`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.
The other extension types already worked this way and it can be useful to track some state along with the extension.
I also removed the `BasicMacroExpander` and `BasicIdentMacroExpander` since the span inside of them was never used. The expander function types now directly implement the relevant trait.
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.
Few visitors used the context passing feature and it can be easily emulated.
The added lifetime threading allows a visitor to keep safe references to AST
nodes it visits, making a non-owning ast_map design possible, for #13316.
`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.
The Guide isn't 100% perfect, but it's basically complete. It's
certainly better than the tutorial is. Time to start pointing more
people its way.
I also just made it consistent to call all things 'guides' rather than
tutorials.
Fixes#9874. This is the big one.
And two bugs that just go away.
Fixes#14503.
Fixes#15009.
The Guide isn't 100% perfect, but it's basically complete. It's
certainly better than the tutorial is. Time to start pointing more
people its way.
I also just made it consistent to call all things 'guides' rather than
tutorials.
Fixes#9874. This is the big one.
And two bugs that just go away.
Fixes#14503.
Fixes#15009.
gcc, ld, ar, dlltool, windres go into $(RUST)/bin/rustlib/<triple>/bin/
platform libraries and startup objects got into $(RUST)/bin/rustlib/<triple>/lib/
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
Bugs in pdflatex (#12804) are preventing the guide from landing (https://github.com/rust-lang/rust/pull/16657). This solves the immediate problem by changing the build system to prefer lualatex, xelatex to pdflatex (which is apparently obsolete). Because the xelatex on the snapshot bot seems to completely ignore the `-output-directory` option, I also had to frob the makefiles a bit for that case.
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
The spans inside of these types were always None and never used. Pass
the expander function directly instead of wrapping it in one of these
types.
[breaking-change]
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.
