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, 460 deletions

diff --git a/src/libstd/io/impls.rs b/src/libstd/io/impls.rs
deleted file mode 100644
index 01dff0b3eb3..00000000000
--- a/src/libstd/io/impls.rs
+++ /dev/null
@@ -1,460 +0,0 @@
-use crate::cmp;
-use crate::fmt;
-use crate::io::{
-    self, BufRead, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write,
-};
-use crate::mem;
-
-// =============================================================================
-// Forwarding implementations
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<R: Read + ?Sized> Read for &mut R {
-    #[inline]
-    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        (**self).read(buf)
-    }
-
-    #[inline]
-    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
-        (**self).read_vectored(bufs)
-    }
-
-    #[inline]
-    fn is_read_vectored(&self) -> bool {
-        (**self).is_read_vectored()
-    }
-
-    #[inline]
-    unsafe fn initializer(&self) -> Initializer {
-        (**self).initializer()
-    }
-
-    #[inline]
-    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
-        (**self).read_to_end(buf)
-    }
-
-    #[inline]
-    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
-        (**self).read_to_string(buf)
-    }
-
-    #[inline]
-    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
-        (**self).read_exact(buf)
-    }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<W: Write + ?Sized> Write for &mut W {
-    #[inline]
-    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        (**self).write(buf)
-    }
-
-    #[inline]
-    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
-        (**self).write_vectored(bufs)
-    }
-
-    #[inline]
-    fn is_write_vectored(&self) -> bool {
-        (**self).is_write_vectored()
-    }
-
-    #[inline]
-    fn flush(&mut self) -> io::Result<()> {
-        (**self).flush()
-    }
-
-    #[inline]
-    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
-        (**self).write_all(buf)
-    }
-
-    #[inline]
-    fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
-        (**self).write_fmt(fmt)
-    }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<S: Seek + ?Sized> Seek for &mut S {
-    #[inline]
-    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
-        (**self).seek(pos)
-    }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<B: BufRead + ?Sized> BufRead for &mut B {
-    #[inline]
-    fn fill_buf(&mut self) -> io::Result<&[u8]> {
-        (**self).fill_buf()
-    }
-
-    #[inline]
-    fn consume(&mut self, amt: usize) {
-        (**self).consume(amt)
-    }
-
-    #[inline]
-    fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
-        (**self).read_until(byte, buf)
-    }
-
-    #[inline]
-    fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
-        (**self).read_line(buf)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<R: Read + ?Sized> Read for Box<R> {
-    #[inline]
-    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        (**self).read(buf)
-    }
-
-    #[inline]
-    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
-        (**self).read_vectored(bufs)
-    }
-
-    #[inline]
-    fn is_read_vectored(&self) -> bool {
-        (**self).is_read_vectored()
-    }
-
-    #[inline]
-    unsafe fn initializer(&self) -> Initializer {
-        (**self).initializer()
-    }
-
-    #[inline]
-    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
-        (**self).read_to_end(buf)
-    }
-
-    #[inline]
-    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
-        (**self).read_to_string(buf)
-    }
-
-    #[inline]
-    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
-        (**self).read_exact(buf)
-    }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<W: Write + ?Sized> Write for Box<W> {
-    #[inline]
-    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        (**self).write(buf)
-    }
-
-    #[inline]
-    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
-        (**self).write_vectored(bufs)
-    }
-
-    #[inline]
-    fn is_write_vectored(&self) -> bool {
-        (**self).is_write_vectored()
-    }
-
-    #[inline]
-    fn flush(&mut self) -> io::Result<()> {
-        (**self).flush()
-    }
-
-    #[inline]
-    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
-        (**self).write_all(buf)
-    }
-
-    #[inline]
-    fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
-        (**self).write_fmt(fmt)
-    }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<S: Seek + ?Sized> Seek for Box<S> {
-    #[inline]
-    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
-        (**self).seek(pos)
-    }
-}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<B: BufRead + ?Sized> BufRead for Box<B> {
-    #[inline]
-    fn fill_buf(&mut self) -> io::Result<&[u8]> {
-        (**self).fill_buf()
-    }
-
-    #[inline]
-    fn consume(&mut self, amt: usize) {
-        (**self).consume(amt)
-    }
-
-    #[inline]
-    fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
-        (**self).read_until(byte, buf)
-    }
-
-    #[inline]
-    fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
-        (**self).read_line(buf)
-    }
-}
-
-// Used by panicking::default_hook
-#[cfg(test)]
-/// This impl is only used by printing logic, so any error returned is always
-/// of kind `Other`, and should be ignored.
-impl Write for Box<dyn (::realstd::io::Write) + Send> {
-    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        (**self).write(buf).map_err(|_| ErrorKind::Other.into())
-    }
-
-    fn flush(&mut self) -> io::Result<()> {
-        (**self).flush().map_err(|_| ErrorKind::Other.into())
-    }
-}
-
-// =============================================================================
-// In-memory buffer implementations
-
-/// Read is implemented for `&[u8]` by copying from the slice.
-///
-/// Note that reading updates the slice to point to the yet unread part.
-/// The slice will be empty when EOF is reached.
-#[stable(feature = "rust1", since = "1.0.0")]
-impl Read for &[u8] {
-    #[inline]
-    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        let amt = cmp::min(buf.len(), self.len());
-        let (a, b) = self.split_at(amt);
-
-        // First check if the amount of bytes we want to read is small:
-        // `copy_from_slice` will generally expand to a call to `memcpy`, and
-        // for a single byte the overhead is significant.
