Auto merge of #73265 - mark-i-m:mv-std, r=<try>tmp-nightly

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, 186 deletions

diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
deleted file mode 100644
index 90e2d2531c5..00000000000
--- a/src/liballoc/lib.rs
+++ /dev/null
@@ -1,186 +0,0 @@
-//! # The Rust core allocation and collections library
-//!
-//! This library provides smart pointers and collections for managing
-//! heap-allocated values.
-//!
-//! This library, like libcore, normally doesn’t need to be used directly
-//! since its contents are re-exported in the [`std` crate](../std/index.html).
-//! Crates that use the `#![no_std]` attribute however will typically
-//! not depend on `std`, so they’d use this crate instead.
-//!
-//! ## Boxed values
-//!
-//! The [`Box`] type is a smart pointer type. There can only be one owner of a
-//! [`Box`], and the owner can decide to mutate the contents, which live on the
-//! heap.
-//!
-//! This type can be sent among threads efficiently as the size of a `Box` value
-//! is the same as that of a pointer. Tree-like data structures are often built
-//! with boxes because each node often has only one owner, the parent.
-//!
-//! ## Reference counted pointers
-//!
-//! The [`Rc`] type is a non-threadsafe reference-counted pointer type intended
-//! for sharing memory within a thread. An [`Rc`] pointer wraps a type, `T`, and
-//! only allows access to `&T`, a shared reference.
-//!
-//! This type is useful when inherited mutability (such as using [`Box`]) is too
-//! constraining for an application, and is often paired with the [`Cell`] or
-//! [`RefCell`] types in order to allow mutation.
-//!
-//! ## Atomically reference counted pointers
-//!
-//! The [`Arc`] type is the threadsafe equivalent of the [`Rc`] type. It
-//! provides all the same functionality of [`Rc`], except it requires that the
-//! contained type `T` is shareable. Additionally, [`Arc<T>`][`Arc`] is itself
-//! sendable while [`Rc<T>`][`Rc`] is not.
-//!
-//! This type allows for shared access to the contained data, and is often
-//! paired with synchronization primitives such as mutexes to allow mutation of
-//! shared resources.
-//!
-//! ## Collections
-//!
-//! Implementations of the most common general purpose data structures are
-//! defined in this library. They are re-exported through the
-//! [standard collections library](../std/collections/index.html).
-//!
-//! ## Heap interfaces
-//!
-//! The [`alloc`](alloc/index.html) module defines the low-level interface to the
-//! default global allocator. It is not compatible with the libc allocator API.
-//!
-//! [`Arc`]: sync/index.html
-//! [`Box`]: boxed/index.html
-//! [`Cell`]: ../core/cell/index.html
-//! [`Rc`]: rc/index.html
-//! [`RefCell`]: ../core/cell/index.html
-
-#![allow(unused_attributes)]
-#![stable(feature = "alloc", since = "1.36.0")]
-#![doc(
-    html_root_url = "https://doc.rust-lang.org/nightly/",
-    html_playground_url = "https://play.rust-lang.org/",
-    issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
-    test(no_crate_inject, attr(allow(unused_variables), deny(warnings)))
-)]
-#![no_std]
-#![needs_allocator]
-#![warn(deprecated_in_future)]
-#![warn(missing_docs)]
-#![warn(missing_debug_implementations)]
-#![deny(intra_doc_link_resolution_failure)] // rustdoc is run without -D warnings
-#![allow(explicit_outlives_requirements)]
-#![allow(incomplete_features)]
-#![deny(unsafe_op_in_unsafe_fn)]
-#![cfg_attr(not(test), feature(generator_trait))]
-#![cfg_attr(test, feature(test))]
-#![feature(allocator_api)]
-#![feature(allow_internal_unstable)]
-#![feature(arbitrary_self_types)]
-#![feature(box_patterns)]
-#![feature(box_syntax)]
-#![feature(cfg_sanitize)]
-#![feature(cfg_target_has_atomic)]
-#![feature(coerce_unsized)]
-#![feature(const_btree_new)]
-#![feature(const_generics)]
-#![feature(const_in_array_repeat_expressions)]
-#![feature(cow_is_borrowed)]
-#![feature(deque_range)]
-#![feature(dispatch_from_dyn)]
-#![feature(core_intrinsics)]
-#![feature(container_error_extra)]
-#![feature(dropck_eyepatch)]
-#![feature(exact_size_is_empty)]
-#![feature(extend_one)]
-#![feature(fmt_internals)]
-#![feature(fn_traits)]
-#![feature(fundamental)]
-#![feature(internal_uninit_const)]
-#![feature(lang_items)]
-#![feature(layout_for_ptr)]
-#![feature(libc)]
-#![feature(negative_impls)]
-#![feature(new_uninit)]
-#![feature(nll)]
-#![feature(optin_builtin_traits)]
-#![feature(or_patterns)]
-#![feature(pattern)]
-#![feature(ptr_internals)]
-#![feature(ptr_offset_from)]
-#![feature(raw_ref_op)]
-#![feature(rustc_attrs)]
-#![feature(receiver_trait)]
-#![feature(min_specialization)]
-#![feature(staged_api)]
-#![feature(std_internals)]
-#![feature(str_internals)]
-#![feature(trusted_len)]
-#![feature(try_reserve)]
-#![feature(unboxed_closures)]
-#![feature(unicode_internals)]
-#![feature(unsafe_block_in_unsafe_fn)]
-#![feature(unsize)]
-#![feature(unsized_locals)]
-#![feature(allocator_internals)]
-#![feature(slice_partition_dedup)]
-#![feature(maybe_uninit_extra, maybe_uninit_slice)]
-#![feature(alloc_layout_extra)]
-#![feature(try_trait)]
-#![feature(associated_type_bounds)]
-
-// Allow testing this library
-
-#[cfg(test)]
-#[macro_use]
-extern crate std;
-#[cfg(test)]
-extern crate test;
-
-// Module with internal macros used by other modules (needs to be included before other modules).
-#[macro_use]
-mod macros;
-
-// Heaps provided for low-level allocation strategies
-
-pub mod alloc;
-
-// Primitive types using the heaps above
-
-// Need to conditionally define the mod from `boxed.rs` to avoid
-// duplicating the lang-items when building in test cfg; but also need
-// to allow code to have `use boxed::Box;` declarations.
-#[cfg(not(test))]
-pub mod boxed;
-#[cfg(test)]
-mod boxed {
-    pub use std::boxed::Box;
-}
-pub mod borrow;
-pub mod collections;
-pub mod fmt;
-pub mod prelude;
-pub mod raw_vec;
-pub mod rc;
-pub mod slice;
-pub mod str;
-pub mod string;
-#[cfg(target_has_atomic = "ptr")]
-pub mod sync;
-#[cfg(target_has_atomic = "ptr")]
-pub mod task;
-#[cfg(test)]
-mod tests;
-pub mod vec;
-
-#[cfg(not(test))]
-mod std {
-    pub use core::ops; // RangeFull
-}
-
-#[doc(hidden)]
-#[unstable(feature = "liballoc_internals", issue = "none", reason = "implementation detail")]
-pub mod __export {
-    pub use core::format_args;
-}