Auto merge of rust-lang#114318 - matthiaskrgr:rollup-c7gcw18, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#111081 (impl SliceIndex<str> for (Bound<usize>, Bound<usize>))
 - rust-lang#113394 (style-guide: Document style editions, start 2024 style edition)
 - rust-lang#113588 (bootstrap: use git merge-base for LLVM CI download logic)
 - rust-lang#113743 (Directly link more target docs)
 - rust-lang#114262 (Improve the rust style guide doc)
 - rust-lang#114309 (Update books)
 - rust-lang#114313 ([rustc_data_structures] Simplify SortedMap::insert.)

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

Author: bors

Diff for: compiler/rustc_data_structures/src/sorted_map.rs

@@ -49,12 +49,11 @@ impl<K: Ord, V> SortedMap<K, V> {
     }
 
     #[inline]
-    pub fn insert(&mut self, key: K, mut value: V) -> Option<V> {
+    pub fn insert(&mut self, key: K, value: V) -> Option<V> {
         match self.lookup_index_for(&key) {
             Ok(index) => {
                 let slot = unsafe { self.data.get_unchecked_mut(index) };
-                mem::swap(&mut slot.1, &mut value);
-                Some(value)
+                Some(mem::replace(&mut slot.1, value))
             }
             Err(index) => {
                 self.data.insert(index, (key, value));

Diff for: library/core/src/slice/index.rs

@@ -727,7 +727,7 @@ where
 }
 
 /// Convert pair of `ops::Bound`s into `ops::Range` without performing any bounds checking and (in debug) overflow checking
-fn into_range_unchecked(
+pub(crate) fn into_range_unchecked(
     len: usize,
     (start, end): (ops::Bound<usize>, ops::Bound<usize>),
 ) -> ops::Range<usize> {
@@ -747,7 +747,7 @@ fn into_range_unchecked(
 
 /// Convert pair of `ops::Bound`s into `ops::Range`.
 /// Returns `None` on overflowing indices.
-fn into_range(
+pub(crate) fn into_range(
     len: usize,
     (start, end): (ops::Bound<usize>, ops::Bound<usize>),
 ) -> Option<ops::Range<usize>> {
@@ -772,7 +772,7 @@ fn into_range(
 
 /// Convert pair of `ops::Bound`s into `ops::Range`.
 /// Panics on overflowing indices.
-fn into_slice_range(
+pub(crate) fn into_slice_range(
     len: usize,
     (start, end): (ops::Bound<usize>, ops::Bound<usize>),
 ) -> ops::Range<usize> {

Diff for: library/core/src/slice/mod.rs

@@ -38,7 +38,7 @@ pub mod sort;
 
 mod ascii;
 mod cmp;
-mod index;
+pub(crate) mod index;
 mod iter;
 mod raw;
 mod rotate;

Diff for: library/core/src/str/traits.rs

@@ -252,6 +252,58 @@ unsafe impl SliceIndex<str> for ops::Range<usize> {
     }
 }
 
+/// Implements substring slicing for arbitrary bounds.
+///
+/// Returns a slice of the given string bounded by the byte indices
+/// provided by each bound.
+///
+/// This operation is *O*(1).
+///
+/// # Panics
+///
+/// Panics if `begin` or `end` (if it exists and once adjusted for
+/// inclusion/exclusion) does not point to the starting byte offset of
+/// a character (as defined by `is_char_boundary`), if `begin > end`, or if
+/// `end > len`.
+#[stable(feature = "slice_index_str_with_ops_bound_pair", since = "CURRENT_RUSTC_VERSION")]
+unsafe impl SliceIndex<str> for (ops::Bound<usize>, ops::Bound<usize>) {
+    type Output = str;
+
+    #[inline]
+    fn get(self, slice: &str) -> Option<&str> {
+        crate::slice::index::into_range(slice.len(), self)?.get(slice)
+    }
+
+    #[inline]
+    fn get_mut(self, slice: &mut str) -> Option<&mut str> {
+        crate::slice::index::into_range(slice.len(), self)?.get_mut(slice)
+    }
+
+    #[inline]
+    unsafe fn get_unchecked(self, slice: *const str) -> *const str {
+        let len = (slice as *const [u8]).len();
+        // SAFETY: the caller has to uphold the safety contract for `get_unchecked`.
+        unsafe { crate::slice::index::into_range_unchecked(len, self).get_unchecked(slice) }
+    }
+
+    #[inline]
+    unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut str {
+        let len = (slice as *mut [u8]).len();
+        // SAFETY: the caller has to uphold the safety contract for `get_unchecked_mut`.
+        unsafe { crate::slice::index::into_range_unchecked(len, self).get_unchecked_mut(slice) }
+    }
+
+    #[inline]
+    fn index(self, slice: &str) -> &str {
+        crate::slice::index::into_slice_range(slice.len(), self).index(slice)
+    }
+
+    #[inline]
+    fn index_mut(self, slice: &mut str) -> &mut str {
+        crate::slice::index::into_slice_range(slice.len(), self).index_mut(slice)
+    }
+}
+
 /// Implements substring slicing with syntax `&self[.. end]` or `&mut
 /// self[.. end]`.
 ///

