Kills some warnings, and implements str::each_char_reverse so that it actually iterates. The test case wasn't detecting a failure, since the loop body was never executed.
`let v = [24, ..1000];` now more or less emits the same IR as:
```Rust
let mut i = 0;
while i < 1000 {
v[i] = 24;
i += 1;
}
```
LLVM will still turn it into a memset if possible with optimization on.
The reasoning for doing it this way is that it's much easier to transition method-by-method to the `Map` API than trying to do the migration all at once.
I found an issue unrelated to my changes in one of the run-fail tests - if it uses `LinearMap`, it still fails but exits with 0. I xfailed it for now and opened [an issue](https://github.com/mozilla/rust/issues/5512), because it's not caused by these changes.
r? @nikomatsakis The typechecker previously passed around a boolean return flag to
indicate whether it saw something with type _|_ (that is, something
it knows at compile-time will definitely diverge) and also had some
manual checks for the `ty_err` pseudo-type that represents a previous
type error. This was because the typing rules implemented by the
typechecker didn't properly propagate _|_ and ty_err. I fixed it.
This also required changing expected error messages in a few tests,
as now we're printing out fewer derived errors -- in fact, at this
point we should print out no derived errors, so report any that
you see (ones that include "[type error]") as bugs.
A slice now always refers to something that returns an borrowed pointer, views don't exist anymore. If you want to have an explictit copy of a slice, use `to_owned()`
The typechecker previously passed around a boolean return flag to
indicate whether it saw something with type _|_ (that is, something
it knows at compile-time will definitely diverge) and also had some
manual checks for the `ty_err` pseudo-type that represents a previous
type error. This was because the typing rules implemented by the
typechecker didn't properly propagate _|_ and ty_err. I fixed it.
This also required changing expected error messages in a few tests,
as now we're printing out fewer derived errors -- in fact, at this
point we should print out no derived errors, so report any that
you see (ones that include "[type error]") as bugs.
