Restore indexed formulation of clone_from_slice
For good codegen here, we need a lock step iteration where the loop
bound is only checked once per iteration; .zip() unfortunately does not
optimize this way.
If we use a counted loop, and make sure that llvm sees that the bounds
check condition is the same as the loop bound condition, the bounds
checks are optimized out. For this reason we need to slice `from`
(apparently) redundantly.
This commit restores the old formulation of clone_from_slice. In this
shape, clone_from_slice will again optimize into calling memcpy where possible
(for example for &[u8] or &[i32]).
For good codegen here, we need a lock step iteration where the loop
bound is only checked once per iteration; .zip() unfortunately does not
optimize this way.
If we use a counted loop, and make sure that llvm sees that the bounds
check condition is the same as the loop bound condition, the bounds
checks are optimized out. For this reason we need to slice `from`
(apparently) redundantly.
This commit restores the old formulation of clone_from_slice. In this
shape, clone_from_slice will again optimize into calling memcpy where possible
(for example for &[u8] or &[i32]).
test: Increase resolution of MB/s stat for bench runs close to 1 second
MB/s was based on the number of iterations performed in a second, when
the iteration duration nears 1 second (1e9 ns), the resolution of the
MB/s stat decreases.
* Moved semicolon to the right place in the `let` statement in the ZST section.
* Fixed the missing ZST additions for `RawValIter<T>` from this section in the final code section.
This commit stabilizes and deprecates the FCP (final comment period) APIs for
the upcoming 1.7 beta release. The specific APIs which changed were:
Stabilized
* `Path::strip_prefix` (renamed from `relative_from`)
* `path::StripPrefixError` (new error type returned from `strip_prefix`)
* `Ipv4Addr::is_loopback`
* `Ipv4Addr::is_private`
* `Ipv4Addr::is_link_local`
* `Ipv4Addr::is_multicast`
* `Ipv4Addr::is_broadcast`
* `Ipv4Addr::is_documentation`
* `Ipv6Addr::is_unspecified`
* `Ipv6Addr::is_loopback`
* `Ipv6Addr::is_unique_local`
* `Ipv6Addr::is_multicast`
* `Vec::as_slice`
* `Vec::as_mut_slice`
* `String::as_str`
* `String::as_mut_str`
* `<[T]>::clone_from_slice` - the `usize` return value is removed
* `<[T]>::sort_by_key`
* `i32::checked_rem` (and other signed types)
* `i32::checked_neg` (and other signed types)
* `i32::checked_shl` (and other signed types)
* `i32::checked_shr` (and other signed types)
* `i32::saturating_mul` (and other signed types)
* `i32::overflowing_add` (and other signed types)
* `i32::overflowing_sub` (and other signed types)
* `i32::overflowing_mul` (and other signed types)
* `i32::overflowing_div` (and other signed types)
* `i32::overflowing_rem` (and other signed types)
* `i32::overflowing_neg` (and other signed types)
* `i32::overflowing_shl` (and other signed types)
* `i32::overflowing_shr` (and other signed types)
* `u32::checked_rem` (and other unsigned types)
* `u32::checked_shl` (and other unsigned types)
* `u32::saturating_mul` (and other unsigned types)
* `u32::overflowing_add` (and other unsigned types)
* `u32::overflowing_sub` (and other unsigned types)
* `u32::overflowing_mul` (and other unsigned types)
* `u32::overflowing_div` (and other unsigned types)
* `u32::overflowing_rem` (and other unsigned types)
* `u32::overflowing_neg` (and other unsigned types)
* `u32::overflowing_shl` (and other unsigned types)
* `u32::overflowing_shr` (and other unsigned types)
* `ffi::IntoStringError`
* `CString::into_string`
* `CString::into_bytes`
* `CString::into_bytes_with_nul`
* `From<CString> for Vec<u8>`
* `From<CString> for Vec<u8>`
* `IntoStringError::into_cstring`
* `IntoStringError::utf8_error`
* `Error for IntoStringError`
Deprecated
* `Path::relative_from` - renamed to `strip_prefix`
* `Path::prefix` - use `components().next()` instead
* `os::unix::fs` constants - moved to the `libc` crate
* `fmt::{radix, Radix, RadixFmt}` - not used enough to stabilize
* `IntoCow` - conflicts with `Into` and may come back later
* `i32::{BITS, BYTES}` (and other integers) - not pulling their weight
* `DebugTuple::formatter` - will be removed
* `sync::Semaphore` - not used enough and confused with system semaphores
Closes#23284
cc #27709 (still lots more methods though)
Closes#27712Closes#27722Closes#27728Closes#27735Closes#27729Closes#27755Closes#27782Closes#27798
The only way to get a value for a zero-sized type is `undef`, so
there's really no point in actually having a return type other than
void for such types. Also, while the comment in return_type_is_void
mentioned something about aiding C ABI support, @eddyb correctly
pointed out on IRC that there is no such thing as a zero-sized type in
C. And even with clang, which allows empty structs, those get
translated as void return types as well.
Fixes#28766
This is groundwork for #30587 (typestrong constant integrals), but imo it's a change that in itself is good, too, since we don't just juggle `u64`s around anymore.
`ty::Disr` will be changed to a `ConstInt` in #30587
This is a bit weird since unsized types can't be used in trait objects,
but Any is *also* used as pure marker trait since Reflect isn't stable.
