Merge from rustc

Author: The Miri Cronjob Bot

Cargo.lock

@@ -183,38 +183,6 @@ impl Argument<'_> {
             ArgumentType::Placeholder { .. } => None,
         }
     }
-
-    /// Used by `format_args` when all arguments are gone after inlining,
-    /// when using `&[]` would incorrectly allow for a bigger lifetime.
-    ///
-    /// This fails without format argument inlining, and that shouldn't be different
-    /// when the argument is inlined:
-    ///
-    /// ```compile_fail,E0716
-    /// let f = format_args!("{}", "a");
-    /// println!("{f}");
-    /// ```
-    #[inline]
-    pub const fn none() -> [Self; 0] {
-        []
-    }
-}
-
-/// This struct represents the unsafety of constructing an `Arguments`.
-/// It exists, rather than an unsafe function, in order to simplify the expansion
-/// of `format_args!(..)` and reduce the scope of the `unsafe` block.
-#[lang = "format_unsafe_arg"]
-pub struct UnsafeArg {
-    _private: (),
-}
-
-impl UnsafeArg {
-    /// See documentation where `UnsafeArg` is required to know when it is safe to
-    /// create and use `UnsafeArg`.
-    #[inline]
-    pub const unsafe fn new() -> Self {
-        Self { _private: () }
-    }
 }
 
 /// Used by the format_args!() macro to create a fmt::Arguments object.
@@ -248,8 +216,7 @@ impl<'a> Arguments<'a> {
 
     /// Specifies nonstandard formatting parameters.
     ///
-    /// An `rt::UnsafeArg` is required because the following invariants must be held
-    /// in order for this function to be safe:
+    /// SAFETY: the following invariants must be held:
     /// 1. The `pieces` slice must be at least as long as `fmt`.
     /// 2. Every `rt::Placeholder::position` value within `fmt` must be a valid index of `args`.
     /// 3. Every `rt::Count::Param` within `fmt` must contain a valid index of `args`.
@@ -261,11 +228,10 @@ impl<'a> Arguments<'a> {
     /// const _: () = if false { panic!("a {:1}", "a") };
     /// ```
     #[inline]
-    pub fn new_v1_formatted(
+    pub unsafe fn new_v1_formatted(
         pieces: &'a [&'static str],
         args: &'a [rt::Argument<'a>],
         fmt: &'a [rt::Placeholder],
-        _unsafe_arg: rt::UnsafeArg,
     ) -> Arguments<'a> {
         Arguments { pieces, fmt: Some(fmt), args }
     }

core/src/fmt/rt.rs

@@ -2,6 +2,21 @@ mod builders;
 mod float;
 mod num;
 
+#[test]
+fn test_lifetime() {
+    // Trigger all different forms of expansion,
+    // and check that each of them can be stored as a variable.
+    let a = format_args!("hello");
+    let a = format_args!("hello {a}");
+    let a = format_args!("hello {a:1}");
+    let a = format_args!("hello {a} {a:?}");
+    assert_eq!(a.to_string(), "hello hello hello hello hello hello hello");
+
+    // Without arguments, it should also work in consts.
+    const A: std::fmt::Arguments<'static> = format_args!("hello");
+    assert_eq!(A.to_string(), "hello");
+}
+
 #[test]
 fn test_format_flags() {
     // No residual flags left by pointer formatting

coretests/tests/fmt/mod.rs

@@ -1316,8 +1316,17 @@ impl PathBuf {
             need_sep = false
         }
 
+        let need_clear = if cfg!(target_os = "cygwin") {
+            // If path is absolute and its prefix is none, it is like `/foo`,
+            // and will be handled below.
+            path.prefix().is_some()
+        } else {
+            // On Unix: prefix is always None.
+            path.is_absolute() || path.prefix().is_some()
+        };
+
         // absolute `path` replaces `self`
-        if path.is_absolute() || path.prefix().is_some() {
+        if need_clear {
             self.inner.truncate(0);
 
         // verbatim paths need . and .. removed
@@ -3643,6 +3652,11 @@ impl Error for NormalizeError {}
 /// paths, this is currently equivalent to calling
 /// [`GetFullPathNameW`][windows-path].
 ///
+/// On Cygwin, this is currently equivalent to calling [`cygwin_conv_path`][cygwin-path]
+/// with mode `CCP_WIN_A_TO_POSIX`, and then being processed like other POSIX platforms.
+/// If a Windows path is given, it will be converted to an absolute POSIX path without
+/// keeping `..`.
+///
 /// Note that these [may change in the future][changes].
 ///
 /// # Errors
@@ -3700,6 +3714,7 @@ impl Error for NormalizeError {}
 /// [changes]: io#platform-specific-behavior
 /// [posix-semantics]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13
 /// [windows-path]: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getfullpathnamew
+/// [cygwin-path]: https://cygwin.com/cygwin-api/func-cygwin-conv-path.html
 #[stable(feature = "absolute_path", since = "1.79.0")]
 pub fn absolute<P: AsRef<Path>>(path: P) -> io::Result<PathBuf> {
     let path = path.as_ref();

