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, 148 deletions

diff --git a/src/libstd/sys_common/mod.rs b/src/libstd/sys_common/mod.rs
deleted file mode 100644
index 840f9093e00..00000000000
--- a/src/libstd/sys_common/mod.rs
+++ /dev/null
@@ -1,148 +0,0 @@
-//! Platform-independent platform abstraction
-//!
-//! This is the platform-independent portion of the standard library's
-//! platform abstraction layer, whereas `std::sys` is the
-//! platform-specific portion.
-//!
-//! The relationship between `std::sys_common`, `std::sys` and the
-//! rest of `std` is complex, with dependencies going in all
-//! directions: `std` depending on `sys_common`, `sys_common`
-//! depending on `sys`, and `sys` depending on `sys_common` and `std`.
-//! Ideally `sys_common` would be split into two and the dependencies
-//! between them all would form a dag, facilitating the extraction of
-//! `std::sys` from the standard library.
-
-#![allow(missing_docs)]
-#![allow(missing_debug_implementations)]
-
-use crate::sync::Once;
-use crate::sys;
-
-macro_rules! rtabort {
-    ($($t:tt)*) => (crate::sys_common::util::abort(format_args!($($t)*)))
-}
-
-macro_rules! rtassert {
-    ($e:expr) => {
-        if !$e {
-            rtabort!(concat!("assertion failed: ", stringify!($e)));
-        }
-    };
-}
-
-#[allow(unused_macros)] // not used on all platforms
-macro_rules! rtunwrap {
-    ($ok:ident, $e:expr) => {
-        match $e {
-            $ok(v) => v,
-            ref err => {
-                let err = err.as_ref().map(drop); // map Ok/Some which might not be Debug
-                rtabort!(concat!("unwrap failed: ", stringify!($e), " = {:?}"), err)
-            }
-        }
-    };
-}
-
-pub mod alloc;
-pub mod at_exit_imp;
-pub mod backtrace;
-pub mod bytestring;
-pub mod condvar;
-pub mod fs;
-pub mod io;
-pub mod mutex;
-// `doc` is required because `sys/mod.rs` imports `unix/ext/mod.rs` on Windows
-// when generating documentation.
-#[cfg(any(doc, not(windows)))]
-pub mod os_str_bytes;
-pub mod poison;
-pub mod process;
-pub mod remutex;
-pub mod rwlock;
-pub mod thread;
-pub mod thread_info;
-pub mod thread_local_dtor;
-pub mod thread_local_key;
-pub mod util;
-pub mod wtf8;
-
-cfg_if::cfg_if! {
-    if #[cfg(any(target_os = "cloudabi",
-                 target_os = "l4re",
-                 target_os = "hermit",
-                 feature = "restricted-std",
-                 all(target_arch = "wasm32", not(target_os = "emscripten")),
-                 all(target_vendor = "fortanix", target_env = "sgx")))] {
-        pub use crate::sys::net;
-    } else {
-        pub mod net;
-    }
-}
-
-// common error constructors
-
-/// A trait for viewing representations from std types
-#[doc(hidden)]
-pub trait AsInner<Inner: ?Sized> {
-    fn as_inner(&self) -> &Inner;
-}
-
-/// A trait for viewing representations from std types
-#[doc(hidden)]
-pub trait AsInnerMut<Inner: ?Sized> {
-    fn as_inner_mut(&mut self) -> &mut Inner;
-}
-
-/// A trait for extracting representations from std types
-#[doc(hidden)]
-pub trait IntoInner<Inner> {
-    fn into_inner(self) -> Inner;
-}
-
-/// A trait for creating std types from internal representations
-#[doc(hidden)]
-pub trait FromInner<Inner> {
-    fn from_inner(inner: Inner) -> Self;
-}
-
-/// Enqueues a procedure to run when the main thread exits.
-///
-/// Currently these closures are only run once the main *Rust* thread exits.
-/// Once the `at_exit` handlers begin running, more may be enqueued, but not
-/// infinitely so. Eventually a handler registration will be forced to fail.
-///
-/// Returns `Ok` if the handler was successfully registered, meaning that the
-/// closure will be run once the main thread exits. Returns `Err` to indicate
-/// that the closure could not be registered, meaning that it is not scheduled
-/// to be run.
-pub fn at_exit<F: FnOnce() + Send + 'static>(f: F) -> Result<(), ()> {
-    if at_exit_imp::push(Box::new(f)) { Ok(()) } else { Err(()) }
-}
-
-/// One-time runtime cleanup.
-pub fn cleanup() {
-    static CLEANUP: Once = Once::new();
-    CLEANUP.call_once(|| unsafe {
-        sys::args::cleanup();
-        sys::stack_overflow::cleanup();
-        at_exit_imp::cleanup();
-    });
-}
-
-// Computes (value*numer)/denom without overflow, as long as both
-// (numer*denom) and the overall result fit into i64 (which is the case
-// for our time conversions).
-#[allow(dead_code)] // not used on all platforms
-pub fn mul_div_u64(value: u64, numer: u64, denom: u64) -> u64 {
-    let q = value / denom;
-    let r = value % denom;
-    // Decompose value as (value/denom*denom + value%denom),
-    // substitute into (value*numer)/denom and simplify.
-    // r < denom, so (denom*numer) is the upper bound of (r*numer)
-    q * numer + r * numer / denom
-}
-
-#[test]
-fn test_muldiv() {
-    assert_eq!(mul_div_u64(1_000_000_000_001, 1_000_000_000, 1_000_000), 1_000_000_000_001_000);
-}