This removes the internal type representation of an `External` type and instead
relies on passing around DefId structures and interpreting them accordingly.
Progress on #9539, but there's still the problem of a crate => url mapping.
std::vec: Sane implementations for connect_vec and concat_vec
Avoid unnecessary copying of subvectors, and calculate the needed space
beforehand. These implementations are simple but better than the
previous.
Also only implement it once, for all `Vector<T>` using:
impl<'self, T: Clone, V: Vector<T>> VectorVector<T> for &'self [V]
Closes#9581
Avoid unnecessary copying of subvectors, and calculate the needed space
beforehand. These implementations are simple but better than the
previous.
Also only implement it once, for all `Vector<T>` using:
impl<'self, T: Clone, V: Vector<T>> VectorVector<T> for &'self [V]
performance improved according to the bench test:
before
test vec::bench::concat ... bench: 74818 ns/iter (+/- 408)
test vec::bench::connect ... bench: 87066 ns/iter (+/- 376)
after
test vec::bench::concat ... bench: 17724 ns/iter (+/- 126)
test vec::bench::connect ... bench: 18353 ns/iter (+/- 691)
Closes#9581
std::vec: Use a valid value as lifetime dummy in iterator
The current implementation uses `&v[0]` for the lifetime struct field,
but that is a dangling pointer for iterators derived from zero-length
slices.
Example:
let v: [int, ..0] = []; println!("{:?}", v.iter())
std::vec::VecIterator<,int>{ptr: (0x7f3768626100 as *()), end: (0x7f3768626100 as *()), lifetime: &139875951207128}
To replace this parameter, use a field of type `Option<&'self ()>`
that is simply initialized with `None`, but still allows the iterator to
have a lifetime parameter.
All items have source links back to their actual code. Source files can be
omitted with the doc(html_no_source) attribute on the crate. Currently there is
no syntax highlighting, but that will come with syntax highlighting with all
other snippets.
Closes#2072
This purges doc/{std,extra} entirely during a `make clean` instead of just the
html files in some top level directories. This should help old documentation
from showing up on static.rust-lang.org
This purges doc/{std,extra} entirely during a `make clean` instead of just the
html files in some top level directories. This should help old documentation
from showing up on static.rust-lang.org
As mentioned in #9456, the format! syntax extension would previously consider an
empty format as a 'Unknown' format which could then also get coerced into a
different style of format on another argument.
This is unusual behavior because `{}` is a very common format and if you have
`{0} {0:?}` you wouldn't expect them both to be coereced to the `Poly`
formatter. This commit removes this coercion, but still retains the requirement
that each argument has exactly one format specified for it (an empty format now
counts as well).
Perhaps at a later date we can add support for multiple formats of one argument,
but this puts us in at least a backwards-compatible situation if we decide to do
that.
As mentioned in #9456, the format! syntax extension would previously consider an
empty format as a 'Unknown' format which could then also get coerced into a
different style of format on another argument.
This is unusual behavior because `{}` is a very common format and if you have
`{0} {0:?}` you wouldn't expect them both to be coereced to the `Poly`
formatter. This commit removes this coercion, but still retains the requirement
that each argument has exactly one format specified for it (an empty format now
counts as well).
Perhaps at a later date we can add support for multiple formats of one argument,
but this puts us in at least a backwards-compatible situation if we decide to do
that.
This is broken, and results in poor performance due to the undefined
behaviour in the LLVM IR. LLVM's `mergefunc` is a *much* better way of
doing this since it merges based on the equality of the bytecode.
For example, consider `std::repr`. It generates different code per
type, but is not included in the type bounds of generics.
The `mergefunc` pass works for most of our code but currently hits an
assert on libstd. It is receiving attention upstream so it will be
ready soon, but I don't think removing this broken code should wait any
longer. I've opened #9536 about enabling it by default.
Closes#8651Closes#3547Closes#2537Closes#6971Closes#9222
One of the downsides with `c_str` is that it always forces an allocation, and so this could add unnecessary overhead to various calls. This PR implements one of the suggestions @graydon made in #8296 for `vec.with_c_str` in that for a short string can use a small stack array instead of a malloced array for our temporary c string. This ends up being twice as fast for small strings.
There are two things to consider before landing this commit though. First off, I arbitrarily picked the stack array as 32 bytes, and I'm not sure if this a reasonable amount or not. Second, there is a risk that someone can keep a reference to the interior stack pointer, which could cause mayhem if someone were to dereference the pointer. Since we also can easily grab and return interior pointers to vecs though, I don't think this is that much of an issue.
This now makes it unsafe to save the pointer returned by .with_c_str
as that pointer now may be pointing at a stack allocated array.
I arbitrarily chose 32 bytes as the length of the stack vector, and
so it might not be the most optimal size.
before:
test c_str::bench::bench_with_c_str_long ... bench: 539 ns/iter (+/- 91)
test c_str::bench::bench_with_c_str_medium ... bench: 97 ns/iter (+/- 2)
test c_str::bench::bench_with_c_str_short ... bench: 70 ns/iter (+/- 5)
after:
test c_str::bench::bench_with_c_str_long ... bench: 542 ns/iter (+/- 13)
test c_str::bench::bench_with_c_str_medium ... bench: 53 ns/iter (+/- 6)
test c_str::bench::bench_with_c_str_short ... bench: 19 ns/iter (+/- 0)
The current implementation uses `&v[0]` for the lifetime struct field,
but that is a dangling pointer for iterators derived from zero-length
slices.
Example:
let v: [int, ..0] = []; println!("{:?}", v.iter())
std::vec::VecIterator<,int>{ptr: (0x7f3768626100 as *()), end: (0x7f3768626100 as *()), lifetime: &139875951207128}
To replace this parameter, use a field of type `Option<&'self ()>`
that is simply initialized with `None`, but still allows the iterator to
have a lifetime parameter.
This lifts various restrictions on the runtime, for example the character limit
when logging a message. Right now the old debug!-style macros still involve
allocating (because they use fmt! syntax), but the new debug2! macros don't
involve allocating at all (unless the formatter for a type requires allocation.
