This change is an implementation of [RFC 69][rfc] which adds a third kind of
global to the language, `const`. This global is most similar to what the old
`static` was, and if you're unsure about what to use then you should use a
`const`.
The semantics of these three kinds of globals are:
* A `const` does not represent a memory location, but only a value. Constants
are translated as rvalues, which means that their values are directly inlined
at usage location (similar to a #define in C/C++). Constant values are, well,
constant, and can not be modified. Any "modification" is actually a
modification to a local value on the stack rather than the actual constant
itself.
Almost all values are allowed inside constants, whether they have interior
mutability or not. There are a few minor restrictions listed in the RFC, but
they should in general not come up too often.
* A `static` now always represents a memory location (unconditionally). Any
references to the same `static` are actually a reference to the same memory
location. Only values whose types ascribe to `Sync` are allowed in a `static`.
This restriction is in place because many threads may access a `static`
concurrently. Lifting this restriction (and allowing unsafe access) is a
future extension not implemented at this time.
* A `static mut` continues to always represent a memory location. All references
to a `static mut` continue to be `unsafe`.
This is a large breaking change, and many programs will need to be updated
accordingly. A summary of the breaking changes is:
* Statics may no longer be used in patterns. Statics now always represent a
memory location, which can sometimes be modified. To fix code, repurpose the
matched-on-`static` to a `const`.
static FOO: uint = 4;
match n {
FOO => { /* ... */ }
_ => { /* ... */ }
}
change this code to:
const FOO: uint = 4;
match n {
FOO => { /* ... */ }
_ => { /* ... */ }
}
* Statics may no longer refer to other statics by value. Due to statics being
able to change at runtime, allowing them to reference one another could
possibly lead to confusing semantics. If you are in this situation, use a
constant initializer instead. Note, however, that statics may reference other
statics by address, however.
* Statics may no longer be used in constant expressions, such as array lengths.
This is due to the same restrictions as listed above. Use a `const` instead.
[breaking-change]
Closes#17718
[rfc]: https://github.com/rust-lang/rfcs/pull/246
This is the bare minimum to stop using split stacks on Windows, fixing https://github.com/rust-lang/rust/issues/13259 and #14742, by turning on stack probes for all functions and disabling compiler and runtime support for split stacks on Windows.
It does not restore the out-of-stack error message, which requires more runtime work.
This includes a test that the Windows TCB is no longer being clobbered, but the out-of-stack test itself is pretty weak, only testing that the program exits abnormally, not that it isn't writing to bogus memory, so I haven't truly verified that this is providing the safety we claim.
A more complete solution is in https://github.com/rust-lang/rust/pull/16388, which has some unresolved issues yet.
cc @Zoxc @klutzy @vadimcn
This breaks code like:
struct Foo {
...
}
pub fn make_foo() -> Foo {
...
}
Change this code to:
pub struct Foo { // note `pub`
...
}
pub fn make_foo() -> Foo {
...
}
The `visible_private_types` lint has been removed, since it is now an
error to attempt to expose a private type in a public API. In its place
a `#[feature(visible_private_types)]` gate has been added.
Closes#16463.
RFC #48.
[breaking-change]
Change to resolve and update compiler and libs for uses.
[breaking-change]
Enum variants are now in both the value and type namespaces. This means that
if you have a variant with the same name as a type in scope in a module, you
will get a name clash and thus an error. The solution is to either rename the
type or the variant.
This adds support for lint groups to the compiler. Lint groups are a way of
grouping a number of lints together under one name. For example, this also
defines a default lint for naming conventions, named `bad_style`. Writing
`#[allow(bad_style)]` is equivalent to writing
`#[allow(non_camel_case_types, non_snake_case, non_uppercase_statics)]`. These
lint groups can also be defined as a compiler plugin using the new
`Registry::register_lint_group` method.
This also adds two built-in lint groups, `bad_style` and `unused`. The contents
of these groups can be seen by running `rustc -W help`.
This unifies the `non_snake_case_functions` and `uppercase_variables` lints
into one lint, `non_snake_case`. It also now checks for non-snake-case modules.
