docs: begin a "low-level & unsafe code" guide.
This aims to cover the basics of writing safe unsafe code. At the moment
it is just designed to be a better place for the `asm!()` docs than the
detailed release notes wiki page, and I took the time to write up some
other things.
More examples are needed, especially of things that can subtly go wrong;
and vast areas of `unsafe`-ty aren't covered, e.g. `static mut`s and
thread-safety in general.
This aims to cover the basics of writing safe unsafe code. At the moment
it is just designed to be a better place for the `asm!()` docs than the
detailed release notes wiki page, and I took the time to write up some
other things.
More examples are needed, especially of things that can subtly go wrong;
and vast areas of `unsafe`-ty aren't covered, e.g. `static mut`s and
thread-safety in general.
The old comment of as_mut_slice() did not describe the function correctly. The new one does.
Also refactored option::iter() and option::mut_iter() to use as_ref() and as_mut() instead of match.
I ignored AtomicU64 methods on MIPS target
because libgcc doesn't implement MIPS32 64-bit atomic operations.
Otherwise it would cause link failure.
By the way, the patched LLVM doesn't have MIPS split stack anymore.
Should I file an issue about that?
The `Float` trait provides correct `min` and `max` methods on floating
point types, providing a consistent result regardless of the order the
parameters are passed.
These generic functions do not take the necessary performance hit to
correctly support a partial order, so the true requirement should be
given as a type bound.
Closes#12712
The `Float` trait provides correct `min` and `max` methods on floating
point types, providing a consistent result regardless of the order the
parameters are passed.
These generic functions do not take the necessary performance hit to
correctly support a partial order, so the true requirement should be
given as a type bound.
Closes#12712
On android, libgcc is missing the _Unwind_GetIP symbol because it's defined as a
macro. This is the same case for arm linux, so this commit adds the necessary
cfgs in place to use the "expanded macro" in rust for arm linux.
Previously, the cfg attribute `cfg(not(a, b))` was translated to `(!a && !b)`,
but this isn't very useful because that can already be expressed as
`cfg(not(a), not(b))`. This commit changes the translation to `!(a && b)` which
is more symmetrical of the rest of the `cfg` attribute.
Put another way, I would expect `cfg(clause)` to be the opposite of
`cfg(not(clause))`, but this is not currently the case with multiple element
clauses.
Fix a test that was missed in the chan/port renaming (PR #12815). This was missed because it is skipped on linux and windows, and the mac bots were moving at the time the PR landed.
# Summary
This patch introduces the `_` token into the type grammar, with the meaning "infer this type".
With this change, the following two lines become equivalent:
```
let x = foo();
let x: _ = foo();
```
But due to its composability, it enables partial type hints like this:
```
let x: Bar<_> = baz();
```
Using it on the item level is explicitly forbidden, as the Rust language does not enable global type inference by design.
This implements the feature requested in https://github.com/mozilla/rust/issues/9508.
# Things requiring clarification
- The change to enable it is very small, but I have only limited understanding of the related code, so the approach here might be wrong.
- In particular, while this patch works, it does so in a way not originally intended according to the code comments.
- This probably needs more tests, or rather feedback for which tests are still missing.
- I'm unsure how this interacts with lifetime parameters, and whether it is correct in regard to them.
- Partial type hints on the right side of `as` like `&foo as *_` work in both a normal function contexts and in constexprs like `static foo: *int = &'static 123 as *_`. The question is whether this should be allowed in general.
# Todo for this PR
- The manual and tutorial still needs updating.
# Bugs I'm unsure how to fix
- Requesting inference for the top level of the right hand side of a `as` fails to infer correctly, even if all possible hints are given:
```
.../type_hole_1.rs:35:18: 35:22 error: the type of this value must be known in this context
.../type_hole_1.rs:35 let a: int = 1u32 as _;
^~~~
```
Add some more infrastructure support for demangling `$`-sequences, as well as fixing demangling of closure symbol names if there's more than one closure in a function.
rustc: make stack traces print for .span_bug/.bug.
Previously a call to either of those to diagnostic printers would defer
to the `fatal` equivalents, which explicitly silence the stderr
printing, including a stack trace from `RUST_LOG=std::rt::backtrace`.
This splits the bug printers out to their own diagnostic type so that
things work properly.
Also, this removes the `Ok(...)` that was being printed around the
subtask's stderr output.
