Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+hashbrown = "0.16"
 os-std-macros = { path = "../os-std-macros" }
 shared = { path = "../shared", features = ["user"] }
 io = { path = "../io", features = ["alloc"] }

crates/std/src/collections/hash/mod.rs

@@ -0,0 +1,4 @@
+//! Unordered containers, implemented as hash-tables
+
+pub mod map;
+pub mod set;

crates/std/src/collections/mod.rs

@@ -0,0 +1,6 @@
+use core::marker::PhantomData;
+
+pub struct HashMap<K, V, T> {
+    _phantom: PhantomData<(K, V, T)>,
+}
+pub use alloc_crate::collections;

crates/std/src/env.rs

@@ -0,0 +1,5 @@
+use crate::ffi::OsString;
+
+pub fn var_os(s: &str) -> Option<OsString> {
+    None
+}

crates/std/src/io.rs

@@ -9,7 +9,7 @@ pub mod copy;
 pub mod cursor;
 pub mod impls;
 pub mod pipe;
-// pub mod stdio;
+pub mod stdio;
 pub mod prelude;
 pub mod util;
 
@@ -18,7 +18,9 @@ use crate::ops::{Deref, DerefMut};
 use crate::{cmp, fmt, slice, str, sys};
 #[unstable(feature = "read_buf", issue = "78485")]
 pub use core::io::{BorrowedBuf, BorrowedCursor};
+pub use cursor::Cursor;
 use core::slice::memchr;
+pub use stdio::try_set_output_capture;
 
 use crate::fs::File;
 use io::IoBase;

crates/std/src/lib.rs

@@ -267,6 +267,11 @@ pub use core::{
     stringify, trace_macros,
 };
 
+#[rustc_std_internal_symbol]
+pub unsafe fn __rust_start_panic(_payload: &mut dyn core::panic::PanicPayload) -> u32 {
+    todo!()
+}
+
 pub mod ffi;
 pub mod hash;
 pub mod io;
@@ -280,6 +285,10 @@ pub mod process;
 pub mod rt;
 pub mod alloc;
 pub mod bstr;
+pub mod collections;
+pub mod env;
+pub mod panic;
+pub mod panicking;
 pub mod sync;
 pub mod sys;
 pub mod thread;

