Auto merge of #73265 - mark-i-m:mv-std, r=Mark-Simulacrum,mark-i-m

mv std libs to library/

This is the first step in refactoring the directory layout of this repository, with further followup steps planned (but not done yet).

Background: currently, all crates are under src/, without nested src directories and with the unconventional `lib*` prefixes (e.g., `src/libcore/lib.rs`). This directory structures is not idiomatic and makes the `src/` directory rather overwhelming. To improve contributor experience and make things a bit more approachable, we are reorganizing the repo a bit.

In this PR, we move the standard libs (basically anything that is "runtime", as opposed to part of the compiler, build system, or one of the tools, etc). The new layout moves these libraries to a new `library/` directory in the root of the repo. Additionally, we remove the `lib*` prefixes and add nested `src/` directories.  The other crates/tools in this repo are not touched. So in summary:

```
library/<crate>/src/*.rs
src/<all the rest>     // unchanged
```

where `<crate>` is:
- core
- alloc
- std
- test
- proc_macro
- panic_abort
- panic_unwind
- profiler_builtins
- term
- unwind
- rtstartup
- backtrace
- rustc-std-workspace-*

There was a lot of discussion about this and a few rounds of compiler team approvals, FCPs, MCPs, and nominations. The original MCP is https://github.com/rust-lang/compiler-team/issues/298. The final approval of the compiler team was given here: https://github.com/rust-lang/rust/pull/73265#issuecomment-659498446.

The name `library` was chosen to complement a later move of the compiler crates to a `compiler/` directory. There was a lot of discussion around adding the nested `src/` directories. Note that this does increase the nesting depth (plausibly important for manual traversal of the tree, e.g., through GitHub's UI or `cd`), but this is deemed to be better as it fits the standard layout of Rust crates throughout most of the ecosystem, though there is some debate about how much this should apply to multi-crate projects. Overall, there seem to be more people in favor of nested `src/` than against.

After this PR, there are no dependencies out of the `library/` directory except on the `build_helper` (or crates.io crates).

