docs: simplify wording
It took me more then a moment to decipher "with no non-`'static`" thing :)
"`'static` type" should say the same thing more clearly.
r? @steveklabnik
Fix wrong statement in compare_exchange doc
The documentation for `core::sync::atomic::AtomicSomething::compare_exchange` contains a wrong, or imprecise, statement about the return value. It goes:
The return value is a result indicating whether the new value was written and containing
the previous value. On success this value is guaranteed to be equal to `new`.
In the second sentence, `this value` is gramatically understood as referring to `return value` from the first sentence. Due to how CAS works, the returned value is always what was in the atomic variable _before_ the operation occurred, not what was written into it during the operation. Hence, the fixed doc should say:
The return value is a result indicating whether the new value was written and containing
the previous value. On success this value is guaranteed to be equal to `current`.
This version is confirmed by the runnable examples in variants of `AtomicSomething`, e.g.
assert_eq!(some_bool.compare_exchange(true, false, Ordering::Acquire, Ordering::Relaxed),
Ok(true));
where the returned value is `Ok(current)`. This PR fixes all occurrences of this bug I could find.
An alternative solution would be to modify the second sentence so that it refers to the value _written_ into the Atomic rather than what was there before, in which case it would be correct. Example alternative formulation:
On success the value written into the `bool`/`usize`/`whatever` is guaranteed to be equal to `new`.
r? @steveklabnik
This was using an invalid iterator so is likely to end with buggy
behaviour.
It also doesn't even benefit many type in std including Vec so removing it
shouldn't cause any problems.
Support 16-bit pointers as well as i/usize
I'm opening this pull request to get some feedback from the community.
Although Rust doesn't support any platforms with a native 16-bit pointer at the moment, the [AVR-Rust][ar] fork is working towards that goal. Keeping this forked logic up-to-date with the changes in master has been onerous so I'd like to merge these changes so that they get carried along when refactoring happens. I do not believe this should increase the maintenance burden.
This is based on the original work of Dylan McKay (@dylanmckay).
[ar]: https://github.com/avr-rust/rust
core: check pointer equality when comparing byte slices
If pointer address and length are the same, it should be the same slice.
In experiments, I've seen that this doesn't happen as often in debug builds, but release builds seem to optimize to using a single pointer more often.
Implement `count` for `EscapeUnicode`
and cleanup the code for `count` for `EscapeDefault` (instead of repeating the `match` for `size_hint` and `count`).
This PR marks EscapeUnicode and EscapeDefault as ExactSizeIterator. The constraints for the trait implementations held even before this PR, but I am not sure if this is something we want to guarantee/expose (I would love feedback on this, especially on what would be the appropriate way to handle stabilisation, if needed).
Part of #24214, split from #31049.
The test for `count` was added in #33103.
Trait documentation clarifications
Hi! I've felt a bit of friction lately in figuring out how to write custom implementations of the `derive`able traits, so I decided to add to the docs :)
The docs for `Copy` are already excellent-- clear, useful sections that I only reordered a bit-- they're now:
* General explanation
* When can my type be `Copy`?
* When can my type _not_ be `Copy`?
* When should my type be `Copy`?
* Derivable
* How can I implement `Copy`?
I didn't add all these sections for all the traits, but I did make sure all the derivable traits had a consistent "Derivable" section that explained what the derived implementation does and a "How can I implement" section that has an example.
Please check me for correctness-- I tried to do research to make sure I was saying accurate things but I'm still learning! ❤️ I'd also love suggestions on information to add that is still missing-- I think these traits are important and deserve to have awesome docs!
Fixes to mir dataflow
Fixes to mir dataflow
This collects a bunch of changes to `rustc_borrowck::borrowck::dataflow` (which others have pointed out should probably migrate to some crate that isn't tied to the borrow-checker -- but I have not attempted that here, especially since there are competing approaches to dataflow that we should also evaluate).
These changes:
1. Provide a family of related analyses: MovingOutStatements (which is what the old AST-based dataflo computed), as well as MaybeInitialized, MaybeUninitalized, and DefinitelyInitialized.
* (The last two are actually inverses of each other; we should pick one and drop the other.)