-        if amt == 1 {
-            buf[0] = a[0];
-        } else {
-            buf[..amt].copy_from_slice(a);
-        }
-
-        *self = b;
-        Ok(amt)
-    }
-
-    #[inline]
-    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
-        let mut nread = 0;
-        for buf in bufs {
-            nread += self.read(buf)?;
-            if self.is_empty() {
-                break;
-            }
-        }
-
-        Ok(nread)
-    }
-
-    #[inline]
-    fn is_read_vectored(&self) -> bool {
-        true
-    }
-
-    #[inline]
-    unsafe fn initializer(&self) -> Initializer {
-        Initializer::nop()
-    }
-
-    #[inline]
-    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
-        if buf.len() > self.len() {
-            return Err(Error::new(ErrorKind::UnexpectedEof, "failed to fill whole buffer"));
-        }
-        let (a, b) = self.split_at(buf.len());
-
-        // First check if the amount of bytes we want to read is small:
-        // `copy_from_slice` will generally expand to a call to `memcpy`, and
-        // for a single byte the overhead is significant.
-        if buf.len() == 1 {
-            buf[0] = a[0];
-        } else {
-            buf.copy_from_slice(a);
-        }
-
-        *self = b;
-        Ok(())
-    }
-
-    #[inline]
-    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
-        buf.extend_from_slice(*self);
-        let len = self.len();
-        *self = &self[len..];
-        Ok(len)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl BufRead for &[u8] {
-    #[inline]
-    fn fill_buf(&mut self) -> io::Result<&[u8]> {
-        Ok(*self)
-    }
-
-    #[inline]
-    fn consume(&mut self, amt: usize) {
-        *self = &self[amt..];
-    }
-}
-
-/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
-/// its data.
-///
-/// Note that writing updates the slice to point to the yet unwritten part.
-/// The slice will be empty when it has been completely overwritten.
-#[stable(feature = "rust1", since = "1.0.0")]
-impl Write for &mut [u8] {
-    #[inline]
-    fn write(&mut self, data: &[u8]) -> io::Result<usize> {
-        let amt = cmp::min(data.len(), self.len());
-        let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
-        a.copy_from_slice(&data[..amt]);
-        *self = b;
-        Ok(amt)
-    }
-
-    #[inline]
-    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
-        let mut nwritten = 0;
-        for buf in bufs {
-            nwritten += self.write(buf)?;
-            if self.is_empty() {
-                break;
-            }
-        }
-
-        Ok(nwritten)
-    }
-
-    #[inline]
-    fn is_write_vectored(&self) -> bool {
-        true
-    }
-
-    #[inline]
-    fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
-        if self.write(data)? == data.len() {
-            Ok(())
-        } else {
-            Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))
-        }
-    }
-
-    #[inline]
-    fn flush(&mut self) -> io::Result<()> {
-        Ok(())
-    }
-}
-
-/// Write is implemented for `Vec<u8>` by appending to the vector.
-/// The vector will grow as needed.
-#[stable(feature = "rust1", since = "1.0.0")]
-impl Write for Vec<u8> {
-    #[inline]
-    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        self.extend_from_slice(buf);
-        Ok(buf.len())
-    }
-
-    #[inline]
-    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
-        let len = bufs.iter().map(|b| b.len()).sum();
-        self.reserve(len);
-        for buf in bufs {
-            self.extend_from_slice(buf);
-        }
-        Ok(len)
-    }
-
-    #[inline]
-    fn is_write_vectored(&self) -> bool {
-        true
-    }
-
-    #[inline]
-    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
-        self.extend_from_slice(buf);
-        Ok(())
-    }
-
-    #[inline]
-    fn flush(&mut self) -> io::Result<()> {
-        Ok(())
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::io::prelude::*;
-
-    #[bench]
-    fn bench_read_slice(b: &mut test::Bencher) {
-        let buf = [5; 1024];
-        let mut dst = [0; 128];
-
-        b.iter(|| {
-            let mut rd = &buf[..];
-            for _ in 0..8 {
-                let _ = rd.read(&mut dst);
-                test::black_box(&dst);
-            }
-        })
-    }
-
-    #[bench]
-    fn bench_write_slice(b: &mut test::Bencher) {
-        let mut buf = [0; 1024];
-        let src = [5; 128];
-
-        b.iter(|| {
-            let mut wr = &mut buf[..];
-            for _ in 0..8 {
-                let _ = wr.write_all(&src);
-                test::black_box(&wr);
-            }
-        })
-    }
-
-    #[bench]
-    fn bench_read_vec(b: &mut test::Bencher) {
-        let buf = vec![5; 1024];
-        let mut dst = [0; 128];
-
-        b.iter(|| {
-            let mut rd = &buf[..];
-            for _ in 0..8 {
-                let _ = rd.read(&mut dst);
-                test::black_box(&dst);
-            }
-        })
-    }
-
-    #[bench]
-    fn bench_write_vec(b: &mut test::Bencher) {
-        let mut buf = Vec::with_capacity(1024);
-        let src = [5; 128];
-
-        b.iter(|| {
-            let mut wr = &mut buf[..];
-            for _ in 0..8 {
-                let _ = wr.write_all(&src);
-                test::black_box(&wr);
-            }
-        })
-    }
-}