Auto merge of #106228 - matthiaskrgr:rollup-jsznhww, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #104402 (Move `ReentrantMutex` to `std::sync`)
 - #104493 (available_parallelism: Gracefully handle zero value cfs_period_us)
 - #105359 (Make sentinel value configurable in `library/std/src/sys_common/thread_local_key.rs`)
 - #105497 (Clarify `catch_unwind` docs about panic hooks)
 - #105570 (Properly calculate best failure in macro matching)
 - #105702 (Format only modified files)
 - #105998 (adjust message on non-unwinding panic)
 - #106161 (Iterator::find: link to Iterator::position in docs for discoverability)

Failed merges:

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

compiler/rustc_expand/src/mbe/diagnostics.rs

@@ -43,7 +43,7 @@ pub(super) fn failed_to_match_macro<'cx>(
         return result;
     }
 
-    let Some((token, label, remaining_matcher)) = tracker.best_failure else {
+    let Some(BestFailure { token, msg: label, remaining_matcher, .. }) = tracker.best_failure else {
         return DummyResult::any(sp);
     };
 
@@ -95,11 +95,24 @@ struct CollectTrackerAndEmitter<'a, 'cx, 'matcher> {
     cx: &'a mut ExtCtxt<'cx>,
     remaining_matcher: Option<&'matcher MatcherLoc>,
     /// Which arm's failure should we report? (the one furthest along)
-    best_failure: Option<(Token, &'static str, MatcherLoc)>,
+    best_failure: Option<BestFailure>,
     root_span: Span,
     result: Option<Box<dyn MacResult + 'cx>>,
 }
 
+struct BestFailure {
+    token: Token,
+    position_in_tokenstream: usize,
+    msg: &'static str,
+    remaining_matcher: MatcherLoc,
+}
+
+impl BestFailure {
+    fn is_better_position(&self, position: usize) -> bool {
+        position > self.position_in_tokenstream
+    }
+}
+
 impl<'a, 'cx, 'matcher> Tracker<'matcher> for CollectTrackerAndEmitter<'a, 'cx, 'matcher> {
     fn before_match_loc(&mut self, parser: &TtParser, matcher: &'matcher MatcherLoc) {
         if self.remaining_matcher.is_none()
@@ -119,18 +132,25 @@ impl<'a, 'cx, 'matcher> Tracker<'matcher> for CollectTrackerAndEmitter<'a, 'cx,
                     "should not collect detailed info for successful macro match",
                 );
             }
-            Failure(token, msg) => match self.best_failure {
-                Some((ref best_token, _, _)) if best_token.span.lo() >= token.span.lo() => {}
-                _ => {
-                    self.best_failure = Some((
-                        token.clone(),
+            Failure(token, approx_position, msg) => {
+                debug!(?token, ?msg, "a new failure of an arm");
+
+                if self
+                    .best_failure
+                    .as_ref()
+                    .map_or(true, |failure| failure.is_better_position(*approx_position))
+                {
+                    self.best_failure = Some(BestFailure {
+                        token: token.clone(),
+                        position_in_tokenstream: *approx_position,
                         msg,
-                        self.remaining_matcher
+                        remaining_matcher: self
+                            .remaining_matcher
                             .expect("must have collected matcher already")
                             .clone(),
-                    ))
+                    })
                 }
-            },
+            }
             Error(err_sp, msg) => {
                 let span = err_sp.substitute_dummy(self.root_span);
                 self.cx.struct_span_err(span, msg).emit();

compiler/rustc_expand/src/mbe/macro_parser.rs

@@ -310,7 +310,8 @@ pub(crate) enum ParseResult<T> {
     Success(T),
     /// Arm failed to match. If the second parameter is `token::Eof`, it indicates an unexpected
     /// end of macro invocation. Otherwise, it indicates that no rules expected the given token.
-    Failure(Token, &'static str),
+    /// The usize is the approximate position of the token in the input token stream.
+    Failure(Token, usize, &'static str),
     /// Fatal error (malformed macro?). Abort compilation.
     Error(rustc_span::Span, String),
     ErrorReported(ErrorGuaranteed),
@@ -455,6 +456,7 @@ impl TtParser {
         &mut self,
         matcher: &'matcher [MatcherLoc],
         token: &Token,
+        approx_position: usize,
         track: &mut T,
     ) -> Option<NamedParseResult> {
         // Matcher positions that would be valid if the macro invocation was over now. Only
@@ -598,6 +600,7 @@ impl TtParser {
                         token::Eof,
                         if token.span.is_dummy() { token.span } else { token.span.shrink_to_hi() },
                     ),
+                    approx_position,
                     "missing tokens in macro arguments",
                 ),
             })
@@ -627,7 +630,12 @@ impl TtParser {
 
