Auto merge of #84206 - Dylan-DPC:rollup-knl2jgq, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - #82492 (Move `std::sys_common::alloc` to new module `std::sys::common`)
 - #84177 (Fix join_paths error display.)
 - #84185 (add more pat2021 tests)
 - #84191 (Update books)
 - #84192 (Fix typos in rustc_codegen_ssa/src/back/write.rs.)
 - #84196 (:arrow_up: rust-analyzer)
 - #84201 (rustdoc: Note that forbidding anchors in links to primitives is a bug)

Failed merges:

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

Author: bors

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -1094,7 +1094,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
     //   only place where we have access to the compiler `Session`.
     // - LLVM work can be done on any thread.
     // - Codegen can only happen on the main thread.
-    // - Each thread doing substantial work most be in possession of a `Token`
+    // - Each thread doing substantial work must be in possession of a `Token`
     //   from the `Jobserver`.
     // - The compiler process always holds one `Token`. Any additional `Tokens`
     //   have to be requested from the `Jobserver`.
@@ -1146,7 +1146,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
     // if possible. These two goals are at odds with each other: If memory
     // consumption were not an issue, we could just let the main thread produce
     // LLVM WorkItems at full speed, assuring maximal utilization of
-    // Tokens/LLVM worker threads. However, since codegen usual is faster
+    // Tokens/LLVM worker threads. However, since codegen is usually faster
     // than LLVM processing, the queue of LLVM WorkItems would fill up and each
     // WorkItem potentially holds on to a substantial amount of memory.
     //

library/std/src/sys_common/alloc.rs renamed to library/std/src/sys/common/alloc.rs

@@ -1,5 +1,3 @@
-#![allow(dead_code)]
-
 use crate::alloc::{GlobalAlloc, Layout, System};
 use crate::cmp;
 use crate::ptr;

library/std/src/sys/common/mod.rs

@@ -0,0 +1,13 @@
+// This module contains code that is shared between all platforms, mostly utility or fallback code.
+// This explicitly does not include code that is shared between only a few platforms,
+// such as when reusing an implementation from `unix` or `unsupported`.
+// In those cases the desired code should be included directly using the #[path] attribute,
+// not moved to this module.
+//
+// Currently `sys_common` contains a lot of code that should live in this module,
+// ideally `sys_common` would only contain platform-independent abstractions on top of `sys`.
+// Progress on this is tracked in #84187.
+
+#![allow(dead_code)]
+
+pub mod alloc;

library/std/src/sys/mod.rs

@@ -22,6 +22,8 @@
 
 #![allow(missing_debug_implementations)]
 
+mod common;
+
 cfg_if::cfg_if! {
     if #[cfg(target_os = "vxworks")] {
         mod vxworks;

library/std/src/sys/unix/alloc.rs

@@ -1,6 +1,6 @@
 use crate::alloc::{GlobalAlloc, Layout, System};
 use crate::ptr;
-use crate::sys_common::alloc::{realloc_fallback, MIN_ALIGN};
+use crate::sys::common::alloc::{realloc_fallback, MIN_ALIGN};
 
 #[stable(feature = "alloc_system_type", since = "1.28.0")]
 unsafe impl GlobalAlloc for System {

library/std/src/sys/unix/os.rs

@@ -223,7 +223,7 @@ where
 
 impl fmt::Display for JoinPathsError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "path segment contains separator `{}`", PATH_SEPARATOR)
+        write!(f, "path segment contains separator `{}`", char::from(PATH_SEPARATOR))
     }
 }
 

library/std/src/sys/windows/alloc.rs

@@ -5,7 +5,7 @@ use crate::ffi::c_void;
 use crate::ptr;
 use crate::sync::atomic::{AtomicPtr, Ordering};
 use crate::sys::c;
-use crate::sys_common::alloc::{realloc_fallback, MIN_ALIGN};
+use crate::sys::common::alloc::{realloc_fallback, MIN_ALIGN};
 
 #[cfg(test)]
 mod tests;

library/std/src/sys_common/mod.rs

@@ -8,9 +8,11 @@
 //! 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.
+//! This is because `sys_common` not only contains platform-independent code,
+//! but also code that is shared between the different platforms in `sys`.
+//! Ideally all that shared code should be moved to `sys::common`,
+//! and the dependencies between `std`, `sys_common` and `sys` all would form a dag.
+//! Progress on this is tracked in #84187.
 
 #![allow(missing_docs)]
 #![allow(missing_debug_implementations)]
@@ -46,7 +48,6 @@ macro_rules! rtunwrap {
     };
 }
 
-pub mod alloc;
 pub mod at_exit_imp;
 pub mod backtrace;
 pub mod bytestring;