From b0fb57bd8d18946787a79d1244154f2512dcf15b Mon Sep 17 00:00:00 2001
From: Josh Stone <jistone@redhat.com>
Date: Wed, 22 Apr 2020 13:03:05 -0700
Subject: [PATCH 1/4] impl From<Cow> for boxed slices and strings
These forward `Borrowed`/`Owned` values to existing `Box::from` impls.
- `From<Cow<'_, [T]>> for Box<[T]>`
- `From<Cow<'_, str>> for Box<str>`
- `From<Cow<'_, CStr>> for Box<CStr>`
- `From<Cow<'_, OsStr>> for Box<OsStr>`
- `From<Cow<'_, Path>> for Box<Path>`
---
src/liballoc/boxed.rs | 23 +++++++++++++++++++++++
src/libstd/ffi/c_str.rs | 11 +++++++++++
src/libstd/ffi/os_str.rs | 11 +++++++++++
src/libstd/path.rs | 11 +++++++++++
4 files changed, 56 insertions(+)
diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index db7420954a091..de906c7f7b08b 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -146,6 +146,7 @@ use core::ptr::{self, NonNull, Unique};
use core::task::{Context, Poll};
use crate::alloc::{self, AllocInit, AllocRef, Global};
+use crate::borrow::Cow;
use crate::raw_vec::RawVec;
use crate::str::from_boxed_utf8_unchecked;
use crate::vec::Vec;
@@ -774,6 +775,17 @@ impl<T: Copy> From<&[T]> for Box<[T]> {
}
}
+#[stable(feature = "box_from_cow", since = "1.45.0")]
+impl<T: Copy> From<Cow<'_, [T]>> for Box<[T]> {
+ #[inline]
+ fn from(cow: Cow<'_, [T]>) -> Box<[T]> {
+ match cow {
+ Cow::Borrowed(slice) => Box::from(slice),
+ Cow::Owned(slice) => Box::from(slice),
+ }
+ }
+}
+
#[stable(feature = "box_from_slice", since = "1.17.0")]
impl From<&str> for Box<str> {
/// Converts a `&str` into a `Box<str>`
@@ -792,6 +804,17 @@ impl From<&str> for Box<str> {
}
}
+#[stable(feature = "box_from_cow", since = "1.45.0")]
+impl From<Cow<'_, str>> for Box<str> {
+ #[inline]
+ fn from(cow: Cow<'_, str>) -> Box<str> {
+ match cow {
+ Cow::Borrowed(s) => Box::from(s),
+ Cow::Owned(s) => Box::from(s),
+ }
+ }
+}
+
#[stable(feature = "boxed_str_conv", since = "1.19.0")]
impl From<Box<str>> for Box<[u8]> {
/// Converts a `Box<str>>` into a `Box<[u8]>`
diff --git a/src/libstd/ffi/c_str.rs b/src/libstd/ffi/c_str.rs
index 0a4802fb2c80d..4bac9a4917d8f 100644
--- a/src/libstd/ffi/c_str.rs
+++ b/src/libstd/ffi/c_str.rs
@@ -730,6 +730,17 @@ impl From<&CStr> for Box<CStr> {
}
}
+#[stable(feature = "box_from_cow", since = "1.45.0")]
+impl From<Cow<'_, CStr>> for Box<CStr> {
+ #[inline]
+ fn from(cow: Cow<'_, CStr>) -> Box<CStr> {
+ match cow {
+ Cow::Borrowed(s) => Box::from(s),
+ Cow::Owned(s) => Box::from(s),
+ }
+ }
+}
+
#[stable(feature = "c_string_from_box", since = "1.18.0")]
impl From<Box<CStr>> for CString {
/// Converts a [`Box`]`<CStr>` into a [`CString`] without copying or allocating.
