Implement Zero for unit
Remove unused variables.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>
Give tasks useful names. #2891
Move atomically to unstable::sync, and document what it actually does. Close #7872.
std: Remove PortSet. Not supported by new scheduler. Replace uses with SharedChan.
test: add more codegen tests, add copyright headers to all.
mk/tests.mk: fix typo "srcrustllvm"
mk/tests.mk: remove mention of nonexistent files
rm ancient error for lowercase kinds

3 of these kinds no longer even exist in the CamelCase form
remove `copy` as a keyword
test: Disable morestack tests

The new scheduler does not yet implement split stacks
extra: Remove dbg module and rt support code

This stuff is ancient, unused, and tied to oldsched
make `in` and `foreach` get treated as keywords
convert `pure` to a reserved keyword
auto merge of #8162 : thestinger/rust/no-copy, r=brson
auto merge of #8149 : omasanori/rust/cleanup, r=alexcrichton

Fixed a warning.
rc: from_{owned,const} -> from_{send,freeze}
Resolve globals having different addresses across crates

* All globals marked as `pub` won't have the `internal` linkage type set
* All global references across crates are forced to use the address of the
  global in the other crate via an external reference.
migrate many `for` loops to `foreach`
auto merge of #8184 : thestinger/rust/retreat, r=huonw