crates/std/src/panic.rs

@@ -0,0 +1,534 @@
+//! Panic support in the standard library.
+
+#![stable(feature = "std_panic", since = "1.9.0")]
+
+use crate::any::Any;
+use crate::sync::atomic::{Atomic, AtomicU8, Ordering};
+use crate::sync::{Condvar, Mutex, RwLock};
+use crate::thread::Result;
+use crate::{collections, fmt, panicking};
+
+#[stable(feature = "panic_hooks", since = "1.10.0")]
+#[deprecated(
+    since = "1.82.0",
+    note = "use `PanicHookInfo` instead",
+    suggestion = "std::panic::PanicHookInfo"
+)]
+/// A struct providing information about a panic.
+///
+/// `PanicInfo` has been renamed to [`PanicHookInfo`] to avoid confusion with
+/// [`core::panic::PanicInfo`].
+pub type PanicInfo<'a> = PanicHookInfo<'a>;
+
+/// A struct providing information about a panic.
+///
+/// `PanicHookInfo` structure is passed to a panic hook set by the [`set_hook`] function.
+///
+/// # Examples
+///
+/// ```should_panic
+/// use std::panic;
+///
+/// panic::set_hook(Box::new(|panic_info| {
+///     println!("panic occurred: {panic_info}");
+/// }));
+///
+/// panic!("critical system failure");
+/// ```
+///
+/// [`set_hook`]: ../../std/panic/fn.set_hook.html
+#[stable(feature = "panic_hook_info", since = "1.81.0")]
+#[derive(Debug)]
+pub struct PanicHookInfo<'a> {
+    payload: &'a (dyn Any + Send),
+    location: &'a Location<'a>,
+    can_unwind: bool,
+    force_no_backtrace: bool,
+}
+
+impl<'a> PanicHookInfo<'a> {
+    #[inline]
+    pub(crate) fn new(
+        location: &'a Location<'a>,
+        payload: &'a (dyn Any + Send),
+        can_unwind: bool,
+        force_no_backtrace: bool,
+    ) -> Self {
+        PanicHookInfo { payload, location, can_unwind, force_no_backtrace }
+    }
+
+    /// Returns the payload associated with the panic.
+    ///
+    /// This will commonly, but not always, be a `&'static str` or [`String`].
+    /// If you only care about such payloads, use [`payload_as_str`] instead.
+    ///
+    /// A invocation of the `panic!()` macro in Rust 2021 or later will always result in a
+    /// panic payload of type `&'static str` or `String`.
+    ///
+    /// Only an invocation of [`panic_any`]
+    /// (or, in Rust 2018 and earlier, `panic!(x)` where `x` is something other than a string)
+    /// can result in a panic payload other than a `&'static str` or `String`.
+    ///
+    /// [`String`]: ../../std/string/struct.String.html
+    /// [`payload_as_str`]: PanicHookInfo::payload_as_str
+    ///
+    /// # Examples
+    ///
+    /// ```should_panic
+    /// use std::panic;
+    ///
+    /// panic::set_hook(Box::new(|panic_info| {
+    ///     if let Some(s) = panic_info.payload().downcast_ref::<&str>() {
+    ///         println!("panic occurred: {s:?}");
+    ///     } else if let Some(s) = panic_info.payload().downcast_ref::<String>() {
+    ///         println!("panic occurred: {s:?}");
+    ///     } else {
+    ///         println!("panic occurred");
+    ///     }
+    /// }));
+    ///
+    /// panic!("Normal panic");
+    /// ```
+    #[must_use]
+    #[inline]
+    #[stable(feature = "panic_hooks", since = "1.10.0")]
+    pub fn payload(&self) -> &(dyn Any + Send) {
+        self.payload
+    }
+
+    /// Returns the payload associated with the panic, if it is a string.
+    ///
+    /// This returns the payload if it is of type `&'static str` or `String`.
+    ///
+    /// A invocation of the `panic!()` macro in Rust 2021 or later will always result in a
+    /// panic payload where `payload_as_str` returns `Some`.
+    ///
+    /// Only an invocation of [`panic_any`]
+    /// (or, in Rust 2018 and earlier, `panic!(x)` where `x` is something other than a string)
+    /// can result in a panic payload where `payload_as_str` returns `None`.
+    ///
+    /// # Example
+    ///
+    /// ```should_panic
+    /// std::panic::set_hook(Box::new(|panic_info| {
+    ///     if let Some(s) = panic_info.payload_as_str() {
+    ///         println!("panic occurred: {s:?}");
+    ///     } else {
+    ///         println!("panic occurred");
+    ///     }
+    /// }));
+    ///
+    /// panic!("Normal panic");
+    /// ```
+    #[must_use]
+    #[inline]
+    #[stable(feature = "panic_payload_as_str", since = "1.91.0")]
+    pub fn payload_as_str(&self) -> Option<&str> {
+        if let Some(s) = self.payload.downcast_ref::<&str>() {
+            Some(s)
+        } else if let Some(s) = self.payload.downcast_ref::<String>() {
+            Some(s)
+        } else {
+            None
+        }
+    }
+
+    /// Returns information about the location from which the panic originated,
+    /// if available.
+    ///
+    /// This method will currently always return [`Some`], but this may change
+    /// in future versions.
+    ///
+    /// # Examples
+    ///
+    /// ```should_panic
+    /// use std::panic;
+    ///
+    /// panic::set_hook(Box::new(|panic_info| {
+    ///     if let Some(location) = panic_info.location() {
+    ///         println!("panic occurred in file '{}' at line {}",
+    ///             location.file(),
+    ///             location.line(),
+    ///         );
+    ///     } else {
+    ///         println!("panic occurred but can't get location information...");
+    ///     }
+    /// }));
+    ///
+    /// panic!("Normal panic");
+    /// ```
+    #[must_use]
+    #[inline]
+    #[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 core::panicking::panic_fmt.
+        Some(&self.location)
+    }
+
+    /// Returns whether the panic handler is allowed to unwind the stack from
+    /// the point where the panic occurred.
+    ///
+    /// This is true for most kinds of panics with the exception of panics
+    /// caused by trying to unwind out of a `Drop` implementation or a function
+    /// whose ABI does not support unwinding.
+    ///
+    /// It is safe for a panic handler to unwind even when this function returns
+    /// false, however this will simply cause the panic handler to be called
+    /// again.
+    #[must_use]
+    #[inline]
+    #[unstable(feature = "panic_can_unwind", issue = "92988")]
+    pub fn can_unwind(&self) -> bool {
+        self.can_unwind
+    }
+
+    #[unstable(
+        feature = "panic_internals",
+        reason = "internal details of the implementation of the `panic!` and related macros",
+        issue = "none"
+    )]
+    #[doc(hidden)]
+    #[inline]
+    pub fn force_no_backtrace(&self) -> bool {
+        self.force_no_backtrace
+    }
+}
+
+#[stable(feature = "panic_hook_display", since = "1.26.0")]
+impl fmt::Display for PanicHookInfo<'_> {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        formatter.write_str("panicked at ")?;
+        self.location.fmt(formatter)?;
+        if let Some(payload) = self.payload_as_str() {
+            formatter.write_str(":\n")?;
+            formatter.write_str(payload)?;
+        }
+        Ok(())
+    }
+}
+
+#[doc(hidden)]
+#[unstable(feature = "edition_panic", issue = "none", reason = "use panic!() instead")]
+#[allow_internal_unstable(libstd_sys_internals, const_format_args, panic_internals, rt)]
+#[cfg_attr(not(test), rustc_diagnostic_item = "std_panic_2015_macro")]
+#[rustc_macro_transparency = "semiopaque"]
+pub macro panic_2015 {
+    () => ({
+        $crate::rt::begin_panic("explicit panic")
+    }),
+    ($msg:expr $(,)?) => ({
+        $crate::rt::begin_panic($msg);
+    }),
+    // Special-case the single-argument case for const_panic.
+    ("{}", $arg:expr $(,)?) => ({
+        $crate::rt::panic_display(&$arg);
+    }),
+    ($fmt:expr, $($arg:tt)+) => ({
+        // Semicolon to prevent temporaries inside the formatting machinery from
+        // being considered alive in the caller after the panic_fmt call.
+        $crate::rt::panic_fmt($crate::const_format_args!($fmt, $($arg)+));
+    }),
+}
+
+#[stable(feature = "panic_hooks", since = "1.10.0")]
+pub use core::panic::Location;
+#[doc(hidden)]
+#[unstable(feature = "edition_panic", issue = "none", reason = "use panic!() instead")]
+pub use core::panic::panic_2021;
+#[stable(feature = "catch_unwind", since = "1.9.0")]
+pub use core::panic::{AssertUnwindSafe, RefUnwindSafe, UnwindSafe};
+
+#[unstable(feature = "panic_update_hook", issue = "92649")]
+pub use crate::panicking::update_hook;
+#[stable(feature = "panic_hooks", since = "1.10.0")]
+pub use crate::panicking::{set_hook, take_hook};
+
+/// Panics the current thread with the given message as the panic payload.
+///
+/// The message can be of any (`Any + Send`) type, not just strings.
+///
+/// The message is wrapped in a `Box<'static + Any + Send>`, which can be
+/// accessed later using [`PanicHookInfo::payload`].
+///
+/// See the [`panic!`] macro for more information about panicking.
+#[stable(feature = "panic_any", since = "1.51.0")]
+#[inline]
+#[track_caller]
+#[cfg_attr(not(test), rustc_diagnostic_item = "panic_any")]
+pub fn panic_any<M: 'static + Any + Send>(msg: M) -> ! {
+    crate::panicking::begin_panic(msg);
+}
+
+#[stable(feature = "catch_unwind", since = "1.9.0")]
+impl<T: ?Sized> UnwindSafe for Mutex<T> {}
+#[stable(feature = "catch_unwind", since = "1.9.0")]
+impl<T: ?Sized> UnwindSafe for RwLock<T> {}
+#[stable(feature = "catch_unwind", since = "1.9.0")]
+impl UnwindSafe for Condvar {}
+
+#[stable(feature = "unwind_safe_lock_refs", since = "1.12.0")]
+impl<T: ?Sized> RefUnwindSafe for Mutex<T> {}
+#[stable(feature = "unwind_safe_lock_refs", since = "1.12.0")]
+impl<T: ?Sized> RefUnwindSafe for RwLock<T> {}
+#[stable(feature = "unwind_safe_lock_refs", since = "1.12.0")]
+impl RefUnwindSafe for Condvar {}
+
+// https://github.com/rust-lang/rust/issues/62301
+#[stable(feature = "hashbrown", since = "1.36.0")]
+impl<K, V, S> UnwindSafe for collections::HashMap<K, V, S>
+where
+    K: UnwindSafe,
+    V: UnwindSafe,
+    S: UnwindSafe,
+{
+}
+
+#[unstable(feature = "abort_unwind", issue = "130338")]
+pub use core::panic::abort_unwind;
+
+/// Invokes a closure, capturing the cause of an unwinding panic if one occurs.
+///
+/// This function will return `Ok` with the closure's result if the closure does
+/// not panic, and will return `Err(cause)` if the closure panics. The `cause`
+/// returned is the object with which panic was originally invoked.
+///
+/// Rust functions that are expected to be called from foreign code that does
+/// not support unwinding (such as C compiled with `-fno-exceptions`) should be
+/// defined using `extern "C"`, which ensures that if the Rust code panics, it
+/// is automatically caught and the process is aborted. If this is the desired
+/// behavior, it is not necessary to use `catch_unwind` explicitly. This
+/// function should instead be used when more graceful error-handling is needed.
+///
+/// It is **not** recommended to use this function for a general try/catch
+/// mechanism. The [`Result`] type is more appropriate to use for functions that
+/// can fail on a regular basis. Additionally, this function is not guaranteed
+/// to catch all panics, see the "Notes" section below.
+///
+/// The closure provided is required to adhere to the [`UnwindSafe`] trait to
+/// ensure that all captured variables are safe to cross this boundary. The
+/// purpose of this bound is to encode the concept of [exception safety][rfc] in
+/// the type system. Most usage of this function should not need to worry about
+/// this bound as programs are naturally unwind safe without `unsafe` code. If
+/// it becomes a problem the [`AssertUnwindSafe`] wrapper struct can be used to
+/// quickly assert that the usage here is indeed unwind safe.
+///
+/// [rfc]: https://github.com/rust-lang/rfcs/blob/master/text/1236-stabilize-catch-panic.md
+///
+/// # Notes
+///
+/// This function **might not catch all Rust panics**. A Rust panic is not
+/// always implemented via unwinding, but can be implemented by aborting the
+/// process as well. This function *only* catches unwinding panics, not those
+/// that abort the process.
+///
+/// If a custom panic hook has been set, it will be invoked before the panic is
+/// caught, before unwinding.
+///
+/// Although unwinding into Rust code with a foreign exception (e.g. an
+/// exception thrown from C++ code, or a `panic!` in Rust code compiled or
+/// linked with a different runtime) via an appropriate ABI (e.g. `"C-unwind"`)
+/// is permitted, catching such an exception using this function will have one
+/// of two behaviors, and it is unspecified which will occur:
+///
+/// * The process aborts, after executing all destructors of `f` and the
+///   functions it called.
+/// * The function returns a `Result::Err` containing an opaque type.
+///
+/// Finally, be **careful in how you drop the result of this function**. If it
+/// is `Err`, it contains the panic payload, and dropping that may in turn
+/// panic!
+///
+/// # Examples
+///
+/// ```
+/// use std::panic;
+///
+/// let result = panic::catch_unwind(|| {
+///     println!("hello!");
+/// });
+/// assert!(result.is_ok());
+///
+/// let result = panic::catch_unwind(|| {
+///     panic!("oh no!");
+/// });
+/// assert!(result.is_err());
+/// ```
+#[stable(feature = "catch_unwind", since = "1.9.0")]
+pub fn catch_unwind<F: FnOnce() -> R + UnwindSafe, R>(f: F) -> Result<R> {
+    unsafe { panicking::catch_unwind(f) }
+}
+
+/// Triggers a panic without invoking the panic hook.
+///
+/// This is designed to be used in conjunction with [`catch_unwind`] to, for
+/// example, carry a panic across a layer of C code.
+///
+/// # Notes
+///
+/// Note that panics in Rust are not always implemented via unwinding, but they
+/// may be implemented by aborting the process. If this function is called when
+/// panics are implemented this way then this function will abort the process,
+/// not trigger an unwind.
+///
+/// # Examples
+///
+/// ```should_panic
+/// use std::panic;
+///
+/// let result = panic::catch_unwind(|| {
+///     if 1 != 2 {
+///         panic!("oh no!");
+///     }
+/// });
+///
+/// if let Err(err) = result {
+///     panic::resume_unwind(err);
+/// }
+/// ```
+#[stable(feature = "resume_unwind", since = "1.9.0")]
+pub fn resume_unwind(payload: Box<dyn Any + Send>) -> ! {
+    panicking::resume_unwind(payload)
+}
+
+/// Makes all future panics abort directly without running the panic hook or unwinding.
+///
+/// There is no way to undo this; the effect lasts until the process exits or
+/// execs (or the equivalent).
+///
+/// # Use after fork
+///
+/// This function is particularly useful for calling after `libc::fork`.  After `fork`, in a
+/// multithreaded program it is (on many platforms) not safe to call the allocator.  It is also
+/// generally highly undesirable for an unwind to unwind past the `fork`, because that results in
+/// the unwind propagating to code that was only ever expecting to run in the parent.
+///
+/// `panic::always_abort()` helps avoid both of these.  It directly avoids any further unwinding,
+/// and if there is a panic, the abort will occur without allocating provided that the arguments to
+/// panic can be formatted without allocating.
+///
+/// Examples
+///
+/// ```no_run
+/// #![feature(panic_always_abort)]
+/// use std::panic;
+///
+/// panic::always_abort();
+///
+/// let _ = panic::catch_unwind(|| {
+///     panic!("inside the catch");
+/// });
+///
+/// // We will have aborted already, due to the panic.
+/// unreachable!();
+/// ```
+#[unstable(feature = "panic_always_abort", issue = "84438")]
+pub fn always_abort() {
+    crate::panicking::panic_count::set_always_abort();
+}
+
+/// The configuration for whether and how the default panic hook will capture
+/// and display the backtrace.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[unstable(feature = "panic_backtrace_config", issue = "93346")]
+#[non_exhaustive]
+pub enum BacktraceStyle {
+    /// Prints a terser backtrace which ideally only contains relevant
+    /// information.
+    Short,
+    /// Prints a backtrace with all possible information.
+    Full,
+    /// Disable collecting and displaying backtraces.
+    Off,
+}
+
+impl BacktraceStyle {
+    pub(crate) fn full() -> Option<Self> {
+        if cfg!(feature = "backtrace") { Some(BacktraceStyle::Full) } else { None }
+    }
+
+    fn as_u8(self) -> u8 {
+        match self {
+            BacktraceStyle::Short => 1,
+            BacktraceStyle::Full => 2,
+            BacktraceStyle::Off => 3,
+        }
+    }
+
+    fn from_u8(s: u8) -> Option<Self> {
+        match s {
+            1 => Some(BacktraceStyle::Short),
+            2 => Some(BacktraceStyle::Full),
+            3 => Some(BacktraceStyle::Off),
+            _ => None,
+        }
+    }
+}
+
+// Tracks whether we should/can capture a backtrace, and how we should display
+// that backtrace.
+//
+// Internally stores equivalent of an Option<BacktraceStyle>.
+static SHOULD_CAPTURE: Atomic<u8> = AtomicU8::new(0);
+
+/// Configures whether the default panic hook will capture and display a
+/// backtrace.
+///
+/// The default value for this setting may be set by the `RUST_BACKTRACE`
+/// environment variable; see the details in [`get_backtrace_style`].
+#[unstable(feature = "panic_backtrace_config", issue = "93346")]
+pub fn set_backtrace_style(style: BacktraceStyle) {
+    if cfg!(feature = "backtrace") {
+        // If the `backtrace` feature of this crate is enabled, set the backtrace style.
+        SHOULD_CAPTURE.store(style.as_u8(), Ordering::Relaxed);
+    }
+}
+
+/// Checks whether the standard library's panic hook will capture and print a
+/// backtrace.
+///
+/// This function will, if a backtrace style has not been set via
+/// [`set_backtrace_style`], read the environment variable `RUST_BACKTRACE` to
+/// determine a default value for the backtrace formatting:
+///
+/// The first call to `get_backtrace_style` may read the `RUST_BACKTRACE`
+/// environment variable if `set_backtrace_style` has not been called to
+/// override the default value. After a call to `set_backtrace_style` or
+/// `get_backtrace_style`, any changes to `RUST_BACKTRACE` will have no effect.
+///
+/// `RUST_BACKTRACE` is read according to these rules:
+///
+/// * `0` for `BacktraceStyle::Off`
+/// * `full` for `BacktraceStyle::Full`
+/// * `1` for `BacktraceStyle::Short`
+/// * Other values are currently `BacktraceStyle::Short`, but this may change in
+///   the future
+///
+/// Returns `None` if backtraces aren't currently supported.
+#[unstable(feature = "panic_backtrace_config", issue = "93346")]
+pub fn get_backtrace_style() -> Option<BacktraceStyle> {
+    if !cfg!(feature = "backtrace") {
+        // If the `backtrace` feature of this crate isn't enabled quickly return
+        // `Unsupported` so this can be constant propagated all over the place
+        // to optimize away callers.
+        return None;
+    }
+
+    let current = SHOULD_CAPTURE.load(Ordering::Relaxed);
+    if let Some(style) = BacktraceStyle::from_u8(current) {
+        return Some(style);
+    }
+
+    let format = match crate::env::var_os("RUST_BACKTRACE") {
+        Some(x) if &x == "0" => BacktraceStyle::Off,
+        Some(x) if &x == "full" => BacktraceStyle::Full,
+        Some(_) => BacktraceStyle::Short,
+        None if crate::sys::backtrace::FULL_BACKTRACE_DEFAULT => BacktraceStyle::Full,
+        None => BacktraceStyle::Off,
+    };
+
+    match SHOULD_CAPTURE.compare_exchange(0, format.as_u8(), Ordering::Relaxed, Ordering::Relaxed) {
+        Ok(_) => Some(format),
+        Err(new) => BacktraceStyle::from_u8(new),
+    }
+}

