/// `NULL`. This ensures that such FFI calls cannot start using the handle without
/// checking for `NULL` first.
///
-/// This type concerns any value other than `NULL` to be valid, including `INVALID_HANDLE_VALUE`.
+/// This type considers any value other than `NULL` to be valid, including `INVALID_HANDLE_VALUE`.
/// This is because APIs that use `NULL` as their sentry value don't treat `INVALID_HANDLE_VALUE`
/// as special.
///
/// `INVALID_HANDLE_VALUE`. This ensures that such FFI calls cannot start using the handle without
/// checking for `INVALID_HANDLE_VALUE` first.
///
-/// This type concerns any value other than `INVALID_HANDLE_VALUE` to be valid, including `NULL`.
+/// This type considers any value other than `INVALID_HANDLE_VALUE` to be valid, including `NULL`.
/// This is because APIs that use `INVALID_HANDLE_VALUE` as their sentry value may return `NULL`
/// under `windows_subsystem = "windows"` or other situations where I/O devices are detached.
///
}
impl TryFrom<HandleOrNull> for OwnedHandle {
- type Error = ();
+ type Error = NullHandleError;
#[inline]
- fn try_from(handle_or_null: HandleOrNull) -> Result<Self, ()> {
+ fn try_from(handle_or_null: HandleOrNull) -> Result<Self, NullHandleError> {
let owned_handle = handle_or_null.0;
if owned_handle.handle.is_null() {
// Don't call `CloseHandle`; it'd be harmless, except that it could
// overwrite the `GetLastError` error.
forget(owned_handle);
- Err(())
+ Err(NullHandleError(()))
} else {
Ok(owned_handle)
}
}
impl TryFrom<HandleOrInvalid> for OwnedHandle {
- type Error = ();
+ type Error = InvalidHandleError;
#[inline]
- fn try_from(handle_or_invalid: HandleOrInvalid) -> Result<Self, ()> {
+ fn try_from(handle_or_invalid: HandleOrInvalid) -> Result<Self, InvalidHandleError> {
let owned_handle = handle_or_invalid.0;
if owned_handle.handle == c::INVALID_HANDLE_VALUE {
// Don't call `CloseHandle`; it'd be harmless, except that it could
// overwrite the `GetLastError` error.
forget(owned_handle);
- Err(())
+ Err(InvalidHandleError(()))
} else {
Ok(owned_handle)
}
}
}
+/// This is the error type used by [`HandleOrNull`] when attempting to convert
+/// into a handle, to indicate that the value is null.
+// The empty field prevents constructing this, and allows extending it in the future.
+#[unstable(feature = "io_safety", issue = "87074")]
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct NullHandleError(());
+
+#[unstable(feature = "io_safety", issue = "87074")]
+impl fmt::Display for NullHandleError {
+ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+ "A HandleOrNull could not be converted to a handle because it was null".fmt(fmt)
+ }
+}
+
+#[unstable(feature = "io_safety", issue = "87074")]
+impl crate::error::Error for NullHandleError {}
+
+/// This is the error type used by [`HandleOrInvalid`] when attempting to
+/// convert into a handle, to indicate that the value is
+/// `INVALID_HANDLE_VALUE`.
+// The empty field prevents constructing this, and allows extending it in the future.
+#[unstable(feature = "io_safety", issue = "87074")]
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct InvalidHandleError(());
+
+#[unstable(feature = "io_safety", issue = "87074")]
+impl fmt::Display for InvalidHandleError {
+ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+ "A HandleOrInvalid could not be converted to a handle because it was INVALID_HANDLE_VALUE"
+ .fmt(fmt)
+ }
+}
+
+#[unstable(feature = "io_safety", issue = "87074")]
+impl crate::error::Error for InvalidHandleError {}
+
impl AsRawHandle for BorrowedHandle<'_> {
#[inline]
fn as_raw_handle(&self) -> RawHandle {
--- /dev/null
+error[E0277]: the trait bound `(): std::error::Error` is not satisfied
+ --> $DIR/coerce-issue-49593-box-never-windows.rs:18:53
+ |
+LL | /* *mut $0 is coerced to Box<dyn Error> here */ Box::<_ /* ! */>::new(x)
+ | ^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::error::Error` is not implemented for `()`
+ |
+ = help: the following other types implement trait `std::error::Error`:
+ !
+ &'a T
+ AccessError
+ AddrParseError
+ Arc<T>
+ BorrowError
+ BorrowMutError
+ Box<T>
+ and 45 others
+ = note: required for the cast to the object type `dyn std::error::Error`
+
+error[E0277]: the trait bound `(): std::error::Error` is not satisfied
+ --> $DIR/coerce-issue-49593-box-never-windows.rs:23:49
+ |
+LL | /* *mut $0 is coerced to *mut Error here */ raw_ptr_box::<_ /* ! */>(x)
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::error::Error` is not implemented for `()`
+ |
+ = help: the following other types implement trait `std::error::Error`:
+ !
+ &'a T
+ AccessError
+ AddrParseError
+ Arc<T>
+ BorrowError
+ BorrowMutError
+ Box<T>
+ and 45 others
+ = note: required for the cast to the object type `(dyn std::error::Error + 'static)`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
--- /dev/null
+// revisions: nofallback fallback
+// only-windows - the number of `Error` impls is platform-dependent
+//[fallback] check-pass
+//[nofallback] check-fail
+
+#![feature(never_type)]
+#![cfg_attr(fallback, feature(never_type_fallback))]
+#![allow(unreachable_code)]
+
+use std::error::Error;
+use std::mem;
+
+fn raw_ptr_box<T>(t: T) -> *mut T {
+ panic!()
+}
+
+fn foo(x: !) -> Box<dyn Error> {
+ /* *mut $0 is coerced to Box<dyn Error> here */ Box::<_ /* ! */>::new(x)
+ //[nofallback]~^ ERROR trait bound `(): std::error::Error` is not satisfied
+}
+
+fn foo_raw_ptr(x: !) -> *mut dyn Error {
+ /* *mut $0 is coerced to *mut Error here */ raw_ptr_box::<_ /* ! */>(x)
+ //[nofallback]~^ ERROR trait bound `(): std::error::Error` is not satisfied
+}
+
+fn no_coercion(d: *mut dyn Error) -> *mut dyn Error {
+ /* an unsize coercion won't compile here, and it is indeed not used
+ because there is nothing requiring the _ to be Sized */
+ d as *mut _
+}
+
+trait Xyz {}
+struct S;
+struct T;
+impl Xyz for S {}
+impl Xyz for T {}
+
+fn foo_no_never() {
+ let mut x /* : Option<S> */ = None;
+ let mut first_iter = false;
+ loop {
+ if !first_iter {
+ let y: Box<dyn Xyz>
+ = /* Box<$0> is coerced to Box<Xyz> here */ Box::new(x.unwrap());
+ }
+
+ x = Some(S);
+ first_iter = true;
+ }
+
+ let mut y : Option<S> = None;
+ // assert types are equal
+ mem::swap(&mut x, &mut y);
+}
+
+fn main() {
+}
projects / rust.git / commitdiff