This also extends the non-camel-case types lint to check type parameters, and
merges the `non_uppercase_pattern_statics` lint into the
`non_uppercase_statics` lint.
Because the `uppercase_variables` lint is now part of the `non_snake_case`
lint, all non-snake-case variables that start with lowercase characters (such
as `fooBar`) will now trigger the `non_snake_case` lint.
New code should be updated to use the new `non_snake_case` lint instead of the
previous `non_snake_case_functions` and `uppercase_variables` lints. All use of
the `non_uppercase_pattern_statics` should be replaced with the
`non_uppercase_statics` lint. Any code that previously contained non-snake-case
module or variable names should be updated to use snake case names or disable
the `non_snake_case` lint. Any code with non-camel-case type parameters should
be changed to use camel case or disable the `non_camel_case_types` lint.
[breaking-change]
Per API meeting
https://github.com/rust-lang/meeting-minutes/blob/master/Meeting-API-review-2014-08-13.md
# Changes to `core::option`
Most of the module is marked as stable or unstable; most of the unstable items are awaiting resolution of conventions issues.
However, a few methods have been deprecated, either due to lack of use or redundancy:
* `take_unwrap`, `get_ref` and `get_mut_ref` (redundant, and we prefer for this functionality to go through an explicit .unwrap)
* `filtered` and `while`
* `mutate` and `mutate_or_set`
* `collect`: this functionality is being moved to a new `FromIterator` impl.
# Changes to `core::result`
Most of the module is marked as stable or unstable; most of the unstable items are awaiting resolution of conventions issues.
* `collect`: this functionality is being moved to a new `FromIterator` impl.
* `fold_` is deprecated due to lack of use
* Several methods found in `core::option` are added here, including `iter`, `as_slice`, and variants.
Due to deprecations, this is a:
[breaking-change]
This commits implements {Tcp,Unix}Acceptor::{clone,close_accept} methods for
unix. A windows implementation is coming in a later commit.
The clone implementation is based on atomic reference counting (as with all
other clones), and the close_accept implementation is based on selecting on a
self-pipe which signals that a close has been seen.
As of RFC 18, struct layout is undefined. Opting into a C-compatible struct
layout is now down with #[repr(C)]. For consistency, specifying a packed
layout is now also down with #[repr(packed)]. Both can be specified.
To fix errors caused by this, just add #[repr(C)] to the structs, and change
#[packed] to #[repr(packed)]
Closes#14309
[breaking-change]
declared with the same name in the same scope.
This breaks several common patterns. First are unused imports:
use foo::bar;
use baz::bar;
Change this code to the following:
use baz::bar;
Second, this patch breaks globs that import names that are shadowed by
subsequent imports. For example:
use foo::*; // including `bar`
use baz::bar;
Change this code to remove the glob:
use foo::{boo, quux};
use baz::bar;
Or qualify all uses of `bar`:
use foo::{boo, quux};
use baz;
... baz::bar ...
Finally, this patch breaks code that, at top level, explicitly imports
`std` and doesn't disable the prelude.
extern crate std;
Because the prelude imports `std` implicitly, there is no need to
explicitly import it; just remove such directives.
The old behavior can be opted into via the `import_shadowing` feature
gate. Use of this feature gate is discouraged.
This implements RFC #116.
Closes#16464.
[breaking-change]
This leaves the `Share` trait at `std::kinds` via a `#[deprecated]` `pub use`
statement, but the `NoShare` struct is no longer part of `std::kinds::marker`
due to #12660 (the build cannot bootstrap otherwise).
All code referencing the `Share` trait should now reference the `Sync` trait,
and all code referencing the `NoShare` type should now reference the `NoSync`
type. The functionality and meaning of this trait have not changed, only the
naming.
Closes#16281
[breaking-change]
This leaves the `Share` trait at `std::kinds` via a `#[deprecated]` `pub use`
statement, but the `NoShare` struct is no longer part of `std::kinds::marker`
due to #12660 (the build cannot bootstrap otherwise).
All code referencing the `Share` trait should now reference the `Sync` trait,
and all code referencing the `NoShare` type should now reference the `NoSync`
type. The functionality and meaning of this trait have not changed, only the
naming.
