improve clone_from_slice performance
add intmax
Add assume intrinsic

Adds an `assume` intrinsic that gets translated to llvm.assume. It is
used on a boolean expression and allows the optimizer to assume that
the expression is true.

This implements #18051.
Improve documentation of assume intrinsic.
Guide: articulate the advantages of ownership over garbage collection.

Explain the primary disadvantage of garbage collection is runtime
overhead and unpredictable pauses.  Elucidate where the name "race
condition" comes from.  Emphasize that Rust can guarantee your code is
free of race conditions and other memory errors, with no runtime
overhead.
Guide: Change >= to > in closure
Use local cache when there are unbound type variables and where clauses in scope.

Fixes #18209.
Fixed single quote around string slice and simplify example

This patch contains a fix for:
- single quote around string slice
- string: String is confusing for newbies and it's more readble if the
  argument name is different that the argument type name
Fix codegen breaking aliasing rules for functions with sret results

This reverts commit a0ec902e239b2219edf1a18b036dd32c18d3be42 "Avoid
unnecessary temporary on assignments".

Leaving out the temporary for the functions return value can lead to a
situation that conflicts with rust's aliasing rules.

Given this:

````rust
fn func(f: &mut Foo) -> Foo { /* ... */ }

fn bar() {
    let mut foo = Foo { /* ... */ };

    foo = func(&mut foo);
}
````

We effectively get two mutable references to the same variable `foo` at
the same time. One for the parameter `f`, and one for the hidden
out-pointer. So we can't just `trans_into` the destination directly, but
must use `trans` to get a new temporary slot from which the result can
be copied.
build the crates guide
Add syntax::print::pprint::view_item_to_string

… similar to the existing `item_to_string`.

There may be more missing like this.
plugin-guide: nicer creation of the parser
Register new snapshots

This in theory enables uncommenting IndexMut implementations, but upon doing so
the compiler immediately segfaulted in stage1, so I'll leave those to a later
time.
Fail immediately if linking returns status code != 0
Update .mailmap
s/vtable2/vtable
auto merge of #17960 : mahkoh/rust/clone_from_slice, r=pcwalton

Old vs. New vs. Vec::push_all

```
test slice     ... bench:   3091942 ns/iter (+/- 54460)
test slice_new ... bench:   1800065 ns/iter (+/- 69513)
test vec       ... bench:   1804805 ns/iter (+/- 75609)
```
Fix sigaction on OS X
Add a lint for not using field pattern shorthands

Closes #17792.
auto merge of #17896 : mahkoh/rust/intmax, r=alexcrichton

Closes #17075

I don't know if this is correct. The easiest way to find out is to run the following program on all targets but I can't do it myself.
```c
#include <stdint.h>
#include <stdio.h>

int main(void)
{
	if (sizeof(intmax_t) != 8) {
		puts("ERROR");
		return 1;
	}
}
```