Refactor writeback code. cc #5527
Remove error message that refactor suppresses
rustc: Fix enum variant privacy across crates

The code in resolve erroneously assumed that private enums weren't visited, so
the logic was adjusted to check to see if the enum definition itself was public.

Closes #11680
Add testcase for #11493
std: Extract format string parsing out of libstd

This code does not belong in libstd, and rather belongs in a dedicated crate. In
the future, the syntax::ext::format module should move to the fmt_macros crate
(hence the name of the crate), but for now the fmt_macros crate will only
contain the format string parser.

The entire fmt_macros crate is marked #[experimental] because it is not meant
for general consumption, only the format!() interface is officially supported,
not the internals.

This is a breaking change for anyone using the internals of std::fmt::parse.
Some of the flags have moved to std::fmt::rt, while the actual parsing support
has all moved to the fmt_macros library.

[breaking-change]
auto merge of #13985 : alexcrichton/rust/libfmt, r=brson

This code does not belong in libstd, and rather belongs in a dedicated crate. In
the future, the syntax::ext::format module should move to the fmt_macros crate
(hence the name of the crate), but for now the fmt_macros crate will only
contain the format string parser.

The entire fmt_macros crate is marked #[experimental] because it is not meant
for general consumption, only the format!() interface is officially supported,
not the internals.

This is a breaking change for anyone using the internals of std::fmt::parse.
Some of the flags have moved to std::fmt::rt, while the actual parsing support
has all moved to the fmt_macros library.

[breaking-change]
auto merge of #13990 : nikomatsakis/rust/issue-5527-cleanup-writeback, r=pcwalton

As part of #5527 I had to make some changes here and I just couldn't take it anymore. Refactor the writeback code. Should be functionally equivalent to the old stuff.

r? @pcwalton
auto merge of #14010 : richo/rust/tests/11493, r=alexcrichton

Is this what you had in mind?

Closes #11493
auto merge of #14001 : alexcrichton/rust/issue-11680, r=pcwalton

The code in resolve erroneously assumed that private enums weren't visited, so
the logic was adjusted to check to see if the enum definition itself was public.

Closes #11680