Closes#16281
[breaking-change]
This commit stabilizes the `std::sync::atomics` module, renaming it to
`std::sync::atomic` to match library precedent elsewhere, and tightening
up behavior around incorrect memory ordering annotations.
The vast majority of the module is now `stable`. However, the
`AtomicOption` type has been deprecated, since it is essentially unused
and is not truly a primitive atomic type. It will eventually be replaced
by a higher-level abstraction like MVars.
Due to deprecations, this is a:
[breaking-change]
The original trick used to trigger unwinds would not work with GCC's implementation of SEH, so I had to invent a new one: rust_try now consists of two routines: the outer one, whose handler triggers unwinds, and the inner one, that stops unwinds by having a landing pad that swallows exceptions and passes them on to the outer routine via a normal return.
This commit stabilizes the `std::sync::atomics` module, renaming it to
`std::sync::atomic` to match library precedent elsewhere, and tightening
up behavior around incorrect memory ordering annotations.
The vast majority of the module is now `stable`. However, the
`AtomicOption` type has been deprecated, since it is essentially unused
and is not truly a primitive atomic type. It will eventually be replaced
by a higher-level abstraction like MVars.
Due to deprecations, this is a:
[breaking-change]
As discovered in #15460, a particular #[link(kind = "static", ...)] line is not
actually guaranteed to link the library at all. The reason for this is that if
the external library doesn't have any referenced symbols in the object generated
by rustc, the entire library is dropped by the linker.
For dynamic native libraries, this is solved by passing -lfoo for all downstream
compilations unconditionally. For static libraries in rlibs this is solved
because the entire archive is bundled in the rlib. The only situation in which
this was a problem was when a static native library was linked to a rust dynamic
library.
This commit brings the behavior of dylibs in line with rlibs by passing the
--whole-archive flag to the linker when linking native libraries. On OSX, this
uses the -force_load flag. This flag ensures that the entire archive is
considered candidate for being linked into the final dynamic library.
This is a breaking change because if any static library is included twice in the
same compilation unit then the linker will start emitting errors about duplicate
definitions now. The fix for this would involve only statically linking to a
library once.
Closes#15460
[breaking-change]
This was motivated by a desire to remove allocation in the common
pattern of
let old = key.replace(None)
do_something();
key.replace(old);
This also switched the map representation from a Vec to a TreeMap. A Vec
may be reasonable if there's only a couple TLD keys, but a TreeMap
provides better behavior as the number of keys increases.
Like the Vec, this TreeMap implementation does not shrink the container
when a value is removed. Unlike Vec, this TreeMap implementation cannot
reuse an empty node for a different key. Therefore any key that has been
inserted into the TLD at least once will continue to take up space in
the Map until the task ends. The expectation is that the majority of
keys that are inserted into TLD will be expected to have a value for
most of the rest of the task's lifetime. If this assumption is wrong,
there are two reasonable ways to fix this that could be implemented in
the future:
1. Provide an API call to either remove a specific key from the TLD and
destruct its node (e.g. `remove()`), or instead to explicitly clean
up all currently-empty nodes in the map (e.g. `compact()`). This is
simple, but requires the user to explicitly call it.
2. Keep track of the number of empty nodes in the map and when the map
is mutated (via `replace()`), if the number of empty nodes passes
some threshold, compact it automatically. Alternatively, whenever a
new key is inserted that hasn't been used before, compact the map at
that point.
---
Benchmarks:
I ran 3 benchmarks. tld_replace_none just replaces the tld key with None
repeatedly. tld_replace_some replaces it with Some repeatedly. And
tld_replace_none_some simulates the common behavior of replacing with
None, then replacing with the previous value again (which was a Some).
Old implementation:
test tld_replace_none ... bench: 20 ns/iter (+/- 0)
test tld_replace_none_some ... bench: 77 ns/iter (+/- 4)
test tld_replace_some ... bench: 57 ns/iter (+/- 2)
New implementation:
test tld_replace_none ... bench: 11 ns/iter (+/- 0)
test tld_replace_none_some ... bench: 23 ns/iter (+/- 0)
test tld_replace_some ... bench: 12 ns/iter (+/- 0)
This was motivated by a desire to remove allocation in the common
pattern of
let old = key.replace(None)
do_something();
key.replace(old);
This also switched the map representation from a Vec to a TreeMap. A Vec
may be reasonable if there's only a couple TLD keys, but a TreeMap
provides better behavior as the number of keys increases.
