Auto merge of #101611 - GuillaumeGomez:rollup-yw3qtug, r=GuillaumeGomez

Rollup of 5 pull requests

Successful merges:

 - #101475 (Use futex-based locks and thread parker on Hermit)
 - #101492 (Suggest adding array lengths to references to arrays if possible)
 - #101495 (Compile spin_loop_hint as pause on x86 even without sse2 enabled)
 - #101529 (Fix the example code and doctest for Formatter::sign_plus)
 - #101600 (rustdoc: simplify the codeblock tooltip)

Failed merges:

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

Cargo.lock

@@ -1656,12 +1656,13 @@ dependencies = [
 
 [[package]]
 name = "hermit-abi"
-version = "0.2.0"
+version = "0.2.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ab7905ea95c6d9af62940f9d7dd9596d54c334ae2c15300c482051292d5637f"
+checksum = "ee512640fe35acbfb4bb779db6f0d80704c2cacfa2e39b601ef3e3f47d1ae4c7"
 dependencies = [
  "compiler_builtins",
  "libc",
+ "rustc-std-workspace-alloc",
  "rustc-std-workspace-core",
 ]
 
@@ -4608,7 +4609,7 @@ dependencies = [
  "dlmalloc",
  "fortanix-sgx-abi",
  "hashbrown",
- "hermit-abi 0.2.0",
+ "hermit-abi 0.2.6",
  "libc",
  "miniz_oxide 0.4.0",
  "object 0.26.2",

compiler/rustc_hir/src/hir.rs

@@ -2401,6 +2401,14 @@ impl<'hir> Ty<'hir> {
             _ => None,
         }
     }
+
+    pub fn peel_refs(&self) -> &Self {
+        let mut final_ty = self;
+        while let TyKind::Rptr(_, MutTy { ty, .. }) = &final_ty.kind {
+            final_ty = &ty;
+        }
+        final_ty
+    }
 }
 
 /// Not represented directly in the AST; referred to by name through a `ty_path`.

compiler/rustc_typeck/src/check/expr.rs

@@ -1305,31 +1305,30 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     }
 
     fn suggest_array_len(&self, expr: &'tcx hir::Expr<'tcx>, array_len: u64) {
-        if let Some(parent_hir_id) = self.tcx.hir().find_parent_node(expr.hir_id) {
-            let ty = match self.tcx.hir().find(parent_hir_id) {
-                Some(
-                    hir::Node::Local(hir::Local { ty: Some(ty), .. })
-                    | hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(ty, _), .. }),
-                ) => Some(ty),
-                _ => None,
-            };
-            if let Some(ty) = ty
-                && let hir::TyKind::Array(_, length) = ty.kind
-                && let hir::ArrayLen::Body(hir::AnonConst { hir_id, .. }) = length
-                && let Some(span) = self.tcx.hir().opt_span(hir_id)
-            {
-                match self.tcx.sess.diagnostic().steal_diagnostic(span, StashKey::UnderscoreForArrayLengths) {
-                    Some(mut err) => {
-                        err.span_suggestion(
-                            span,
-                            "consider specifying the array length",
-                            array_len,
-                            Applicability::MaybeIncorrect,
-                        );
-                        err.emit();
-                    }
-                    None => ()
+        let parent_node = self.tcx.hir().parent_iter(expr.hir_id).find(|(_, node)| {
+            !matches!(node, hir::Node::Expr(hir::Expr { kind: hir::ExprKind::AddrOf(..), .. }))
+        });
+        let Some((_,
+            hir::Node::Local(hir::Local { ty: Some(ty), .. })
+            | hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(ty, _), .. }))
+        ) = parent_node else {
+            return
+        };
+        if let hir::TyKind::Array(_, length) = ty.peel_refs().kind
+            && let hir::ArrayLen::Body(hir::AnonConst { hir_id, .. }) = length
+            && let Some(span) = self.tcx.hir().opt_span(hir_id)
+        {
+            match self.tcx.sess.diagnostic().steal_diagnostic(span, StashKey::UnderscoreForArrayLengths) {
+                Some(mut err) => {
+                    err.span_suggestion(
+                        span,
+                        "consider specifying the array length",
+                        array_len,
+                        Applicability::MaybeIncorrect,
+                    );
+                    err.emit();
                 }
+                None => ()
             }
         }
     }

library/core/src/fmt/mod.rs

@@ -1819,14 +1819,15 @@ impl<'a> Formatter<'a> {
     ///             write!(formatter,
     ///                    "Foo({}{})",
     ///                    if self.0 < 0 { '-' } else { '+' },
-    ///                    self.0)
+    ///                    self.0.abs())
     ///         } else {
     ///             write!(formatter, "Foo({})", self.0)
     ///         }
     ///     }
     /// }
     ///
     /// assert_eq!(&format!("{:+}", Foo(23)), "Foo(+23)");
+    /// assert_eq!(&format!("{:+}", Foo(-23)), "Foo(-23)");
     /// assert_eq!(&format!("{}", Foo(23)), "Foo(23)");
     /// ```
     #[must_use]

