Precompute ancestors when checking privacy

[tmiasko]

Precompute ancestors of the old error node set so that check for private
types and traits in public interfaces can in constant time determine if
the current item has any descendants in the old error set.

This removes disparity in compilation time between public and private type
aliases reported in #50614 (from 30 s to 5 s, in an example making extensive use
of private type aliases).

No functional changes intended.

[rust-highfive]

r? @oli-obk

(rust-highfive has picked a reviewer for you, use r? to override)

[tmiasko]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

[bors]

⌛ Trying commit b01976a with merge 1e3fee80c53fecef512bac75b0b96f4e90484bbe...

[bors]

☀️ Try build successful - checks-actions
Build commit: 1e3fee80c53fecef512bac75b0b96f4e90484bbe (1e3fee80c53fecef512bac75b0b96f4e90484bbe)

[rust-timer]

Queued 1e3fee80c53fecef512bac75b0b96f4e90484bbe with parent fd20a8b, future comparison URL.

@rustbot label: +S-waiting-on-perf

[rust-timer]

Finished benchmarking try commit (1e3fee80c53fecef512bac75b0b96f4e90484bbe): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf

[tmiasko]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

[bors]

⌛ Trying commit 712bb1c15a6a987c4feb8d4f64a6f573c33c9e31 with merge 7aa7d821ffc49849236e46d009860941d8106fac...

[bors]

☀️ Try build successful - checks-actions
Build commit: 7aa7d821ffc49849236e46d009860941d8106fac (7aa7d821ffc49849236e46d009860941d8106fac)

[rust-timer]

Queued 7aa7d821ffc49849236e46d009860941d8106fac with parent 04caa63, future comparison URL.

@rustbot label: +S-waiting-on-perf

[rust-timer]

Finished benchmarking try commit (7aa7d821ffc49849236e46d009860941d8106fac): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf

[tmiasko]

There was an extra commit that attempted an additional micro optimization, but it is far from clear if it has any benefits so I removed it.

There is a large regression for deeply-nested-async. The old error set is empty for this benchmark. Using artifiacts from CI, the regression is reproducible but instruction count differences are in unrelated area of privacy checking. The cause appears to be different codegen partitioning of rustc-privacy as far as I can see.

[oli-obk]

The regression can potentially be fixed by adding some targeted #[inline] attributes, but considering that is a 0.005s regression when the improvements are in the 0.2ms region without any increase in code complexity let's merge this

@bors r+

[bors]

📌 Commit b01976a has been approved by oli-obk

[bors]

⌛ Testing commit b01976a with merge 3e1d74b413edb132708fb24af1ed3ddc29e9dfcc...

[bors]

💥 Test timed out

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[oli-obk]

@bors retry

[tmiasko]

Opened #82221 to track test hang which caused time out. It seems to be happening quite a bit, although I haven't encountered one locally.

[bors]

⌛ Testing commit b01976a with merge cb2effd...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing cb2effd to master...

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

  CACHE_DOMAIN: ci-caches.rust-lang.org
  TOOLSTATE_REPO_ACCESS_TOKEN: ***
##[endgroup]
Cloning into 'rust-toolstate'...
/home/runner/work/rust/rust/src/tools/publish_toolstate.py:121: DeprecationWarning: 'U' mode is deprecated
📣 Toolstate changed by rust-lang/rust#81574!
  with open(path, 'rU') as f:

Tested on commit rust-lang/rust@cb2effd44e667d133e31ef334e30d10195218ce6.
Direct link to PR: <https://github.com/rust-lang/rust/pull/81574>

💔 miri on windows: test-fail → build-fail (cc @RalfJung @eddyb @oli-obk).
💔 miri on linux: test-fail → build-fail (cc @RalfJung @eddyb @oli-obk).
Traceback (most recent call last):
Traceback (most recent call last):
  File "/home/runner/work/rust/rust/src/tools/publish_toolstate.py", line 338, in <module>
    response = urllib2.urlopen(urllib2.Request(
  File "/usr/lib/python3.8/urllib/request.py", line 222, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/lib/python3.8/urllib/request.py", line 522, in open
    req = meth(req)
  File "/usr/lib/python3.8/urllib/request.py", line 1281, in do_request_
    raise TypeError(msg)
TypeError: POST data should be bytes, an iterable of bytes, or a file object. It cannot be of type str.
##[error]Process completed with exit code 1.