This commit is an implementation of [RFC 1183][rfc] which allows swapping out
the default allocator on nightly Rust. No new stable surface area should be
added as a part of this commit.
[rfc]: https://github.com/rust-lang/rfcs/pull/1183
Two new attributes have been added to the compiler:
* `#![needs_allocator]` - this is used by liballoc (and likely only liballoc) to
indicate that it requires an allocator crate to be in scope.
* `#![allocator]` - this is a indicator that the crate is an allocator which can
satisfy the `needs_allocator` attribute above.
The ABI of the allocator crate is defined to be a set of symbols that implement
the standard Rust allocation/deallocation functions. The symbols are not
currently checked for exhaustiveness or typechecked. There are also a number of
restrictions on these crates:
* An allocator crate cannot transitively depend on a crate that is flagged as
needing an allocator (e.g. allocator crates can't depend on liballoc).
* There can only be one explicitly linked allocator in a final image.
* If no allocator is explicitly requested one will be injected on behalf of the
compiler. Binaries and Rust dylibs will use jemalloc by default where
available and staticlibs/other dylibs will use the system allocator by
default.
Two allocators are provided by the distribution by default, `alloc_system` and
`alloc_jemalloc` which operate as advertised.
Closes#27389
This commit removes all unstable and deprecated functions in the standard
library. A release was recently cut (1.3) which makes this a good time for some
spring cleaning of the deprecated functions.
The replacements are functions that usually use a single `mem::transmute` in
their body and restrict input and output via more concrete types than `T` and
`U`. Worth noting are the `transmute` functions for slices and the `from_utf8*`
family for mutable slices. Additionally, `mem::transmute` was often used for
casting raw pointers, when you can already cast raw pointers just fine with
`as`.
This commit is an implementation of [RFC 1184][rfc] which tweaks the behavior of
the `#![no_std]` attribute and adds a new `#![no_core]` attribute. The
`#![no_std]` attribute now injects `extern crate core` at the top of the crate
as well as the libcore prelude into all modules (in the same manner as the
standard library's prelude). The `#![no_core]` attribute disables both std and
core injection.
[rfc]: https://github.com/rust-lang/rfcs/pull/1184
This is a minor [breaking-change], as it changes what
`boxed_str.to_owned()` does (previously it would deref to `&str` and
call `to_owned` on that to get a `String`). However `Box<str>` is such an
exceptionally rare type that this is not expected to be a serious
concern. Also a `Box<str>` can be freely converted to a `String` to
obtain the previous result anyway.
This is a minor [breaking-change], as it changes what
`boxed_str.to_owned()` does (previously it would deref to `&str` and
call `to_owned` on that to get a `String`). However `Box<str>` is such an
exceptionally rare type that this is not expected to be a serious
concern. Also a `Box<str>` can be freely converted to a `String` to
obtain the previous behaviour anyway.
Many of these have long since reached their stage of being obsolete, so this
commit starts the removal process for all of them. The unstable features that
were deprecated are:
* cmp_partial
* fs_time
* hash_default
* int_slice
* iter_min_max
* iter_reset_fuse
* iter_to_vec
* map_in_place
* move_from
* owned_ascii_ext
* page_size
* read_and_zero
* scan_state
* slice_chars
* slice_position_elem
* subslice_offset
These new snapshots contain the knowledge of how to build the new triples of
32-bit MSVC and 32-bit FreeBSD, both of which should soon start having
nightlies/auto builders!
This does not currently register bitrig/freebsd snapshots but I believe those
will be retroactively added in the near future.
This commit starts passing the `--whole-archive` flag (`-force_load` on OSX) to
the linker when linking rlibs into dylibs. The primary purpose of this commit is
to ensure that the linker doesn't strip out objects from an archive when
creating a dynamic library. Information on how this can go wrong can be found in
issues #14344 and #25185.
The unfortunate part about passing this flag to the linker is that we have to
preprocess the rlib to remove the metadata and compressed bytecode found within.
This means that creating a dylib will now take longer to link as we've got to
copy around the input rlibs to a temporary location, modify them, and then
invoke the linker. This isn't done for executables, however, so the "hello
world" compile time is not affected.
This fix was instigated because of the previous commit where rlibs may not
contain multiple object files instead of one due to codegen units being greater
than one. That change prevented the main distribution from being compiled with
more than one codegen-unit and this commit fixes that.
Closes#14344Closes#25185
This commit resolves the race condition in the `get_mut` and
`make_unique` functions, which arose through interaction with weak
pointers. The basic strategy is to "lock" the weak pointer count when
trying to establish uniqueness, by reusing the field as a simple
spinlock. The overhead for normal use of `Arc` is expected to be minimal
-- it will be *none* when only strong pointers are used, and only
requires a move from atomic increment to CAS for usage of weak pointers.
The commit also removes the `unsafe` and deprecated status of these functions.
Closes#24880
r? @alexcrichton
cc @metajack @SimonSapin @Ms2ger
This commit resolves the race condition in the `get_mut` and
`make_unique` functions, which arose through interaction with weak
pointers. The basic strategy is to "lock" the weak pointer count when
trying to establish uniqueness, by reusing the field as a simple
spinlock. The overhead for normal use of `Arc` is expected to be minimal
-- it will be *none* when only strong pointers are used, and only
requires a move from atomic increment to CAS for usage of weak pointers.
The commit also removes the `unsafe` and deprecated status of these
functions.
Along the way, the commit also improves several memory orderings, and
adds commentary about why various orderings suffice.
This removes a footgun, since it is a reasonable assumption to make that
pointers to `T` will be aligned to `align_of::<T>()`. This also matches
the behaviour of C/C++. `min_align_of` is now deprecated.
Closes#21611.
This commit moves the free functions in the `rc`, `arc`, and `boxed` modules to
associated functions on their respective types, following the recent trend
towards this pattern. The previous free functions are all left in-place with
`#[deprecated]` pointers towards the new locations.
This commit also deprecates `arc::get_mut` and `Arc::make_unique` with no
replacement as they are racy in the face of weak pointers.
This commit shards the broad `core` feature of the libcore library into finer
grained features. This split groups together similar APIs and enables tracking
each API separately, giving a better sense of where each feature is within the
stabilization process.
A few minor APIs were deprecated along the way:
* Iterator::reverse_in_place
* marker::NoCopy
This is a revert of PR #26008 which caused the unintended breakage reported in #26096. We may want to add these implementations in the long run, but for now this revert allows us to take some more time to evaluate the impact of such a change (e.g. run it through crater).
Closes#26096
