Auto merge of rust-lang#127840 - tgross35:rollup-jfkg1dq, r=tgross35

Rollup of 9 pull requests

Successful merges:

 - rust-lang#125206 (Simplify environment variable examples)
 - rust-lang#126271 (Skip fast path for dec2flt when optimize_for_size)
 - rust-lang#126776 (Clean up more comments near use declarations)
 - rust-lang#127444 (`impl Send + Sync` and override `count` for the `CStr::bytes` iterator)
 - rust-lang#127512 (Terminate `--print link-args` output with newline)
 - rust-lang#127792 (std: Use `read_unaligned` for reads from DWARF)
 - rust-lang#127807 (Use futex.rs for Windows thread parking)
 - rust-lang#127833 (zkvm: add `#[forbid(unsafe_op_in_unsafe_fn)]` in `stdlib`)
 - rust-lang#127836 (std: Forbid unwrapped unsafe ops in xous and uefi modules)

Failed merges:

 - rust-lang#127813 (Prevent double reference in generic futex)

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

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -750,7 +750,7 @@ fn link_natively(
 
     for print in &sess.opts.prints {
         if print.kind == PrintKind::LinkArgs {
-            let content = format!("{cmd:?}");
+            let content = format!("{cmd:?}\n");
             print.out.overwrite(&content, sess);
         }
     }

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -34,7 +34,6 @@ use super::{
     Pointer, Projectable, Scalar, ValueVisitor,
 };
 
-// for the validation errors
 use super::InterpError::UndefinedBehavior as Ub;
 use super::InterpError::Unsupported as Unsup;
 use super::UndefinedBehaviorInfo::*;

compiler/rustc_lint/src/lib.rs

@@ -120,7 +120,6 @@ use types::*;
 use unit_bindings::*;
 use unused::*;
 
-/// Useful for other parts of the compiler / Clippy.
 pub use builtin::{MissingDoc, SoftLints};
 pub use context::{CheckLintNameResult, FindLintError, LintStore};
 pub use context::{EarlyContext, LateContext, LintContext};

compiler/rustc_pattern_analysis/src/lib.rs

@@ -21,9 +21,7 @@ rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
 use std::fmt;
 
-// Re-exports to avoid rustc_index version issues.
-pub use rustc_index::Idx;
-pub use rustc_index::IndexVec;
+pub use rustc_index::{Idx, IndexVec}; // re-exported to avoid rustc_index version issues
 
 #[cfg(feature = "rustc")]
 use rustc_middle::ty::Ty;

compiler/rustc_smir/src/rustc_internal/internal.rs

@@ -4,6 +4,7 @@
 //! due to incomplete stable coverage.
 
 // Prefer importing stable_mir over internal rustc constructs to make this file more readable.
+
 use crate::rustc_smir::Tables;
 use rustc_middle::ty::{self as rustc_ty, Const as InternalConst, Ty as InternalTy, TyCtxt};
 use rustc_span::Symbol;

library/alloc/src/testing/crash_test.rs

@@ -1,5 +1,4 @@
-// We avoid relying on anything else in the crate, apart from the `Debug` trait.
-use crate::fmt::Debug;
+use crate::fmt::Debug; // the `Debug` trait is the only thing we use from `crate::fmt`
 use std::cmp::Ordering;
 use std::sync::atomic::{AtomicUsize, Ordering::SeqCst};
 

library/core/src/char/mod.rs

@@ -24,19 +24,17 @@ mod convert;
 mod decode;
 mod methods;
 
-// stable re-exports
 #[stable(feature = "try_from", since = "1.34.0")]
 pub use self::convert::CharTryFromError;
 #[stable(feature = "char_from_str", since = "1.20.0")]
 pub use self::convert::ParseCharError;
 #[stable(feature = "decode_utf16", since = "1.9.0")]
 pub use self::decode::{DecodeUtf16, DecodeUtf16Error};
 
-// perma-unstable re-exports
 #[unstable(feature = "char_internals", reason = "exposed only for libstd", issue = "none")]
-pub use self::methods::encode_utf16_raw;
+pub use self::methods::encode_utf16_raw; // perma-unstable
 #[unstable(feature = "char_internals", reason = "exposed only for libstd", issue = "none")]
-pub use self::methods::encode_utf8_raw;
+pub use self::methods::encode_utf8_raw; // perma-unstable
 
 use crate::ascii;
 use crate::error::Error;