2. Fix bugs in the pre-existing analysis implementation, which was untested and thus some obvious bugs went unnoticed, which brings us to the third point:
3. Add a unit test infrastructure for the MIR dataflow analysis.
* The tests work by adding a new intrinsic that is able to query the analysis state for a particular expression (technically, a particular L-value).
* See the examples in compile-fail/mir-dataflow/inits-1.rs and compile-fail/mir-dataflow/uninits-1.rs
* These tests are only checking the results for MaybeInitialized, MaybeUninitalized, and DefinitelyInitialized; I am not sure if it will be feasible to generalize this testing strategy to the MovingOutStatements dataflow operator.
Add explicit "Derivable" and "How can I implement `Default`" sections.
Copied relevant sections from the module-level documentation, but also
linked to there-- it has a more comprehensive narrative with examples
that show implementation AND use. Decided to just put implementation
example in the trait documentation.
The new order puts all the "when" questions together and puts the "how"
question with the "derivable" section. So you have to scroll past (and
hopefully read) the can/cannot/should caveats and guidelines to get to
the information about how to actually go about doing it once you've
determined that you can and should, with derivable information first so
that you can just use the derived implementation if that applies.
Previous order:
* General explanation
* When can my type be `Copy`?
* How can I implement `Copy`?
* When can my type _not_ be `Copy`?
* When should my type be `Copy`?
* Derivable
New order:
* General explanation
* When can my type be `Copy`?
* When can my type _not_ be `Copy`?
* When should my type be `Copy`?
* Derivable
* How can I implement `Copy`?
I think these just got out of sync, but both use a lexicographic
ordering.
Relevant commits in the history of these explanations:
* 8b81f76 on 2015-06-30
* e22770b on 2016-02-09
Implement `last` for `EscapeUnicode`
The implementation is quite trivial as the last character is always `'{'`.
As a side-effect it also improves the implementation of `last` for `EscapeUnicode`.
Part of #24214, split from #31049.
Maybe this (and the other changes that I will split from #31049) should wait for a test like `ed_iterator_specializations` to be added. Would it be sufficient to do the same for each possible escape length?
Fix fast path of float parsing on x87
The fast path of the float parser relies on the rounding to happen
exactly and directly to the correct number of bits. On x87, instead,
double rounding would occour as the FPU stack defaults to 80 bits of
precision.
This can be fixed by setting the precision of the FPU stack before
performing the int to float conversion. This can be achieved by
changing the value of the x87 control word. This is a somewhat common
operation that is in fact performed whenever a float needs to be
truncated to an integer, but it is undesirable to add its overhead for
code that does not rely on x87 for computations (i.e. on non-x86
architectures, or x86 architectures which perform FPU computations on
using SSE).
Fixes `num::dec2flt::fast_path_correct` (on x87).
Remove irrelevant information (and instead provide pointer to
reference documentation), replace ASCII-art table with the
corresponding MarkDown one, and minor fixes.
Make AtomicBool the same size as bool
Reopening #32365
This allows `AtomicBool` to be transmuted to a `bool`, which makes it more consistent with the other atomic types. Note that this now guarantees that the atomic type will always contain a valid `bool` value, which wasn't the case before (due to `fetch_nand`).
r? @alexcrichton
Explain the meaning of the fields of the control word and provide more
details about how the relevant one (Precision Control) is updated in
the fast path.
The fast path of the float parser relies on the rounding to happen
exactly and directly to the correct number of bits. On x87, instead,
double rounding would occour as the FPU stack defaults to 80 bits of
precision.
This can be fixed by setting the precision of the FPU stack before
performing the int to float conversion. This can be achieved by
changing the value of the x87 control word. This is a somewhat common
operation that is in fact performed whenever a float needs to be
truncated to an integer, but it is undesirable to add its overhead for
code that does not rely on x87 for computations (i.e. on non-x86
architectures, or x86 architectures which perform FPU computations on
using SSE).
Fixes `num::dec2flt::fast_path_correct` (on x87).
rustbuild: Add support for crate tests + doctests
This commit adds support to rustbuild to run crate unit tests (those defined by
`#[test]`) as well as documentation tests. All tests are powered by `cargo test`
under the hood.
Each step requires the `libtest` library is built for that corresponding stage.
Ideally the `test` crate would be a dev-dependency, but for now it's just easier
to ensure that we sequence everything in the right order.