std/src/path.rs

@@ -0,0 +1,92 @@
+use crate::ffi::OsString;
+use crate::os::unix::ffi::OsStringExt;
+use crate::path::{Path, PathBuf};
+use crate::sys::common::small_c_string::run_path_with_cstr;
+use crate::sys::cvt;
+use crate::{io, ptr};
+
+#[inline]
+pub fn is_sep_byte(b: u8) -> bool {
+    b == b'/' || b == b'\\'
+}
+
+/// Cygwin allways prefers `/` over `\`, and it always converts all `/` to `\`
+/// internally when calling Win32 APIs. Therefore, the server component of path
+/// `\\?\UNC\localhost/share` is `localhost/share` on Win32, but `localhost`
+/// on Cygwin.
+#[inline]
+pub fn is_verbatim_sep(b: u8) -> bool {
+    b == b'/' || b == b'\\'
+}
+
+pub use super::windows_prefix::parse_prefix;
+
+pub const MAIN_SEP_STR: &str = "/";
+pub const MAIN_SEP: char = '/';
+
+unsafe extern "C" {
+    // Doc: https://cygwin.com/cygwin-api/func-cygwin-conv-path.html
+    // Src: https://github.com/cygwin/cygwin/blob/718a15ba50e0d01c79800bd658c2477f9a603540/winsup/cygwin/path.cc#L3902
+    // Safety:
+    // * `what` should be `CCP_WIN_A_TO_POSIX` here
+    // * `from` is null-terminated UTF-8 path
+    // * `to` is buffer, the buffer size is `size`.
+    //
+    // Converts a path to an absolute POSIX path, no matter the input is Win32 path or POSIX path.
+    fn cygwin_conv_path(
+        what: libc::c_uint,
+        from: *const libc::c_char,
+        to: *mut u8,
+        size: libc::size_t,
+    ) -> libc::ssize_t;
+}
+
+const CCP_WIN_A_TO_POSIX: libc::c_uint = 2;
+
+/// Make a POSIX path absolute.
+pub(crate) fn absolute(path: &Path) -> io::Result<PathBuf> {
+    run_path_with_cstr(path, &|path| {
+        let conv = CCP_WIN_A_TO_POSIX;
+        let size = cvt(unsafe { cygwin_conv_path(conv, path.as_ptr(), ptr::null_mut(), 0) })?;
+        // If success, size should not be 0.
+        debug_assert!(size >= 1);
+        let size = size as usize;
+        let mut buffer = Vec::with_capacity(size);
+        cvt(unsafe { cygwin_conv_path(conv, path.as_ptr(), buffer.as_mut_ptr(), size) })?;
+        unsafe {
+            buffer.set_len(size - 1);
+        }
+        Ok(PathBuf::from(OsString::from_vec(buffer)))
+    })
+    .map(|path| {
+        if path.prefix().is_some() {
+            return path;
+        }
+
+        // From unix.rs
+        let mut components = path.components();
+        let path_os = path.as_os_str().as_encoded_bytes();
+
+        let mut normalized = if path_os.starts_with(b"//") && !path_os.starts_with(b"///") {
+            components.next();
+            PathBuf::from("//")
+        } else {
+            PathBuf::new()
+        };
+        normalized.extend(components);
+
+        if path_os.ends_with(b"/") {
+            normalized.push("");
+        }
+
+        normalized
+    })
+}
+
+pub(crate) fn is_absolute(path: &Path) -> bool {
+    if path.as_os_str().as_encoded_bytes().starts_with(b"\\") {
+        path.has_root() && path.prefix().is_some()
+    } else {
+        path.has_root()
+    }
+}

std/src/sys/path/cygwin.rs

@@ -1,6 +1,7 @@
 cfg_if::cfg_if! {
     if #[cfg(target_os = "windows")] {
         mod windows;
+        mod windows_prefix;
         pub use windows::*;
     } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
         mod sgx;
@@ -11,6 +12,10 @@ cfg_if::cfg_if! {
     } else if #[cfg(target_os = "uefi")] {
         mod uefi;
         pub use uefi::*;
+    } else if #[cfg(target_os = "cygwin")] {
+        mod cygwin;
+        mod windows_prefix;
+        pub use cygwin::*;
     } else {
         mod unix;
         pub use unix::*;