Auto merge of #96123 - Dylan-DPC:rollup-qjog6n1, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - #94985 (Parse inner attributes on inline const block)
 - #95006 (Reject `#[thread_local]` attribute on non-static items)
 - #95426 (Include Refs in Valtree Creation)
 - #95908 (Inline `shallow_resolve_ty` into `ShallowResolver`)
 - #96058 (separate flock implementations into separate modules)
 - #96088 (Update mdbook)
 - #96118 (rustdoc: Rename `def_id` into `item_id` when the type is `ItemId` for readability)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

4 files changed, 184 insertions, 0 deletions

diff --git a/compiler/rustc_data_structures/src/flock/linux.rs b/compiler/rustc_data_structures/src/flock/linux.rs
new file mode 100644
index 00000000000..bb3ecfbc370
--- /dev/null
+++ b/compiler/rustc_data_structures/src/flock/linux.rs
@@ -0,0 +1,40 @@
+//! We use `flock` rather than `fcntl` on Linux, because WSL1 does not support
+//! `fcntl`-style advisory locks properly (rust-lang/rust#72157). For other Unix
+//! targets we still use `fcntl` because it's more portable than `flock`.
+
+use std::fs::{File, OpenOptions};
+use std::io;
+use std::os::unix::prelude::*;
+use std::path::Path;
+
+#[derive(Debug)]
+pub struct Lock {
+    _file: File,
+}
+
+impl Lock {
+    pub fn new(p: &Path, wait: bool, create: bool, exclusive: bool) -> io::Result<Lock> {
+        let file = OpenOptions::new()
+            .read(true)
+            .write(true)
+            .create(create)
+            .mode(libc::S_IRWXU as u32)
+            .open(p)?;
+
+        let mut operation = if exclusive { libc::LOCK_EX } else { libc::LOCK_SH };
+        if !wait {
+            operation |= libc::LOCK_NB
+        }
+
+        let ret = unsafe { libc::flock(file.as_raw_fd(), operation) };
+        if ret == -1 { Err(io::Error::last_os_error()) } else { Ok(Lock { _file: file }) }
+    }
+
+    pub fn error_unsupported(err: &io::Error) -> bool {
+        matches!(err.raw_os_error(), Some(libc::ENOTSUP) | Some(libc::ENOSYS))
+    }
+}
+
+// Note that we don't need a Drop impl to execute `flock(fd, LOCK_UN)`. A lock acquired by
+// `flock` is associated with the file descriptor and closing the file releases it
+// automatically.
diff --git a/compiler/rustc_data_structures/src/flock/unix.rs b/compiler/rustc_data_structures/src/flock/unix.rs
new file mode 100644
index 00000000000..4e5297d582e
--- /dev/null
+++ b/compiler/rustc_data_structures/src/flock/unix.rs
@@ -0,0 +1,51 @@
+use std::fs::{File, OpenOptions};
+use std::io;
+use std::mem;
+use std::os::unix::prelude::*;
+use std::path::Path;
+
+#[derive(Debug)]
+pub struct Lock {
+    file: File,
+}
+
+impl Lock {
+    pub fn new(p: &Path, wait: bool, create: bool, exclusive: bool) -> io::Result<Lock> {
+        let file = OpenOptions::new()
+            .read(true)
+            .write(true)
+            .create(create)
+            .mode(libc::S_IRWXU as u32)
+            .open(p)?;
+
+        let lock_type = if exclusive { libc::F_WRLCK } else { libc::F_RDLCK };
+
+        let mut flock: libc::flock = unsafe { mem::zeroed() };
+        flock.l_type = lock_type as libc::c_short;
+        flock.l_whence = libc::SEEK_SET as libc::c_short;
+        flock.l_start = 0;
+        flock.l_len = 0;
+
+        let cmd = if wait { libc::F_SETLKW } else { libc::F_SETLK };
+        let ret = unsafe { libc::fcntl(file.as_raw_fd(), cmd, &flock) };
+        if ret == -1 { Err(io::Error::last_os_error()) } else { Ok(Lock { file }) }
+    }
+
+    pub fn error_unsupported(err: &io::Error) -> bool {
+        matches!(err.raw_os_error(), Some(libc::ENOTSUP) | Some(libc::ENOSYS))
+    }
+}
+
+impl Drop for Lock {
+    fn drop(&mut self) {