The old 'while' needed to match 2 times for each iteration. With the new 'loop' there is just one match needed.
I have also replaced 'blk' by 'f' to be more consistent with parameter names in other functions that are implemented for Option<T>
lint: add lint for use of a `~[T]`.
This is useless at the moment (since pretty much every crate uses
`~[]`), but should help avoid regressions once completely removed from a
crate.
This is something that is plausibly useful, and is provided by libuv. This is
not currently surfaced as part of the `TcpStream` type, but it may possibly
appear in the future. For now only the raw functionality is provided through the
Rtio objects.
## read+write modifier '+'
This small sugar was left out in the original implementation (#5359).
When an output operand with the '+' modifier is encountered, we store the index of that operand alongside the expression to create and append an input operand later. The following lines are equivalent:
```
asm!("" : "+m"(expr));
asm!("" : "=m"(expr) : "0"(expr));
```
## misplaced options and clobbers give a warning
It's really annoying when a small typo might change behavior without any warning.
```
asm!("mov $1, $0" : "=r"(x) : "r"(8u) : "cc" , "volatile");
//~^ WARNING expected a clobber, but found an option
```
## liveness
Fixed incorrect order of propagation.
Sometimes it caused spurious warnings in code: `warning: value assigned to `i` is never read, #[warn(dead_assignment)] on by default`
~~Note: Rebased on top of another PR. (uses other changes)~~
* [x] Implement read+write
* [x] Warn about misplaced options
* [x] Fix liveness (`dead_assignment` lint)
* [x] Add all tests
These are wildly incomplete, but having something there is better than
nothing, e.g. so that people know it exists, and many of the functions
behaviour can be guessed from the name or by checking the source: it's
knowing they exist at all that's the hard part.
This commit goes back to using `gensym` to generate unique tokens to put into
the names of closures, allowing closures to be able to get demangled in
backtraces.
Closes#12400
The rust compiler not only outputs symbols in the form that C++ does, but it
also mangle symbols like '&' and '~' to special compiler-defined escape
sequences. For convenience, these symbols are demangled when printing
backtraces.
Previously a call to either of those to diagnostic printers would defer
to the `fatal` equivalents, which explicitly silence the stderr
printing, including a stack trace from `RUST_LOG=std::rt::backtrace`.
This splits the bug printers out to their own diagnostic type so that
things work properly.
Also, this removes the `Ok(...)` that was being printed around the
subtask's stderr output.
This is something that is plausibly useful, and is provided by libuv. This is
not currently surfaced as part of the `TcpStream` type, but it may possibly
appear in the future. For now only the raw functionality is provided through the
Rtio objects.
The old 'while' needed to match 2 times for each iteration. With the new
'loop' there is just one match needed.
I have also replaced 'blk' by 'f' to be more consistent with parameter
names in other functions that are implemented for Option
As mentioned in #6109, ```mkdir_recursive``` doesn't really need to use recursive calls, so here is an iterative version.
The other points of the proposed overhaul (renaming and existing permissions) still need to be resolved.
I also bundled an iterative ```rmdir_recursive```, for the same reason.
Please do not hesitate to provide feedback on style as this is my first code change in rust.
Added common and simple case folding, i.e. mapping one to one character mapping. For more information see http://www.unicode.org/faq/casemap_charprop.html
Removed auto-generated dead code which wasn't used.
For the following code snippet:
```rust
struct Foo { bar: int }
fn foo1(x: &Foo) -> &int {
&x.bar
}
```
This PR generates the following error message:
```rust
test.rs:2:1: 4:2 note: consider using an explicit lifetime parameter as shown: fn foo1<'a>(x: &'a Foo) -> &'a int
test.rs:2 fn foo1(x: &Foo) -> &int {
test.rs:3 &x.bar
test.rs:4 }
test.rs:3:5: 3:11 error: cannot infer an appropriate lifetime for borrow expression due to conflicting requirements
test.rs:3 &x.bar
^~~~~~
```
Currently it does not support methods.
This enables the lowering of llvm 64b intrinsics to hardware ops, resolving issues around `__kernel_cmpxchg64` on older kernels on ARM devices, and also enables use of the hardware floating point unit, resolving https://github.com/mozilla/rust/issues/10482.
Enables the dereference overloads introduced by #12491 to be applied wherever automatic dereferences would be used (field accesses, method calls and indexing).
