Remove 'not reporting regions error due to nll' warning

[zilbuz]

Fix #52768

[rust-highfive]

r? @michaelwoerister

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[zilbuz]

Do not merge until a decision has been made in #52768

I don't mind keeping the PR updated until a decision is made. Feel free to close it if the decision is "do not remove the warning" :)

In addition to removing the warning, I took the liberty of implementing the FIXME (ie. directly matching on BorrowckMode instead of using use_mir_borrowck() and migrate_borrowck(). Let me know if I should make this modification in a separate PR or just not do it :).

Also note that the check on the nll feature disappear since without the warning printed we do an early return in any case.

For some tests like ui/in-band-lifetimes/mismatched_trait.rs, the entire .nll.stderr file is deleted, removing the associated "error[E0621]: explicit lifetime required in the type of y". I don't know if this is a regression or if this is expected. Every .nll.stderr file removed here contained the warning and an E0621 error. What should I do?

[rust-highfive]

The job x86_64-gnu-llvm-5.0 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

[00:04:54] travis_fold:start:tidy
travis_time:start:tidy
tidy check
[00:04:54] tidy error: /checkout/src/librustc/infer/error_reporting/mod.rs:307: trailing whitespace
[00:04:54] tidy error: /checkout/src/librustc/infer/error_reporting/mod.rs:313: trailing whitespace
[00:04:55] some tidy checks failed
[00:04:55] 
[00:04:55] 
[00:04:55] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/tidy" "/checkout/src" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "--no-vendor" "--quiet"
[00:04:55] 
[00:04:55] 
[00:04:55] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
[00:04:55] Build completed unsuccessfully in 0:00:53
[00:04:55] Build completed unsuccessfully in 0:00:53
[00:04:55] make: *** [tidy] Error 1
[00:04:55] Makefile:79: recipe for target 'tidy' failed

The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:06805eb4
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
---
travis_time:end:024c56c8:start=1535742524270038409,finish=1535742524276731092,duration=6692683
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:32eeb0e2
$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
travis_fold:end:after_failure.4
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travis_time:start:1a898f72
travis_time:start:1a898f72
$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:000940d0
$ dmesg | grep -i kill

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[matthewjasper]

the entire .nll.stderr file is deleted, ... What should I do?

The output is the same with both borrow checkers now. So you don't need to do anything.

[pnkfelix]

@bors r+

[bors]

📌 Commit b01550a has been approved by pnkfelix

[bors]

⌛ Testing commit b01550a with merge f3bb231...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: pnkfelix
Pushing f3bb231 to master...