Auto merge of #140165 - ChrisDenton:rollup-on2dpr5, r=ChrisDenton

Rollup of 8 pull requests

Successful merges:

 - #139617 (Use posix_spawn on cygwin)
 - #139921 (improve diagnostic for raw pointer field access with ->)
 - #140031 (compiletest: Fix deadline bugs in new executor)
 - #140072 (handle function alignment in miri)
 - #140104 (Fix auto diff failing on inherent impl blocks)
 - #140124 (Update books)
 - #140144 (Handle another negated literal in `eat_token_lit`.)
 - #140149 (test_nan: ensure the NAN contant is quiet)

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

Author: bors

compiler/rustc_builtin_macros/src/autodiff.rs

@@ -217,14 +217,12 @@ mod llvm_enzyme {
                 ast::StmtKind::Item(iitem) => extract_item_info(iitem),
                 _ => None,
             },
-            Annotatable::AssocItem(assoc_item, Impl { of_trait: false }) => {
-                match &assoc_item.kind {
-                    ast::AssocItemKind::Fn(box ast::Fn { sig, ident, .. }) => {
-                        Some((assoc_item.vis.clone(), sig.clone(), ident.clone()))
-                    }
-                    _ => None,
+            Annotatable::AssocItem(assoc_item, Impl { .. }) => match &assoc_item.kind {
+                ast::AssocItemKind::Fn(box ast::Fn { sig, ident, .. }) => {
+                    Some((assoc_item.vis.clone(), sig.clone(), ident.clone()))
                 }
-            }
+                _ => None,
+            },
             _ => None,
         }) else {
             dcx.emit_err(errors::AutoDiffInvalidApplication { span: item.span() });
@@ -365,7 +363,7 @@ mod llvm_enzyme {
                 }
                 Annotatable::Item(iitem.clone())
             }
-            Annotatable::AssocItem(ref mut assoc_item, i @ Impl { of_trait: false }) => {
+            Annotatable::AssocItem(ref mut assoc_item, i @ Impl { .. }) => {
                 if !assoc_item.attrs.iter().any(|a| same_attribute(&a.kind, &attr.kind)) {
                     assoc_item.attrs.push(attr);
                 }

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -872,8 +872,21 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
 
         // # Function pointers
         // (both global from `alloc_map` and local from `extra_fn_ptr_map`)
-        if self.get_fn_alloc(id).is_some() {
-            return AllocInfo::new(Size::ZERO, Align::ONE, AllocKind::Function, Mutability::Not);
+        if let Some(fn_val) = self.get_fn_alloc(id) {
+            let align = match fn_val {
+                FnVal::Instance(instance) => {
+                    // Function alignment can be set globally with the `-Zmin-function-alignment=<n>` flag;
+                    // the alignment from a `#[repr(align(<n>))]` is used if it specifies a higher alignment.
+                    let fn_align = self.tcx.codegen_fn_attrs(instance.def_id()).alignment;
+                    let global_align = self.tcx.sess.opts.unstable_opts.min_function_alignment;
+
+                    Ord::max(global_align, fn_align).unwrap_or(Align::ONE)
+                }
+                // Machine-specific extra functions currently do not support alignment restrictions.
+                FnVal::Other(_) => Align::ONE,
+            };
+
+            return AllocInfo::new(Size::ZERO, align, AllocKind::Function, Mutability::Not);
         }
 
         // # Global allocations

compiler/rustc_hir_typeck/src/expr.rs

@@ -3289,8 +3289,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         err.multipart_suggestion(
             format!("{val} is a raw pointer; try dereferencing it"),
             vec![
-                (base.span.shrink_to_lo(), "(*".to_string()),
-                (base.span.shrink_to_hi(), ")".to_string()),
+                (base.span.shrink_to_lo(), "(*".into()),
+                (base.span.between(field.span), format!(").")),
             ],
             Applicability::MaybeIncorrect,
         );

compiler/rustc_parse/messages.ftl

@@ -246,9 +246,9 @@ parse_expected_struct_field = expected one of `,`, `:`, or `{"}"}`, found `{$tok
 
 parse_expected_trait_in_trait_impl_found_type = expected a trait, found type
 
-parse_expr_rarrow_call = `->` used for field access or method call
+parse_expr_rarrow_call = `->` is not valid syntax for field accesses and method calls
     .suggestion = try using `.` instead
-    .help = the `.` operator will dereference the value if needed
+    .help = the `.` operator will automatically dereference the value, except if the value is a raw pointer
 