library/core/src/hint.rs

@@ -160,19 +160,16 @@ pub const unsafe fn unreachable_unchecked() -> ! {
 #[inline]
 #[stable(feature = "renamed_spin_loop", since = "1.49.0")]
 pub fn spin_loop() {
-    #[cfg(all(any(target_arch = "x86", target_arch = "x86_64"), target_feature = "sse2"))]
+    #[cfg(target_arch = "x86")]
     {
-        #[cfg(target_arch = "x86")]
-        {
-            // SAFETY: the `cfg` attr ensures that we only execute this on x86 targets.
-            unsafe { crate::arch::x86::_mm_pause() };
-        }
+        // SAFETY: the `cfg` attr ensures that we only execute this on x86 targets.
+        unsafe { crate::arch::x86::_mm_pause() };
+    }
 
-        #[cfg(target_arch = "x86_64")]
-        {
-            // SAFETY: the `cfg` attr ensures that we only execute this on x86_64 targets.
-            unsafe { crate::arch::x86_64::_mm_pause() };
-        }
+    #[cfg(target_arch = "x86_64")]
+    {
+        // SAFETY: the `cfg` attr ensures that we only execute this on x86_64 targets.
+        unsafe { crate::arch::x86_64::_mm_pause() };
     }
 
     // RISC-V platform spin loop hint implementation

library/std/Cargo.toml

@@ -42,7 +42,7 @@ dlmalloc = { version = "0.2.3", features = ['rustc-dep-of-std'] }
 fortanix-sgx-abi = { version = "0.5.0", features = ['rustc-dep-of-std'] }
 
 [target.'cfg(target_os = "hermit")'.dependencies]
-hermit-abi = { version = "0.2.0", features = ['rustc-dep-of-std'] }
+hermit-abi = { version = "0.2.6", features = ['rustc-dep-of-std'] }
 
 [target.wasm32-wasi.dependencies]
 wasi = { version = "0.11.0", features = ['rustc-dep-of-std'], default-features = false }

library/std/src/sys/hermit/futex.rs

@@ -0,0 +1,39 @@
+use super::abi;
+use crate::ptr::null;
+use crate::sync::atomic::AtomicU32;
+use crate::time::Duration;
+
+pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -> bool {
+    // Calculate the timeout as a relative timespec.
+    //
+    // Overflows are rounded up to an infinite timeout (None).
+    let timespec = timeout.and_then(|dur| {
+        Some(abi::timespec {
+            tv_sec: dur.as_secs().try_into().ok()?,
+            tv_nsec: dur.subsec_nanos().into(),
+        })
+    });
+
+    let r = unsafe {
+        abi::futex_wait(
+            futex.as_mut_ptr(),
+            expected,
+            timespec.as_ref().map_or(null(), |t| t as *const abi::timespec),
+            abi::FUTEX_RELATIVE_TIMEOUT,
+        )
+    };
+
+    r != -abi::errno::ETIMEDOUT
+}
+
+#[inline]
+pub fn futex_wake(futex: &AtomicU32) -> bool {
+    unsafe { abi::futex_wake(futex.as_mut_ptr(), 1) > 0 }
+}
+
+#[inline]
+pub fn futex_wake_all(futex: &AtomicU32) {
+    unsafe {
+        abi::futex_wake(futex.as_mut_ptr(), i32::MAX);
+    }
+}

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

@@ -25,6 +25,7 @@ pub mod cmath;
 pub mod env;
 pub mod fd;
 pub mod fs;
+pub mod futex;
 #[path = "../unsupported/io.rs"]
 pub mod io;
 pub mod memchr;
@@ -45,14 +46,14 @@ pub mod thread_local_dtor;
 pub mod thread_local_key;
 pub mod time;
 
-mod condvar;
-mod mutex;
-mod rwlock;
-
+#[path = "../unix/locks"]
 pub mod locks {
-    pub use super::condvar::*;
-    pub use super::mutex::*;
-    pub use super::rwlock::*;
+    mod futex_condvar;
+    mod futex_mutex;
+    mod futex_rwlock;
+    pub(crate) use futex_condvar::MovableCondvar;
+    pub(crate) use futex_mutex::{MovableMutex, Mutex};
+    pub(crate) use futex_rwlock::{MovableRwLock, RwLock};
 }
 
 use crate::io::ErrorKind;