diff --git a/src/libstd/ffi/os_str.rs b/src/libstd/ffi/os_str.rs
index 4fde33169733e..7a2d34968e087 100644
--- a/src/libstd/ffi/os_str.rs
+++ b/src/libstd/ffi/os_str.rs
@@ -849,6 +849,17 @@ impl From<&OsStr> for Box<OsStr> {
}
}
+#[stable(feature = "box_from_cow", since = "1.45.0")]
+impl From<Cow<'_, OsStr>> for Box<OsStr> {
+ #[inline]
+ fn from(cow: Cow<'_, OsStr>) -> Box<OsStr> {
+ match cow {
+ Cow::Borrowed(s) => Box::from(s),
+ Cow::Owned(s) => Box::from(s),
+ }
+ }
+}
+
#[stable(feature = "os_string_from_box", since = "1.18.0")]
impl From<Box<OsStr>> for OsString {
/// Converts a [`Box`]`<`[`OsStr`]`>` into a `OsString` without copying or
diff --git a/src/libstd/path.rs b/src/libstd/path.rs
index 173d6d1cfa7ef..ed1dc78732985 100644
--- a/src/libstd/path.rs
+++ b/src/libstd/path.rs
@@ -1433,6 +1433,17 @@ impl From<&Path> for Box<Path> {
}
}
+#[stable(feature = "box_from_cow", since = "1.45.0")]
+impl From<Cow<'_, Path>> for Box<Path> {
+ #[inline]
+ fn from(cow: Cow<'_, Path>) -> Box<Path> {
+ match cow {
+ Cow::Borrowed(path) => Box::from(path),
+ Cow::Owned(path) => Box::from(path),
+ }
+ }
+}
+
#[stable(feature = "path_buf_from_box", since = "1.18.0")]
impl From<Box<Path>> for PathBuf {
/// Converts a `Box<Path>` into a `PathBuf`
From 6d40751b37ef453bee5d8a9c47b00ef205d61738 Mon Sep 17 00:00:00 2001
From: Josh Stone <jistone@redhat.com>
Date: Wed, 22 Apr 2020 13:33:42 -0700
Subject: [PATCH 2/4] impl From<Cow> for Rc and Arc
These forward `Borrowed`/`Owned` values to existing `From` impls.
impl<'a, B> From<Cow<'a, B>> for Rc<B>
where
B: ToOwned + ?Sized,
Rc<B>: From<&'a B> + From<B::Owned>,
impl<'a, B> From<Cow<'a, B>> for Arc<B>
where
B: ToOwned + ?Sized,
Arc<B>: From<&'a B> + From<B::Owned>,
---
src/liballoc/rc.rs | 16 ++++++++++++++++
src/liballoc/sync.rs | 16 ++++++++++++++++
2 files changed, 32 insertions(+)
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index e106b4354e4e9..44a390c3ec343 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -252,6 +252,7 @@ use core::ptr::{self, NonNull};
use core::slice::{self, from_raw_parts_mut};
use crate::alloc::{box_free, handle_alloc_error, AllocInit, AllocRef, Global, Layout};
+use crate::borrow::{Cow, ToOwned};
use crate::string::String;
use crate::vec::Vec;
@@ -1492,6 +1493,21 @@ impl<T> From<Vec<T>> for Rc<[T]> {
}
}
+#[stable(feature = "shared_from_cow", since = "1.45.0")]
+impl<'a, B> From<Cow<'a, B>> for Rc<B>
+where
+ B: ToOwned + ?Sized,
+ Rc<B>: From<&'a B> + From<B::Owned>,
+{
+ #[inline]
+ fn from(cow: Cow<'a, B>) -> Rc<B> {
+ match cow {
+ Cow::Borrowed(s) => Rc::from(s),
+ Cow::Owned(s) => Rc::from(s),
+ }
+ }
+}
+
#[stable(feature = "boxed_slice_try_from", since = "1.43.0")]
impl<T, const N: usize> TryFrom<Rc<[T]>> for Rc<[T; N]>
where
diff --git a/src/liballoc/sync.rs b/src/liballoc/sync.rs
index 54df2b6085780..a45929e86fc19 100644
--- a/src/liballoc/sync.rs
+++ b/src/liballoc/sync.rs
