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 PR implements the majority of RFC 1214. In particular, it implements:
- the new outlives relation
- comprehensive WF checking
For the most part, new code receives warnings, not errors, though 3 regressions were found via a crater run.
There are some deviations from RFC 1214. Most notably:
- we still consider implied bounds from fn ret; this intersects other soundness issues that I intend to address in detail in a follow-up RFC. Fixing this without breaking a lot of code probably requires rewriting compare-method somewhat (which is probably a good thing).
- object types do not check trait bounds for fear of encountering `Self`; this was left as an unresolved question in RFC 1214, but ultimately feels inconsistent.
Both of those two issues are highlighted in the tracking issue, https://github.com/rust-lang/rust/issues/27579. #27579 also includes a testing matrix with new tests that I wrote -- these probably duplicate some existing tests, I tried to check but wasn't quite sure what to look for. I tried to be thorough in testing the WF relation, at least, but would welcome suggestions for missing tests.
r? @nrc (or perhaps someone else?)
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.
Initial version of PR had an DerefMut implementation, which was later removed
because it may cause mutable reference aliasing.
Suggest how to implement mutability with reentrant mutex and remove the claim we
implement DerefMut.
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.
Initial version of PR had an DerefMut implementation, which was later removed
because it may cause mutable reference aliasing.
Suggest how to implement mutability with reentrant mutex and remove the claim we
implement DerefMut.
This commit leverages the runtime support for DWARF exception info added
in #27210 to enable unwinding by default on 64-bit MSVC. This also additionally
adds a few minor fixes here and there in the test harness and such to get
`make check` entirely passing on 64-bit MSVC:
* The invocation of `maketest.py` now works with spaces/quotes in CC
* debuginfo tests are disabled on MSVC
* A link error for librustc was hacked around (see #27438)
This commit leverages the runtime support for DWARF exception info added
in #27210 to enable unwinding by default on 64-bit MSVC. This also additionally
adds a few minor fixes here and there in the test harness and such to get
`make check` entirely passing on 64-bit MSVC:
* The invocation of `maketest.py` now works with spaces/quotes in CC
* debuginfo tests are disabled on MSVC
* A link error for librustc was hacked around (see #27438)
`FormatMessageW` always inserts trailing `\r\n` to system messages which is a minor annoyance when they're fed to `Debug` but can break formatting with `Display`.
```rust
fn main() {
use std::env;
if let Err(err) = env::set_current_dir("???") {
println!("{:#?}\n{}", err, err);
}
}
```
```_
Error {
repr: Os {
code: 2,
message: "The system cannot find the file specified.\r\n"
}
}
The system cannot find the file specified.
(os error 2)
```
This commit stabilizes the `std::time` module and the `Duration` type.
`Duration::span` remains unstable, and the `Display` implementation for
`Duration` has been removed as it is still being reworked and all trait
implementations for stable types are de facto stable.
This is a [breaking-change] to those using `Duration`'s `Display`
implementation.
I'm opening this PR as a platform for discussion - there may be some method renaming to do as part of the stabilization process.
This commit stabilizes the `std::time` module and the `Duration` type.
`Duration::span` remains unstable, and the `Display` implementation for
`Duration` has been removed as it is still being reworked and all trait
implementations for stable types are de facto stable.
This is a [breaking-change] to those using `Duration`'s `Display`
implementation.
This commit removes all morestack support from the compiler which entails:
* Segmented stacks are no longer emitted in codegen.
* We no longer build or distribute libmorestack.a
* The `stack_exhausted` lang item is no longer required
The only current use of the segmented stack support in LLVM is to detect stack
overflow. This is no longer really required, however, because we already have
guard pages for all threads and registered signal handlers watching for a
segfault on those pages (to print out a stack overflow message). Additionally,
major platforms (aka Windows) already don't use morestack.
This means that Rust is by default less likely to catch stack overflows because
if a function takes up more than one page of stack space it won't hit the guard
page. This is what the purpose of morestack was (to catch this case), but it's
better served with stack probes which have more cross platform support and no
runtime support necessary. Until LLVM supports this for all platform it looks
like morestack isn't really buying us much.
cc #16012 (still need stack probes)
Closes#26458 (a drive-by fix to help diagnostics on stack overflow)
r? @brson
This commit removes all morestack support from the compiler which entails:
* Segmented stacks are no longer emitted in codegen.
* We no longer build or distribute libmorestack.a
* The `stack_exhausted` lang item is no longer required
The only current use of the segmented stack support in LLVM is to detect stack
overflow. This is no longer really required, however, because we already have
guard pages for all threads and registered signal handlers watching for a
segfault on those pages (to print out a stack overflow message). Additionally,
major platforms (aka Windows) already don't use morestack.
This means that Rust is by default less likely to catch stack overflows because
if a function takes up more than one page of stack space it won't hit the guard
page. This is what the purpose of morestack was (to catch this case), but it's
better served with stack probes which have more cross platform support and no
runtime support necessary. Until LLVM supports this for all platform it looks
like morestack isn't really buying us much.
cc #16012 (still need stack probes)
Closes#26458 (a drive-by fix to help diagnostics on stack overflow)
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 builds upon #27233.
The investigation into #14232 discovered that it's possible that signal delivery
to a newly spawned process is racy on OSX. This test has been failing spuriously
on the OSX bots for some time now, so ignore it as we don't currently know a
solution and it looks like it may be out of our control.
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`.
