From 7cc438d9d7712d681a505d857912a91169d02e7f Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Sun, 27 Mar 2022 15:41:13 -0700 Subject: [PATCH 1/6] Define a dedicated error type for `HandleOrNull` and `HandleOrInvalid`. Define a `NotHandle` type, that implements `std::error::Error`, and use it as the error type in `HandleOrNull` and `HandleOrInvalid`. --- library/std/src/error.rs | 4 ++++ library/std/src/os/windows/io/handle.rs | 26 +++++++++++++++++++------ 2 files changed, 24 insertions(+), 6 deletions(-) diff --git a/library/std/src/error.rs b/library/std/src/error.rs index 4fb94908c80fd..7a770640f193a 100644 --- a/library/std/src/error.rs +++ b/library/std/src/error.rs @@ -612,6 +612,10 @@ impl Error for alloc::collections::TryReserveError {} #[unstable(feature = "duration_checked_float", issue = "83400")] impl Error for time::FromFloatSecsError {} +#[cfg(windows)] +#[unstable(feature = "io_safety", issue = "87074")] +impl Error for crate::os::windows::io::NotHandle {} + // Copied from `any.rs`. impl dyn Error + 'static { /// Returns `true` if the inner type is the same as `T`. diff --git a/library/std/src/os/windows/io/handle.rs b/library/std/src/os/windows/io/handle.rs index ee30cc8be6b57..1fb448be5dedf 100644 --- a/library/std/src/os/windows/io/handle.rs +++ b/library/std/src/os/windows/io/handle.rs @@ -143,17 +143,17 @@ impl BorrowedHandle<'_> { } impl TryFrom for OwnedHandle { - type Error = (); + type Error = NotHandle; #[inline] - fn try_from(handle_or_null: HandleOrNull) -> Result { + fn try_from(handle_or_null: HandleOrNull) -> Result { 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(NotHandle(())) } else { Ok(owned_handle) } @@ -201,23 +201,37 @@ impl OwnedHandle { } impl TryFrom for OwnedHandle { - type Error = (); + type Error = NotHandle; #[inline] - fn try_from(handle_or_invalid: HandleOrInvalid) -> Result { + fn try_from(handle_or_invalid: HandleOrInvalid) -> Result { 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(NotHandle(())) } else { Ok(owned_handle) } } } +/// This is the error type used by [`HandleOrInvalid`] and +/// [`HandleOrNull`] when attempting to convert into a handle, +/// to indicate that the value is not a handle. +#[unstable(feature = "io_safety", issue = "87074")] +#[derive(Debug, Copy, Clone, PartialEq, Eq)] +pub struct NotHandle(()); + +#[unstable(feature = "io_safety", issue = "87074")] +impl fmt::Display for NotHandle { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + "the return value of a Windows API call indicated an error".fmt(fmt) + } +} + impl AsRawHandle for BorrowedHandle<'_> { #[inline] fn as_raw_handle(&self) -> RawHandle { From 1bb38faefd3dcfe14f0e88973c9ae2ee739fdec4 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Sun, 27 Mar 2022 16:53:56 -0700 Subject: [PATCH 2/6] Fix an incorrect word in a comment. --- library/std/src/os/windows/io/handle.rs | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/library/std/src/os/windows/io/handle.rs b/library/std/src/os/windows/io/handle.rs index 1fb448be5dedf..1bed22a4ce50a 100644 --- a/library/std/src/os/windows/io/handle.rs +++ b/library/std/src/os/windows/io/handle.rs @@ -76,7 +76,7 @@ pub struct OwnedHandle { /// `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. /// @@ -96,7 +96,7 @@ pub struct HandleOrNull(OwnedHandle); /// `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. /// From 135b8e0c09e666c03e1136d272a09b05d7b71a55 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Sun, 27 Mar 2022 16:54:58 -0700 Subject: [PATCH 3/6] Move the `Error` impl for `NotHandle` out of platform-independent code. --- library/std/src/error.rs | 4 ---- library/std/src/os/windows/io/handle.rs | 3 +++ 2 files changed, 3 insertions(+), 4 deletions(-) diff --git a/library/std/src/error.rs b/library/std/src/error.rs index 7a770640f193a..4fb94908c80fd 100644 --- a/library/std/src/error.rs +++ b/library/std/src/error.rs @@ -612,10 +612,6 @@ impl Error for alloc::collections::TryReserveError {} #[unstable(feature = "duration_checked_float", issue = "83400")] impl Error for time::FromFloatSecsError {} -#[cfg(windows)] -#[unstable(feature = "io_safety", issue = "87074")] -impl Error for crate::os::windows::io::NotHandle {} - // Copied from `any.rs`. impl dyn Error + 'static { /// Returns `true` if the inner type is the same as `T`. diff --git a/library/std/src/os/windows/io/handle.rs b/library/std/src/os/windows/io/handle.rs index 1bed22a4ce50a..c6b84b6e5d300 100644 --- a/library/std/src/os/windows/io/handle.rs +++ b/library/std/src/os/windows/io/handle.rs @@ -232,6 +232,9 @@ impl fmt::Display for