@@ -25,6 +25,7 @@ use core::sync::atomic;
use core::sync::atomic::Ordering::{Acquire, Relaxed, Release, SeqCst};
use crate::alloc::{box_free, handle_alloc_error, AllocInit, AllocRef, Global, Layout};
+use crate::borrow::{Cow, ToOwned};
use crate::boxed::Box;
use crate::rc::is_dangling;
use crate::string::String;
@@ -2047,6 +2048,21 @@ impl<T> From<Vec<T>> for Arc<[T]> {
}
}
+#[stable(feature = "shared_from_cow", since = "1.45.0")]
+impl<'a, B> From<Cow<'a, B>> for Arc<B>
+where
+ B: ToOwned + ?Sized,
+ Arc<B>: From<&'a B> + From<B::Owned>,
+{
+ #[inline]
+ fn from(cow: Cow<'a, B>) -> Arc<B> {
+ match cow {
+ Cow::Borrowed(s) => Arc::from(s),
+ Cow::Owned(s) => Arc::from(s),
+ }
+ }
+}
+
#[stable(feature = "boxed_slice_try_from", since = "1.43.0")]
impl<T, const N: usize> TryFrom<Arc<[T]>> for Arc<[T; N]>
where
From 23f71fe5b518c6136990f79733155b4fa1314d2b Mon Sep 17 00:00:00 2001
From: Josh Stone <jistone@redhat.com>
Date: Wed, 22 Apr 2020 14:16:21 -0700
Subject: [PATCH 3/4] Add tests from Cow
---
src/liballoc/tests/borrow.rs | 47 ++++++++++++++++++++++++++++++++++++
src/liballoc/tests/lib.rs | 1 +
2 files changed, 48 insertions(+)
create mode 100644 src/liballoc/tests/borrow.rs
diff --git a/src/liballoc/tests/borrow.rs b/src/liballoc/tests/borrow.rs
new file mode 100644
index 0000000000000..8bfcf323f674a
--- /dev/null
+++ b/src/liballoc/tests/borrow.rs
@@ -0,0 +1,47 @@
+use std::borrow::{Cow, ToOwned};
+use std::ffi::{CStr, OsStr};
+use std::path::Path;
+use std::rc::Rc;
+use std::sync::Arc;
+
+macro_rules! test_from_cow {
+ ($value:ident => $($ty:ty),+) => {$(
+ let borrowed = <$ty>::from(Cow::Borrowed($value));
+ let owned = <$ty>::from(Cow::Owned($value.to_owned()));
+ assert_eq!($value, &*borrowed);
+ assert_eq!($value, &*owned);
+ )+};
+ ($value:ident : & $ty:ty) => {
+ test_from_cow!($value => Box<$ty>, Rc<$ty>, Arc<$ty>);
+ }
+}
+
+#[test]
+fn test_from_cow_slice() {
+ let slice: &[i32] = &[1, 2, 3];
+ test_from_cow!(slice: &[i32]);
+}
+
+#[test]
+fn test_from_cow_str() {
+ let string = "hello";
+ test_from_cow!(string: &str);
+}
+
+#[test]
+fn test_from_cow_c_str() {
+ let string = CStr::from_bytes_with_nul(b"hello\0").unwrap();
+ test_from_cow!(string: &CStr);
+}
+
+#[test]
+fn test_from_cow_os_str() {
+ let string = OsStr::new("hello");
+ test_from_cow!(string: &OsStr);
+}
+
+#[test]
+fn test_from_cow_path() {
+ let path = Path::new("hello");
+ test_from_cow!(path: &Path);
+}
diff --git a/src/liballoc/tests/lib.rs b/src/liballoc/tests/lib.rs
index ad6feaeebc67f..cbeceec6d7827 100644
--- a/src/liballoc/tests/lib.rs
+++ b/src/liballoc/tests/lib.rs
@@ -20,6 +20,7 @@ use std::hash::{Hash, Hasher};
mod arc;
mod binary_heap;
+mod borrow;
mod boxed;
mod btree;
mod cow_str;
From 22efd959109b9a231edbc81a8bc818eaa5763e78 Mon Sep 17 00:00:00 2001
From: Josh Stone <jistone@redhat.com>
Date: Wed, 22 Apr 2020 14:40:27 -0700