Like the Vec, this TreeMap implementation does not shrink the container
when a value is removed. Unlike Vec, this TreeMap implementation cannot
reuse an empty node for a different key. Therefore any key that has been
inserted into the TLD at least once will continue to take up space in
the Map until the task ends. The expectation is that the majority of
keys that are inserted into TLD will be expected to have a value for
most of the rest of the task's lifetime. If this assumption is wrong,
there are two reasonable ways to fix this that could be implemented in
the future:
1. Provide an API call to either remove a specific key from the TLD and
destruct its node (e.g. `remove()`), or instead to explicitly clean
up all currently-empty nodes in the map (e.g. `compact()`). This is
simple, but requires the user to explicitly call it.
2. Keep track of the number of empty nodes in the map and when the map
is mutated (via `replace()`), if the number of empty nodes passes
some threshold, compact it automatically. Alternatively, whenever a
new key is inserted that hasn't been used before, compact the map at
that point.
---
Benchmarks:
I ran 3 benchmarks. tld_replace_none just replaces the tld key with None
repeatedly. tld_replace_some replaces it with Some repeatedly. And
tld_replace_none_some simulates the common behavior of replacing with
None, then replacing with the previous value again (which was a Some).
Old implementation:
test tld_replace_none ... bench: 20 ns/iter (+/- 0)
test tld_replace_none_some ... bench: 77 ns/iter (+/- 4)
test tld_replace_some ... bench: 57 ns/iter (+/- 2)
New implementation:
test tld_replace_none ... bench: 11 ns/iter (+/- 0)
test tld_replace_none_some ... bench: 23 ns/iter (+/- 0)
test tld_replace_some ... bench: 12 ns/iter (+/- 0)
Closes#16097 (fix variable name in tutorial)
Closes#16100 (More defailbloating)
Closes#16104 (Fix deprecation commment on `core::cmp::lexical_ordering`)
Closes#16105 (fix formatting in pointer guide table)
Closes#16107 (remove serialize::ebml, add librbml)
Closes#16108 (Fix heading levels in pointer guide)
Closes#16109 (rustrt: Don't conditionally init the at_exit QUEUE)
Closes#16111 (hexfloat: Deprecate to move out of the repo)
Closes#16113 (Add examples for GenericPath methods.)
Closes#16115 (Byte literals!)
Closes#16116 (Add a non-regression test for issue #8372)
Closes#16120 (Deprecate semver)
Closes#16124 (Deprecate uuid)
Closes#16126 (Deprecate fourcc)
Closes#16127 (Remove incorrect example)
Closes#16129 (Add note about production deployments.)
Closes#16131 (librustc: Don't ICE when trying to subst regions in destructor call.)
Closes#16133 (librustc: Don't ICE with struct exprs where the name is not a valid struct.)
Closes#16136 (Implement slice::Vector for Option<T> and CVec<T>)
Closes#16137 (alloc, arena, test, url, uuid: Elide lifetimes.)
Not included are two required patches:
* LLVM: segmented stack support for DragonFly [1]
* jemalloc: simple configure patches
[1]: http://reviews.llvm.org/D4705
The correct terminology is Task-Local Data, or TLD. Task-Local Storage,
or TLS, is the old terminology that was abandoned because of the
confusion with Thread-Local Storage (TLS).
Like with libnative, when a green task failed to spawn it would leave the world
in a corrupt state where the local scheduler had been dropped as well as the
local task. Also like libnative, this patch sets up a "bomb" which when it goes
off will restore the state of the world.
Previously, the call to bookkeeping::increment() was never paired with a
decrement when the spawn failed (due to unwinding). This fixes the problem by
returning a "bomb" from increment() which will decrement on drop, and then
moving the bomb into the child task's procedure which will be dropped naturally.