Currently no filtering is implemented, so there's not actually a method of
testing *only* libstd or *only* libcore, but rather entire swaths of crates are
tested all at once.
A few points of note here are:
* The `coretest` and `collectionstest` crates are just listed as `[[test]]`
entires for `cargo test` to naturally pick up. This mean that `cargo test -p
core` actually runs all the tests for libcore.
* Libraries that aren't tested all mention `test = false` in their `Cargo.toml`
* Crates aren't currently allowed to have dev-dependencies due to
rust-lang/cargo#860, but we can likely alleviate this restriction once
workspaces are implemented.
cc #31590
This commit adds support to rustbuild to run crate unit tests (those defined by
`#[test]`) as well as documentation tests. All tests are powered by `cargo test`
under the hood.
Each step requires the `libtest` library is built for that corresponding stage.
Ideally the `test` crate would be a dev-dependency, but for now it's just easier
to ensure that we sequence everything in the right order.
Currently no filtering is implemented, so there's not actually a method of
testing *only* libstd or *only* libcore, but rather entire swaths of crates are
tested all at once.
A few points of note here are:
* The `coretest` and `collectionstest` crates are just listed as `[[test]]`
entires for `cargo test` to naturally pick up. This mean that `cargo test -p
core` actually runs all the tests for libcore.
* Libraries that aren't tested all mention `test = false` in their `Cargo.toml`
* Crates aren't currently allowed to have dev-dependencies due to
rust-lang/cargo#860, but we can likely alleviate this restriction once
workspaces are implemented.
cc #31590
Add rustc_on_unimplemented for Index implementation on slice
Reopening of #31071.
It also extends the possibility of `#[rustc_on_unimplemented]` by providing a small type filter in order to find the ones which corresponds the most.
r? @pnkfelix
implement RFC 1521
Adds documentation to Clone, specifying that Copy types should have a trivial Clone impl.
Fixes#33416.
I tried to use "should" and "must" as defined [here](https://tools.ietf.org/html/rfc2119).
cc @ubsan
Short-cut `T: Sized` trait selection for ADTs
Basically avoids all nested obligations when checking whether an ADT is sized - this speeds up typeck by ~15%
The refactoring fixed#32963, but I also want to make `Copy` not object-safe (will commit that soon).
Fixes#33201
r? @nikomatsakis
This is safe since the borrow checker ensures that we have the only
mutable reference to the struct, thus we can safely borrow its interior.
Tracking issue is #33444.
This requirement appears to be missing from RFC1214, but is clearly
necessary for translation. The last field of a tuple/enum remains in
a state of limbo, compiling but causing an ICE when it is used - we
should eventually fix that somehow.
this is a [breaking-change] - a soundness fix - and requires a
crater run.
docs: Changed docs for `size_of` to describe size as a stride offset
Current documentation for `std::mem::size_of` is ambiguous, and the documentation for `std::intrinsics::size_of` incorrectly defines size.
This fix re-defines size as the offset in bytes between successive instances of a type, as described in LLVM's [getTypeAllocSize](http://llvm.org/docs/doxygen/html/classllvm_1_1DataLayout.html#a1d6fcc02e91ba24510aba42660c90e29).
Fixes: #33266
Current description of `std::mem::size_of` is ambiguous, and the
`std::intrinsics::size_of` description incorrectly defines size
as the number of bytes necessary to exactly overwrite a value,
not including the padding between elements necessary in a vector
or structure.
special-case #[derive(Copy, Clone)] with a shallow clone
If a type is Copy then its Clone implementation can be a no-op. Currently `#[derive(Clone)]` generates a deep clone anyway. This can lead to lots of code bloat.
This PR detects the case where Copy and Clone are both being derived (the general case of "is this type Copy" can't be determined by a syntax extension) and generates the shallow Clone impl. Right now this can only be done if there are no type parameters (see https://github.com/rust-lang/rust/issues/31085#issuecomment-178988663), but this restriction can be removed after specialization.
Fixes#31085.
Changes #[derive(Copy, Clone)] to use a faster impl of Clone when
both derives are present, and there are no generics in the type.
The faster impl is simply returning *self (which works because the
type is also Copy). See the comments in libsyntax_ext/deriving/clone.rs
for more details.
