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, 118 deletions

diff --git a/src/libstd/sys/cloudabi/thread.rs b/src/libstd/sys/cloudabi/thread.rs
deleted file mode 100644
index a15dc8653e8..00000000000
--- a/src/libstd/sys/cloudabi/thread.rs
+++ /dev/null
@@ -1,118 +0,0 @@
-use crate::cmp;
-use crate::ffi::CStr;
-use crate::io;
-use crate::mem;
-use crate::ptr;
-use crate::sys::cloudabi::abi;
-use crate::sys::time::checked_dur2intervals;
-use crate::time::Duration;
-
-pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
-
-pub struct Thread {
-    id: libc::pthread_t,
-}
-
-// CloudABI has pthread_t as a pointer in which case we still want
-// a thread to be Send/Sync
-unsafe impl Send for Thread {}
-unsafe impl Sync for Thread {}
-
-impl Thread {
-    // unsafe: see thread::Builder::spawn_unchecked for safety requirements
-    pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
-        let p = Box::into_raw(box p);
-        let mut native: libc::pthread_t = mem::zeroed();
-        let mut attr: libc::pthread_attr_t = mem::zeroed();
-        assert_eq!(libc::pthread_attr_init(&mut attr), 0);
-
-        let stack_size = cmp::max(stack, min_stack_size(&attr));
-        assert_eq!(libc::pthread_attr_setstacksize(&mut attr, stack_size), 0);
-
-        let ret = libc::pthread_create(&mut native, &attr, thread_start, p as *mut _);
-        // Note: if the thread creation fails and this assert fails, then p will
-        // be leaked. However, an alternative design could cause double-free
-        // which is clearly worse.
-        assert_eq!(libc::pthread_attr_destroy(&mut attr), 0);
-
-        return if ret != 0 {
-            // The thread failed to start and as a result p was not consumed. Therefore, it is
-            // safe to reconstruct the box so that it gets deallocated.
-            drop(Box::from_raw(p));
-            Err(io::Error::from_raw_os_error(ret))
-        } else {
-            Ok(Thread { id: native })
-        };
-
-        extern "C" fn thread_start(main: *mut libc::c_void) -> *mut libc::c_void {
-            unsafe {
-                // Let's run some code.
-                Box::from_raw(main as *mut Box<dyn FnOnce()>)();
-            }
-            ptr::null_mut()
-        }
-    }
-
-    pub fn yield_now() {
-        let ret = unsafe { abi::thread_yield() };
-        debug_assert_eq!(ret, abi::errno::SUCCESS);
-    }
-
-    pub fn set_name(_name: &CStr) {
-        // CloudABI has no way to set a thread name.
-    }
-
-    pub fn sleep(dur: Duration) {
-        let timeout =
-            checked_dur2intervals(&dur).expect("overflow converting duration to nanoseconds");
-        unsafe {
-            let subscription = abi::subscription {
-                type_: abi::eventtype::CLOCK,
-                union: abi::subscription_union {
-                    clock: abi::subscription_clock {
-                        clock_id: abi::clockid::MONOTONIC,
-                        timeout,
-                        ..mem::zeroed()
-                    },
-                },
-                ..mem::zeroed()
-            };
-            let mut event = mem::MaybeUninit::<abi::event>::uninit();
-            let mut nevents = mem::MaybeUninit::<usize>::uninit();
-            let ret = abi::poll(&subscription, event.as_mut_ptr(), 1, nevents.as_mut_ptr());
-            assert_eq!(ret, abi::errno::SUCCESS);
-            let event = event.assume_init();
-            assert_eq!(event.error, abi::errno::SUCCESS);
-        }
-    }
-
-    pub fn join(self) {
-        unsafe {
-            let ret = libc::pthread_join(self.id, ptr::null_mut());
-            mem::forget(self);
-            assert!(ret == 0, "failed to join thread: {}", io::Error::from_raw_os_error(ret));
-        }
-    }
-}
-
-impl Drop for Thread {
-    fn drop(&mut self) {
-        let ret = unsafe { libc::pthread_detach(self.id) };
-        debug_assert_eq!(ret, 0);
-    }
-}
-
-#[cfg_attr(test, allow(dead_code))]
-pub mod guard {
-    pub type Guard = !;
-    pub unsafe fn current() -> Option<Guard> {
-        None
-    }
-    pub unsafe fn init() -> Option<Guard> {
-        None
-    }
-}
-
-fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
-    libc::PTHREAD_STACK_MIN
-}