crates/std/src/panicking.rs

@@ -0,0 +1,894 @@
+//! Implementation of various bits and pieces of the `panic!` macro and
+//! associated runtime pieces.
+//!
+//! Specifically, this module contains the implementation of:
+//!
+//! * Panic hooks
+//! * Executing a panic up to doing the actual implementation
+//! * Shims around "try"
+
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use core::panic::{Location, PanicPayload};
+
+// make sure to use the stderr output configured
+// by libtest in the real copy of std
+#[cfg(test)]
+use realstd::io::try_set_output_capture;
+
+use crate::any::Any;
+#[cfg(not(test))]
+use crate::io::try_set_output_capture;
+use crate::mem::{self, ManuallyDrop};
+use crate::panic::{BacktraceStyle, PanicHookInfo};
+use crate::sync::atomic::{Atomic, AtomicBool, Ordering};
+use crate::sync::nonpoison::RwLock;
+use crate::sys::backtrace;
+use crate::sys::stdio::panic_output;
+use crate::{fmt, intrinsics, process, thread};
+
+// This forces codegen of the function called by panic!() inside the std crate, rather than in
+// downstream crates. Primarily this is useful for rustc's codegen tests, which rely on noticing
+// complete removal of panic from generated IR. Since begin_panic is inline(never), it's only
+// codegen'd once per crate-graph so this pushes that to std rather than our codegen test crates.
+//
+// (See https://github.com/rust-lang/rust/pull/123244 for more info on why).
+//
+// If this is causing problems we can also modify those codegen tests to use a crate type like
+// cdylib which doesn't export "Rust" symbols to downstream linkage units.
+#[unstable(feature = "libstd_sys_internals", reason = "used by the panic! macro", issue = "none")]
+#[doc(hidden)]
+#[allow(dead_code)]
+#[used(compiler)]
+pub static EMPTY_PANIC: fn(&'static str) -> ! =
+    begin_panic::<&'static str> as fn(&'static str) -> !;
+
+// Binary interface to the panic runtime that the standard library depends on.
+//
+// The standard library is tagged with `#![needs_panic_runtime]` (introduced in
+// RFC 1513) to indicate that it requires some other crate tagged with
+// `#![panic_runtime]` to exist somewhere. Each panic runtime is intended to
+// implement these symbols (with the same signatures) so we can get matched up
+// to them.
+//
+// One day this may look a little less ad-hoc with the compiler helping out to
+// hook up these functions, but it is not this day!
+#[allow(improper_ctypes)]
+unsafe extern "C" {
+    #[rustc_std_internal_symbol]
+    fn __rust_panic_cleanup(payload: *mut u8) -> *mut (dyn Any + Send + 'static);
+}
+
+unsafe extern "Rust" {
+    /// `PanicPayload` lazily performs allocation only when needed (this avoids
+    /// allocations when using the "abort" panic runtime).
+    #[rustc_std_internal_symbol]
+    fn __rust_start_panic(payload: &mut dyn PanicPayload) -> u32;
+}
+
+/// This function is called by the panic runtime if FFI code catches a Rust
+/// panic but doesn't rethrow it. We don't support this case since it messes
+/// with our panic count.
+#[cfg(not(test))]
+#[rustc_std_internal_symbol]
+extern "C" fn __rust_drop_panic() -> ! {
+    rtabort!("Rust panics must be rethrown");
+}
+
+/// This function is called by the panic runtime if it catches an exception
+/// object which does not correspond to a Rust panic.
+#[cfg(not(test))]
+#[rustc_std_internal_symbol]
+extern "C" fn __rust_foreign_exception() -> ! {
+    rtabort!("Rust cannot catch foreign exceptions");
+}
+
+#[derive(Default)]
+enum Hook {
+    #[default]
+    Default,
+    Custom(Box<dyn Fn(&PanicHookInfo<'_>) + 'static + Sync + Send>),
+}
+
+impl Hook {
+    #[inline]
+    fn into_box(self) -> Box<dyn Fn(&PanicHookInfo<'_>) + 'static + Sync + Send> {
+        match self {
+            Hook::Default => Box::new(default_hook),
+            Hook::Custom(hook) => hook,
+        }
+    }
+}
+
+static HOOK: RwLock<Hook> = RwLock::new(Hook::Default);
+
+/// Registers a custom panic hook, replacing the previously registered hook.
+///
+/// The panic hook is invoked when a thread panics, but before the panic runtime
+/// is invoked. As such, the hook will run with both the aborting and unwinding
+/// runtimes.
+///
+/// The default hook, which is registered at startup, prints a message to standard error and
+/// generates a backtrace if requested. This behavior can be customized using the `set_hook` function.
+/// The current hook can be retrieved while reinstating the default hook with the [`take_hook`]
+/// function.
+///
+/// [`take_hook`]: ./fn.take_hook.html
+///
+/// The hook is provided with a `PanicHookInfo` struct which contains information
+/// about the origin of the panic, including the payload passed to `panic!` and
+/// the source code location from which the panic originated.
+///
+/// The panic hook is a global resource.
+///
+/// # Panics
+///
+/// Panics if called from a panicking thread.
+///
+/// # Examples
+///
+/// The following will print "Custom panic hook":
+///
+/// ```should_panic
+/// use std::panic;
+///
+/// panic::set_hook(Box::new(|_| {
+///     println!("Custom panic hook");
+/// }));
+///
+/// panic!("Normal panic");
+/// ```
+#[stable(feature = "panic_hooks", since = "1.10.0")]
+pub fn set_hook(hook: Box<dyn Fn(&PanicHookInfo<'_>) + 'static + Sync + Send>) {
+    if thread::panicking() {
+        panic!("cannot modify the panic hook from a panicking thread");
+    }
+
+    // Drop the old hook after changing the hook to avoid deadlocking if its
+    // destructor panics.
+    drop(HOOK.replace(Hook::Custom(hook)));
+}
+
+/// Unregisters the current panic hook and returns it, registering the default hook
+/// in its place.
+///
+/// *See also the function [`set_hook`].*
+///
+/// [`set_hook`]: ./fn.set_hook.html
+///
+/// If the default hook is registered it will be returned, but remain registered.
+///
+/// # Panics
+///
+/// Panics if called from a panicking thread.
+///
+/// # Examples
+///
+/// The following will print "Normal panic":
+///
+/// ```should_panic
+/// use std::panic;
+///
+/// panic::set_hook(Box::new(|_| {
+///     println!("Custom panic hook");
+/// }));
+///
+/// let _ = panic::take_hook();
+///
+/// panic!("Normal panic");
+/// ```
+#[must_use]
+#[stable(feature = "panic_hooks", since = "1.10.0")]
+pub fn take_hook() -> Box<dyn Fn(&PanicHookInfo<'_>) + 'static + Sync + Send> {
+    if thread::panicking() {
+        panic!("cannot modify the panic hook from a panicking thread");
+    }
+
+    HOOK.replace(Hook::Default).into_box()
+}
+
+/// Atomic combination of [`take_hook`] and [`set_hook`]. Use this to replace the panic handler with
+/// a new panic handler that does something and then executes the old handler.
+///
+/// [`take_hook`]: ./fn.take_hook.html
+/// [`set_hook`]: ./fn.set_hook.html
+///
+/// # Panics
+///
+/// Panics if called from a panicking thread.
+///
+/// # Examples
+///
+/// The following will print the custom message, and then the normal output of panic.
+///
+/// ```should_panic
+/// #![feature(panic_update_hook)]
+/// use std::panic;
+///
+/// // Equivalent to
+/// // let prev = panic::take_hook();
+/// // panic::set_hook(Box::new(move |info| {
+/// //     println!("...");
+/// //     prev(info);
+/// // }));
+/// panic::update_hook(move |prev, info| {
+///     println!("Print custom message and execute panic handler as usual");
+///     prev(info);
+/// });
+///
+/// panic!("Custom and then normal");
+/// ```
+#[unstable(feature = "panic_update_hook", issue = "92649")]
+pub fn update_hook<F>(hook_fn: F)
+where
+    F: Fn(&(dyn Fn(&PanicHookInfo<'_>) + Send + Sync + 'static), &PanicHookInfo<'_>)
+        + Sync
+        + Send
+        + 'static,
+{
+    if thread::panicking() {
+        panic!("cannot modify the panic hook from a panicking thread");
+    }
+
+    let mut hook = HOOK.write();
+    let prev = mem::take(&mut *hook).into_box();
+    *hook = Hook::Custom(Box::new(move |info| hook_fn(&prev, info)));
+}
+
+/// The default panic handler.
+#[optimize(size)]
+fn default_hook(info: &PanicHookInfo<'_>) {
+    // If this is a double panic, make sure that we print a backtrace
+    // for this panic. Otherwise only print it if logging is enabled.
+    let backtrace = if info.force_no_backtrace() {
+        None
+    } else if panic_count::get_count() >= 2 {
+        BacktraceStyle::full()
+    } else {
+        crate::panic::get_backtrace_style()
+    };
+
+    // The current implementation always returns `Some`.
+    let location = info.location().unwrap();
+
+    let msg = payload_as_str(info.payload());
+
+    let write = #[optimize(size)]
+    |err: &mut dyn crate::io::Write| {
+        // Use a lock to prevent mixed output in multithreading context.
+        // Some platforms also require it when printing a backtrace, like `SymFromAddr` on Windows.
+        let mut lock = backtrace::lock();
+
+        thread::with_current_name(|name| {
+            let name = name.unwrap_or("<unnamed>");
+            let tid = thread::current_os_id();
+
+            // Try to write the panic message to a buffer first to prevent other concurrent outputs
+            // interleaving with it.
+            let mut buffer = [0u8; 512];
+            let mut cursor = crate::io::Cursor::new(&mut buffer[..]);
+
+            let write_msg = |dst: &mut dyn crate::io::Write| {
+                // We add a newline to ensure the panic message appears at the start of a line.
+                writeln!(dst, "\nthread '{name}' ({tid}) panicked at {location}:\n{msg}")
+            };
+
+            if write_msg(&mut cursor).is_ok() {
+                let pos = cursor.position() as usize;
+                let _ = err.write_all(&buffer[0..pos]);
+            } else {
+                // The message did not fit into the buffer, write it directly instead.
+                let _ = write_msg(err);
+            };
+        });
+
+        static FIRST_PANIC: Atomic<bool> = AtomicBool::new(true);
+
+        match backtrace {
+            Some(BacktraceStyle::Short) => {
+    todo!()
+            }
+            Some(BacktraceStyle::Full) => {
+    todo!()
+            }
+            Some(BacktraceStyle::Off) => {
+                if FIRST_PANIC.swap(false, Ordering::Relaxed) {
+                    let _ = writeln!(
+                        err,
+                        "note: run with `RUST_BACKTRACE=1` environment variable to display a \
+                             backtrace"
+                    );
+                    if cfg!(miri) {
+                        let _ = writeln!(
+                            err,
+                            "note: in Miri, you may have to set `MIRIFLAGS=-Zmiri-env-forward=RUST_BACKTRACE` \
+                                for the environment variable to have an effect"
+                        );
+                    }
+                }
+            }
+            // If backtraces aren't supported or are forced-off, do nothing.
+            None => {}
+        }
+    };
+
+    if let Ok(Some(local)) = try_set_output_capture(None) {
+        write(&mut *local.lock().unwrap_or_else(|e| e.into_inner()));
+        try_set_output_capture(Some(local)).ok();
+    } else if let Some(mut out) = panic_output() {
+        write(&mut out);
+    }
+}
+
+#[cfg(not(test))]
+#[doc(hidden)]
+#[cfg(panic = "immediate-abort")]
+#[unstable(feature = "update_panic_count", issue = "none")]
+pub mod panic_count {
+    /// A reason for forcing an immediate abort on panic.
+    #[derive(Debug)]
+    pub enum MustAbort {
+        AlwaysAbort,
+        PanicInHook,
+    }
+
+    #[inline]
+    pub fn increase(run_panic_hook: bool) -> Option<MustAbort> {
+        None
+    }
+
+    #[inline]
+    pub fn finished_panic_hook() {}
+
+    #[inline]
+    pub fn decrease() {}
+
+    #[inline]
+    pub fn set_always_abort() {}
+
+    // Disregards ALWAYS_ABORT_FLAG
+    #[inline]
+    #[must_use]
+    pub fn get_count() -> usize {
+        0
+    }
+
+    #[must_use]
+    #[inline]
+    pub fn count_is_zero() -> bool {
+        true
+    }
+}
+
+#[cfg(not(test))]
+#[doc(hidden)]
+#[cfg(not(panic = "immediate-abort"))]
+#[unstable(feature = "update_panic_count", issue = "none")]
+pub mod panic_count {
+    use crate::cell::Cell;
+    use crate::sync::atomic::{Atomic, AtomicUsize, Ordering};
+
+    const ALWAYS_ABORT_FLAG: usize = 1 << (usize::BITS - 1);
+
+    /// A reason for forcing an immediate abort on panic.
+    #[derive(Debug)]
+    pub enum MustAbort {
+        AlwaysAbort,
+        PanicInHook,
+    }
+
+    // Panic count for the current thread and whether a panic hook is currently
+    // being executed..
+    thread_local! {
+        static LOCAL_PANIC_COUNT: Cell<(usize, bool)> = const { Cell::new((0, false)) }
+    }
+
+    // Sum of panic counts from all threads. The purpose of this is to have
+    // a fast path in `count_is_zero` (which is used by `panicking`). In any particular
+    // thread, if that thread currently views `GLOBAL_PANIC_COUNT` as being zero,
+    // then `LOCAL_PANIC_COUNT` in that thread is zero. This invariant holds before
+    // and after increase and decrease, but not necessarily during their execution.
+    //
+    // Additionally, the top bit of GLOBAL_PANIC_COUNT (GLOBAL_ALWAYS_ABORT_FLAG)
+    // records whether panic::always_abort() has been called. This can only be
+    // set, never cleared.
+    // panic::always_abort() is usually called to prevent memory allocations done by
+    // the panic handling in the child created by `libc::fork`.
+    // Memory allocations performed in a child created with `libc::fork` are undefined
+    // behavior in most operating systems.
+    // Accessing LOCAL_PANIC_COUNT in a child created by `libc::fork` would lead to a memory
+    // allocation. Only GLOBAL_PANIC_COUNT can be accessed in this situation. This is
+    // sufficient because a child process will always have exactly one thread only.
+    // See also #85261 for details.
+    //
+    // This could be viewed as a struct containing a single bit and an n-1-bit
+    // value, but if we wrote it like that it would be more than a single word,
+    // and even a newtype around usize would be clumsy because we need atomics.
+    // But we use such a tuple for the return type of increase().
+    //
+    // Stealing a bit is fine because it just amounts to assuming that each
+    // panicking thread consumes at least 2 bytes of address space.
+    static GLOBAL_PANIC_COUNT: Atomic<usize> = AtomicUsize::new(0);
+
+    // Increases the global and local panic count, and returns whether an
+    // immediate abort is required.
+    //
+    // This also updates thread-local state to keep track of whether a panic
+    // hook is currently executing.
+    pub fn increase(run_panic_hook: bool) -> Option<MustAbort> {
+        let global_count = GLOBAL_PANIC_COUNT.fetch_add(1, Ordering::Relaxed);
+        if global_count & ALWAYS_ABORT_FLAG != 0 {
+            // Do *not* access thread-local state, we might be after a `fork`.
+            return Some(MustAbort::AlwaysAbort);
+        }
+
+        LOCAL_PANIC_COUNT.with(|c| {
+            let (count, in_panic_hook) = c.get();
+            if in_panic_hook {
+                return Some(MustAbort::PanicInHook);
+            }
+            c.set((count + 1, run_panic_hook));
+            None
+        })
+    }
+
+    pub fn finished_panic_hook() {
+        LOCAL_PANIC_COUNT.with(|c| {
+            let (count, _) = c.get();
+            c.set((count, false));
+        });
+    }
+
+    pub fn decrease() {
+        GLOBAL_PANIC_COUNT.fetch_sub(1, Ordering::Relaxed);
+        LOCAL_PANIC_COUNT.with(|c| {
+            let (count, _) = c.get();
+            c.set((count - 1, false));
+        });
+    }
+
+    pub fn set_always_abort() {
+        GLOBAL_PANIC_COUNT.fetch_or(ALWAYS_ABORT_FLAG, Ordering::Relaxed);
+    }
+
+    // Disregards ALWAYS_ABORT_FLAG
+    #[must_use]
+    pub fn get_count() -> usize {
+        LOCAL_PANIC_COUNT.with(|c| c.get().0)
+    }
+
+    // Disregards ALWAYS_ABORT_FLAG
+    #[must_use]
+    #[inline]
+    pub fn count_is_zero() -> bool {
+        if GLOBAL_PANIC_COUNT.load(Ordering::Relaxed) & !ALWAYS_ABORT_FLAG == 0 {
+            // Fast path: if `GLOBAL_PANIC_COUNT` is zero, all threads
+            // (including the current one) will have `LOCAL_PANIC_COUNT`
+            // equal to zero, so TLS access can be avoided.
+            //
