Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 108 insertions, 0 deletions

diff --git a/vendor/io-lifetimes/examples/flexible-apis.rs b/vendor/io-lifetimes/examples/flexible-apis.rs
new file mode 100644
index 000000000..8eb19a287
--- /dev/null
+++ b/vendor/io-lifetimes/examples/flexible-apis.rs
@@ -0,0 +1,108 @@
+//! io-lifetimes provides two different options for library authors
+//! writing APIs which accept untyped I/O resources.
+//!
+//! The following uses the POSIX-ish `Fd` types; similar considerations
+//! apply to the Windows and portable types.
+
+#![cfg_attr(io_lifetimes_use_std, feature(io_safety))]
+
+#[cfg(all(feature = "close", not(windows)))]
+use io_lifetimes::{AsFd, BorrowedFd, IntoFd, OwnedFd};
+
+/// The simplest way to accept a borrowed I/O resource is to simply use a
+/// `BorrwedFd` as an argument. This doesn't require the function to have any
+/// type parameters. It also works in FFI signatures, as `BorrowedFd` and (on
+/// Rust nightly) `Option<BorrowedFd>` are guaranteed to have the same layout
+/// as `RawFd`.
+///
+/// Callers with an `AsFd`-implementing type would call `.as_fd()` and pass
+/// the result.
+#[cfg(all(feature = "close", not(windows)))]
+fn use_fd_a(fd: BorrowedFd<'_>) {
+    let _ = fd;
+}
+
+/// Another way to do this is to use an `AsFd` type parameter. This is more
+/// verbose at the function definition site, and entails monomorphization, but
+/// it has the advantage of allowing users to pass in any type implementing
+/// `AsFd` directly, without having to call `.as_fd()` themselves.
+#[cfg(all(feature = "close", not(windows)))]
+fn use_fd_b<Fd: AsFd>(fd: Fd) {
+    let _ = fd.as_fd();
+}
+
+/// Another way to do this is to use an `impl AsFd` parameter.
+#[cfg(all(feature = "close", not(windows)))]
+fn use_fd_c(fd: impl AsFd) {
+    let _ = fd.as_fd();
+}
+
+/// The simplest way to accept a consumed I/O resource is to simply use an
+/// `OwnedFd` as an argument. Similar to `use_fd_a`, this doesn't require the
+/// function to have any type parameters, and also works in FFI signatures.
+///
+/// Callers with an `IntoFd`-implementing type would call `.into_fd()` and pass
+/// the result.
+#[cfg(all(feature = "close", not(windows)))]
+fn consume_fd_a(fd: OwnedFd) {
+    let _ = fd;
+}
+
+/// Another way to do this is to use an `IntoFd` type parameter. Similar to
+/// `use_fd_b`, this is more verbose here and entails monomorphization, but it
+/// has the advantage of allowing users to pass in any type implementing
+/// `IntoFd` directly.
+#[cfg(all(feature = "close", not(windows)))]
+fn consume_fd_b<Fd: IntoFd>(fd: Fd) {
+    let _ = fd.into_fd();
+}
+
+/// Another way to do this is to use an `impl IntoFd` parameter.
+#[cfg(all(feature = "close", not(windows)))]
+fn consume_fd_c(fd: impl IntoFd) {
+    let _ = fd.into_fd();
+}
+
+/// Now let's see how the APIs look for users.
+#[cfg(all(feature = "close", not(windows)))]
+fn main() {
+    let f = std::fs::File::open("Cargo.toml").unwrap();
+
+    // The simple option requires an `.as_fd()` at the callsite.
+    use_fd_a(f.as_fd());
+
+    // Another option can take a reference to any owning type directly.
+    use_fd_b(&f);
+
+    // Of course, users can still pass in `BorrowedFd` values if they want to.
+    use_fd_b(f.as_fd());
+
+    // The other option is `impl AsFd`.
+    use_fd_c(&f);
+
+    // Users can still pass in `BorrowedFd` values if they want to here too.
+    use_fd_c(f.as_fd());
+
+    let a = std::fs::File::open("Cargo.toml").unwrap();
+    let b = std::fs::File::open("Cargo.toml").unwrap();
+    let c = std::fs::File::open("Cargo.toml").unwrap();
+
+    // The simple option requires an `.into_fd()` at the callsite.
+    consume_fd_a(a.into_fd());
+
+    // Another option can take any `IntoFd` type directly.
+    consume_fd_b(b);
+
+    // The other option can take any `IntoFd` type directly.
+    consume_fd_c(c);
+}
+
+#[cfg(windows)]
+fn main() {
+    println!("This example uses non-Windows APIs.");
+}
+
+#[cfg(all(not(feature = "close"), not(windows)))]
+fn main() {
+    println!("This example requires the \"close\" feature.");
+}