Enable NLL migrate mode on the 2015 edition

[matthewjasper]

What is in this PR?

• Remove the -Zborrowck=ast flag option from rustc.
• The default in the 2015 edition is now -Zborrowck=migrate.
• The 2018 edition default is unchanged: it's still -Zborrowck=migrate.
• Enable two-phase borrows (currently toggled via the -Ztwo-phase-borrows flag) on all editions.
• Remove most dead code that handled these options.
• Update tests for the above changes.

What is not in this PR?

These are left for future PRs

• Use -Zborrowck=mir in NLL compare mode tests (region tests incorrectly passing with NLL enabled #56993)
• Remove the -Zborrowck=compare option (Remove -Zborrowck=compare #59193)
• Remove the -Ztwo-phase-borrows flag. It's kept, as a flag that does nothing so that perf.rlo has time to stop using it (cc @Mark-Simulacrum)
• Remove MIR typeck as its own MIR pass - it's now run by NLL.
• Enabling -Zborrowck=mir by default (NLL: turn off migration mode #58781)
• Replace allow_bind_by_move_patterns_with_guards and check_for_mutation_in_guard_via_ast_walk with just using the feature gate. (Simplify handling of feature(bind_by_move_pattern_guards) #59192)

Soundness issues that are fixed by NLL will stay open until full NLL is emitting hard errors. However, these diagnostics and completeness issues can now be closed:

Closes #18330
Closes #22323
Closes #23591
Closes #26736
Closes #27487
Closes #28092
Closes #28970
Closes #29733
Closes #30104
Closes #38915
Closes #39908
Closes #43407
Closes #47524
Closes #48540
Closes #49073
Closes #52614
Closes #55085
Closes #56093
Closes #56496
Closes #57804

cc #43234

r? @pnkfelix
cc @rust-lang/lang
cc @rust-lang/wg-compiler-nll

[Mark-Simulacrum]

I can remove the flag from perf quickly so will do so as soon as this PR lands.

@bors try for perf

[bors]

⌛ Trying commit 4eebb5e with merge 65cb35a...

[bors]

☀️ Try build successful - checks-travis
Build commit: 65cb35a

[Mark-Simulacrum]

@rust-timer build 65cb35a

[rust-timer]

Success: Queued 65cb35a with parent e68bf8a, comparison URL.

[rust-timer]

Finished benchmarking try commit 65cb35a

[Mark-Simulacrum]

Looks like perf results are as expected - just bringing over the regressions from the NLL dashboard.

[rust-highfive]

The job x86_64-gnu-llvm-6.0 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.

travis_time:end:0c62b7a0:start=1552422638011955282,finish=1552422640388468460,duration=2376513178
$ git checkout -qf FETCH_HEAD
travis_fold:end:git.checkout

Encrypted environment variables have been removed for security reasons.
See https://docs.travis-ci.com/user/pull-requests/#pull-requests-and-security-restrictions
$ export SCCACHE_BUCKET=rust-lang-ci-sccache2
$ export SCCACHE_REGION=us-west-1
$ export GCP_CACHE_BUCKET=rust-lang-ci-cache
Setting environment variables from .travis.yml
---
travis_time:start:test_debuginfo
Check compiletest suite=debuginfo mode=debuginfo-both (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
[01:21:07] 
[01:21:07] running 120 tests
[01:21:32] .iiiii...i.....i..i...i..i.i...i.ii...i.....i..i....i..........iiii..........i...ii...i.......ii.i.i 100/120
[01:21:36] .i......iii.i.....ii
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[01:21:36]  finished in 30.003
[01:21:36] travis_fold:end:test_debuginfo