+            // In terms of performance, a relaxed atomic load is similar to a normal
+            // aligned memory read (e.g., a mov instruction in x86), but with some
+            // compiler optimization restrictions. On the other hand, a TLS access
+            // might require calling a non-inlinable function (such as `__tls_get_addr`
+            // when using the GD TLS model).
+            true
+        } else {
+            is_zero_slow_path()
+        }
+    }
+
+    // Slow path is in a separate function to reduce the amount of code
+    // inlined from `count_is_zero`.
+    #[inline(never)]
+    #[cold]
+    fn is_zero_slow_path() -> bool {
+        LOCAL_PANIC_COUNT.with(|c| c.get().0 == 0)
+    }
+}
+
+#[cfg(test)]
+pub use realstd::rt::panic_count;
+
+/// Invoke a closure, capturing the cause of an unwinding panic if one occurs.
+#[cfg(panic = "immediate-abort")]
+pub unsafe fn catch_unwind<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
+    Ok(f())
+}
+
+/// Invoke a closure, capturing the cause of an unwinding panic if one occurs.
+#[cfg(not(panic = "immediate-abort"))]
+pub unsafe fn catch_unwind<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
+    union Data<F, R> {
+        f: ManuallyDrop<F>,
+        r: ManuallyDrop<R>,
+        p: ManuallyDrop<Box<dyn Any + Send>>,
+    }
+
+    // We do some sketchy operations with ownership here for the sake of
+    // performance. We can only pass pointers down to `do_call` (can't pass
+    // objects by value), so we do all the ownership tracking here manually
+    // using a union.
+    //
+    // We go through a transition where:
+    //
+    // * First, we set the data field `f` to be the argumentless closure that we're going to call.
+    // * When we make the function call, the `do_call` function below, we take
+    //   ownership of the function pointer. At this point the `data` union is
+    //   entirely uninitialized.
+    // * If the closure successfully returns, we write the return value into the
+    //   data's return slot (field `r`).
+    // * If the closure panics (`do_catch` below), we write the panic payload into field `p`.
+    // * Finally, when we come back out of the `try` intrinsic we're
+    //   in one of two states:
+    //
+    //      1. The closure didn't panic, in which case the return value was
+    //         filled in. We move it out of `data.r` and return it.
+    //      2. The closure panicked, in which case the panic payload was
+    //         filled in. We move it out of `data.p` and return it.
+    //
+    // Once we stack all that together we should have the "most efficient'
+    // method of calling a catch panic whilst juggling ownership.
+    let mut data = Data { f: ManuallyDrop::new(f) };
+
+    let data_ptr = (&raw mut data) as *mut u8;
+    // SAFETY:
+    //
+    // Access to the union's fields: this is `std` and we know that the `catch_unwind`
+    // intrinsic fills in the `r` or `p` union field based on its return value.
+    //
+    // The call to `intrinsics::catch_unwind` is made safe by:
+    // - `do_call`, the first argument, can be called with the initial `data_ptr`.
+    // - `do_catch`, the second argument, can be called with the `data_ptr` as well.
+    // See their safety preconditions for more information
+    unsafe {
+        return if intrinsics::catch_unwind(do_call::<F, R>, data_ptr, do_catch::<F, R>) == 0 {
+            Ok(ManuallyDrop::into_inner(data.r))
+        } else {
+            Err(ManuallyDrop::into_inner(data.p))
+        };
+    }
+
+    // We consider unwinding to be rare, so mark this function as cold. However,
+    // do not mark it no-inline -- that decision is best to leave to the
+    // optimizer (in most cases this function is not inlined even as a normal,
+    // non-cold function, though, as of the writing of this comment).
+    #[cold]
+    #[optimize(size)]
+    unsafe fn cleanup(payload: *mut u8) -> Box<dyn Any + Send + 'static> {
+        // SAFETY: The whole unsafe block hinges on a correct implementation of
+        // the panic handler `__rust_panic_cleanup`. As such we can only
+        // assume it returns the correct thing for `Box::from_raw` to work
+        // without undefined behavior.
+        let obj = unsafe { Box::from_raw(__rust_panic_cleanup(payload)) };
+        panic_count::decrease();
+        obj
+    }
+
+    // SAFETY:
+    // data must be non-NUL, correctly aligned, and a pointer to a `Data<F, R>`
+    // Its must contains a valid `f` (type: F) value that can be use to fill
+    // `data.r`.
+    //
+    // This function cannot be marked as `unsafe` because `intrinsics::catch_unwind`
+    // expects normal function pointers.
+    #[inline]
+    fn do_call<F: FnOnce() -> R, R>(data: *mut u8) {
+        // SAFETY: this is the responsibility of the caller, see above.
+        unsafe {
+            let data = data as *mut Data<F, R>;
+            let data = &mut (*data);
+            let f = ManuallyDrop::take(&mut data.f);
+            data.r = ManuallyDrop::new(f());
+        }
+    }
+
+    // We *do* want this part of the catch to be inlined: this allows the
+    // compiler to properly track accesses to the Data union and optimize it
+    // away most of the time.
+    //
+    // SAFETY:
+    // data must be non-NUL, correctly aligned, and a pointer to a `Data<F, R>`
+    // Since this uses `cleanup` it also hinges on a correct implementation of
+    // `__rustc_panic_cleanup`.
+    //
+    // This function cannot be marked as `unsafe` because `intrinsics::catch_unwind`
+    // expects normal function pointers.
+    #[inline]
+    #[rustc_nounwind] // `intrinsic::catch_unwind` requires catch fn to be nounwind
+    fn do_catch<F: FnOnce() -> R, R>(data: *mut u8, payload: *mut u8) {
+        // SAFETY: this is the responsibility of the caller, see above.
+        //
+        // When `__rustc_panic_cleaner` is correctly implemented we can rely
+        // on `obj` being the correct thing to pass to `data.p` (after wrapping
+        // in `ManuallyDrop`).
+        unsafe {
+            let data = data as *mut Data<F, R>;
+            let data = &mut (*data);
+            let obj = cleanup(payload);
+            data.p = ManuallyDrop::new(obj);
+        }
+    }
+}
+
+/// Determines whether the current thread is unwinding because of panic.
+#[inline]
+pub fn panicking() -> bool {
+    !panic_count::count_is_zero()
+}
+
+/// Entry point of panics from the core crate (`panic_impl` lang item).
+#[cfg(not(any(test, doctest)))]
+#[panic_handler]
+pub fn panic_handler(info: &core::panic::PanicInfo<'_>) -> ! {
+    struct FormatStringPayload<'a> {
+        inner: &'a core::panic::PanicMessage<'a>,
+        string: Option<String>,
+    }
+
+    impl FormatStringPayload<'_> {
+        fn fill(&mut self) -> &mut String {
+            let inner = self.inner;
+            // Lazily, the first time this gets called, run the actual string formatting.
+            self.string.get_or_insert_with(|| {
+                let mut s = String::new();
+                let mut fmt = fmt::Formatter::new(&mut s, fmt::FormattingOptions::new());
+                let _err = fmt::Display::fmt(&inner, &mut fmt);
+                s
+            })
+        }
+    }
+
+    unsafe impl PanicPayload for FormatStringPayload<'_> {
+        fn take_box(&mut self) -> *mut (dyn Any + Send) {
+            // We do two allocations here, unfortunately. But (a) they're required with the current
+            // scheme, and (b) we don't handle panic + OOM properly anyway (see comment in
+            // begin_panic below).
+            let contents = mem::take(self.fill());
+            Box::into_raw(Box::new(contents))
+        }
+
+        fn get(&mut self) -> &(dyn Any + Send) {
+            self.fill()
+        }
+    }
+
+    impl fmt::Display for FormatStringPayload<'_> {
+        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+            if let Some(s) = &self.string {
+                f.write_str(s)
+            } else {
+                fmt::Display::fmt(&self.inner, f)
+            }
+        }
+    }
+
+    struct StaticStrPayload(&'static str);
+
+    unsafe impl PanicPayload for StaticStrPayload {
+        fn take_box(&mut self) -> *mut (dyn Any + Send) {
+            Box::into_raw(Box::new(self.0))
+        }
+
+        fn get(&mut self) -> &(dyn Any + Send) {
+            &self.0
+        }
+
+        fn as_str(&mut self) -> Option<&str> {
+            Some(self.0)
+        }
+    }
+
+    impl fmt::Display for StaticStrPayload {
+        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+            f.write_str(self.0)
+        }
+    }
+
+    let loc = info.location().unwrap(); // The current implementation always returns Some
+    let msg = info.message();
+    crate::sys::backtrace::__rust_end_short_backtrace(move || {
+        if let Some(s) = msg.as_str() {
+            panic_with_hook(
+                &mut StaticStrPayload(s),
+                loc,
+                info.can_unwind(),
+                info.force_no_backtrace(),
+            );
+        } else {
+            panic_with_hook(
+                &mut FormatStringPayload { inner: &msg, string: None },
+                loc,
+                info.can_unwind(),
+                info.force_no_backtrace(),
+            );
+        }
+    })
+}
+
+/// This is the entry point of panicking for the non-format-string variants of
+/// panic!() and assert!(). In particular, this is the only entry point that supports
+/// arbitrary payloads, not just format strings.
+#[unstable(feature = "libstd_sys_internals", reason = "used by the panic! macro", issue = "none")]
+#[cfg_attr(not(any(test, doctest)), lang = "begin_panic")]
+// lang item for CTFE panic support
+// never inline unless panic=immediate-abort to avoid code
+// bloat at the call sites as much as possible
+#[cfg_attr(not(panic = "immediate-abort"), inline(never), cold, optimize(size))]
+#[cfg_attr(panic = "immediate-abort", inline)]
+#[track_caller]
+#[rustc_do_not_const_check] // hooked by const-eval
+pub const fn begin_panic<M: Any + Send>(msg: M) -> ! {
+    if cfg!(panic = "immediate-abort") {
+        intrinsics::abort()
+    }
+
+    struct Payload<A> {
+        inner: Option<A>,
+    }
+
+    unsafe impl<A: Send + 'static> PanicPayload for Payload<A> {
+        fn take_box(&mut self) -> *mut (dyn Any + Send) {
+            // Note that this should be the only allocation performed in this code path. Currently
+            // this means that panic!() on OOM will invoke this code path, but then again we're not
+            // really ready for panic on OOM anyway. If we do start doing this, then we should
+            // propagate this allocation to be performed in the parent of this thread instead of the
+            // thread that's panicking.
+            let data = match self.inner.take() {
+                Some(a) => Box::new(a) as Box<dyn Any + Send>,
+                None => process::abort(),
+            };
+            Box::into_raw(data)
+        }
+
+        fn get(&mut self) -> &(dyn Any + Send) {
+            match self.inner {
+                Some(ref a) => a,
+                None => process::abort(),
+            }
+        }
+    }
+
+    impl<A: 'static> fmt::Display for Payload<A> {
+        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+            match &self.inner {
+                Some(a) => f.write_str(payload_as_str(a)),
+                None => process::abort(),
+            }
+        }
+    }
+
+    let loc = Location::caller();
+    crate::sys::backtrace::__rust_end_short_backtrace(move || {
+        panic_with_hook(
+            &mut Payload { inner: Some(msg) },
+            loc,
+            /* can_unwind */ true,
+            /* force_no_backtrace */ false,
+        )
+    })
+}
+
+fn payload_as_str(payload: &dyn Any) -> &str {
+    if let Some(&s) = payload.downcast_ref::<&'static str>() {
+        s
+    } else if let Some(s) = payload.downcast_ref::<String>() {
+        s.as_str()
+    } else {
+        "Box<dyn Any>"
+    }
+}
+
+/// Central point for dispatching panics.
+///
+/// Executes the primary logic for a panic, including checking for recursive
+/// panics, panic hooks, and finally dispatching to the panic runtime to either
+/// abort or unwind.
+#[optimize(size)]
+fn panic_with_hook(
+    payload: &mut dyn PanicPayload,
+    location: &Location<'_>,
+    can_unwind: bool,
+    force_no_backtrace: bool,
+) -> ! {
+    let must_abort = panic_count::increase(true);
+
+    // Check if we need to abort immediately.
+    if let Some(must_abort) = must_abort {
+        match must_abort {
+            panic_count::MustAbort::PanicInHook => {
+                // Don't try to format the message in this case, perhaps that is causing the
+                // recursive panics. However if the message is just a string, no user-defined
+                // code is involved in printing it, so that is risk-free.
+                let message: &str = payload.as_str().unwrap_or_default();
+                rtprintpanic!(
+                    "panicked at {location}:\n{message}\nthread panicked while processing panic. aborting.\n"
+                );
+            }
+            panic_count::MustAbort::AlwaysAbort => {
+                // Unfortunately, this does not print a backtrace, because creating
+                // a `Backtrace` will allocate, which we must avoid here.
+                rtprintpanic!("aborting due to panic at {location}:\n{payload}\n");
+            }
+        }
+        crate::process::abort();
+    }
+
+    match *HOOK.read() {
+        // Some platforms (like wasm) know that printing to stderr won't ever actually
+        // print anything, and if that's the case we can skip the default
+        // hook. Since string formatting happens lazily when calling `payload`
+        // methods, this means we avoid formatting the string at all!
+        // (The panic runtime might still call `payload.take_box()` though and trigger
+        // formatting.)
+        Hook::Default if panic_output().is_none() => {}
+        Hook::Default => {
+            default_hook(&PanicHookInfo::new(
+                location,
+                payload.get(),
+                can_unwind,
+                force_no_backtrace,
+            ));
+        }
+        Hook::Custom(ref hook) => {
+            hook(&PanicHookInfo::new(location, payload.get(), can_unwind, force_no_backtrace));
+        }
+    }
+
+    // Indicate that we have finished executing the panic hook. After this point
+    // it is fine if there is a panic while executing destructors, as long as it
+    // it contained within a `catch_unwind`.
+    panic_count::finished_panic_hook();
+
+    if !can_unwind {
+        // If a thread panics while running destructors or tries to unwind
+        // through a nounwind function (e.g. extern "C") then we cannot continue
+        // unwinding and have to abort immediately.
+        rtprintpanic!("thread caused non-unwinding panic. aborting.\n");
+        crate::process::abort();
+    }
+
+    rust_panic(payload)
+}
+
+/// This is the entry point for `resume_unwind`.
+/// It just forwards the payload to the panic runtime.
+#[cfg_attr(panic = "immediate-abort", inline)]
+pub fn resume_unwind(payload: Box<dyn Any + Send>) -> ! {
+    panic_count::increase(false);
+
+    struct RewrapBox(Box<dyn Any + Send>);
+
+    unsafe impl PanicPayload for RewrapBox {
+        fn take_box(&mut self) -> *mut (dyn Any + Send) {
+            Box::into_raw(mem::replace(&mut self.0, Box::new(())))
+        }
+
+        fn get(&mut self) -> &(dyn Any + Send) {
+            &*self.0
+        }
+    }
+
+    impl fmt::Display for RewrapBox {
+        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+            f.write_str(payload_as_str(&self.0))
+        }
+    }
+
+    rust_panic(&mut RewrapBox(payload))
+}
+
+/// A function with a fixed suffix (through `rustc_std_internal_symbol`)
+/// on which to slap yer breakpoints.
+#[inline(never)]
+#[cfg_attr(not(test), rustc_std_internal_symbol)]
+#[cfg(not(panic = "immediate-abort"))]
+fn rust_panic(msg: &mut dyn PanicPayload) -> ! {
+    let code = unsafe { __rust_start_panic(msg) };
+    rtabort!("failed to initiate panic, error {code}")
+}
+
+#[cfg_attr(not(test), rustc_std_internal_symbol)]
+#[cfg(panic = "immediate-abort")]
+fn rust_panic(_: &mut dyn PanicPayload) -> ! {
+    crate::intrinsics::abort();
+}