 parse_extern_crate_name_with_dashes = crate name using dashes are not valid in `extern crate` statements
     .label = dash-separated idents are not valid

compiler/rustc_parse/src/parser/expr.rs

@@ -2146,6 +2146,17 @@ impl<'a> Parser<'a> {
     /// Keep this in sync with `Token::can_begin_literal_maybe_minus` and
     /// `Lit::from_token` (excluding unary negation).
     fn eat_token_lit(&mut self) -> Option<token::Lit> {
+        let check_expr = |expr: P<Expr>| {
+            if let ast::ExprKind::Lit(token_lit) = expr.kind {
+                Some(token_lit)
+            } else if let ast::ExprKind::Unary(UnOp::Neg, inner) = &expr.kind
+                && let ast::Expr { kind: ast::ExprKind::Lit(_), .. } = **inner
+            {
+                None
+            } else {
+                panic!("unexpected reparsed expr/literal: {:?}", expr.kind);
+            }
+        };
         match self.token.uninterpolate().kind {
             token::Ident(name, IdentIsRaw::No) if name.is_bool_lit() => {
                 self.bump();
@@ -2159,26 +2170,15 @@ impl<'a> Parser<'a> {
                 let lit = self
                     .eat_metavar_seq(MetaVarKind::Literal, |this| this.parse_literal_maybe_minus())
                     .expect("metavar seq literal");
-                let ast::ExprKind::Lit(token_lit) = lit.kind else {
-                    panic!("didn't reparse a literal");
-                };
-                Some(token_lit)
+                check_expr(lit)
             }
             token::OpenInvisible(InvisibleOrigin::MetaVar(
                 mv_kind @ MetaVarKind::Expr { can_begin_literal_maybe_minus: true, .. },
             )) => {
                 let expr = self
                     .eat_metavar_seq(mv_kind, |this| this.parse_expr())
                     .expect("metavar seq expr");
-                if let ast::ExprKind::Lit(token_lit) = expr.kind {
-                    Some(token_lit)
-                } else if let ast::ExprKind::Unary(UnOp::Neg, inner) = &expr.kind
-                    && let ast::Expr { kind: ast::ExprKind::Lit(_), .. } = **inner
-                {
-                    None
-                } else {
-                    panic!("unexpected reparsed expr: {:?}", expr.kind);
-                }
+                check_expr(expr)
             }
             _ => None,
         }

library/core/src/num/f128.rs

@@ -145,6 +145,9 @@ impl f128 {
     pub const RADIX: u32 = 2;
 
     /// Number of significant digits in base 2.
+    ///
+    /// Note that the size of the mantissa in the bitwise representation is one
+    /// smaller than this since the leading 1 is not stored explicitly.
     #[unstable(feature = "f128", issue = "116909")]
     pub const MANTISSA_DIGITS: u32 = 113;
 

library/core/src/num/f16.rs

@@ -140,6 +140,9 @@ impl f16 {
     pub const RADIX: u32 = 2;
 
     /// Number of significant digits in base 2.
+    ///
+    /// Note that the size of the mantissa in the bitwise representation is one
+    /// smaller than this since the leading 1 is not stored explicitly.
     #[unstable(feature = "f16", issue = "116909")]
     pub const MANTISSA_DIGITS: u32 = 11;
 

library/core/src/num/f32.rs

@@ -390,6 +390,9 @@ impl f32 {
     pub const RADIX: u32 = 2;
 
     /// Number of significant digits in base 2.
+    ///
+    /// Note that the size of the mantissa in the bitwise representation is one
+    /// smaller than this since the leading 1 is not stored explicitly.
     #[stable(feature = "assoc_int_consts", since = "1.43.0")]
     pub const MANTISSA_DIGITS: u32 = 24;
 

library/core/src/num/f64.rs

@@ -390,6 +390,9 @@ impl f64 {
     pub const RADIX: u32 = 2;
 
     /// Number of significant digits in base 2.
+    ///
+    /// Note that the size of the mantissa in the bitwise representation is one
+    /// smaller than this since the leading 1 is not stored explicitly.
     #[stable(feature = "assoc_int_consts", since = "1.43.0")]
     pub const MANTISSA_DIGITS: u32 = 53;
     /// Approximate number of significant digits in base 10.