1 files changed, 0 insertions, 366 deletions

diff --git a/src/libcore/array/mod.rs b/src/libcore/array/mod.rs
deleted file mode 100644
index c0bf3833b9c..00000000000
--- a/src/libcore/array/mod.rs
+++ /dev/null
@@ -1,366 +0,0 @@
-//! Implementations of things like `Eq` for fixed-length arrays
-//! up to a certain length. Eventually, we should be able to generalize
-//! to all lengths.
-//!
-//! *[See also the array primitive type](../../std/primitive.array.html).*
-
-#![stable(feature = "core_array", since = "1.36.0")]
-
-use crate::borrow::{Borrow, BorrowMut};
-use crate::cmp::Ordering;
-use crate::convert::{Infallible, TryFrom};
-use crate::fmt;
-use crate::hash::{self, Hash};
-use crate::marker::Unsize;
-use crate::slice::{Iter, IterMut};
-
-mod iter;
-
-#[unstable(feature = "array_value_iter", issue = "65798")]
-pub use iter::IntoIter;
-
-/// Utility trait implemented only on arrays of fixed size
-///
-/// This trait can be used to implement other traits on fixed-size arrays
-/// without causing much metadata bloat.
-///
-/// The trait is marked unsafe in order to restrict implementors to fixed-size
-/// arrays. User of this trait can assume that implementors have the exact
-/// layout in memory of a fixed size array (for example, for unsafe
-/// initialization).
-///
-/// Note that the traits [`AsRef`] and [`AsMut`] provide similar methods for types that
-/// may not be fixed-size arrays. Implementors should prefer those traits
-/// instead.
-///
-/// [`AsRef`]: ../convert/trait.AsRef.html
-/// [`AsMut`]: ../convert/trait.AsMut.html
-#[unstable(feature = "fixed_size_array", issue = "27778")]
-pub unsafe trait FixedSizeArray<T> {
-    /// Converts the array to immutable slice
-    #[unstable(feature = "fixed_size_array", issue = "27778")]
-    fn as_slice(&self) -> &[T];
-    /// Converts the array to mutable slice
-    #[unstable(feature = "fixed_size_array", issue = "27778")]
-    fn as_mut_slice(&mut self) -> &mut [T];
-}
-
-#[unstable(feature = "fixed_size_array", issue = "27778")]
-unsafe impl<T, A: Unsize<[T]>> FixedSizeArray<T> for A {
-    #[inline]
-    fn as_slice(&self) -> &[T] {
-        self
-    }
-    #[inline]
-    fn as_mut_slice(&mut self) -> &mut [T] {
-        self
-    }
-}
-
-/// The error type returned when a conversion from a slice to an array fails.
-#[stable(feature = "try_from", since = "1.34.0")]
-#[derive(Debug, Copy, Clone)]
-pub struct TryFromSliceError(());
-
-#[stable(feature = "core_array", since = "1.36.0")]
-impl fmt::Display for TryFromSliceError {
-    #[inline]
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(self.__description(), f)
-    }
-}
-
-impl TryFromSliceError {
-    #[unstable(
-        feature = "array_error_internals",
-        reason = "available through Error trait and this method should not \
-                     be exposed publicly",
-        issue = "none"
-    )]
-    #[inline]
-    #[doc(hidden)]
-    pub fn __description(&self) -> &str {
-        "could not convert slice to array"
-    }
-}
-
-#[stable(feature = "try_from_slice_error", since = "1.36.0")]
-impl From<Infallible> for TryFromSliceError {
-    fn from(x: Infallible) -> TryFromSliceError {
-        match x {}
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, const N: usize> AsRef<[T]> for [T; N] {
-    #[inline]
-    fn as_ref(&self) -> &[T] {
-        &self[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, const N: usize> AsMut<[T]> for [T; N] {
-    #[inline]
-    fn as_mut(&mut self) -> &mut [T] {
-        &mut self[..]
-    }
-}
-
-#[stable(feature = "array_borrow", since = "1.4.0")]
-impl<T, const N: usize> Borrow<[T]> for [T; N] {
-    fn borrow(&self) -> &[T] {
-        self
-    }
-}
-
-#[stable(feature = "array_borrow", since = "1.4.0")]
-impl<T, const N: usize> BorrowMut<[T]> for [T; N] {
-    fn borrow_mut(&mut self) -> &mut [T] {
-        self
-    }
-}
-
-#[stable(feature = "try_from", since = "1.34.0")]
-impl<T, const N: usize> TryFrom<&[T]> for [T; N]
-where
-    T: Copy,
-{
-    type Error = TryFromSliceError;
-
-    fn try_from(slice: &[T]) -> Result<[T; N], TryFromSliceError> {
-        <&Self>::try_from(slice).map(|r| *r)
-    }
-}
-
-#[stable(feature = "try_from", since = "1.34.0")]
-impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N] {
-    type Error = TryFromSliceError;
-
-    fn try_from(slice: &[T]) -> Result<&[T; N], TryFromSliceError> {
-        if slice.len() == N {
-            let ptr = slice.as_ptr() as *const [T; N];
-            // SAFETY: ok because we just checked that the length fits
-            unsafe { Ok(&*ptr) }
-        } else {
-            Err(TryFromSliceError(()))
-        }
-    }
-}
-
-#[stable(feature = "try_from", since = "1.34.0")]
-impl<'a, T, const N: usize> TryFrom<&'a mut [T]> for &'a mut [T; N] {
-    type Error = TryFromSliceError;
-
-    fn try_from(slice: &mut [T]) -> Result<&mut [T; N], TryFromSliceError> {