There are many cases (e.g. TypeMap) where all you need is a TypeId.
r? @aturon
Despite being over 700 lines shorter, this implementation should use less memory than the previous one and is faster on at least insertions and iteration, the latter improving approximately 5x.
Technically a [breaking-change] due to removal of deprecated functions.
cc @apasel422 @Gankro @goyox86
Fixes#27865.
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MB/s was based on the number of iterations performed in a second, when
the iteration duration nears 1 second (1e9 ns), the resolution of the
MB/s stat decreases.
This commit stabilizes and deprecates the FCP (final comment period) APIs for
the upcoming 1.7 beta release. The specific APIs which changed were:
Stabilized
* `Path::strip_prefix` (renamed from `relative_from`)
* `path::StripPrefixError` (new error type returned from `strip_prefix`)
* `Ipv4Addr::is_loopback`
* `Ipv4Addr::is_private`
* `Ipv4Addr::is_link_local`
* `Ipv4Addr::is_multicast`
* `Ipv4Addr::is_broadcast`
* `Ipv4Addr::is_documentation`
* `Ipv6Addr::is_unspecified`
* `Ipv6Addr::is_loopback`
* `Ipv6Addr::is_unique_local`
* `Ipv6Addr::is_multicast`
* `Vec::as_slice`
* `Vec::as_mut_slice`
* `String::as_str`
* `String::as_mut_str`
* `<[T]>::clone_from_slice` - the `usize` return value is removed
* `<[T]>::sort_by_key`
* `i32::checked_rem` (and other signed types)
* `i32::checked_neg` (and other signed types)
* `i32::checked_shl` (and other signed types)
* `i32::checked_shr` (and other signed types)
* `i32::saturating_mul` (and other signed types)
* `i32::overflowing_add` (and other signed types)
* `i32::overflowing_sub` (and other signed types)
* `i32::overflowing_mul` (and other signed types)
* `i32::overflowing_div` (and other signed types)
* `i32::overflowing_rem` (and other signed types)
* `i32::overflowing_neg` (and other signed types)
* `i32::overflowing_shl` (and other signed types)
* `i32::overflowing_shr` (and other signed types)
* `u32::checked_rem` (and other unsigned types)
* `u32::checked_neg` (and other unsigned types)
* `u32::checked_shl` (and other unsigned types)
* `u32::saturating_mul` (and other unsigned types)
* `u32::overflowing_add` (and other unsigned types)
* `u32::overflowing_sub` (and other unsigned types)
* `u32::overflowing_mul` (and other unsigned types)
* `u32::overflowing_div` (and other unsigned types)
* `u32::overflowing_rem` (and other unsigned types)
* `u32::overflowing_neg` (and other unsigned types)
* `u32::overflowing_shl` (and other unsigned types)
* `u32::overflowing_shr` (and other unsigned types)
* `ffi::IntoStringError`
* `CString::into_string`
* `CString::into_bytes`
* `CString::into_bytes_with_nul`
* `From<CString> for Vec<u8>`
* `From<CString> for Vec<u8>`
* `IntoStringError::into_cstring`
* `IntoStringError::utf8_error`
* `Error for IntoStringError`
Deprecated
* `Path::relative_from` - renamed to `strip_prefix`
* `Path::prefix` - use `components().next()` instead
* `os::unix::fs` constants - moved to the `libc` crate
* `fmt::{radix, Radix, RadixFmt}` - not used enough to stabilize
* `IntoCow` - conflicts with `Into` and may come back later
* `i32::{BITS, BYTES}` (and other integers) - not pulling their weight
* `DebugTuple::formatter` - will be removed
* `sync::Semaphore` - not used enough and confused with system semaphores
Closes#23284
cc #27709 (still lots more methods though)
Closes#27712Closes#27722Closes#27728Closes#27735Closes#27729Closes#27755Closes#27782Closes#27798
This PR introduces an `ObligationForest` data structure that the fulfillment context can use to track what's going on, instead of the current flat vector. This enables a number of improvements:
1. transactional support, at least for pushing new obligations
2. remove the "errors will be reported" hack -- instead, we only add types to the global cache once their entire subtree has been proven safe. Before, we never knew when this point was reached because we didn't track the subtree.
- this in turn allows us to limit coinductive reasoning to structural traits, which sidesteps #29859
3. keeping the backtrace should allow for an improved error message, where we give the user full context
- we can also remove chained obligation causes
This PR is not 100% complete. In particular:
- [x] Currently, types that embed themselves like `struct Foo { f: Foo }` give an overflow when evaluating whether `Foo: Sized`. This is not a very user-friendly error message, and this is a common beginner error. I plan to special-case this scenario, I think.
- [x] I should do some perf. measurements. (Update: 2% regression.)
- [x] More tests targeting #29859
- [ ] The transactional support is not fully integrated, though that should be easy enough.
- [ ] The error messages are not taking advantage of the backtrace.
I'd certainly like to do 1 through 3 before landing, but 4 and 5 could come as separate PRs.
r? @aturon // good way to learn more about this part of the trait system
f? @arielb1 // already knows this part of the trait system :)
to get the `Sized` error usable, since that hits new users
frequently. Further work is needed for the error reporting for non-Sized
cycle cases; those currently just fallback to the old path. Also adjust tests.
