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, 97 deletions

diff --git a/src/libstd/sys/unix/alloc.rs b/src/libstd/sys/unix/alloc.rs
deleted file mode 100644
index 8e193935460..00000000000
--- a/src/libstd/sys/unix/alloc.rs
+++ /dev/null
@@ -1,97 +0,0 @@
-use crate::alloc::{GlobalAlloc, Layout, System};
-use crate::ptr;
-use crate::sys_common::alloc::{realloc_fallback, MIN_ALIGN};
-
-#[stable(feature = "alloc_system_type", since = "1.28.0")]
-unsafe impl GlobalAlloc for System {
-    #[inline]
-    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
-        // jemalloc provides alignment less than MIN_ALIGN for small allocations.
-        // So only rely on MIN_ALIGN if size >= align.
-        // Also see <https://github.com/rust-lang/rust/issues/45955> and
-        // <https://github.com/rust-lang/rust/issues/62251#issuecomment-507580914>.
-        if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
-            libc::malloc(layout.size()) as *mut u8
-        } else {
-            #[cfg(target_os = "macos")]
-            {
-                if layout.align() > (1 << 31) {
-                    return ptr::null_mut();
-                }
-            }
-            aligned_malloc(&layout)
-        }
-    }
-
-    #[inline]
-    unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
-        // See the comment above in `alloc` for why this check looks the way it does.
-        if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
-            libc::calloc(layout.size(), 1) as *mut u8
-        } else {
-            let ptr = self.alloc(layout);
-            if !ptr.is_null() {
-                ptr::write_bytes(ptr, 0, layout.size());
-            }
-            ptr
-        }
-    }
-
-    #[inline]
-    unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
-        libc::free(ptr as *mut libc::c_void)
-    }
-
-    #[inline]
-    unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
-        if layout.align() <= MIN_ALIGN && layout.align() <= new_size {
-            libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8
-        } else {
-            realloc_fallback(self, ptr, layout, new_size)
-        }
-    }
-}
-
-#[cfg(any(
-    target_os = "android",
-    target_os = "illumos",
-    target_os = "redox",
-    target_os = "solaris"
-))]
-#[inline]
-unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
-    // On android we currently target API level 9 which unfortunately
-    // doesn't have the `posix_memalign` API used below. Instead we use
-    // `memalign`, but this unfortunately has the property on some systems
-    // where the memory returned cannot be deallocated by `free`!
-    //
-    // Upon closer inspection, however, this appears to work just fine with
-    // Android, so for this platform we should be fine to call `memalign`
-    // (which is present in API level 9). Some helpful references could
-    // possibly be chromium using memalign [1], attempts at documenting that
-    // memalign + free is ok [2] [3], or the current source of chromium
-    // which still uses memalign on android [4].
-    //
-    // [1]: https://codereview.chromium.org/10796020/
-    // [2]: https://code.google.com/p/android/issues/detail?id=35391
-    // [3]: https://bugs.chromium.org/p/chromium/issues/detail?id=138579
-    // [4]: https://chromium.googlesource.com/chromium/src/base/+/master/
-    //                                       /memory/aligned_memory.cc
-    libc::memalign(layout.align(), layout.size()) as *mut u8
-}
-
-#[cfg(not(any(
-    target_os = "android",
-    target_os = "illumos",
-    target_os = "redox",
-    target_os = "solaris"
-)))]
-#[inline]
-unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
-    let mut out = ptr::null_mut();
-    // posix_memalign requires that the alignment be a multiple of `sizeof(void*)`.
-    // Since these are all powers of 2, we can just use max.
-    let align = layout.align().max(crate::mem::size_of::<usize>());
-    let ret = libc::posix_memalign(&mut out, align, layout.size());
-    if ret != 0 { ptr::null_mut() } else { out as *mut u8 }
-}