There are a few types which are Copy but not Clone, in violation
of the definition of Copy. These include large arrays and tuples. The
very existence of these types is arguably a bug, but in order for this
optimization not to change the applicability of #[derive(Copy, Clone)],
the faster Clone impl also injects calls to a new function,
core::clone::assert_receiver_is_clone, to verify that all members are
actually Clone.
This is not a breaking change, because pursuant to RFC 1521, any type
that implements Copy should not do any observable work in its Clone
impl.
The example uses integers for the value being iterated over, but the indices
added by `enumerate` are also integers, so I always end up double taking and
thinking harder than I should when parsing the documentation. I also always
forget which order the index and value are in the tuple so I frequently hit this
stumbling block. This commit changes the documentation to iterate over
characters so that it is immediately obvious which part of the tuple is the
index and which is the value.
Split core::iter module implementation into parts
Split core::iter module implementation into parts
split iter.rs into a directory of (implementation private) modules.
+ mod (adaptor structs whose private fields need to be available both for them and Iterator
+ iterator (Iterator trait)
+ traits (FromIterator, etc; all traits but Iterator itself)
+ range (range related)
+ sources (Repeat, Once, Empty)
mk: Bootstrap from stable instead of snapshots
This commit removes all infrastructure from the repository for our so-called
snapshots to instead bootstrap the compiler from stable releases. Bootstrapping
from a previously stable release is a long-desired feature of distros because
they're not fans of downloading binary stage0 blobs from us. Additionally, this
makes our own CI easier as we can decommission all of the snapshot builders and
start having a regular cadence to when we update the stage0 compiler.
A new `src/etc/get-stage0.py` script was added which shares some code with
`src/bootstrap/bootstrap.py` to read a new file, `src/stage0.txt`, which lists
the current stage0 compiler as well as cargo that we bootstrap from. This script
will download the relevant `rustc` package an unpack it into `$target/stage0` as
we do today.
One problem of bootstrapping from stable releases is that we're not able to
compile unstable code (e.g. all the `#![feature]` directives in libcore/libstd).
To overcome this we employ two strategies:
* The bootstrap key of the previous compiler is hardcoded into `src/stage0.txt`
(enabled as a result of #32731) and exported by the build system. This enables
nightly features in the compiler we download.
* The standard library and compiler are pinned to a specific stage0, which
doesn't change, so we're guaranteed that we'll continue compiling as we start
from a known fixed source.
The process for making a release will also need to be tweaked now to continue to
cadence of bootstrapping from the previous release. This process looks like:
1. Merge `beta` to `stable`
2. Produce a new stable compiler.
3. Change `master` to bootstrap from this new stable compiler.
4. Merge `master` to `beta`
5. Produce a new beta compiler
6. Change `master` to bootstrap from this new beta compiler.
Step 3 above should involve very few changes as `master` was previously
bootstrapping from `beta` which is the same as `stable` at that point in time.
Step 6, however, is where we benefit from removing lots of `#[cfg(stage0)]` and
get to use new features. This also shouldn't slow the release too much as steps
1-5 requires little work other than waiting and step 6 just needs to happen at
some point during a release cycle, it's not time sensitive.
Closes#29555Closes#29557
Improve computation of offset in `EscapeUnicode`
Unify the computation of `offset` and use `leading_zeros` instead of manually scanning the bits.
This PR removes some duplicated code and makes it a little simpler .
The computation of `offset` is also faster, but it is unlikely to have an impact on actual code.
(split from #31049)
This commit removes all infrastructure from the repository for our so-called
snapshots to instead bootstrap the compiler from stable releases. Bootstrapping
from a previously stable release is a long-desired feature of distros because
they're not fans of downloading binary stage0 blobs from us. Additionally, this
makes our own CI easier as we can decommission all of the snapshot builders and
start having a regular cadence to when we update the stage0 compiler.
A new `src/etc/get-stage0.py` script was added which shares some code with
`src/bootstrap/bootstrap.py` to read a new file, `src/stage0.txt`, which lists
the current stage0 compiler as well as cargo that we bootstrap from. This script
will download the relevant `rustc` package an unpack it into `$target/stage0` as
we do today.
One problem of bootstrapping from stable releases is that we're not able to
compile unstable code (e.g. all the `#![feature]` directives in libcore/libstd).
