This should fix rust-lang#31754 and follow-up rust-lang#25343.  Before the latter, the
closure was visited twice in the context of the enclosing fn, which
made even a single closure with a loop label emit a warning.

With this change, the closure is still visited within the context
of the main fn (which is intended, since it is not a separate item)
but resets the found loop labels while being visited.

Fixes: rust-lang#31754

fix too long column

fix typo of help on pattern guard

one nit

fix compile fail

Removed unnecessary use of threads from E0504

Cleaned up line ending on E0504

Added more examples for E0504

Changed to erroneous code wording

Switched Rc example to thread/Arc example

Added comments describing why errors no longer occur

Change `fast an loose` to `fast and loose`.

This was causing terrible error reports, because the algorithm was
incorrectly identifying the constraints.

Doc improvement on std::fmt module

Part of rust-lang#29355.

r? @steveklabnik

…illaumegomez

add help on pattern guard

middle: reset loop labels while visiting closure

This should fix rust-lang#31754 and follow-up rust-lang#25343.  Before the latter, the closure was visited twice in the context of the enclosing fn, which made even a single closure with a loop label emit a warning.

With this change, the closure is still visited within the context of the main fn (which is intended, since it is not a separate item) but resets the found loop labels while being visited.

Fixes: rust-lang#31754

Note: I amended the test file from rust-lang#25343, but I don't know if the original or amended test are effective, since as far as I could see, compiletest's run-pass tests do not check for zero warnings emitted?

/cc @Manishearth

Add detailed error explanation for E0504

Part of rust-lang#32777

Inline RawVec::cap

This was showing up in a Servo profile.

…d-loose, r=steveklabnik

doc: Fix tiny typo in vec-alloc.md

Change `fast an loose` to `fast and loose`.

E0061 typo fix

Fixed silly typo.

fix DFS for region error reporting

This was causing terrible error reports, because the algorithm was incorrectly identifying the constraints.

r? @eddyb

…labnik

Improve "since" tag placement

Continuation of rust-lang#33431.

r? @steveklabnik