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 behind the feature gate `tuple_indexing`:
```rust
#![feature(tuple_indexing)]
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);
```
Implements [RFC 53](https://github.com/rust-lang/rfcs/blob/master/active/0053-tuple-accessors.md). Closes#16950.
Based on an observation that strings and arguments are always interleaved, thanks to #15832. Additionally optimize invocations where formatting parameters are unspecified for all arguments, e.g. `"{} {:?} {:x}"`, by emptying the `__STATIC_FMTARGS` array. Next, `Arguments::new` replaces an empty slice with `None` so that passing empty `__STATIC_FMTARGS` generates slightly less machine code when `Arguments::new` is inlined. Furthermore, formatting itself treats these cases separately without making redundant copies of formatting parameters.
All in all, this adds a single mov instruction per `write!` in most cases. That's why code size has increased.
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]
This breaks code that uses the `..xs` form anywhere but at the end of a
slice. For example:
match foo {
[ 1, ..xs, 2 ]
[ ..xs, 1, 2 ]
}
Add the `#![feature(advanced_slice_patterns)]` gate to reenable the
syntax.
RFC #54.
Closes#16951.
[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]
This code used to produce the following ICE:
error: internal compiler error: get_unique_type_id_of_type() -
unexpected type: closure,
ty_unboxed_closure(syntax::ast::DefId{krate: 0u32, node: 66u32},
ReScope(63u32))
This is a regression test for issue #17021.
Closes#16813
r? @nikomatsakis I feel like I should be checking more things in check_rvalues, but not sure what - I don't properly understand expr_use_visitor
This code used to produce an ICE on the definition of trait Bar
with the following message:
Type parameter out of range when substituting in region 'a (root
type=fn(Self) -> 'astr) (space=FnSpace, index=0)
Closes#16218.
This branch adds support for running LLVM optimization and codegen on different parts of a crate in parallel. Instead of translating the crate into a single LLVM compilation unit, `rustc` now distributes items in the crate among several compilation units, and spawns worker threads to optimize and codegen each compilation unit independently. This improves compile times on multicore machines, at the cost of worse performance in the compiled code. The intent is to speed up build times during development without sacrificing too much optimization.
On the machine I tested this on, `librustc` build time with `-O` went from 265 seconds (master branch, single-threaded) to 115s (this branch, with 4 threads), a speedup of 2.3x. For comparison, the build time without `-O` was 90s (single-threaded). Bootstrapping `rustc` using 4 threads gets a 1.6x speedup over the default settings (870s vs. 1380s), and building `librustc` with the resulting stage2 compiler takes 1.3x as long as the master branch (44s vs. 55s, single threaded, ignoring time spent in LLVM codegen).
The user-visible changes from this branch are two new codegen flags:
* `-C codegen-units=N`: Distribute items across `N` compilation units.
* `-C codegen-threads=N`: Spawn `N` worker threads for running optimization and codegen. (It is possible to set `codegen-threads` larger than `codegen-units`, but this is not very useful.)
Internal changes to the compiler are described in detail on the individual commit messages.
Note: The first commit on this branch is copied from #16359, which this branch depends on.
r? @nick29581
- Ensures the propagated negation sign is properly utilized during type
checking.
- Removed redundant type checking, specifically regarding the out of bounds checking
on a bounded type.
- Closes#16684