To overcome this we employ two strategies:
* The bootstrap key of the previous compiler is hardcoded into `src/stage0.txt`
(enabled as a result of #32731) and exported by the build system. This enables
nightly features in the compiler we download.
* The standard library and compiler are pinned to a specific stage0, which
doesn't change, so we're guaranteed that we'll continue compiling as we start
from a known fixed source.
The process for making a release will also need to be tweaked now to continue to
cadence of bootstrapping from the previous release. This process looks like:
1. Merge `beta` to `stable`
2. Produce a new stable compiler.
3. Change `master` to bootstrap from this new stable compiler.
4. Merge `master` to `beta`
5. Produce a new beta compiler
6. Change `master` to bootstrap from this new beta compiler.
Step 3 above should involve very few changes as `master` was previously
bootstrapping from `beta` which is the same as `stable` at that point in time.
Step 6, however, is where we benefit from removing lots of `#[cfg(stage0)]` and
get to use new features. This also shouldn't slow the release too much as steps
1-5 requires little work other than waiting and step 6 just needs to happen at
some point during a release cycle, it's not time sensitive.
Closes#29555Closes#29557
split iter.rs into a directory of (implementation private) modules.
+ mod Adaptor structs
- Private fields need to be available both for them and Iterator
+ iterator (Iterator trait)
+ traits (FromIterator, traits but Iterator itself)
+ range (range related)
+ sources (Repeat, Once, Empty)
collections: Add slice::binary_search_by_key
This method adds to the family of `_by_key` methods, and is the
counterpart of `slice::sort_by_key`. It was mentioned on #30423 but
was not implemented at that time.
Refs #30423
This method adds to the family of `_by_key` methods, and is the
counterpart of `slice::sort_by_key`. It was mentioned on #30423 but
was not implemented at that time.
Refs #30423
std: Stabilize APIs for the 1.9 release
This commit applies all stabilizations, renamings, and deprecations that the
library team has decided on for the upcoming 1.9 release. All tracking issues
have gone through a cycle-long "final comment period" and the specific APIs
stabilized/deprecated are:
Stable
* `std::panic`
* `std::panic::catch_unwind` (renamed from `recover`)
* `std::panic::resume_unwind` (renamed from `propagate`)
* `std::panic::AssertUnwindSafe` (renamed from `AssertRecoverSafe`)
* `std::panic::UnwindSafe` (renamed from `RecoverSafe`)
* `str::is_char_boundary`
* `<*const T>::as_ref`
* `<*mut T>::as_ref`
* `<*mut T>::as_mut`
* `AsciiExt::make_ascii_uppercase`
* `AsciiExt::make_ascii_lowercase`
* `char::decode_utf16`
* `char::DecodeUtf16`
* `char::DecodeUtf16Error`
* `char::DecodeUtf16Error::unpaired_surrogate`
* `BTreeSet::take`
* `BTreeSet::replace`
* `BTreeSet::get`
* `HashSet::take`
* `HashSet::replace`
* `HashSet::get`
* `OsString::with_capacity`
* `OsString::clear`
* `OsString::capacity`
* `OsString::reserve`
* `OsString::reserve_exact`
* `OsStr::is_empty`
* `OsStr::len`
* `std::os::unix::thread`
* `RawPthread`
* `JoinHandleExt`
* `JoinHandleExt::as_pthread_t`
* `JoinHandleExt::into_pthread_t`
* `HashSet::hasher`
* `HashMap::hasher`
* `CommandExt::exec`
* `File::try_clone`
* `SocketAddr::set_ip`
* `SocketAddr::set_port`
* `SocketAddrV4::set_ip`
* `SocketAddrV4::set_port`
* `SocketAddrV6::set_ip`
* `SocketAddrV6::set_port`
* `SocketAddrV6::set_flowinfo`
* `SocketAddrV6::set_scope_id`
* `<[T]>::copy_from_slice`
* `ptr::read_volatile`
* `ptr::write_volatile`
* The `#[deprecated]` attribute
* `OpenOptions::create_new`
Deprecated
* `std::raw::Slice` - use raw parts of `slice` module instead
* `std::raw::Repr` - use raw parts of `slice` module instead
* `str::char_range_at` - use slicing plus `chars()` plus `len_utf8`
* `str::char_range_at_reverse` - use slicing plus `chars().rev()` plus `len_utf8`
* `str::char_at` - use slicing plus `chars()`
* `str::char_at_reverse` - use slicing plus `chars().rev()`
* `str::slice_shift_char` - use `chars()` plus `Chars::as_str`
* `CommandExt::session_leader` - use `before_exec` instead.