Subject: [PATCH 4/4] Bless From<Cow> UI changes
---
.../array-impls/alloc-types-no-impls-length-33.stderr | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/src/test/ui/const-generics/array-impls/alloc-types-no-impls-length-33.stderr b/src/test/ui/const-generics/array-impls/alloc-types-no-impls-length-33.stderr
index d795840551c50..3a3f6e3d4208c 100644
--- a/src/test/ui/const-generics/array-impls/alloc-types-no-impls-length-33.stderr
+++ b/src/test/ui/const-generics/array-impls/alloc-types-no-impls-length-33.stderr
@@ -18,7 +18,7 @@ LL | let boxed_array = <Box<[i32; 33]>>::try_from(boxed_slice);
<std::boxed::Box<(dyn std::error::Error + 'static)> as std::convert::From<&str>>
<std::boxed::Box<(dyn std::error::Error + 'static)> as std::convert::From<std::borrow::Cow<'a, str>>>
<std::boxed::Box<(dyn std::error::Error + 'static)> as std::convert::From<std::string::String>>
- and 16 others
+ and 21 others
= note: required because of the requirements on the impl of `std::convert::Into<std::boxed::Box<[i32; 33]>>` for `std::boxed::Box<[i32]>`
= note: required because of the requirements on the impl of `std::convert::TryFrom<std::boxed::Box<[i32]>>` for `std::boxed::Box<[i32; 33]>`
@@ -38,11 +38,11 @@ LL | let boxed_array = <Rc<[i32; 33]>>::try_from(boxed_slice);
| ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::convert::From<std::rc::Rc<[i32]>>` is not implemented for `std::rc::Rc<[i32; 33]>`
|
= help: the following implementations were found:
+ <std::rc::Rc<B> as std::convert::From<std::borrow::Cow<'a, B>>>
<std::rc::Rc<T> as std::convert::From<T>>
<std::rc::Rc<T> as std::convert::From<std::boxed::Box<T>>>
<std::rc::Rc<[T]> as std::convert::From<&[T]>>
- <std::rc::Rc<[T]> as std::convert::From<std::vec::Vec<T>>>
- and 8 others
+ and 9 others
= note: required because of the requirements on the impl of `std::convert::Into<std::rc::Rc<[i32; 33]>>` for `std::rc::Rc<[i32]>`
= note: required because of the requirements on the impl of `std::convert::TryFrom<std::rc::Rc<[i32]>>` for `std::rc::Rc<[i32; 33]>`
@@ -62,11 +62,11 @@ LL | let boxed_array = <Arc<[i32; 33]>>::try_from(boxed_slice);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::convert::From<std::sync::Arc<[i32]>>` is not implemented for `std::sync::Arc<[i32; 33]>`
|
= help: the following implementations were found:
+ <std::sync::Arc<B> as std::convert::From<std::borrow::Cow<'a, B>>>
<std::sync::Arc<T> as std::convert::From<T>>
<std::sync::Arc<T> as std::convert::From<std::boxed::Box<T>>>
<std::sync::Arc<[T]> as std::convert::From<&[T]>>
- <std::sync::Arc<[T]> as std::convert::From<std::vec::Vec<T>>>
- and 8 others
+ and 9 others
= note: required because of the requirements on the impl of `std::convert::Into<std::sync::Arc<[i32; 33]>>` for `std::sync::Arc<[i32]>`
= note: required because of the requirements on the impl of `std::convert::TryFrom<std::sync::Arc<[i32]>>` for `std::sync::Arc<[i32; 33]>`