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

@@ -415,6 +415,7 @@ impl Command {
         all(target_os = "linux", target_env = "musl"),
         target_os = "nto",
         target_vendor = "apple",
+        target_os = "cygwin",
     )))]
     fn posix_spawn(
         &mut self,
@@ -433,6 +434,7 @@ impl Command {
         all(target_os = "linux", target_env = "musl"),
         target_os = "nto",
         target_vendor = "apple",
+        target_os = "cygwin",
     ))]
     fn posix_spawn(
         &mut self,
@@ -584,7 +586,7 @@ impl Command {
         /// Some platforms can set a new working directory for a spawned process in the
         /// `posix_spawn` path. This function looks up the function pointer for adding
         /// such an action to a `posix_spawn_file_actions_t` struct.
-        #[cfg(not(all(target_os = "linux", target_env = "musl")))]
+        #[cfg(not(any(all(target_os = "linux", target_env = "musl"), target_os = "cygwin")))]
         fn get_posix_spawn_addchdir() -> Option<PosixSpawnAddChdirFn> {
             use crate::sys::weak::weak;
 
@@ -618,7 +620,9 @@ impl Command {
         /// Weak symbol lookup doesn't work with statically linked libcs, so in cases
         /// where static linking is possible we need to either check for the presence
         /// of the symbol at compile time or know about it upfront.
-        #[cfg(all(target_os = "linux", target_env = "musl"))]
+        ///
+        /// Cygwin doesn't support weak symbol, so just link it.
+        #[cfg(any(all(target_os = "linux", target_env = "musl"), target_os = "cygwin"))]
         fn get_posix_spawn_addchdir() -> Option<PosixSpawnAddChdirFn> {
             // Our minimum required musl supports this function, so we can just use it.
             Some(libc::posix_spawn_file_actions_addchdir_np)

library/std/tests/floats/f128.rs

@@ -112,6 +112,8 @@ fn test_nan() {
     assert!(!nan.is_sign_negative());
     assert!(!nan.is_normal());
     assert_eq!(Fp::Nan, nan.classify());
+    // Ensure the quiet bit is set.
+    assert!(nan.to_bits() & (1 << (f128::MANTISSA_DIGITS - 2)) != 0);
 }
 
 #[test]

library/std/tests/floats/f16.rs

@@ -95,6 +95,8 @@ fn test_nan() {
     assert!(!nan.is_sign_negative());
     assert!(!nan.is_normal());
     assert_eq!(Fp::Nan, nan.classify());
+    // Ensure the quiet bit is set.
+    assert!(nan.to_bits() & (1 << (f16::MANTISSA_DIGITS - 2)) != 0);
 }
 
 #[test]

library/std/tests/floats/f32.rs

@@ -72,6 +72,8 @@ fn test_nan() {
     assert!(nan.is_sign_positive());
     assert!(!nan.is_sign_negative());
     assert_eq!(Fp::Nan, nan.classify());
+    // Ensure the quiet bit is set.
+    assert!(nan.to_bits() & (1 << (f32::MANTISSA_DIGITS - 2)) != 0);
 }
 
 #[test]

library/std/tests/floats/f64.rs

@@ -60,6 +60,8 @@ fn test_nan() {
     assert!(nan.is_sign_positive());
     assert!(!nan.is_sign_negative());
     assert_eq!(Fp::Nan, nan.classify());
+    // Ensure the quiet bit is set.
+    assert!(nan.to_bits() & (1 << (f64::MANTISSA_DIGITS - 2)) != 0);
 }
 
 #[test]

src/doc/nomicon

@@ -57,9 +57,11 @@ pub(crate) fn run_tests(config: &Config, tests: Vec<CollectedTest>) -> bool {
         }
 
         let completion = deadline_queue
-            .read_channel_while_checking_deadlines(&completion_rx, |_id, test| {
-                listener.test_timed_out(test);
-            })
+            .read_channel_while_checking_deadlines(
+                &completion_rx,
+                |id| running_tests.contains_key(&id),
+                |_id, test| listener.test_timed_out(test),
+            )
             .expect("receive channel should never be closed early");
 
         let RunningTest { test, join_handle } = running_tests.remove(&completion.id).unwrap();

src/doc/reference

@@ -21,16 +21,26 @@ impl<'a> DeadlineQueue<'a> {
         Self { queue: VecDeque::with_capacity(capacity) }
     }
 
