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auto merge of #18338 : chastell/rust/guide_pointer_fixes, r=alexcrichton

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This removes some leftover line-numbering cruft from elided error examples and brings some minor clarifications.

I’m not super happy about the ‘we cannot have two mutable pointers that point to the same memory’ wording (to the best of my understanding we can’t even have one mutable and one immutable), but other attempts to word this were derailing the flow a bit too much.
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bors 2014-11-04 21:26:23 +00:00
commit ceeac26de8
1 changed files with 8 additions and 8 deletions
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src/doc/guide.md
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@ -3448,7 +3448,7 @@ let y = &mut x;
Rust will complain:
```{ignore,notrust}
6:19 error: cannot borrow immutable local variable `x` as mutable
error: cannot borrow immutable local variable `x` as mutable
let y = &mut x;
^
```
@ -3492,7 +3492,7 @@ note: previous borrow ends here
This is a big error message. Let's dig into it for a moment. There are three
parts: the error and two notes. The error says what we expected, we cannot have
two pointers that point to the same memory.
two mutable pointers that point to the same memory.
The two notes give some extra context. Rust's error messages often contain this
kind of extra information when the error is complex. Rust is telling us two
@ -3763,10 +3763,10 @@ let y = &mut x;
This gives us this error:
```{notrust,ignore}
8:7 error: cannot use `*x` because it was mutably borrowed
error: cannot use `*x` because it was mutably borrowed
*x;
^~
6:19 note: borrow of `x` occurs here
note: borrow of `x` occurs here
let y = &mut x;
^
```
@ -3791,7 +3791,7 @@ value that must persist as long as any of several referrers, read on.
## Rc and Arc
Sometimes, you need a variable that is referenced from multiple places
Sometimes you need a variable that is referenced from multiple places
(immutably!), lasting as long as any of those places, and disappearing when it
is no longer referenced. For instance, in a graph-like data structure, a node
might be referenced from all of its neighbors. In this case, it is not possible
@ -3887,7 +3887,7 @@ match x {
```
If you're matching on an enum which has variants, you can use `..` to
ignore the value in the variant:
ignore the value and type in the variant:
```{rust}
enum OptionalInt {
@ -4559,8 +4559,8 @@ So this would give us the numbers from `2-100`. Well, almost! If you
compile the example, you'll get a warning:
```{notrust,ignore}
2:37 warning: unused result which must be used: iterator adaptors are lazy and
do nothing unless consumed, #[warn(unused_must_use)] on by default
warning: unused result which must be used: iterator adaptors are lazy and
do nothing unless consumed, #[warn(unused_must_use)] on by default
range(1i, 100i).map(|x| x + 1i);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```