When a new task fails to spawn, it triggers a task failure of the spawning task.
This ends up causing runtime aborts today because of the destructor bomb in the
Task structure. The bomb doesn't actually need to go off until *after* the task
has run at least once.
This now prevents a runtime abort when a native thread fails to spawn.
Not included are two required patches:
* LLVM: segmented stack support for DragonFly [1]
* jemalloc: simple configure patches
[1]: http://reviews.llvm.org/D4705
This commit applies stability attributes to the contents of these modules,
summarized here:
* The `unit` and `bool` modules have become #[unstable] as they are purely meant
for documentation purposes and are candidates for removal.
* The `ty` module has been deprecated, and the inner `Unsafe` type has been
renamed to `UnsafeCell` and moved to the `cell` module. The `marker1` field
has been removed as the compiler now always infers `UnsafeCell` to be
invariant. The `new` method i stable, but the `value` field, `get` and
`unwrap` methods are all unstable.
* The `tuple` module has its name as stable, the naming of the `TupleN` traits
as stable while the methods are all #[unstable]. The other impls in the module
have appropriate stability for the corresponding trait.
* The `arc` module has received the exact same treatment as the `rc` module
previously did.
* The `any` module has its name as stable. The `Any` trait is also stable, with
a new private supertrait which now contains the `get_type_id` method. This is
to make the method a private implementation detail rather than a public-facing
detail.
The two extension traits in the module are marked #[unstable] as they will not
be necessary with DST. The `is` method is #[stable], the as_{mut,ref} methods
have been renamed to downcast_{mut,ref} and are #[unstable].
The extension trait `BoxAny` has been clarified as to why it is unstable as it
will not be necessary with DST.
This is a breaking change because the `marker1` field was removed from the
`UnsafeCell` type. To deal with this change, you can simply delete the field and
only specify the value of the `data` field in static initializers.
[breaking-change]
This eliminates the last vestige of the `~` syntax.
Instead of `~self`, write `self: Box<TypeOfSelf>`; instead of `mut
~self`, write `mut self: Box<TypeOfSelf>`, replacing `TypeOfSelf` with
the self-type parameter as specified in the implementation.
Closes#13885.
[breaking-change]
This also removes checks in other methods of `CString`
Breaking changes:
* `CString::new` now fails if `buf` is null. To avoid this add a check
before creatng a new `CString` .
* The `is_null` and `is_not_null` methods are deprecated, because a
`CString` cannot be null.
* Other methods which used to fail if the `CString` was null do not fail anymore
[breaking-change]
Implement for Vec, DList, RingBuf. Add MutableSeq to the prelude.
Since the collections traits are in the prelude most consumers of
these methods will continue to work without change.
[breaking-change]
Adds a new runtime unwinding function that encapsulates the printing of the words "explicit failure" when `fail!()` is called w/o arguments.
The before/after optimized assembly:
```
leaq "str\"str\"(1412)"(%rip), %rax
movq %rax, 24(%rsp)
movq $16, 32(%rsp)
leaq "str\"str\"(1413)"(%rip), %rax
movq %rax, 8(%rsp)
movq $19, 16(%rsp)
leaq 24(%rsp), %rdi
leaq 8(%rsp), %rsi
movl $11, %edx
callq _ZN6unwind12begin_unwind21h15836560661922107792E
```
```
leaq "str\"str\"(1369)"(%rip), %rax
movq %rax, 8(%rsp)
movq $19, 16(%rsp)
leaq 8(%rsp), %rdi
movl $11, %esi
callq _ZN6unwind31begin_unwind_no_time_to_explain20hd1c720cdde6a116480dE@PLT
```
Before/after filesizes:
rwxrwxr-x 1 brian brian 21479503 Jul 20 22:09 stage2-old/lib/librustc-4e7c5e5c.so
rwxrwxr-x 1 brian brian 21475415 Jul 20 22:30 x86_64-unknown-linux-gnu/stage2/lib/librustc-4e7c5e5c.so
This is the lowest-hanging fruit in the fail-bloat wars. Further fixes are going to require harder tradeoffs.
r? @pcwalton