Diff for: src/bootstrap/llvm.rs

@@ -24,6 +24,7 @@ use crate::util::{self, exe, output, t, up_to_date};
 use crate::{CLang, GitRepo, Kind};
 
 use build_helper::ci::CiEnv;
+use build_helper::git::get_git_merge_base;
 
 #[derive(Clone)]
 pub struct LlvmResult {
@@ -128,13 +129,19 @@ pub fn prebuilt_llvm_config(
 /// This retrieves the LLVM sha we *want* to use, according to git history.
 pub(crate) fn detect_llvm_sha(config: &Config, is_git: bool) -> String {
     let llvm_sha = if is_git {
+        // We proceed in 2 steps. First we get the closest commit that is actually upstream. Then we
+        // walk back further to the last bors merge commit that actually changed LLVM. The first
+        // step will fail on CI because only the `auto` branch exists; we just fall back to `HEAD`
+        // in that case.
+        let closest_upstream =
+            get_git_merge_base(Some(&config.src)).unwrap_or_else(|_| "HEAD".into());
         let mut rev_list = config.git();
         rev_list.args(&[
             PathBuf::from("rev-list"),
             format!("--author={}", config.stage0_metadata.config.git_merge_commit_email).into(),
             "-n1".into(),
             "--first-parent".into(),
-            "HEAD".into(),
+            closest_upstream.into(),
             "--".into(),
             config.src.join("src/llvm-project"),
             config.src.join("src/bootstrap/download-ci-llvm-stamp"),

Diff for: src/doc/reference

@@ -101,7 +101,7 @@ target | notes
 `x86_64-unknown-freebsd` | 64-bit FreeBSD
 `x86_64-unknown-illumos` | illumos
 `x86_64-unknown-linux-musl` | 64-bit Linux with MUSL
-`x86_64-unknown-netbsd` | NetBSD/amd64
+[`x86_64-unknown-netbsd`](platform-support/netbsd.md) | NetBSD/amd64
 
 ## Tier 2
 
@@ -128,7 +128,7 @@ target | std | notes
 `aarch64-apple-ios` | ✓ | ARM64 iOS
 [`aarch64-apple-ios-sim`](platform-support/aarch64-apple-ios-sim.md) | ✓ | Apple iOS Simulator on ARM64
 `aarch64-fuchsia` | ✓ | Alias for `aarch64-unknown-fuchsia`
-`aarch64-unknown-fuchsia` | ✓ | ARM64 Fuchsia
+[`aarch64-unknown-fuchsia`](platform-support/fuchsia.md) | ✓ | ARM64 Fuchsia
 [`aarch64-linux-android`](platform-support/android.md) | ✓ | ARM64 Android
 `aarch64-unknown-none-softfloat` | * | Bare ARM64, softfloat
 `aarch64-unknown-none` | * | Bare ARM64, hardfloat
@@ -159,7 +159,7 @@ target | std | notes
 `mips64-unknown-linux-muslabi64` | ✓ | MIPS64 Linux, n64 ABI, MUSL
 `mips64el-unknown-linux-muslabi64` | ✓ | MIPS64 (LE) Linux, n64 ABI, MUSL
 `mipsel-unknown-linux-musl` | ✓ | MIPS (LE) Linux with MUSL
-`nvptx64-nvidia-cuda` | * | --emit=asm generates PTX code that [runs on NVIDIA GPUs]
+[`nvptx64-nvidia-cuda`](platform-support/nvptx64-nvidia-cuda.md) | * | --emit=asm generates PTX code that [runs on NVIDIA GPUs]
 `riscv32i-unknown-none-elf` | * | Bare RISC-V (RV32I ISA)
 `riscv32imac-unknown-none-elf` | * | Bare RISC-V (RV32IMAC ISA)
 `riscv32imc-unknown-none-elf` | * | Bare RISC-V (RV32IMC ISA)
@@ -183,7 +183,7 @@ target | std | notes
 `x86_64-apple-ios` | ✓ | 64-bit x86 iOS
 [`x86_64-fortanix-unknown-sgx`](platform-support/x86_64-fortanix-unknown-sgx.md) | ✓ | [Fortanix ABI] for 64-bit Intel SGX
 `x86_64-fuchsia` | ✓ | Alias for `x86_64-unknown-fuchsia`
-`x86_64-unknown-fuchsia` | ✓ | 64-bit Fuchsia
+[`x86_64-unknown-fuchsia`](platform-support/fuchsia.md) | ✓ | 64-bit x86 Fuchsia
 [`x86_64-linux-android`](platform-support/android.md) | ✓ | 64-bit x86 Android
 `x86_64-pc-solaris` | ✓ | 64-bit Solaris 10/11, illumos
 `x86_64-unknown-linux-gnux32` | ✓ | 64-bit Linux (x32 ABI) (kernel 4.15, glibc 2.27)
@@ -337,6 +337,6 @@ target | std | host | notes
 `x86_64-uwp-windows-gnu` | ✓ |  |
 `x86_64-uwp-windows-msvc` | ✓ |  |
 `x86_64-wrs-vxworks` | ? |  |
-`x86_64h-apple-darwin` | ✓ | ✓ | macOS with late-gen Intel (at least Haswell)
+[`x86_64h-apple-darwin`](platform-support/x86_64h-apple-darwin.md) | ✓ | ✓ | macOS with late-gen Intel (at least Haswell)
 
 [runs on NVIDIA GPUs]: https://github.com/japaric-archived/nvptx#targets

Diff for: src/doc/rust-by-example

@@ -36,10 +36,10 @@ options.
 