crates/std/src/prelude.rs

@@ -150,11 +150,11 @@ pub mod rust_2024 {
         }
     }
 
-    #[panic_handler]
+    // #[panic_handler]
-    fn panic(_panic_info: &core::panic::PanicInfo) -> ! {
+    // fn panic(_panic_info: &core::panic::PanicInfo) -> ! {
-        // TODO print
+    //     // TODO print
-        loop {}
+    //     loop {}
-    }
+    // }
 
     /// # Safety
     /// `argc` and `argv` are passed by the kernel

crates/std/src/process.rs

@@ -27,3 +27,7 @@ impl Termination for isize {
         ExitCode(self)
     }
 }
+
+pub fn abort() -> ! {
+    loop {}
+}

crates/std/src/rt.rs

@@ -1,5 +1,7 @@
 macro_rules! rtabort {
-    ($($t:tt)*) => {{}};
+    ($($t:tt)*) => {{
+        loop {}
+    }};
 }
 macro_rules! rtprintpanic {
     ($($t:tt)*) => {{}};

crates/std/src/sync.rs

@@ -16,10 +16,70 @@ pub use once::OnceState;
 
 pub use poison::LockResult;
 pub use poison::Mutex;
+pub use poison::MutexGuard;
 pub use poison::PoisonError;
 pub use poison::TryLockError;
 pub use poison::TryLockResult;
+pub use poison::Condvar;
+pub use poison::RwLock;
+pub use once_lock::OnceLock;
+pub use reentrant_lock::ReentrantLock;
+pub use reentrant_lock::ReentrantLockGuard;
+pub use alloc_crate::sync::Arc;
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[stable(feature = "wait_timeout", since = "1.5.0")]
 pub struct WaitTimeoutResult(bool);
+
+impl WaitTimeoutResult {
+    /// Returns `true` if the wait was known to have timed out.
+    ///
+    /// # Examples
+    ///
+    /// This example spawns a thread which will sleep 20 milliseconds before
+    /// updating a boolean value and then notifying the condvar.
+    ///
+    /// The main thread will wait with a 10 millisecond timeout on the condvar
+    /// and will leave the loop upon timeout.
+    ///
+    /// ```
+    /// use std::sync::{Arc, Condvar, Mutex};
+    /// use std::thread;
+    /// use std::time::Duration;
+    ///
+    /// let pair = Arc::new((Mutex::new(false), Condvar::new()));
+    /// let pair2 = Arc::clone(&pair);
+    ///
+    /// # let handle =
+    /// thread::spawn(move || {
+    ///     let (lock, cvar) = &*pair2;
+    ///
+    ///     // Let's wait 20 milliseconds before notifying the condvar.
+    ///     thread::sleep(Duration::from_millis(20));
+    ///
+    ///     let mut started = lock.lock().unwrap();
+    ///     // We update the boolean value.
+    ///     *started = true;
+    ///     cvar.notify_one();
+    /// });
+    ///
+    /// // Wait for the thread to start up.
+    /// let (lock, cvar) = &*pair;
+    /// loop {
+    ///     // Let's put a timeout on the condvar's wait.
+    ///     let result = cvar.wait_timeout(lock.lock().unwrap(), Duration::from_millis(10)).unwrap();
+    ///     // 10 milliseconds have passed.
+    ///     if result.1.timed_out() {
+    ///         // timed out now and we can leave.
+    ///         break
+    ///     }
+    /// }
+    /// # // Prevent leaks for Miri.
+    /// # let _ = handle.join();
+    /// ```
+    #[must_use]
+    #[stable(feature = "wait_timeout", since = "1.5.0")]
+    pub fn timed_out(&self) -> bool {
+        self.0
+    }
+}

crates/std/src/sync/barrier.rs

@@ -1,5 +1,5 @@
 use crate::fmt;
-use core::panic::RefUnwindSafe;
+use crate::panic::RefUnwindSafe;
 use crate::sync::nonpoison::{Condvar, Mutex};
 
 /// A barrier enables multiple threads to synchronize the beginning

crates/std/src/sync/lazy_lock.rs

@@ -2,7 +2,7 @@ use super::once::OnceExclusiveState;
 use crate::cell::UnsafeCell;
 use crate::mem::ManuallyDrop;
 use crate::ops::{Deref, DerefMut};
-use core::panic::{RefUnwindSafe, UnwindSafe};
+use crate::panic::{RefUnwindSafe, UnwindSafe};
 use crate::sync::Once;
 use crate::{fmt, ptr};
 

crates/std/src/sync/mpmc/mod.rs

@@ -150,7 +150,7 @@ mod zero;
 pub use error::*;
 
 use crate::fmt;
-use core::panic::{RefUnwindSafe, UnwindSafe};
+use crate::panic::{RefUnwindSafe, UnwindSafe};
 use crate::time::{Duration, Instant};
 
 /// Creates a new asynchronous channel, returning the sender/receiver halves.

crates/std/src/sync/once.rs

@@ -4,7 +4,7 @@
 //! example use case would be for initializing an FFI library.
 
 use crate::fmt;
-use core::panic::{RefUnwindSafe, UnwindSafe};
+use crate::panic::{RefUnwindSafe, UnwindSafe};
 use crate::sys::sync as sys;
 
 /// A low-level synchronization primitive for one-time global execution.

crates/std/src/sync/once_lock.rs

@@ -3,7 +3,7 @@ use crate::cell::UnsafeCell;
 use crate::fmt;
 use crate::marker::PhantomData;
 use crate::mem::MaybeUninit;
-use core::panic::{RefUnwindSafe, UnwindSafe};
+use crate::panic::{RefUnwindSafe, UnwindSafe};
 use crate::sync::Once;
 
 /// A synchronization primitive which can nominally be written to only once.

