Fix many warnings.
Register snapshots
auto merge of #6632 : steveklabnik/rust/remove_more_warnings, r=thestinger

With this, the build is almost 100% warning free.

One more can be fixed after the next snapshot, and there's one other that I filed an issue about already.
auto merge of #6635 : brson/rust/snapshot, r=brson
Typo corrected and updated copyright years
Add ARC::get method and implements the function from it. Add an example showing a simple use of ARC.
Remove outdated function transmute_for_stage0

The function was a workaround for bootstrapping that isn't required
anymore and just degrades hashmap performance, as it doesn't get inlined
cross-crate and turns a no-op into a call.
auto merge of #6640 : dotdash/rust/hash_perf, r=bstrie

The function was a workaround for bootstrapping that isn't required
anymore and just degrades hashmap performance, as it doesn't get inlined
cross-crate and turns a no-op into a call.
Remove legacy_modes
Remove two warnings about unneccesary safe blocks.

Since a snapshot was done last night, these are good to go.
auto merge of #6643 : sanxiyn/rust/legacy-modes, r=bstrie
auto merge of #6644 : steveklabnik/rust/remove_unsafe_warning, r=bstrie

Since a snapshot was done last night, these are good to go.
refactoring test functions
parser comment
detect unused attrs in one more place, allow parsing to continue for all

changed a bunch of fatal()'s into err()'s, to allow parsing to proceed.
hygiene infrastructure.

- added a hash table to memoize rename and mark operations.
- added rename, mark, and resolve fold fns
getting rid of interner_key! macro
added and rewrote text for 'do' and 'for' loops
auto merge of #6559 : jbclements/rust/hygiene-fns-and-cleanup, r=jbclements

This includes new, tested, hygiene support functions. It also removes the interner_key! macro and replaces it with a function, which should be inline-able. It also contains some parser patch-ups and some docfixes.

On my machine, this patch passes all tests.
Replace all uses of rust-intrinsic ABI with calls to unstable::intrinsics