library/core/src/ffi/c_str.rs

@@ -781,8 +781,15 @@ const unsafe fn strlen(ptr: *const c_char) -> usize {
 pub struct Bytes<'a> {
     // since we know the string is nul-terminated, we only need one pointer
     ptr: NonNull<u8>,
-    phantom: PhantomData<&'a u8>,
+    phantom: PhantomData<&'a [c_char]>,
 }
+
+#[unstable(feature = "cstr_bytes", issue = "112115")]
+unsafe impl Send for Bytes<'_> {}
+
+#[unstable(feature = "cstr_bytes", issue = "112115")]
+unsafe impl Sync for Bytes<'_> {}
+
 impl<'a> Bytes<'a> {
     #[inline]
     fn new(s: &'a CStr) -> Self {
@@ -815,7 +822,7 @@ impl Iterator for Bytes<'_> {
             if ret == 0 {
                 None
             } else {
-                self.ptr = self.ptr.offset(1);
+                self.ptr = self.ptr.add(1);
                 Some(ret)
             }
         }
@@ -825,6 +832,12 @@ impl Iterator for Bytes<'_> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         if self.is_empty() { (0, Some(0)) } else { (1, None) }
     }
+
+    #[inline]
+    fn count(self) -> usize {
+        // SAFETY: We always hold a valid pointer to a C string
+        unsafe { strlen(self.ptr.as_ptr().cast()) }
+    }
 }
 
 #[unstable(feature = "cstr_bytes", issue = "112115")]

library/core/src/num/dec2flt/mod.rs

@@ -250,8 +250,10 @@ pub fn dec2flt<F: RawFloat>(s: &str) -> Result<F, ParseFloatError> {
         None => return Err(pfe_invalid()),
     };
     num.negative = negative;
-    if let Some(value) = num.try_fast_path::<F>() {
-        return Ok(value);
+    if !cfg!(feature = "optimize_for_size") {
+        if let Some(value) = num.try_fast_path::<F>() {
+            return Ok(value);
+        }
     }
 
     // If significant digits were truncated, then we can have rounding error

library/core/src/prelude/common.rs

@@ -2,6 +2,9 @@
 //!
 //! See the [module-level documentation](super) for more.
 
+// No formatting: this file is nothing but re-exports, and their order is worth preserving.
+#![cfg_attr(rustfmt, rustfmt::skip)]
+
 // Re-exported core operators
 #[stable(feature = "core_prelude", since = "1.4.0")]
 #[doc(no_inline)]
@@ -33,10 +36,7 @@ pub use crate::convert::{AsMut, AsRef, From, Into};
 pub use crate::default::Default;
 #[stable(feature = "core_prelude", since = "1.4.0")]
 #[doc(no_inline)]
-pub use crate::iter::{DoubleEndedIterator, ExactSizeIterator};
-#[stable(feature = "core_prelude", since = "1.4.0")]
-#[doc(no_inline)]
-pub use crate::iter::{Extend, IntoIterator, Iterator};
+pub use crate::iter::{DoubleEndedIterator, ExactSizeIterator, Extend, IntoIterator, Iterator};
 #[stable(feature = "core_prelude", since = "1.4.0")]
 #[doc(no_inline)]
 pub use crate::option::Option::{self, None, Some};

library/core/src/prelude/mod.rs

@@ -4,6 +4,9 @@
 //! This module is imported by default when `#![no_std]` is used in the same
 //! manner as the standard library's prelude.
 
+// No formatting: this file is nothing but re-exports, and their order is worth preserving.
+#![cfg_attr(rustfmt, rustfmt::skip)]
+
 #![stable(feature = "core_prelude", since = "1.4.0")]
 
 mod common;

library/core/src/ptr/mod.rs

@@ -1809,10 +1809,9 @@ pub(crate) const unsafe fn align_offset<T: Sized>(p: *const T, a: usize) -> usiz
     // FIXME(#75598): Direct use of these intrinsics improves codegen significantly at opt-level <=
     // 1, where the method versions of these operations are not inlined.
     use intrinsics::{
-        assume, cttz_nonzero, exact_div, mul_with_overflow, unchecked_rem, unchecked_sub,
-        wrapping_add, wrapping_mul, wrapping_sub,
+        assume, cttz_nonzero, exact_div, mul_with_overflow, unchecked_rem, unchecked_shl,
+        unchecked_shr, unchecked_sub, wrapping_add, wrapping_mul, wrapping_sub,
     };
-    use intrinsics::{unchecked_shl, unchecked_shr};
 
     /// Calculate multiplicative modular inverse of `x` modulo `m`.
     ///

library/core/src/unicode/mod.rs

@@ -1,6 +1,19 @@
 #![unstable(feature = "unicode_internals", issue = "none")]
 #![allow(missing_docs)]
 