crates/std/src/sync/poison/mutex.rs

@@ -88,8 +88,8 @@ use crate::sys::sync as sys;
 /// [`unwrap()`]: Result::unwrap
 /// [`PoisonError`]: super::PoisonError
 /// [`into_inner`]: super::PoisonError::into_inner
-/// [panic hook]: core::panic::set_hook
+/// [panic hook]: crate::panic::set_hook
-/// [`catch_unwind`]: core::panic::catch_unwind
+/// [`catch_unwind`]: crate::panic::catch_unwind
 /// [`Cell`]: crate::cell::Cell
 ///
 /// # Examples

crates/std/src/sync/reentrant_lock.rs

@@ -1,7 +1,7 @@
 use crate::cell::UnsafeCell;
 use crate::fmt;
 use crate::ops::Deref;
-use core::panic::{RefUnwindSafe, UnwindSafe};
+use crate::panic::{RefUnwindSafe, UnwindSafe};
 use crate::sys::sync as sys;
 use crate::thread::{ThreadId, current_id};
 

crates/std/src/sys/backtrace.rs

@@ -0,0 +1,242 @@
+//! Common code for printing backtraces.
+#![forbid(unsafe_op_in_unsafe_fn)]
+
+// use crate::backtrace_rs::{self, BacktraceFmt, BytesOrWideString, PrintFmt};
+use crate::borrow::Cow;
+use crate::io::prelude::*;
+use crate::path::{self, Path, PathBuf};
+use crate::sync::{Mutex, MutexGuard, PoisonError};
+use crate::{env, fmt, io};
+
+/// Max number of frames to print.
+const MAX_NB_FRAMES: usize = 100;
+
+pub(crate) const FULL_BACKTRACE_DEFAULT: bool = cfg_select! {
+    // Fuchsia components default to full backtrace.
+    target_os = "fuchsia" => true,
+    _ => false,
+};
+
+pub(crate) struct BacktraceLock<'a>(#[allow(dead_code)] MutexGuard<'a, ()>);
+
+pub(crate) fn lock<'a>() -> BacktraceLock<'a> {
+    static LOCK: Mutex<()> = Mutex::new(());
+    BacktraceLock(LOCK.lock().unwrap_or_else(PoisonError::into_inner))
+}
+
+// impl BacktraceLock<'_> {
+//     /// Prints the current backtrace.
+//     pub(crate) fn print(&mut self, w: &mut dyn Write, format: PrintFmt) -> io::Result<()> {
+//         // There are issues currently linking libbacktrace into tests, and in
+//         // general during std's own unit tests we're not testing this path. In
+//         // test mode immediately return here to optimize away any references to the
+//         // libbacktrace symbols
+//         if cfg!(test) {
+//             return Ok(());
+//         }
+
+//         struct DisplayBacktrace {
+//             format: PrintFmt,
+//         }
+//         impl fmt::Display for DisplayBacktrace {
+//             fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+//                 // SAFETY: the backtrace lock is held
+//                 unsafe { _print_fmt(fmt, self.format) }
+//             }
+//         }
+//         write!(w, "{}", DisplayBacktrace { format })
+//     }
+// }
+
+// /// # Safety
+// ///
+// /// This function is not Sync. The caller must hold a mutex lock, or there must be only one thread in the program.
+// unsafe fn _print_fmt(fmt: &mut fmt::Formatter<'_>, print_fmt: PrintFmt) -> fmt::Result {
+//     // Always 'fail' to get the cwd when running under Miri -
+//     // this allows Miri to display backtraces in isolation mode
+//     let cwd = if !cfg!(miri) {
+//         env::current_dir().ok()
+//     } else {
+//         None
+//     };
+
+//     let mut print_path = move |fmt: &mut fmt::Formatter<'_>, bows: BytesOrWideString<'_>| {
+//         output_filename(fmt, bows, print_fmt, cwd.as_ref())
+//     };
+//     writeln!(fmt, "stack backtrace:")?;
+//     let mut bt_fmt = BacktraceFmt::new(fmt, print_fmt, &mut print_path);
+//     bt_fmt.add_context()?;
+//     let mut idx = 0;
+//     let mut res = Ok(());
+//     let mut omitted_count: usize = 0;
+//     let mut first_omit = true;
+//     // If we're using a short backtrace, ignore all frames until we're told to start printing.
+//     let mut print = print_fmt != PrintFmt::Short;
+//     set_image_base();
+//     // SAFETY: we roll our own locking in this town
+//     unsafe {
+//         backtrace_rs::trace_unsynchronized(|frame| {
+//             if print_fmt == PrintFmt::Short && idx > MAX_NB_FRAMES {
+//                 return false;
+//             }
+
+//             if cfg!(feature = "backtrace-trace-only") {
+//                 const HEX_WIDTH: usize = 2 + 2 * size_of::<usize>();
+//                 let frame_ip = frame.ip();
+//                 res = writeln!(bt_fmt.formatter(), "{idx:4}: {frame_ip:HEX_WIDTH$?}");
+//             } else {
+//                 let mut hit = false;
+//                 backtrace_rs::resolve_frame_unsynchronized(frame, |symbol| {
+//                     hit = true;
+
+//                     // `__rust_end_short_backtrace` means we are done hiding symbols
+//                     // for now. Print until we see `__rust_begin_short_backtrace`.
+//                     if print_fmt == PrintFmt::Short {
+//                         if let Some(sym) = symbol.name().and_then(|s| s.as_str()) {
+//                             if sym.contains("__rust_end_short_backtrace") {
+//                                 print = true;
+//                                 return;
+//                             }
+//                             if print && sym.contains("__rust_begin_short_backtrace") {
+//                                 print = false;
+//                                 return;
+//                             }
+//                             if !print {
+//                                 omitted_count += 1;
+//                             }
+//                         }
+//                     }
+
+//                     if print {
+//                         if omitted_count > 0 {
+//                             debug_assert!(print_fmt == PrintFmt::Short);
+//                             // only print the message between the middle of frames
+//                             if !first_omit {
+//                                 let _ = writeln!(
+//                                     bt_fmt.formatter(),
+//                                     "      [... omitted {} frame{} ...]",
+//                                     omitted_count,
+//                                     if omitted_count > 1 { "s" } else { "" }
+//                                 );
+//                             }
+//                             first_omit = false;
+//                             omitted_count = 0;
+//                         }
+//                         res = bt_fmt.frame().symbol(frame, symbol);
+//                     }
+//                 });
+//                 #[cfg(all(target_os = "nto", any(target_env = "nto70", target_env = "nto71")))]
+//                 if libc::__my_thread_exit as *mut libc::c_void == frame.ip() {
+//                     if !hit && print {
+//                         use crate::backtrace_rs::SymbolName;
+//                         res = bt_fmt.frame().print_raw(
+//                             frame.ip(),
+//                             Some(SymbolName::new("__my_thread_exit".as_bytes())),
+//                             None,
+//                             None,
+//                         );
+//                     }
+//                     return false;
+//                 }
+//                 if !hit && print {
+//                     res = bt_fmt.frame().print_raw(frame.ip(), None, None, None);
+//                 }
+//             }
+
+//             idx += 1;
+//             res.is_ok()
+//         })
+//     };
+//     res?;
+//     bt_fmt.finish()?;
+//     if print_fmt == PrintFmt::Short {
+//         writeln!(
+//             fmt,
+//             "note: Some details are omitted, \
+//              run with `RUST_BACKTRACE=full` for a verbose backtrace."
+//         )?;
+//     }
+//     Ok(())
+// }
+
+/// Fixed frame used to clean the backtrace with `RUST_BACKTRACE=1`. Note that
+/// this is only inline(never) when backtraces in std are enabled, otherwise
+/// it's fine to optimize away.
+#[cfg_attr(feature = "backtrace", inline(never))]
+pub fn __rust_begin_short_backtrace<F, T>(f: F) -> T
+where
+    F: FnOnce() -> T,
+{
+    let result = f();
+
+    // prevent this frame from being tail-call optimised away
+    crate::hint::black_box(());
+
+    result
+}
+
+/// Fixed frame used to clean the backtrace with `RUST_BACKTRACE=1`. Note that
+/// this is only inline(never) when backtraces in std are enabled, otherwise
+/// it's fine to optimize away.
+#[cfg_attr(feature = "backtrace", inline(never))]
+pub fn __rust_end_short_backtrace<F, T>(f: F) -> T
+where
+    F: FnOnce() -> T,
+{
+    let result = f();
+
+    // prevent this frame from being tail-call optimised away
+    crate::hint::black_box(());
+
+    result
+}
+
+// /// Prints the filename of the backtrace frame.
+// ///
+// /// See also `output`.
+// pub fn output_filename(
+//     fmt: &mut fmt::Formatter<'_>,
+//     bows: BytesOrWideString<'_>,
+//     print_fmt: PrintFmt,
+//     cwd: Option<&PathBuf>,
+// ) -> fmt::Result {
+//     let file: Cow<'_, Path> = match bows {
+//         #[cfg(unix)]
+//         BytesOrWideString::Bytes(bytes) => {
+//             use crate::os::unix::prelude::*;
+//             Path::new(crate::ffi::OsStr::from_bytes(bytes)).into()
+//         }
+//         #[cfg(not(unix))]
+//         BytesOrWideString::Bytes(bytes) => {
+//             Path::new(crate::str::from_utf8(bytes).unwrap_or("<unknown>")).into()
+//         }
+//         #[cfg(windows)]
+//         BytesOrWideString::Wide(wide) => {
+//             use crate::os::windows::prelude::*;
+//             Cow::Owned(crate::ffi::OsString::from_wide(wide).into())
+//         }
+//         #[cfg(not(windows))]
+//         BytesOrWideString::Wide(_wide) => Path::new("<unknown>").into(),
+//     };
+//     if print_fmt == PrintFmt::Short && file.is_absolute() {
+//         if let Some(cwd) = cwd {
+//             if let Ok(stripped) = file.strip_prefix(&cwd) {
+//                 if let Some(s) = stripped.to_str() {
+//                     return write!(fmt, ".{}{s}", path::MAIN_SEPARATOR);
+//                 }
+//             }
+//         }
+//     }
+//     fmt::Display::fmt(&file.display(), fmt)
+// }
+
+#[cfg(all(target_vendor = "fortanix", target_env = "sgx"))]
+pub fn set_image_base() {
+    let image_base = crate::os::fortanix_sgx::mem::image_base();
+    backtrace_rs::set_image_base(crate::ptr::without_provenance_mut(image_base as _));
+}
+
+#[cfg(not(all(target_vendor = "fortanix", target_env = "sgx")))]
+pub fn set_image_base() {
+    // nothing to do for platforms other than SGX
+}

crates/std/src/sys/mod.rs

@@ -14,6 +14,7 @@ pub mod alloc;
 pub mod io;
 pub mod pipe;
 pub mod stdio;
+pub mod backtrace;
 // pub mod fs;
 
 /// A trait for viewing representations from std types.

crates/std/src/sys/sync/mod.rs

@@ -2,8 +2,10 @@ mod condvar;
 mod mutex;
 mod once;
 mod rwlock;
+mod thread_parking;
 
 pub use condvar::Condvar;
 pub use mutex::Mutex;
 pub use once::{Once, OnceState};
 pub use rwlock::RwLock;
+pub use thread_parking::Parker;

crates/std/src/sys/sync/thread_parking/mod.rs

@@ -0,0 +1,49 @@
+cfg_select! {
+    any(
+        all(target_os = "windows", not(target_vendor = "win7")),
+        target_os = "linux",
+        target_os = "android",
+        all(target_arch = "wasm32", target_feature = "atomics"),
+        target_os = "freebsd",
+        target_os = "openbsd",
+        target_os = "dragonfly",
+        target_os = "fuchsia",
+        target_os = "motor",
+        target_os = "hermit",
+    ) => {
+        mod futex;
+        pub use futex::Parker;
+    }
+    any(
+        target_os = "netbsd",
+        all(target_vendor = "fortanix", target_env = "sgx"),
+        target_os = "solid_asp3",
+    ) => {
+        mod id;
+        pub use id::Parker;
+    }
+    target_vendor = "win7" => {
+        mod windows7;
+        pub use windows7::Parker;
+    }
+    all(target_vendor = "apple", not(miri)) => {
+        // Doesn't work in Miri, see <https://github.com/rust-lang/miri/issues/2589>.
+        mod darwin;
+        pub use darwin::Parker;
+    }
+    target_os = "xous" => {
+        mod xous;
+        pub use xous::Parker;
+    }
+    any(
+        target_family = "unix",
+        target_os = "teeos",
+    ) => {
+        mod pthread;
+        pub use pthread::Parker;
+    }
+    _ => {
+        mod unsupported;
+        pub use unsupported::Parker;
+    }
+}

crates/std/src/sys/sync/thread_parking/unsupported.rs

@@ -0,0 +1,11 @@
+use crate::pin::Pin;
+use crate::time::Duration;
+
+pub struct Parker {}
+
+impl Parker {
+    pub unsafe fn new_in_place(_parker: *mut Parker) {}
+    pub unsafe fn park(self: Pin<&Self>) {}
+    pub unsafe fn park_timeout(self: Pin<&Self>, _dur: Duration) {}
+    pub fn unpark(self: Pin<&Self>) {}
+}

crates/std/src/sys/thread_local/os.rs

@@ -5,7 +5,7 @@ use crate::cell::Cell;
 use crate::marker::PhantomData;
 use crate::mem::ManuallyDrop;
 use crate::ops::Deref;
-use core::panic::{AssertUnwindSafe, catch_unwind, resume_unwind};
+use crate::panic::{AssertUnwindSafe, catch_unwind, resume_unwind};
 use crate::ptr::{self, NonNull};
 