             // Process `cur_mps` until either we have finished the input or we need to get some
             // parsing from the black-box parser done.
-            let res = self.parse_tt_inner(matcher, &parser.token, track);
+            let res = self.parse_tt_inner(
+                matcher,
+                &parser.token,
+                parser.approx_token_stream_pos(),
+                track,
+            );
             if let Some(res) = res {
                 return res;
             }
@@ -642,6 +650,7 @@ impl TtParser {
                     // parser: syntax error.
                     return Failure(
                         parser.token.clone(),
+                        parser.approx_token_stream_pos(),
                         "no rules expected this token in macro call",
                     );
                 }

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -326,8 +326,8 @@ pub(super) fn try_match_macro<'matcher, T: Tracker<'matcher>>(
 
                 return Ok((i, named_matches));
             }
-            Failure(_, _) => {
-                trace!("Failed to match arm, trying the next one");
+            Failure(_, reached_position, _) => {
+                trace!(%reached_position, "Failed to match arm, trying the next one");
                 // Try the next arm.
             }
             Error(_, _) => {
@@ -432,7 +432,7 @@ pub fn compile_declarative_macro(
     let argument_map =
         match tt_parser.parse_tt(&mut Cow::Owned(parser), &argument_gram, &mut NoopTracker) {
             Success(m) => m,
-            Failure(token, msg) => {
+            Failure(token, _, msg) => {
                 let s = parse_failure_msg(&token);
                 let sp = token.span.substitute_dummy(def.span);
                 let mut err = sess.parse_sess.span_diagnostic.struct_span_err(sp, &s);

compiler/rustc_parse/src/parser/mod.rs

@@ -1499,6 +1499,10 @@ impl<'a> Parser<'a> {
     pub fn clear_expected_tokens(&mut self) {
         self.expected_tokens.clear();
     }
+
+    pub fn approx_token_stream_pos(&self) -> usize {
+        self.token_cursor.num_next_calls
+    }
 }
 
 pub(crate) fn make_unclosed_delims_error(

library/core/src/iter/traits/iterator.rs

@@ -2654,7 +2654,10 @@ pub trait Iterator {
     /// argument is a double reference. You can see this effect in the
     /// examples below, with `&&x`.
     ///
+    /// If you need the index of the element, see [`position()`].
+    ///
     /// [`Some(element)`]: Some
+    /// [`position()`]: Iterator::position
     ///
     /// # Examples
     ///

library/std/src/io/stdio.rs

@@ -10,9 +10,8 @@ use crate::fmt;
 use crate::fs::File;
 use crate::io::{self, BufReader, IoSlice, IoSliceMut, LineWriter, Lines};
 use crate::sync::atomic::{AtomicBool, Ordering};
-use crate::sync::{Arc, Mutex, MutexGuard, OnceLock};
+use crate::sync::{Arc, Mutex, MutexGuard, OnceLock, ReentrantMutex, ReentrantMutexGuard};
 use crate::sys::stdio;
-use crate::sys_common::remutex::{ReentrantMutex, ReentrantMutexGuard};
 
 type LocalStream = Arc<Mutex<Vec<u8>>>;
 

library/std/src/panic.rs

@@ -114,6 +114,9 @@ where
 /// aborting the process as well. This function *only* catches unwinding panics,
 /// not those that abort the process.
 ///
+/// Note that if a custom panic hook has been set, it will be invoked before
+/// the panic is caught, before unwinding.
+///
 /// Also note that unwinding into Rust code with a foreign exception (e.g.
 /// an exception thrown from C++ code) is undefined behavior.
 ///

library/std/src/panicking.rs

@@ -699,7 +699,11 @@ fn rust_panic_with_hook(
         // have limited options. Currently our preference is to
         // just abort. In the future we may consider resuming
         // unwinding or otherwise exiting the thread cleanly.
-        rtprintpanic!("thread panicked while panicking. aborting.\n");
+        if !can_unwind {
+            rtprintpanic!("thread caused non-unwinding panic. aborting.\n");
+        } else {
+            rtprintpanic!("thread panicked while panicking. aborting.\n");
+        }
         crate::sys::abort_internal();
     }
 

library/std/src/sync/mod.rs

@@ -177,6 +177,8 @@ pub use self::lazy_lock::LazyLock;
 #[unstable(feature = "once_cell", issue = "74465")]
 pub use self::once_lock::OnceLock;
 
+pub(crate) use self::remutex::{ReentrantMutex, ReentrantMutexGuard};
+
 pub mod mpsc;
 
 mod barrier;
@@ -187,4 +189,5 @@ mod mutex;
 mod once;
 mod once_lock;
 mod poison;
+mod remutex;
 mod rwlock;

library/std/src/sys_common/remutex/tests.rs → library/std/src/sync/remutex/tests.rs

@@ -1,6 +1,6 @@
+use super::{ReentrantMutex, ReentrantMutexGuard};
 use crate::cell::RefCell;
 use crate::sync::Arc;
-use crate::sys_common::remutex::{ReentrantMutex, ReentrantMutexGuard};
 use crate::thread;
 
 #[test]