-        if slice.len() == N {
-            let ptr = slice.as_mut_ptr() as *mut [T; N];
-            // SAFETY: ok because we just checked that the length fits
-            unsafe { Ok(&mut *ptr) }
-        } else {
-            Err(TryFromSliceError(()))
-        }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Hash, const N: usize> Hash for [T; N] {
-    fn hash<H: hash::Hasher>(&self, state: &mut H) {
-        Hash::hash(&self[..], state)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: fmt::Debug, const N: usize> fmt::Debug for [T; N] {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Debug::fmt(&&self[..], f)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T, const N: usize> IntoIterator for &'a [T; N] {
-    type Item = &'a T;
-    type IntoIter = Iter<'a, T>;
-
-    fn into_iter(self) -> Iter<'a, T> {
-        self.iter()
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T, const N: usize> IntoIterator for &'a mut [T; N] {
-    type Item = &'a mut T;
-    type IntoIter = IterMut<'a, T>;
-
-    fn into_iter(self) -> IterMut<'a, T> {
-        self.iter_mut()
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<A, B, const N: usize> PartialEq<[B; N]> for [A; N]
-where
-    A: PartialEq<B>,
-{
-    #[inline]
-    fn eq(&self, other: &[B; N]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &[B; N]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<A, B, const N: usize> PartialEq<[B]> for [A; N]
-where
-    A: PartialEq<B>,
-{
-    #[inline]
-    fn eq(&self, other: &[B]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &[B]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<A, B, const N: usize> PartialEq<[A; N]> for [B]
-where
-    B: PartialEq<A>,
-{
-    #[inline]
-    fn eq(&self, other: &[A; N]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &[A; N]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'b, A, B, const N: usize> PartialEq<&'b [B]> for [A; N]
-where
-    A: PartialEq<B>,
-{
-    #[inline]
-    fn eq(&self, other: &&'b [B]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &&'b [B]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'b, A, B, const N: usize> PartialEq<[A; N]> for &'b [B]
-where
-    B: PartialEq<A>,
-{
-    #[inline]
-    fn eq(&self, other: &[A; N]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &[A; N]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'b, A, B, const N: usize> PartialEq<&'b mut [B]> for [A; N]
-where
-    A: PartialEq<B>,
-{
-    #[inline]
-    fn eq(&self, other: &&'b mut [B]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &&'b mut [B]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'b, A, B, const N: usize> PartialEq<[A; N]> for &'b mut [B]
-where
-    B: PartialEq<A>,
-{
-    #[inline]
-    fn eq(&self, other: &[A; N]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &[A; N]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-// NOTE: some less important impls are omitted to reduce code bloat
-// __impl_slice_eq2! { [A; $N], &'b [B; $N] }
-// __impl_slice_eq2! { [A; $N], &'b mut [B; $N] }
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Eq, const N: usize> Eq for [T; N] {}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: PartialOrd, const N: usize> PartialOrd for [T; N] {
-    #[inline]
-    fn partial_cmp(&self, other: &[T; N]) -> Option<Ordering> {
-        PartialOrd::partial_cmp(&&self[..], &&other[..])
-    }
-    #[inline]
-    fn lt(&self, other: &[T; N]) -> bool {
-        PartialOrd::lt(&&self[..], &&other[..])
-    }
-    #[inline]
-    fn le(&self, other: &[T; N]) -> bool {
-        PartialOrd::le(&&self[..], &&other[..])
-    }
-    #[inline]
-    fn ge(&self, other: &[T; N]) -> bool {
-        PartialOrd::ge(&&self[..], &&other[..])
-    }
-    #[inline]
-    fn gt(&self, other: &[T; N]) -> bool {
-        PartialOrd::gt(&&self[..], &&other[..])
-    }
-}
-
-/// Implements comparison of arrays lexicographically.
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Ord, const N: usize> Ord for [T; N] {
-    #[inline]
-    fn cmp(&self, other: &[T; N]) -> Ordering {
-        Ord::cmp(&&self[..], &&other[..])
-    }
-}
-
-// The Default impls cannot be generated using the array_impls! macro because
-// they require array literals.
-
-macro_rules! array_impl_default {
-    {$n:expr, $t:ident $($ts:ident)*} => {
-        #[stable(since = "1.4.0", feature = "array_default")]
-        impl<T> Default for [T; $n] where T: Default {
-            fn default() -> [T; $n] {
-                [$t::default(), $($ts::default()),*]
-            }
-        }
-        array_impl_default!{($n - 1), $($ts)*}
-    };
-    {$n:expr,} => {
-        #[stable(since = "1.4.0", feature = "array_default")]
-        impl<T> Default for [T; $n] {
-            fn default() -> [T; $n] { [] }
-        }
-    };
-}
-
-array_impl_default! {32, T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T}