 #[doc(hidden)]

crates/std/src/thread.rs

@@ -6,18 +6,23 @@ pub mod join_handle;
 pub mod lifecycle;
 pub mod local;
 pub mod main_thread;
+pub mod scoped;
+pub mod spawnhook;
 pub mod thread;
 
 use core::any::Any;
 
 pub use crate::sys::thread::yield_now;
-pub(crate) use current::current_or_unnamed;
 pub use current::current_id;
+pub(crate) use current::current_or_unnamed;
+pub(crate) use current::current_os_id;
+pub(crate) use current::with_current_name;
 pub use functions::sleep;
 pub use id::ThreadId;
+pub(crate) use lifecycle::ThreadInit;
 pub use local::LocalKey;
 pub use thread::Thread;
-pub(crate) use lifecycle::ThreadInit;
+pub use local::AccessError;
 
 // Implementation details used by the thread_local!{} macro.
 #[doc(hidden)]
@@ -30,3 +35,7 @@ pub mod local_impl {
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(search_unbox)]
 pub type Result<T> = crate::result::Result<T, Box<dyn Any + Send + 'static>>;
+
+pub fn panicking() -> ! {
+    todo!()
+}

crates/std/src/thread/functions.rs

@@ -7,7 +7,7 @@ use crate::mem::forget;
 use crate::num::NonZero;
 use crate::sys::thread as imp;
 use crate::time::{Duration, Instant};
-use crate::io;use core::panicking;
+use crate::{io, panicking};
 
 /// Spawns a new thread, returning a [`JoinHandle`] for it.
 ///

crates/std/src/thread/lifecycle.rs

@@ -11,7 +11,7 @@ use crate::mem::{ManuallyDrop, MaybeUninit};
 use alloc_crate::sync::Arc;
 use crate::sync::atomic::{Atomic, AtomicUsize, Ordering};
 use crate::sys::{AsInner, IntoInner, thread as imp};
-use crate::{env, io};use core::panic;
+use crate::{env, io, panic};
 
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 pub(super) unsafe fn spawn_unchecked<'scope, F, T>(

crates/std/src/thread/scoped.rs

@@ -0,0 +1,358 @@
+use super::Result;
+use super::builder::Builder;
+use super::current::current_or_unnamed;
+use super::lifecycle::{JoinInner, spawn_unchecked};
+use super::thread::Thread;
+use crate::marker::PhantomData;
+use crate::panic::{AssertUnwindSafe, catch_unwind, resume_unwind};
+use alloc_crate::sync::Arc;
+use crate::sync::atomic::{Atomic, AtomicBool, AtomicUsize, Ordering};
+use crate::{fmt, io};
+
+/// A scope to spawn scoped threads in.
+///
+/// See [`scope`] for details.
+#[stable(feature = "scoped_threads", since = "1.63.0")]
+pub struct Scope<'scope, 'env: 'scope> {
+    data: Arc<ScopeData>,
+    /// Invariance over 'scope, to make sure 'scope cannot shrink,
+    /// which is necessary for soundness.
+    ///
+    /// Without invariance, this would compile fine but be unsound:
+    ///
+    /// ```compile_fail,E0373
+    /// std::thread::scope(|s| {
+    ///     s.spawn(|| {
+    ///         let a = String::from("abcd");
+    ///         s.spawn(|| println!("{a:?}")); // might run after `a` is dropped
+    ///     });
+    /// });
+    /// ```
+    scope: PhantomData<&'scope mut &'scope ()>,
+    env: PhantomData<&'env mut &'env ()>,
+}
+
+/// An owned permission to join on a scoped thread (block on its termination).
+///
+/// See [`Scope::spawn`] for details.
+#[stable(feature = "scoped_threads", since = "1.63.0")]
+pub struct ScopedJoinHandle<'scope, T>(JoinInner<'scope, T>);
+
+pub(super) struct ScopeData {
+    num_running_threads: Atomic<usize>,
+    a_thread_panicked: Atomic<bool>,
+    main_thread: Thread,
+}
+
+impl ScopeData {
+    pub(super) fn increment_num_running_threads(&self) {
+        // We check for 'overflow' with usize::MAX / 2, to make sure there's no
+        // chance it overflows to 0, which would result in unsoundness.
+        if self.num_running_threads.fetch_add(1, Ordering::Relaxed) > usize::MAX / 2 {
+            // This can only reasonably happen by mem::forget()'ing a lot of ScopedJoinHandles.
+            self.overflow();
+        }
+    }
+
+    #[cold]
+    fn overflow(&self) {
+        self.decrement_num_running_threads(false);
+        panic!("too many running threads in thread scope");
+    }
+
+    pub(super) fn decrement_num_running_threads(&self, panic: bool) {
+        if panic {
+            self.a_thread_panicked.store(true, Ordering::Relaxed);
+        }
+        if self.num_running_threads.fetch_sub(1, Ordering::Release) == 1 {
+            self.main_thread.unpark();
+        }
+    }
+}
+
+/// Creates a scope for spawning scoped threads.
+///
+/// The function passed to `scope` will be provided a [`Scope`] object,
+/// through which scoped threads can be [spawned][`Scope::spawn`].
+///
+/// Unlike non-scoped threads, scoped threads can borrow non-`'static` data,
+/// as the scope guarantees all threads will be joined at the end of the scope.
+///
+/// All threads spawned within the scope that haven't been manually joined
+/// will be automatically joined before this function returns.
+/// However, note that joining will only wait for the main function of these threads to finish; even
+/// when this function returns, destructors of thread-local variables in these threads might still
+/// be running.
+///
+/// # Panics
+///
+/// If any of the automatically joined threads panicked, this function will panic.
+///
+/// If you want to handle panics from spawned threads,
+/// [`join`][ScopedJoinHandle::join] them before the end of the scope.
+///
+/// # Example
+///
+/// ```
+/// use std::thread;
+///
+/// let mut a = vec![1, 2, 3];
+/// let mut x = 0;
+///
+/// thread::scope(|s| {
+///     s.spawn(|| {
+///         println!("hello from the first scoped thread");
+///         // We can borrow `a` here.
+///         dbg!(&a);
+///     });
+///     s.spawn(|| {
+///         println!("hello from the second scoped thread");
+///         // We can even mutably borrow `x` here,
+///         // because no other threads are using it.
+///         x += a[0] + a[2];
+///     });
+///     println!("hello from the main thread");
+/// });
+///
+/// // After the scope, we can modify and access our variables again:
+/// a.push(4);
+/// assert_eq!(x, a.len());
+/// ```
+///
+/// # Lifetimes
+///
+/// Scoped threads involve two lifetimes: `'scope` and `'env`.
+///
+/// The `'scope` lifetime represents the lifetime of the scope itself.
+/// That is: the time during which new scoped threads may be spawned,
+/// and also the time during which they might still be running.
+/// Once this lifetime ends, all scoped threads are joined.
+/// This lifetime starts within the `scope` function, before `f` (the argument to `scope`) starts.
+/// It ends after `f` returns and all scoped threads have been joined, but before `scope` returns.
+///
+/// The `'env` lifetime represents the lifetime of whatever is borrowed by the scoped threads.
+/// This lifetime must outlast the call to `scope`, and thus cannot be smaller than `'scope`.
+/// It can be as small as the call to `scope`, meaning that anything that outlives this call,
+/// such as local variables defined right before the scope, can be borrowed by the scoped threads.
+///
+/// The `'env: 'scope` bound is part of the definition of the `Scope` type.
+#[track_caller]
+#[stable(feature = "scoped_threads", since = "1.63.0")]
+pub fn scope<'env, F, T>(f: F) -> T
+where
+    F: for<'scope> FnOnce(&'scope Scope<'scope, 'env>) -> T,
+{
+    // We put the `ScopeData` into an `Arc` so that other threads can finish their
+    // `decrement_num_running_threads` even after this function returns.
+    let scope = Scope {
+        data: Arc::new(ScopeData {
+            num_running_threads: AtomicUsize::new(0),
+            main_thread: current_or_unnamed(),
+            a_thread_panicked: AtomicBool::new(false),
+        }),
+        env: PhantomData,
+        scope: PhantomData,
+    };
+
+    // Run `f`, but catch panics so we can make sure to wait for all the threads to join.
+    let result = catch_unwind(AssertUnwindSafe(|| f(&scope)));
+
+    // Wait until all the threads are finished.
+    while scope.data.num_running_threads.load(Ordering::Acquire) != 0 {
+        // SAFETY: this is the main thread, the handle belongs to us.
+        unsafe { scope.data.main_thread.park() };
+    }
+
+    // Throw any panic from `f`, or the return value of `f` if no thread panicked.
+    match result {
+        Err(e) => resume_unwind(e),
+        Ok(_) if scope.data.a_thread_panicked.load(Ordering::Relaxed) => {
+            panic!("a scoped thread panicked")
+        }
+        Ok(result) => result,
+    }
+}
+
+impl<'scope, 'env> Scope<'scope, 'env> {
+    /// Spawns a new thread within a scope, returning a [`ScopedJoinHandle`] for it.
+    ///
+    /// Unlike non-scoped threads, threads spawned with this function may
+    /// borrow non-`'static` data from the outside the scope. See [`scope`] for
+    /// details.
+    ///
+    /// The join handle provides a [`join`] method that can be used to join the spawned
+    /// thread. If the spawned thread panics, [`join`] will return an [`Err`] containing
+    /// the panic payload.
+    ///
+    /// If the join handle is dropped, the spawned thread will be implicitly joined at the
+    /// end of the scope. In that case, if the spawned thread panics, [`scope`] will
+    /// panic after all threads are joined.
+    ///
+    /// This function creates a thread with the default parameters of [`Builder`].
+    /// To specify the new thread's stack size or the name, use [`Builder::spawn_scoped`].
+    ///
+    /// # Panics
+    ///
+    /// Panics if the OS fails to create a thread; use [`Builder::spawn_scoped`]
+    /// to recover from such errors.
+    ///
+    /// [`join`]: ScopedJoinHandle::join
+    #[stable(feature = "scoped_threads", since = "1.63.0")]
+    pub fn spawn<F, T>(&'scope self, f: F) -> ScopedJoinHandle<'scope, T>
+    where
+        F: FnOnce() -> T + Send + 'scope,
+        T: Send + 'scope,
+    {
+        Builder::new().spawn_scoped(self, f).expect("failed to spawn thread")
+    }
+}
+
+impl Builder {
+    /// Spawns a new scoped thread using the settings set through this `Builder`.
+    ///
+    /// Unlike [`Scope::spawn`], this method yields an [`io::Result`] to
+    /// capture any failure to create the thread at the OS level.
+    ///
+    /// # Panics
+    ///
+    /// Panics if a thread name was set and it contained null bytes.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use std::thread;
+    ///
+    /// let mut a = vec![1, 2, 3];
+    /// let mut x = 0;
+    ///
+    /// thread::scope(|s| {
+    ///     thread::Builder::new()
+    ///         .name("first".to_string())
+    ///         .spawn_scoped(s, ||
+    ///     {
+    ///         println!("hello from the {:?} scoped thread", thread::current().name());
+    ///         // We can borrow `a` here.
+    ///         dbg!(&a);
+    ///     })
+    ///     .unwrap();
+    ///     thread::Builder::new()
+    ///         .name("second".to_string())
+    ///         .spawn_scoped(s, ||
+    ///     {
+    ///         println!("hello from the {:?} scoped thread", thread::current().name());
+    ///         // We can even mutably borrow `x` here,
+    ///         // because no other threads are using it.
+    ///         x += a[0] + a[2];
+    ///     })
+    ///     .unwrap();
+    ///     println!("hello from the main thread");
+    /// });
+    ///
+    /// // After the scope, we can modify and access our variables again:
+    /// a.push(4);
+    /// assert_eq!(x, a.len());
+    /// ```
+    #[stable(feature = "scoped_threads", since = "1.63.0")]
+    pub fn spawn_scoped<'scope, 'env, F, T>(
+        self,
+        scope: &'scope Scope<'scope, 'env>,
+        f: F,
+    ) -> io::Result<ScopedJoinHandle<'scope, T>>
+    where
+        F: FnOnce() -> T + Send + 'scope,
+        T: Send + 'scope,
+    {
+        let Builder { name, stack_size, no_hooks } = self;
+        Ok(ScopedJoinHandle(unsafe {
+            spawn_unchecked(name, stack_size, no_hooks, Some(scope.data.clone()), f)
+        }?))
+    }
+}
+
+impl<'scope, T> ScopedJoinHandle<'scope, T> {
+    /// Extracts a handle to the underlying thread.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::thread;
+    ///
+    /// thread::scope(|s| {
+    ///     let t = s.spawn(|| {
+    ///         println!("hello");
+    ///     });
+    ///     println!("thread id: {:?}", t.thread().id());
+    /// });
+    /// ```
+    #[must_use]
+    #[stable(feature = "scoped_threads", since = "1.63.0")]
+    pub fn thread(&self) -> &Thread {
+        self.0.thread()
+    }
+
+    /// Waits for the associated thread to finish.
+    ///
+    /// This function will return immediately if the associated thread has already finished.
+    /// Otherwise, it fully waits for the thread to finish, including all destructors
+    /// for thread-local variables that might be running after the main function of the thread.
+    ///
+    /// In terms of [atomic memory orderings], the completion of the associated
+    /// thread synchronizes with this function returning.
+    /// In other words, all operations performed by that thread
+    /// [happen before](https://doc.rust-lang.org/nomicon/atomics.html#data-accesses)
+    /// all operations that happen after `join` returns.
+    ///
+    /// If the associated thread panics, [`Err`] is returned with the panic payload.
+    ///
+    /// [atomic memory orderings]: crate::sync::atomic
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::thread;
+    ///
+    /// thread::scope(|s| {
+    ///     let t = s.spawn(|| {
+    ///         panic!("oh no");
+    ///     });
+    ///     assert!(t.join().is_err());
+    /// });
+    /// ```
+    #[stable(feature = "scoped_threads", since = "1.63.0")]
+    pub fn join(self) -> Result<T> {
+        self.0.join()
+    }
+
+    /// Checks if the associated thread has finished running its main function.
+    ///
+    /// `is_finished` supports implementing a non-blocking join operation, by checking
+    /// `is_finished`, and calling `join` if it returns `true`. This function does not block. To
+    /// block while waiting on the thread to finish, use [`join`][Self::join].
+    ///
+    /// This might return `true` for a brief moment after the thread's main
+    /// function has returned, but before the thread itself has stopped running.
+    /// However, once this returns `true`, [`join`][Self::join] can be expected
+    /// to return quickly, without blocking for any significant amount of time.
+    #[stable(feature = "scoped_threads", since = "1.63.0")]
+    pub fn is_finished(&self) -> bool {
+        self.0.is_finished()
+    }
+}
+
+#[stable(feature = "scoped_threads", since = "1.63.0")]
+impl fmt::Debug for Scope<'_, '_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Scope")
+            .field("num_running_threads", &self.data.num_running_threads.load(Ordering::Relaxed))
+            .field("a_thread_panicked", &self.data.a_thread_panicked.load(Ordering::Relaxed))
+            .field("main_thread", &self.data.main_thread)
+            .finish_non_exhaustive()
+    }
+}
+
+#[stable(feature = "scoped_threads", since = "1.63.0")]
+impl<'scope, T> fmt::Debug for ScopedJoinHandle<'scope, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("ScopedJoinHandle").finish_non_exhaustive()
+    }
+}