Closes#27719
cc #27751 (deprecating the `Slice` bits)
Closes#27754Closes#27780Closes#27809Closes#27811Closes#27830Closes#28050Closes#29453Closes#29791Closes#29935Closes#30014Closes#30752Closes#31262
cc #31398 (still need to deal with `before_exec`)
Closes#31405Closes#31572Closes#31755Closes#31756
This commit applies all stabilizations, renamings, and deprecations that the
library team has decided on for the upcoming 1.9 release. All tracking issues
have gone through a cycle-long "final comment period" and the specific APIs
stabilized/deprecated are:
Stable
* `std::panic`
* `std::panic::catch_unwind` (renamed from `recover`)
* `std::panic::resume_unwind` (renamed from `propagate`)
* `std::panic::AssertUnwindSafe` (renamed from `AssertRecoverSafe`)
* `std::panic::UnwindSafe` (renamed from `RecoverSafe`)
* `str::is_char_boundary`
* `<*const T>::as_ref`
* `<*mut T>::as_ref`
* `<*mut T>::as_mut`
* `AsciiExt::make_ascii_uppercase`
* `AsciiExt::make_ascii_lowercase`
* `char::decode_utf16`
* `char::DecodeUtf16`
* `char::DecodeUtf16Error`
* `char::DecodeUtf16Error::unpaired_surrogate`
* `BTreeSet::take`
* `BTreeSet::replace`
* `BTreeSet::get`
* `HashSet::take`
* `HashSet::replace`
* `HashSet::get`
* `OsString::with_capacity`
* `OsString::clear`
* `OsString::capacity`
* `OsString::reserve`
* `OsString::reserve_exact`
* `OsStr::is_empty`
* `OsStr::len`
* `std::os::unix::thread`
* `RawPthread`
* `JoinHandleExt`
* `JoinHandleExt::as_pthread_t`
* `JoinHandleExt::into_pthread_t`
* `HashSet::hasher`
* `HashMap::hasher`
* `CommandExt::exec`
* `File::try_clone`
* `SocketAddr::set_ip`
* `SocketAddr::set_port`
* `SocketAddrV4::set_ip`
* `SocketAddrV4::set_port`
* `SocketAddrV6::set_ip`
* `SocketAddrV6::set_port`
* `SocketAddrV6::set_flowinfo`
* `SocketAddrV6::set_scope_id`
* `<[T]>::copy_from_slice`
* `ptr::read_volatile`
* `ptr::write_volatile`
* The `#[deprecated]` attribute
* `OpenOptions::create_new`
Deprecated
* `std::raw::Slice` - use raw parts of `slice` module instead
* `std::raw::Repr` - use raw parts of `slice` module instead
* `str::char_range_at` - use slicing plus `chars()` plus `len_utf8`
* `str::char_range_at_reverse` - use slicing plus `chars().rev()` plus `len_utf8`
* `str::char_at` - use slicing plus `chars()`
* `str::char_at_reverse` - use slicing plus `chars().rev()`
* `str::slice_shift_char` - use `chars()` plus `Chars::as_str`
* `CommandExt::session_leader` - use `before_exec` instead.
Closes#27719
cc #27751 (deprecating the `Slice` bits)
Closes#27754Closes#27780Closes#27809Closes#27811Closes#27830Closes#28050Closes#29453Closes#29791Closes#29935Closes#30014Closes#30752Closes#31262
cc #31398 (still need to deal with `before_exec`)
Closes#31405Closes#31572Closes#31755Closes#31756
Match signed/unsigned integer type docs
* Copy documentation from signed implementation to unsigned implementation, where necessary.
A few functions had elaborate docs in the signed version but not in the unsigned version. This probably happenned because the signed version is at the top and the author didn't realize they had to update the documentation in both locations.
* Use signed integers in signed documentation, where possible.
r? @steveklabnik
Bit-magic for faster is_char_boundary
The asm generated for b < 128 || b >= 192 is not ideal, as it computes
both sub-inequalities. This patch replaces it with bit magic.
Fixes#32471