+// The `pub use` ones are for use in alloc, and are not re-exported in std.
+
+pub(crate) use unicode_data::alphabetic::lookup as Alphabetic;
+pub use unicode_data::case_ignorable::lookup as Case_Ignorable;
+pub use unicode_data::cased::lookup as Cased;
+pub(crate) use unicode_data::cc::lookup as Cc;
+pub use unicode_data::conversions;
+pub(crate) use unicode_data::grapheme_extend::lookup as Grapheme_Extend;
+pub(crate) use unicode_data::lowercase::lookup as Lowercase;
+pub(crate) use unicode_data::n::lookup as N;
+pub(crate) use unicode_data::uppercase::lookup as Uppercase;
+pub(crate) use unicode_data::white_space::lookup as White_Space;
+
 pub(crate) mod printable;
 mod unicode_data;
 
@@ -16,16 +29,3 @@ mod unicode_data;
 /// [Unicode 11.0 or later, Section 3.1 Versions of the Unicode Standard](https://www.unicode.org/versions/Unicode11.0.0/ch03.pdf#page=4).
 #[stable(feature = "unicode_version", since = "1.45.0")]
 pub const UNICODE_VERSION: (u8, u8, u8) = unicode_data::UNICODE_VERSION;
-
-// For use in alloc, not re-exported in std.
-pub use unicode_data::{
-    case_ignorable::lookup as Case_Ignorable, cased::lookup as Cased, conversions,
-};
-
-pub(crate) use unicode_data::alphabetic::lookup as Alphabetic;
-pub(crate) use unicode_data::cc::lookup as Cc;
-pub(crate) use unicode_data::grapheme_extend::lookup as Grapheme_Extend;
-pub(crate) use unicode_data::lowercase::lookup as Lowercase;
-pub(crate) use unicode_data::n::lookup as N;
-pub(crate) use unicode_data::uppercase::lookup as Uppercase;
-pub(crate) use unicode_data::white_space::lookup as White_Space;

library/std/src/env.rs

@@ -120,11 +120,8 @@ pub struct VarsOs {
 /// # Examples
 ///
 /// ```
-/// use std::env;
-///
-/// // We will iterate through the references to the element returned by
-/// // env::vars();
-/// for (key, value) in env::vars() {
+/// // Print all environment variables.
+/// for (key, value) in std::env::vars() {
 ///     println!("{key}: {value}");
 /// }
 /// ```
@@ -150,11 +147,8 @@ pub fn vars() -> Vars {
 /// # Examples
 ///
 /// ```
-/// use std::env;
-///
-/// // We will iterate through the references to the element returned by
-/// // env::vars_os();
-/// for (key, value) in env::vars_os() {
+/// // Print all environment variables.
+/// for (key, value) in std::env::vars_os() {
 ///     println!("{key:?}: {value:?}");
 /// }
 /// ```

library/std/src/lib.rs

@@ -470,7 +470,6 @@ pub mod rt;
 // The Rust prelude
 pub mod prelude;
 
-// Public module declarations and re-exports
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use alloc_crate::borrow;
 #[stable(feature = "rust1", since = "1.0.0")]

library/std/src/os/fortanix_sgx/mod.rs

@@ -28,7 +28,6 @@ pub mod usercalls {
         pub use crate::sys::abi::usercalls::raw::{do_usercall, Usercalls as UsercallNrs};
         pub use crate::sys::abi::usercalls::raw::{Register, RegisterArgument, ReturnValue};
 
-        // fortanix-sgx-abi re-exports
         pub use crate::sys::abi::usercalls::raw::Error;
         pub use crate::sys::abi::usercalls::raw::{
             ByteBuffer, Cancel, FifoDescriptor, Return, Usercall,

library/std/src/os/uefi/mod.rs

@@ -2,6 +2,7 @@
 
 #![unstable(feature = "uefi_std", issue = "100499")]
 #![doc(cfg(target_os = "uefi"))]
+#![forbid(unsafe_op_in_unsafe_fn)]
 
 pub mod env;
 #[path = "../windows/ffi.rs"]

library/std/src/os/xous/mod.rs

@@ -1,5 +1,6 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 #![doc(cfg(target_os = "xous"))]
+#![forbid(unsafe_op_in_unsafe_fn)]
 
 pub mod ffi;
 

library/std/src/prelude/common.rs

@@ -2,6 +2,9 @@
 //!
 //! See the [module-level documentation](super) for more.
 