+        let mut flock: libc::flock = unsafe { mem::zeroed() };
+        flock.l_type = libc::F_UNLCK as libc::c_short;
+        flock.l_whence = libc::SEEK_SET as libc::c_short;
+        flock.l_start = 0;
+        flock.l_len = 0;
+
+        unsafe {
+            libc::fcntl(self.file.as_raw_fd(), libc::F_SETLK, &flock);
+        }
+    }
+}
diff --git a/compiler/rustc_data_structures/src/flock/unsupported.rs b/compiler/rustc_data_structures/src/flock/unsupported.rs
new file mode 100644
index 00000000000..9245fca373d
--- /dev/null
+++ b/compiler/rustc_data_structures/src/flock/unsupported.rs
@@ -0,0 +1,16 @@
+use std::io;
+use std::path::Path;
+
+#[derive(Debug)]
+pub struct Lock(());
+
+impl Lock {
+    pub fn new(_p: &Path, _wait: bool, _create: bool, _exclusive: bool) -> io::Result<Lock> {
+        let msg = "file locks not supported on this platform";
+        Err(io::Error::new(io::ErrorKind::Other, msg))
+    }
+
+    pub fn error_unsupported(_err: &io::Error) -> bool {
+        true
+    }
+}
diff --git a/compiler/rustc_data_structures/src/flock/windows.rs b/compiler/rustc_data_structures/src/flock/windows.rs
new file mode 100644
index 00000000000..43e6caaa18d
--- /dev/null
+++ b/compiler/rustc_data_structures/src/flock/windows.rs
@@ -0,0 +1,77 @@
+use std::fs::{File, OpenOptions};
+use std::io;
+use std::mem;
+use std::os::windows::prelude::*;
+use std::path::Path;
+
+use winapi::shared::winerror::ERROR_INVALID_FUNCTION;
+use winapi::um::fileapi::LockFileEx;
+use winapi::um::minwinbase::{LOCKFILE_EXCLUSIVE_LOCK, LOCKFILE_FAIL_IMMEDIATELY, OVERLAPPED};
+use winapi::um::winnt::{FILE_SHARE_DELETE, FILE_SHARE_READ, FILE_SHARE_WRITE};
+
+#[derive(Debug)]
+pub struct Lock {
+    _file: File,
+}
+
+impl Lock {
+    pub fn new(p: &Path, wait: bool, create: bool, exclusive: bool) -> io::Result<Lock> {
+        assert!(
+            p.parent().unwrap().exists(),
+            "Parent directory of lock-file must exist: {}",
+            p.display()
+        );
+
+        let share_mode = FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE;
+
+        let mut open_options = OpenOptions::new();
+        open_options.read(true).share_mode(share_mode);
+
+        if create {
+            open_options.create(true).write(true);
+        }
+
+        debug!("attempting to open lock file `{}`", p.display());
+        let file = match open_options.open(p) {
+            Ok(file) => {
+                debug!("lock file opened successfully");
+                file
+            }
+            Err(err) => {
+                debug!("error opening lock file: {}", err);
+                return Err(err);
+            }
+        };
+
+        let ret = unsafe {
+            let mut overlapped: OVERLAPPED = mem::zeroed();
+
+            let mut dwFlags = 0;
+            if !wait {
+                dwFlags |= LOCKFILE_FAIL_IMMEDIATELY;
+            }
+
+            if exclusive {
+                dwFlags |= LOCKFILE_EXCLUSIVE_LOCK;
+            }
+
+            debug!("attempting to acquire lock on lock file `{}`", p.display());
+            LockFileEx(file.as_raw_handle(), dwFlags, 0, 0xFFFF_FFFF, 0xFFFF_FFFF, &mut overlapped)
+        };
+        if ret == 0 {
+            let err = io::Error::last_os_error();
+            debug!("failed acquiring file lock: {}", err);
+            Err(err)
+        } else {
+            debug!("successfully acquired lock");
+            Ok(Lock { _file: file })
+        }
+    }
+
+    pub fn error_unsupported(err: &io::Error) -> bool {
+        err.raw_os_error() == Some(ERROR_INVALID_FUNCTION as i32)
+    }
+}
+
+// Note that we don't need a Drop impl on Windows: The file is unlocked
+// automatically when it's closed.