`Box<[T]>` is created by allocating `Box<[T, ..n]>` and coercing it so
this code path is never used. It's also broken because it clamps the
capacity of the memory allocations to 4 elements and that's incompatible
with sized deallocation. This dates back to when `~[T]` was a growable
vector type implemented as:
*{ { tydesc, ref_count, prev, next }, { length, capacity, data[] } }
Since even empty vectors had to allocate, it started off the capacity of
all vectors at 4 as a heuristic. It's not possible to grow `Box<[T]>`
and there is no need for a memory allocation when it's empty, so it
would be a terrible heuristic today even if it worked.
type they provide an implementation for.
This breaks code like:
mod foo {
struct Foo { ... }
}
impl foo::Foo {
...
}
Change this code to:
mod foo {
struct Foo { ... }
impl Foo {
...
}
}
Additionally, if you used the I/O path extension methods `stat`,
`lstat`, `exists`, `is_file`, or `is_dir`, note that these methods have
been moved to the the `std::io::fs::PathExtensions` trait. This breaks
code like:
fn is_it_there() -> bool {
Path::new("/foo/bar/baz").exists()
}
Change this code to:
use std::io::fs::PathExtensions;
fn is_it_there() -> bool {
Path::new("/foo/bar/baz").exists()
}
Closes#17059.
RFC #155.
[breaking-change]
This PR creates a new lint : ``unused_extern_crate``, which do pretty much the same thing as ``unused_import``, but for ``extern crate`` statements. It is related to feature request #10385.
I adapted the code tracking used imports so that it tracks extern crates usage as well. This was mainly trial and error and while I believe all cases are covered, there might be some code I added that is useless (long compile times didn't give me the opportunity to check this in detail).
Also, I removed some unused ``extern crate`` statements from the libs, that where spotted by this new lint.
`Box<[T]>` is created by allocating `Box<[T, ..n]>` and coercing it so
this code path is never used. It's also broken because it clamps the
capacity of the memory allocations to 4 elements and that's incompatible
with sized deallocation. This dates back to when `~[T]` was a growable
vector type implemented as:
*{ { tydesc, ref_count, prev, next }, { length, capacity, data[] } }
Since even empty vectors had to allocate, it started off the capacity of
all vectors at 4 as a heuristic. It's not possible to grow `Box<[T]>`
and there is no need for a memory allocation when it's empty, so it
would be a terrible heuristic today even if it worked.
Avoid ever constructing cyclic types in the first place, rather than detecting them in resolve. This simplifies logic elsewhere in the compiler, in particular on the trait reform branch.
r? @pnkfelix or @pcwalton
cc #5527
The pointer in the slice must not be null, because enum representations
make that assumption. The `exchange_malloc` function returns a non-null
sentinel for the zero size case, and it must not be passed to the
`exchange_free` lang item.
Since the length is always equal to the true capacity, a branch on the
length is enough for most types. Slices of zero size types are
statically special cased to never attempt deallocation. This is the same
implementation as `Vec<T>`.
Closes#14395
This allows code to access the fields of tuples and tuple structs:
let x = (1i, 2i);
assert_eq!(x.1, 2);
struct Point(int, int);
let origin = Point(0, 0);
assert_eq!(origin.0, 0);
assert_eq!(origin.1, 0);
The pointer in the slice must not be null, because enum representations
make that assumption. The `exchange_malloc` function returns a non-null
sentinel for the zero size case, and it must not be passed to the
`exchange_free` lang item.
Since the length is always equal to the true capacity, a branch on the
length is enough for most types. Slices of zero size types are
statically special cased to never attempt deallocation. This is the same
implementation as `Vec<T>`.
Closes#14395
instead of prefix `..`.
This breaks code that looked like:
match foo {
[ first, ..middle, last ] => { ... }
}
Change this code to:
match foo {
[ first, middle.., last ] => { ... }
}
RFC #55.
Closes#16967.
[breaking-change]
itself.
This breaks code like:
for &x in my_vector.iter() {
my_vector[2] = "wibble";
...
}
Change this code to not invalidate iterators. For example:
for i in range(0, my_vector.len()) {
my_vector[2] = "wibble";
...
}
The `for-loop-does-not-borrow-iterators` test for #8372 was incorrect
and has been removed.
Closes#16820.
[breaking-change]
A match in callee.rs was recognizing some foreign fns as named tuple constructors. A reproducible test case for this is nearly impossible since it depends on the way NodeIds happen to be assigned in different crates.
Fixes#15913
Adjust the handling of `#[inline]` items so that they get translated into every
compilation unit that uses them. This is necessary to preserve the semantics
of `#[inline(always)]`.
Crate-local `#[inline]` functions and statics are blindly translated into every
compilation unit. Cross-crate inlined items and monomorphizations of
`#[inline]` functions are translated the first time a reference is seen in each
compilation unit. When using multiple compilation units, inlined items are
given `available_externally` linkage whenever possible to avoid duplicating
object code.
Add a post-processing pass to `trans` that converts symbols from external to
internal when possible. Translation with multiple compilation units initially
makes most symbols external, since it is not clear when translating a
definition whether that symbol will need to be accessed from another
compilation unit. This final pass internalizes symbols that are not reachable
from other crates and not referenced from other compilation units, so that LLVM
can perform more aggressive optimizations on those symbols.
Use a shared lookup table of previously-translated monomorphizations/glue
functions to avoid translating those functions in every compilation unit where
they're used. Instead, the function will be translated in whichever
compilation unit uses it first, and the remaining compilation units will link
against that original definition.
Rotate between compilation units while translating. The "worker threads"
commit added support for multiple compilation units, but only translated into
one, leaving the rest empty. With this commit, `trans` rotates between various
compilation units while translating, using a simple stragtegy: upon entering a
module, switch to translating into whichever compilation unit currently
contains the fewest LLVM instructions.
Most of the actual changes here involve getting symbol linkage right, so that
items translated into different compilation units will link together properly
at the end.
