…Item`.

Now it always implies right-alignment, so that padding zeroes are placed after the sign (if any) and before the digits. In other words, it always takes precedence over explicitly specified `[[fill]align]`. This also affects the '#' flag: zeroes are placed after the prefix (0b, 0o, 0x) and before the digits.

           :05     :<05    :>05    :^05
before   |-0001| |-1000| |-0001| |-0100|
after    |-0001| |-0001| |-0001| |-0001|
          :#05x   :<#05x  :>#05x  :^#05x
before   |0x001| |0x100| |000x1| |0x010|
after    |0x001| |0x001| |0x001| |0x001|

Fixes rust-lang#39997 [breaking-change]

Now it always implies right-alignment, so that padding zeroes are placed after the sign (if any) and before the digits. In other words, it always takes precedence over explicitly specified `[[fill]align]`.

               :06      :<06     :>06     :^06
    before   |-001.2| |-1.200| |-001.2| |-01.20|
    after    |-001.2| |-001.2| |-001.2| |-001.2|

Per discussion on the tracking issue, naming `TryFrom`'s associated type
`Error` is generally more consistent with similar traits in the Rust
ecosystem, and what people seem to assume it should be called. It
also helps disambiguate from `Result::Err`, the most common "Err".

See
rust-lang#33417 (comment).

TryFrom<&str> and FromStr are equivalent, so have the latter provide the
former to ensure that. Using TryFrom in the implementation of
`str::parse` means types that implement either trait can use it.
When we're ready to stabilize `TryFrom`, we should update `FromStr` to
suggest implementing `TryFrom<&str>` instead for new code.

See
rust-lang#33417 (comment)
and
rust-lang#33417 (comment).

Refs rust-lang#33417.

This seems to match other uses of "be accessed" in the document.

… to be more precise.

This removes the duplication between collector, callee, and (eventually)
MIRI.

…R shim

These changes are in the same commit to avoid needing to adapt
meth::trans_object_shim to the new scheme.

One codegen-units test is broken because we instantiate the shims even
when they are not needed. This will be fixed in the next PR.

This avoids the creation of unneeded vtable shims.

Drop of arrays is now translated in trans::block in an ugly way that I
should clean up in a later PR, and does not handle panics in the middle
of an array drop, but this commit & PR are growing too big.

Translate shims using MIR

Still a work in progress.

Change how the `0` flag works in format!

Now it always implies right-alignment, so that padding zeroes are placed after the sign (if any) and before the digits. In other words, it always takes precedence over explicitly specified `[[fill]align]`. This also affects the '#' flag: zeroes are placed after the prefix (0b, 0o, 0x) and before the digits.

Here's a short summary of how similar format strings work in Python and Rust:

```
              :05     :<05    :>05    :^05
Python 3.6  |-0001| |-1000| |000-1| |0-100|
Rust before |-0001| |-1000| |-0001| |-0100|
Rust after  |-0001| |-0001| |-0001| |-0001|

             :#05x   :<#05x  :>#05x  :^#05x
Python 3.6  |0x001| |0x100| |000x1| |00x10|
Rust before |0x001| |0x100| |000x1| |0x010|
Rust after  |0x001| |0x001| |0x001| |0x001|
```

Fixes rust-lang#39997 [breaking-change]

…uron

Rename TryFrom's associated type and implement str::parse using TryFrom.

Per discussion on the tracking issue, naming `TryFrom`'s associated type `Error` is generally more consistent with similar traits in the Rust ecosystem, and what people seem to assume it should be called. It also helps disambiguate from `Result::Err`, the most common "Err".

See rust-lang#33417 (comment).

`TryFrom<&str>` and `FromStr` are equivalent, so have the latter provide the former to ensure that. Using `TryFrom` in the implementation of `str::parse` means types that implement either trait can use it. When we're ready to stabilize `TryFrom`, we should update `FromStr` to
suggest implementing `TryFrom<&str>` instead for new code.

See rust-lang#33417 (comment)
and rust-lang#33417 (comment).

Refs rust-lang#33417.

…, r=nrc

`TokenStream`-based attributes, paths in attribute and derive macro invocations

This PR
 - refactors `Attribute` to use  `Path` and `TokenStream` instead of `MetaItem`.
 - supports macro invocation paths for attribute procedural macros.
   - e.g. `#[::foo::attr_macro] struct S;`, `#[cfg_attr(all(), foo::attr_macro)] struct S;`
 - supports macro invocation paths for derive procedural macros.
   - e.g. `#[derive(foo::Bar, super::Baz)] struct S;`
 - supports arbitrary tokens as arguments to attribute procedural macros.
   - e.g. `#[foo::attr_macro arbitrary + tokens] struct S;`
 - supports using arbitrary tokens in "inert attributes" with derive procedural macros.
   - e.g. `#[derive(Foo)] struct S(#[inert arbitrary + tokens] i32);`
where `#[proc_macro_derive(Foo, attributes(inert))]`

r? @nrc

documented order of conversion between u32 an ipv4addr

This fixes rust-lang#40118

…uillaumeGomez

minor wording tweak to slice::{as_ptr, as_mut_ptr}

Per rust-lang#37334, the slice-as-pointer methods mentioned that "modifying the slice may cause its buffer to be reallocated", when in fact modifying the *slice* itself would cause no such change. (It is a borrow, after all!) This is a tweak to the wording of that line to stress it's the *collection* that could cause the buffer to be reallocated.

r? @steveklabnik

Fix typo in mutex.rs docs

This seems to match other uses of "be accessed" in the document.

…sfackler

Fix a spelling error in HashMap documentation, and slightly reword surrounding text for precision

Noticed while reading docs just now.

It's possible that the prior wording *meant* to state that the seed's randomness depends on the exact instant that the system RNG was created, I guess.  But unless there's an API guarantee that this is the case, the wording seems over-precise.  Is there a formal API guarantee that would forbid, say, the system RNG from generating all output using the Intel RDRAND instruction?  I don't think the quality of output in that case would depend on when the RNG was created.  Yet it seems to me like it could well be a valid source of randomness when computing the initial seed.

For that reason, tying the randomness of the seed, to the quality of the RNG's output *at the precise instant the seed is computed*, seems less confining.  That instantaneous quality level could be determined by the quality at the instant the RNG was created -- but instantaneous quality need not be low for that precise reason.