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

@@ -505,7 +505,7 @@ mod cgroups {
                     let limit = raw_quota.next()?;
                     let period = raw_quota.next()?;
                     match (limit.parse::<usize>(), period.parse::<usize>()) {
-                        (Ok(limit), Ok(period)) => {
+                        (Ok(limit), Ok(period)) if period > 0 => {
                             quota = quota.min(limit / period);
                         }
                         _ => {}
@@ -565,7 +565,7 @@ mod cgroups {
                 let period = parse_file("cpu.cfs_period_us");
 
                 match (limit, period) {
-                    (Some(limit), Some(period)) => quota = quota.min(limit / period),
+                    (Some(limit), Some(period)) if period > 0 => quota = quota.min(limit / period),
                     _ => {}
                 }
 

library/std/src/sys_common/mod.rs

@@ -27,7 +27,6 @@ pub mod lazy_box;
 pub mod memchr;
 pub mod once;
 pub mod process;
-pub mod remutex;
 pub mod thread;
 pub mod thread_info;
 pub mod thread_local_dtor;

library/std/src/sys_common/thread_local_key.rs

@@ -117,10 +117,14 @@ pub struct Key {
 /// This value specifies no destructor by default.
 pub const INIT: StaticKey = StaticKey::new(None);
 
+// Define a sentinel value that is unlikely to be returned
+// as a TLS key (but it may be returned).
+const KEY_SENTVAL: usize = 0;
+
 impl StaticKey {
     #[rustc_const_unstable(feature = "thread_local_internals", issue = "none")]
     pub const fn new(dtor: Option<unsafe extern "C" fn(*mut u8)>) -> StaticKey {
-        StaticKey { key: atomic::AtomicUsize::new(0), dtor }
+        StaticKey { key: atomic::AtomicUsize::new(KEY_SENTVAL), dtor }
     }
 
     /// Gets the value associated with this TLS key
@@ -144,31 +148,36 @@ impl StaticKey {
     #[inline]
     unsafe fn key(&self) -> imp::Key {
         match self.key.load(Ordering::Relaxed) {
-            0 => self.lazy_init() as imp::Key,
+            KEY_SENTVAL => self.lazy_init() as imp::Key,
             n => n as imp::Key,
         }
     }
 
     unsafe fn lazy_init(&self) -> usize {
-        // POSIX allows the key created here to be 0, but the compare_exchange
-        // below relies on using 0 as a sentinel value to check who won the
+        // POSIX allows the key created here to be KEY_SENTVAL, but the compare_exchange
+        // below relies on using KEY_SENTVAL as a sentinel value to check who won the
         // race to set the shared TLS key. As far as I know, there is no
         // guaranteed value that cannot be returned as a posix_key_create key,
         // so there is no value we can initialize the inner key with to
         // prove that it has not yet been set. As such, we'll continue using a
-        // value of 0, but with some gyrations to make sure we have a non-0
+        // value of KEY_SENTVAL, but with some gyrations to make sure we have a non-KEY_SENTVAL
         // value returned from the creation routine.
         // FIXME: this is clearly a hack, and should be cleaned up.
         let key1 = imp::create(self.dtor);
-        let key = if key1 != 0 {
+        let key = if key1 as usize != KEY_SENTVAL {
             key1
         } else {
             let key2 = imp::create(self.dtor);
             imp::destroy(key1);
             key2
         };
-        rtassert!(key != 0);
-        match self.key.compare_exchange(0, key as usize, Ordering::SeqCst, Ordering::SeqCst) {
+        rtassert!(key as usize != KEY_SENTVAL);
+        match self.key.compare_exchange(
+            KEY_SENTVAL,
+            key as usize,
+            Ordering::SeqCst,
+            Ordering::SeqCst,
+        ) {
             // The CAS succeeded, so we've created the actual key
             Ok(_) => key as usize,
             // If someone beat us to the punch, use their key instead

src/bootstrap/CHANGELOG.md

@@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Several unsupported `./configure` options have been removed: `optimize`, `parallel-compiler`. These can still be enabled with `--set`, although it isn't recommended.
 - `remote-test-server`'s `verbose` argument has been removed in favor of the `--verbose` flag
 - `remote-test-server`'s `remote` argument has been removed in favor of the `--bind` flag. Use `--bind 0.0.0.0:12345` to replicate the behavior of the `remote` argument.
+- `x.py fmt` now formats only files modified between the merge-base of HEAD and the last commit in the master branch of the rust-lang repository and the current working directory. To restore old behaviour, use `x.py fmt .`. The check mode is not affected by this change. [#105702](https://github.com/rust-lang/rust/pull/105702)
 
 ### Non-breaking changes
 

src/bootstrap/clean.rs

@@ -94,6 +94,7 @@ fn clean_default(build: &Build, all: bool) {
         rm_rf(&build.out.join("tmp"));
         rm_rf(&build.out.join("dist"));
         rm_rf(&build.out.join("bootstrap"));
+        rm_rf(&build.out.join("rustfmt.stamp"));
 
         for host in &build.hosts {
             let entries = match build.out.join(host.triple).read_dir() {