+// No formatting: this file is nothing but re-exports, and their order is worth preserving.
+#![cfg_attr(rustfmt, rustfmt::skip)]
+
 // Re-exported core operators
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(no_inline)]

library/std/src/prelude/mod.rs

@@ -95,6 +95,9 @@
 //! [book-enums]: ../../book/ch06-01-defining-an-enum.html
 //! [book-iter]: ../../book/ch13-02-iterators.html
 
+// No formatting: this file is nothing but re-exports, and their order is worth preserving.
+#![cfg_attr(rustfmt, rustfmt::skip)]
+
 #![stable(feature = "rust1", since = "1.0.0")]
 
 mod common;

library/std/src/rt.rs

@@ -16,7 +16,6 @@
 #![deny(unsafe_op_in_unsafe_fn)]
 #![allow(unused_macros)]
 
-// Re-export some of our utilities which are expected by other crates.
 pub use crate::panicking::{begin_panic, panic_count};
 pub use core::panicking::{panic_display, panic_fmt};
 

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

@@ -3,6 +3,11 @@ use crate::ptr::null;
 use crate::sync::atomic::AtomicU32;
 use crate::time::Duration;
 
+/// An atomic for use as a futex that is at least 8-bits but may be larger.
+pub type SmallAtomic = AtomicU32;
+/// Must be the underlying type of SmallAtomic
+pub type SmallPrimitive = u32;
+
 pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -> bool {
     // Calculate the timeout as a relative timespec.
     //

library/std/src/sys/pal/uefi/mod.rs

@@ -11,6 +11,7 @@
 //!
 //! [`OsStr`]: crate::ffi::OsStr
 //! [`OsString`]: crate::ffi::OsString
+#![forbid(unsafe_op_in_unsafe_fn)]
 
 pub mod alloc;
 pub mod args;

library/std/src/sys/pal/unix/futex.rs

@@ -11,6 +11,11 @@
 use crate::sync::atomic::AtomicU32;
 use crate::time::Duration;
 
+/// An atomic for use as a futex that is at least 8-bits but may be larger.
+pub type SmallAtomic = AtomicU32;
+/// Must be the underlying type of SmallAtomic
+pub type SmallPrimitive = u32;
+
 /// Wait for a futex_wake operation to wake us.
 ///
 /// Returns directly if the futex doesn't hold the expected value.

library/std/src/sys/pal/wasi/mod.rs

@@ -39,12 +39,15 @@ pub mod time;
 #[deny(unsafe_op_in_unsafe_fn)]
 #[allow(unused)]
 mod common;
+
 pub use common::*;
 
 mod helpers;
-// These exports are listed individually to work around Rust's glob import
-// conflict rules. If we glob export `helpers` and `common` together, then
-// the compiler complains about conflicts.
+
+// The following exports are listed individually to work around Rust's glob
+// import conflict rules. If we glob export `helpers` and `common` together,
+// then the compiler complains about conflicts.
+
 pub use helpers::abort_internal;
 pub use helpers::decode_error_kind;
 use helpers::err2io;

library/std/src/sys/pal/wasip2/mod.rs

@@ -41,13 +41,16 @@ pub mod time;
 #[deny(unsafe_op_in_unsafe_fn)]
 #[allow(unused)]
 mod common;
+
 pub use common::*;
 
 #[path = "../wasi/helpers.rs"]
 mod helpers;
-// These exports are listed individually to work around Rust's glob import
-// conflict rules. If we glob export `helpers` and `common` together, then
-// the compiler complains about conflicts.
+
+// The following exports are listed individually to work around Rust's glob
+// import conflict rules. If we glob export `helpers` and `common` together,
+// then the compiler complains about conflicts.
+
 pub use helpers::abort_internal;
 pub use helpers::decode_error_kind;
 use helpers::err2io;

library/std/src/sys/pal/wasm/atomics/futex.rs

@@ -6,6 +6,11 @@ use core::arch::wasm64 as wasm;
 use crate::sync::atomic::AtomicU32;
 use crate::time::Duration;
 
+/// An atomic for use as a futex that is at least 8-bits but may be larger.
+pub type SmallAtomic = AtomicU32;
+/// Must be the underlying type of SmallAtomic
+pub type SmallPrimitive = u32;
+
 /// Wait for a futex_wake operation to wake us.
 ///
 /// Returns directly if the futex doesn't hold the expected value.

library/std/src/sys/pal/windows/futex.rs

@@ -10,6 +10,11 @@ use core::sync::atomic::{
 };
 use core::time::Duration;
 
+/// An atomic for use as a futex that is at least 8-bits but may be larger.
+pub type SmallAtomic = AtomicU8;
+/// Must be the underlying type of SmallAtomic
+pub type SmallPrimitive = u8;
+
 pub unsafe trait Waitable {
     type Atomic;
 }

library/std/src/sys/pal/xous/mod.rs

@@ -1,4 +1,4 @@
-#![deny(unsafe_op_in_unsafe_fn)]
+#![forbid(unsafe_op_in_unsafe_fn)]
 
 pub mod alloc;
 #[path = "../unsupported/args.rs"]