crates/std/src/thread/spawnhook.rs

@@ -0,0 +1,153 @@
+use super::thread::Thread;
+use crate::cell::Cell;
+use crate::iter;
+use alloc_crate::sync::Arc;
+
+crate::thread_local! {
+    /// A thread local linked list of spawn hooks.
+    ///
+    /// It is a linked list of Arcs, such that it can very cheaply be inherited by spawned threads.
+    ///
+    /// (That technically makes it a set of linked lists with shared tails, so a linked tree.)
+    static SPAWN_HOOKS: Cell<SpawnHooks> = const { Cell::new(SpawnHooks { first: None }) };
+}
+
+#[derive(Default, Clone)]
+struct SpawnHooks {
+    first: Option<Arc<SpawnHook>>,
+}
+
+// Manually implement drop to prevent deep recursion when dropping linked Arc list.
+impl Drop for SpawnHooks {
+    fn drop(&mut self) {
+        let mut next = self.first.take();
+        while let Some(SpawnHook { hook, next: n }) = next.and_then(|n| Arc::into_inner(n)) {
+            drop(hook);
+            next = n;
+        }
+    }
+}
+
+struct SpawnHook {
+    hook: Box<dyn Send + Sync + Fn(&Thread) -> Box<dyn Send + FnOnce()>>,
+    next: Option<Arc<SpawnHook>>,
+}
+
+/// Registers a function to run for every newly thread spawned.
+///
+/// The hook is executed in the parent thread, and returns a function
+/// that will be executed in the new thread.
+///
+/// The hook is called with the `Thread` handle for the new thread.
+///
+/// The hook will only be added for the current thread and is inherited by the threads it spawns.
+/// In other words, adding a hook has no effect on already running threads (other than the current
+/// thread) and the threads they might spawn in the future.
+///
+/// Hooks can only be added, not removed.
+///
+/// The hooks will run in reverse order, starting with the most recently added.
+///
+/// # Usage
+///
+/// ```
+/// #![feature(thread_spawn_hook)]
+///
+/// std::thread::add_spawn_hook(|_| {
+///     ..; // This will run in the parent (spawning) thread.
+///     move || {
+///         ..; // This will run it the child (spawned) thread.
+///     }
+/// });
+/// ```
+///
+/// # Example
+///
+/// A spawn hook can be used to "inherit" a thread local from the parent thread:
+///
+/// ```
+/// #![feature(thread_spawn_hook)]
+///
+/// use std::cell::Cell;
+///
+/// thread_local! {
+///     static X: Cell<u32> = Cell::new(0);
+/// }
+///
+/// // This needs to be done once in the main thread before spawning any threads.
+/// std::thread::add_spawn_hook(|_| {
+///     // Get the value of X in the spawning thread.
+///     let value = X.get();
+///     // Set the value of X in the newly spawned thread.
+///     move || X.set(value)
+/// });
+///
+/// X.set(123);
+///
+/// std::thread::spawn(|| {
+///     assert_eq!(X.get(), 123);
+/// }).join().unwrap();
+/// ```
+#[unstable(feature = "thread_spawn_hook", issue = "132951")]
+pub fn add_spawn_hook<F, G>(hook: F)
+where
+    F: 'static + Send + Sync + Fn(&Thread) -> G,
+    G: 'static + Send + FnOnce(),
+{
+    SPAWN_HOOKS.with(|h| {
+        let mut hooks = h.take();
+        let next = hooks.first.take();
+        hooks.first = Some(Arc::new(SpawnHook {
+            hook: Box::new(move |thread| Box::new(hook(thread))),
+            next,
+        }));
+        h.set(hooks);
+    });
+}
+
+/// Runs all the spawn hooks.
+///
+/// Called on the parent thread.
+///
+/// Returns the functions to be called on the newly spawned thread.
+pub(super) fn run_spawn_hooks(thread: &Thread) -> ChildSpawnHooks {
+    // Get a snapshot of the spawn hooks.
+    // (Increments the refcount to the first node.)
+    if let Ok(hooks) = SPAWN_HOOKS.try_with(|hooks| {
+        let snapshot = hooks.take();
+        hooks.set(snapshot.clone());
+        snapshot
+    }) {
+        // Iterate over the hooks, run them, and collect the results in a vector.
+        let to_run: Vec<_> = iter::successors(hooks.first.as_deref(), |hook| hook.next.as_deref())
+            .map(|hook| (hook.hook)(thread))
+            .collect();
+        // Pass on the snapshot of the hooks and the results to the new thread,
+        // which will then run SpawnHookResults::run().
+        ChildSpawnHooks { hooks, to_run }
+    } else {
+        // TLS has been destroyed. Skip running the hooks.
+        // See https://github.com/rust-lang/rust/issues/138696
+        ChildSpawnHooks::default()
+    }
+}
+
+/// The results of running the spawn hooks.
+///
+/// This struct is sent to the new thread.
+/// It contains the inherited hooks and the closures to be run.
+#[derive(Default)]
+pub(super) struct ChildSpawnHooks {
+    hooks: SpawnHooks,
+    to_run: Vec<Box<dyn FnOnce() + Send>>,
+}
+
+impl ChildSpawnHooks {
+    // This is run on the newly spawned thread, directly at the start.
+    pub(super) fn run(self) {
+        SPAWN_HOOKS.set(self.hooks);
+        for run in self.to_run {
+            run();
+        }
+    }
+}

justfile

@@ -28,6 +28,12 @@ update_std:
     # @just cp_std "fs.rs"
     @just cp_std "time.rs"
     @just cp_std "bstr.rs"
+    @just cp_std "panicking.rs"
+    @just cp_std "panic.rs"
+    @just cp_std "collections/hash/map.rs"
+    @just cp_std "collections/hash/set.rs"
+    @just cp_std "collections/hash/mod.rs"
+    @just cp_std "collections/mod.rs"
     @just cp_std "io/error.rs"
     @just cp_std "io/error/repr_bitpacked.rs"
     @just cp_std "io/error/repr_unpacked.rs"
@@ -44,7 +50,7 @@ update_std:
     @just cp_std "io/copy/tests.rs"
     @just cp_std "io/pipe.rs"
     @just cp_std "io/pipe/tests.rs"
-    @just cp_std "io/stdio.rs"
+    # @just cp_std "io/stdio.rs"
     @just cp_std "io/buffered/mod.rs"
     @just cp_std "io/buffered/bufreader.rs"
     @just cp_std "io/buffered/bufreader/buffer.rs"
@@ -92,6 +98,8 @@ update_std:
     @just cp_std "thread/functions.rs"
     @just cp_std "thread/lifecycle.rs"
     @just cp_std "thread/builder.rs"
+    @just cp_std "thread/scoped.rs"
+    @just cp_std "thread/spawnhook.rs"
     @just cp_std "sys/exit.rs"
     @just cp_std "sys/env_consts.rs"
     @just cp_std "sys/configure_builtins.rs"
@@ -104,6 +112,8 @@ update_std:
     @just cp_std "sys/sync/once/no_threads.rs"
     @just cp_std "sys/sync/rwlock/mod.rs"
     @just cp_std "sys/sync/rwlock/no_threads.rs"
+    @just cp_std "sys/sync/thread_parking/mod.rs"
+    @just cp_std "sys/sync/thread_parking/unsupported.rs"
     @just cp_std "sys/thread/mod.rs"
     @just cp_std "sys/thread/unsupported.rs"
     @just cp_std "sys/thread_local/no_threads.rs"

patches.sed

@@ -5,9 +5,8 @@ s|alloc::slice::Join|alloc_crate::slice::Join|g
 s|alloc::bstr|alloc_crate::bstr|g
 s|alloc::collections::TryReserveError|alloc_crate::collections::TryReserveError|g
 s|crate::collections::VecDeque|alloc_crate::collections::VecDeque|g
-s|crate::panic|core::panic|g
+# s|collections::HashMap|hashbrown::HashMap|g
-s|use crate::{io, panicking};|use crate::io;use core::panicking;|g
+/crate::backtrace_rs/c \    todo!()
-s|use crate::{env, io, panic};|use crate::{env, io};use core::panic;|g
 # /target_os = "xous",/a \    target_os = "survos",
 
 # Ajouter d'autres modifications facilement ici :