+    /// All calls to [`Instant::now`] go through this wrapper method.
+    /// This makes it easier to find all places that read the current time.
+    fn now(&self) -> Instant {
+        Instant::now()
+    }
+
     pub(crate) fn push(&mut self, id: TestId, test: &'a CollectedTest) {
-        let deadline = Instant::now() + Duration::from_secs(TEST_WARN_TIMEOUT_S);
+        let deadline = self.now() + Duration::from_secs(TEST_WARN_TIMEOUT_S);
+        if let Some(back) = self.queue.back() {
+            assert!(back.deadline <= deadline);
+        }
         self.queue.push_back(DeadlineEntry { id, test, deadline });
     }
 
-    /// Equivalent to `rx.read()`, except that if any test exceeds its deadline
+    /// Equivalent to `rx.recv()`, except that if a test exceeds its deadline
     /// during the wait, the given callback will also be called for that test.
     pub(crate) fn read_channel_while_checking_deadlines<T>(
         &mut self,
         rx: &mpsc::Receiver<T>,
+        is_running: impl Fn(TestId) -> bool,
         mut on_deadline_passed: impl FnMut(TestId, &CollectedTest),
     ) -> Result<T, RecvError> {
         loop {
@@ -39,18 +49,18 @@ impl<'a> DeadlineQueue<'a> {
                 // deadline, so do a normal receive.
                 return rx.recv();
             };
-            let wait_duration = next_deadline.saturating_duration_since(Instant::now());
+            let next_deadline_timeout = next_deadline.saturating_duration_since(self.now());
+
+            let recv_result = rx.recv_timeout(next_deadline_timeout);
+            // Process deadlines after every receive attempt, regardless of
+            // outcome, so that we don't build up an unbounded backlog of stale
+            // entries due to a constant stream of tests finishing.
+            self.for_each_entry_past_deadline(&is_running, &mut on_deadline_passed);
 
-            let recv_result = rx.recv_timeout(wait_duration);
             match recv_result {
                 Ok(value) => return Ok(value),
-                Err(RecvTimeoutError::Timeout) => {
-                    // Notify the callback of tests that have exceeded their
-                    // deadline, then loop and do annother channel read.
-                    for DeadlineEntry { id, test, .. } in self.remove_tests_past_deadline() {
-                        on_deadline_passed(id, test);
-                    }
-                }
+                // Deadlines have already been processed, so loop and do another receive.
+                Err(RecvTimeoutError::Timeout) => {}
                 Err(RecvTimeoutError::Disconnected) => return Err(RecvError),
             }
         }
@@ -60,14 +70,28 @@ impl<'a> DeadlineQueue<'a> {
         Some(self.queue.front()?.deadline)
     }
 
-    fn remove_tests_past_deadline(&mut self) -> Vec<DeadlineEntry<'a>> {
-        let now = Instant::now();
-        let mut timed_out = vec![];
-        while let Some(deadline_entry) = pop_front_if(&mut self.queue, |entry| now < entry.deadline)
-        {
-            timed_out.push(deadline_entry);
+    fn for_each_entry_past_deadline(
+        &mut self,
+        is_running: impl Fn(TestId) -> bool,
+        mut on_deadline_passed: impl FnMut(TestId, &CollectedTest),
+    ) {
+        let now = self.now();
+
+        // Clear out entries that are past their deadline, but only invoke the
+        // callback for tests that are still considered running.
+        while let Some(entry) = pop_front_if(&mut self.queue, |entry| entry.deadline <= now) {
+            if is_running(entry.id) {
+                on_deadline_passed(entry.id, entry.test);
+            }
+        }
+
+        // Also clear out any leading entries that are no longer running, even
+        // if their deadline hasn't been reached.
+        while let Some(_) = pop_front_if(&mut self.queue, |entry| !is_running(entry.id)) {}
+
+        if let Some(front) = self.queue.front() {
+            assert!(now < front.deadline);
         }
-        timed_out
     }
 }
 

src/tools/compiletest/src/executor.rs

@@ -0,0 +1,21 @@
+//@compile-flags: -Zmin-function-alignment=8
+#![feature(fn_align)]
+
+// When a function uses `repr(align(N))`, the function address should be a multiple of `N`.
+
+#[repr(align(256))]
+fn foo() {}
+
+#[repr(align(16))]
+fn bar() {}
+
+#[repr(align(4))]
+fn baz() {}
+
+fn main() {
+    assert!((foo as usize).is_multiple_of(256));
+    assert!((bar as usize).is_multiple_of(16));
+
+    // The maximum of `repr(align(N))` and `-Zmin-function-alignment=N` is used.
+    assert!((baz as usize).is_multiple_of(8));
+}