 ### Indentation and line width
 
-* Use spaces, not tabs.
-* Each level of indentation must be 4 spaces (that is, all indentation
+- Use spaces, not tabs.
+- Each level of indentation must be 4 spaces (that is, all indentation
   outside of string literals and comments must be a multiple of 4).
-* The maximum width for a line is 100 characters.
+- The maximum width for a line is 100 characters.
 
 #### Block indent
 
@@ -100,10 +100,12 @@ fn baz() {}
 ```
 
 ### [Module-level items](items.md)
+
 ### [Statements](statements.md)
+
 ### [Expressions](expressions.md)
-### [Types](types.md)
 
+### [Types](types.md)
 
 ### Comments
 

Diff for: src/doc/rustc-dev-guide

@@ -9,4 +9,5 @@
 - [Other style advice](advice.md)
 - [`Cargo.toml` conventions](cargo.md)
 - [Guiding principles and rationale](principles.md)
+- [Rust style editions](editions.md)
 - [Nightly-only syntax](nightly.md)

Diff for: src/doc/rustc/src/platform-support.md

@@ -18,16 +18,16 @@ if y {
 
 ## Names
 
- * Types shall be `UpperCamelCase`,
- * Enum variants shall be `UpperCamelCase`,
- * Struct fields shall be `snake_case`,
- * Function and method names shall be `snake_case`,
- * Local variables shall be `snake_case`,
- * Macro names shall be `snake_case`,
- * Constants (`const`s and immutable `static`s) shall be `SCREAMING_SNAKE_CASE`.
- * When a name is forbidden because it is a reserved word (such as `crate`),
-   either use a raw identifier (`r#crate`) or use a trailing underscore
-   (`crate_`). Don't misspell the word (`krate`).
+- Types shall be `UpperCamelCase`,
+- Enum variants shall be `UpperCamelCase`,
+- Struct fields shall be `snake_case`,
+- Function and method names shall be `snake_case`,
+- Local variables shall be `snake_case`,
+- Macro names shall be `snake_case`,
+- Constants (`const`s and immutable `static`s) shall be `SCREAMING_SNAKE_CASE`.
+- When a name is forbidden because it is a reserved word (such as `crate`),
+  either use a raw identifier (`r#crate`) or use a trailing underscore
+  (`crate_`). Don't misspell the word (`krate`).
 
 ### Modules
 

Diff for: src/doc/style-guide/src/README.md

@@ -0,0 +1,46 @@
+# Rust style editions
+
+The default Rust style evolves over time, as Rust does. However, to avoid
+breaking established code style, and CI jobs checking code style, changes to
+the default Rust style only appear in *style editions*.
+
+Code written in a given
+[Rust edition](https://doc.rust-lang.org/edition-guide/)
+uses the corresponding Rust style edition by default. To make it easier to
+migrate code style separately from the semantic changes between Rust editions,
+formatting tools such as `rustfmt` allow updating the style edition separately
+from the Rust edition.
+
+The current version of the style guide describes the latest Rust style edition.
+Each distinct past style will have a corresponding archived version of the
+style guide.
+
+Note that archived versions of the style guide do not document formatting for
+newer Rust constructs that did not exist at the time that version of the style
+guide was archived. However, each style edition will still format all
+constructs valid in that Rust edition, with the style of newer constructs
+coming from the first subsequent style edition providing formatting rules for
+that construct (without any of the systematic/global changes from that style
+edition).
+
+Not all Rust editions have corresponding changes to the Rust style. For
+instance, Rust 2015, Rust 2018, and Rust 2021 all use the same style edition.
+
+## Rust 2024 style edition
+
+This style guide describes the Rust 2024 style edition. The Rust 2024 style
+edition is currently nightly-only and may change before the release of Rust
+2024.
+
+For a full history of changes in the Rust 2024 style edition, see the git
+history of the style guide. Notable changes in the Rust 2024 style edition
+include:
+
+- Miscellaneous `rustfmt` bugfixes.
+
+## Rust 2015/2018/2021 style edition
+
+The archived version of the style guide at
+<https://github.com/rust-lang/rust/tree/37343f4a4d4ed7ad0891cb79e8eb25acf43fb821/src/doc/style-guide/src>
+describes the style edition corresponding to Rust 2015, Rust 2018, and Rust
+2021.