NotHandle { } } +#[unstable(feature = "io_safety", issue = "87074")] +impl crate::error::Error for NotHandle {} + impl AsRawHandle for BorrowedHandle<'_> { #[inline] fn as_raw_handle(&self) -> RawHandle { From 2b79098ac2d7430776b0118eb53d0ce7993a7eec Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Mon, 28 Mar 2022 10:56:00 -0700 Subject: [PATCH 4/6] Split `NotHandle` into `NullHandleError` and `InvalidHandleError`. Also, make the display messages more specific, and remove the `Copy` implementation. --- library/std/src/os/windows/io/handle.rs | 45 +++++++++++++++++-------- 1 file changed, 31 insertions(+), 14 deletions(-) diff --git a/library/std/src/os/windows/io/handle.rs b/library/std/src/os/windows/io/handle.rs index c6b84b6e5d300..e48f630f76e7f 100644 --- a/library/std/src/os/windows/io/handle.rs +++ b/library/std/src/os/windows/io/handle.rs @@ -143,17 +143,17 @@ impl BorrowedHandle<'_> { } impl TryFrom for OwnedHandle { - type Error = NotHandle; + type Error = NullHandleError; #[inline] - fn try_from(handle_or_null: HandleOrNull) -> Result { + fn try_from(handle_or_null: HandleOrNull) -> Result { 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(NotHandle(())) + Err(NullHandleError(())) } else { Ok(owned_handle) } @@ -201,39 +201,56 @@ impl OwnedHandle { } impl TryFrom for OwnedHandle { - type Error = NotHandle; + type Error = InvalidHandleError; #[inline] - fn try_from(handle_or_invalid: HandleOrInvalid) -> Result { + fn try_from(handle_or_invalid: HandleOrInvalid) -> Result { 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(NotHandle(())) + Err(InvalidHandleError(())) } else { Ok(owned_handle) } } } -/// This is the error type used by [`HandleOrInvalid`] and -/// [`HandleOrNull`] when attempting to convert into a handle, -/// to indicate that the value is not a handle. +/// This is the error type used by [`HandleOrNull`] when attempting to convert +/// into a handle, to indicate that the value is null. #[unstable(feature = "io_safety", issue = "87074")] -#[derive(Debug, Copy, Clone, PartialEq, Eq)] -pub struct NotHandle(()); +#[derive(Debug, Clone, PartialEq, Eq)] +pub struct NullHandleError(()); #[unstable(feature = "io_safety", issue = "87074")] -impl fmt::Display for NotHandle { +impl fmt::Display for NullHandleError { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { - "the return value of a Windows API call indicated an error".fmt(fmt) + "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 NotHandle {} +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`. +#[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] From e0c00205700e7549f5acc82c35c1cf6cda795537 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Wed, 13 Apr 2022 14:32:17 -0700 Subject: [PATCH 5/6] Add a comment explaining the `(())` idiom for empty structs. --- library/std/src/os/windows/io/handle.rs | 2 ++ 1 file changed, 2 insertions(+) diff --git a/library/std/src/os/windows/io/handle.rs b/library/std/src/os/windows/io/handle.rs index e48f630f76e7f..e4de52612ef62 100644 --- a/library/std/src/os/windows/io/handle.rs +++ b/library/std/src/os/windows/io/handle.rs @@ -220,6 +220,7 @@ impl TryFrom for OwnedHandle { /// 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(()); @@ -237,6 +238,7 @@ 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(()); From e886145612f392390ef213ec4cd38f3af694461d Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Thu, 14 Apr 2022 21:54:13 -0700 Subject: [PATCH 6/6] Update the expected stderr for coerce-issue-49593-box-never. This test's expected stderr now includes a count of the number of types that implment `Error`. This PR introduces two new types, so increment the number by two. --- .../coercion/coerce-issue-49593-box-never.nofallback.stderr | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/test/ui/coercion/coerce-issue-49593-box-never.nofallback.stderr b/src/test/ui/coercion/coerce-issue-49593-box-never.nofallback.stderr index 1b1ce67cb0c1f..99f00034eda60 100644 --- a/src/test/ui/coercion/coerce-issue-49593-box-never.nofallback.stderr +++ b/src/test/ui/coercion/coerce-issue-49593-box-never.nofallback.stderr @@ -13,7 +13,7 @@ LL | /* *mut $0 is coerced to Box here */ Box::<_ /* ! */>::new(x BorrowError BorrowMutError Box - and 43 others + 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 @@ -31,7 +31,7 @@ LL | /* *mut $0 is coerced to *mut Error here */ raw_ptr_box::<_ /* ! */>(x) BorrowError BorrowMutError Box - and 43 others + and 45 others = note: required for the cast to the object type `(dyn std::error::Error + 'static)` error: aborting due to 2 previous errors