---
travis_time:start:test_ui-fulldeps
Check compiletest suite=ui-fulldeps mode=ui (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
[01:21:37] 
[01:21:37] running 20 tests
[01:21:43] F.F.................
[01:21:43] 
[01:21:43] ---- [ui] ui-fulldeps/dropck_tarena_unsound_drop.rs stdout ----
[01:21:43] diff of stderr:
[01:21:43] 
[01:21:43] 
[01:21:43] 1 error[E0597]: `arena` does not live long enough
[01:21:43] +   --> $DIR/dropck_tarena_unsound_drop.rs:41:7
[01:21:43] 3    |
[01:21:43] 3    |
[01:21:43] 4 LL |     f(&arena);
[01:21:43] -    |        ^^^^^ borrowed value does not live long enough
[01:21:43] +    |       ^^^^^^ borrowed value does not live long enough
[01:21:43] 6 LL | }
[01:21:43] -    | - `arena` dropped here while still borrowed
[01:21:43] -    |
[01:21:43] -    = note: values in a scope are dropped in the opposite order they are created
[01:21:43] +    | |
[01:21:43] +    | |
[01:21:43] +    | `arena` dropped here while still borrowed
[01:21:43] +    | borrow might be used here, when `arena` is dropped and runs the `Drop` code for type `arena::TypedArena`
[01:21:43] 11 error: aborting due to previous error
[01:21:43] 12 
[01:21:43] 
[01:21:43] 
[01:21:43] 
[01:21:43] The actual stderr differed from the expected stderr.
[01:21:43] Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui-fulldeps/dropck_tarena_unsound_drop/dropck_tarena_unsound_drop.stderr
[01:21:43] To update references, rerun the tests and pass the `--bless` flag
[01:21:43] To only update this specific test, also pass `--test-args dropck_tarena_unsound_drop.rs`
[01:21:43] error: 1 errors occurred comparing output.
[01:21:43] status: exit code: 1
[01:21:43] status: exit code: 1
[01:21:43] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui-fulldeps/dropck_tarena_unsound_drop.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui-fulldeps/dropck_tarena_unsound_drop/a" "-Crpath" "-O" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui-fulldeps/dropck_tarena_unsound_drop/auxiliary" "-A" "unused"
[01:21:43] ------------------------------------------
[01:21:43] 
[01:21:43] ------------------------------------------
[01:21:43] stderr:
[01:21:43] stderr:
[01:21:43] ------------------------------------------
[01:21:43] {"message":"`arena` does not live long enough","code":{"code":"E0597","explanation":"\nThis error occurs because a value was dropped while it was still borrowed\n\nExample of erroneous code:\n\n```compile_fail,E0597\nstruct Foo<'a> {\n    x: Option<&'a u32>,\n}\n\nlet mut x = Foo { x: None };\n{\n    let y = 0;\n    x.x = Some(&y); // error: `y` does not live long enough\n}\nprintln!(\"{:?}\", x.x);\n```\n\nIn here, `y` is dropped at the end of the inner scope, but it is borrowed by\n`x` until the `println`. To fix the previous example, just remove the scope\nso that `y` isn't dropped until after the println\n\n```\nstruct Foo<'a> {\n    x: Option<&'a u32>,\n}\n\nlet mut x = Foo { x: None };\n\nlet y = 0;\nx.x = Some(&y);\n\nprintln!(\"{:?}\", x.x);\n```\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui-fulldeps/dropck_tarena_unsound_drop.rs","byte_start":1291,"byte_end":1297,"line_start":41,"line_end":41,"column_start":7,"column_end":13,"is_primary":true,"text":[{"text":"    f(&arena);","highlight_start":7,"highlight_end":13}],"label":"borrowed value does not live long enough","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui-fulldeps/dropck_tarena_unsound_drop.rs","byte_start":1300,"byte_end":1301,"line_start":42,"line_end":42,"column_start":1,"column_end":2,"is_primary":false,"text":[{"text":"} //~^ ERROR `arena` does not live long enough","highlight_start":1,"highlight_end":2}],"label":"`arena` dropped here while still borrowed","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui-fulldeps/dropck_tarena_unsound_drop.rs","byte_start":1300,"byte_end":1301,"line_start":42,"line_end":42,"column_start":1,"column_end":2,"is_primary":false,"text":[{"text":"} //~^ ERROR `arena` does not live long enough","highlight_start":1,"highlight_end":2}],"label":"borrow might be used here, when `arena` is dropped and runs the `Drop` code for type `arena::TypedArena`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0597]: `arena` does not live long enough\n  --> /checkout/src/test/ui-fulldeps/dropck_tarena_unsound_drop.rs:41:7\n   |\nLL |     f(&arena);\n   |       ^^^^^^ borrowed value does not live long enough\nLL | } //~^ ERROR `arena` does not live long enough\n   | -\n   | |\n   | `arena` dropped here while still borrowed\n   | borrow might be used here, when `arena` is dropped and runs the `Drop` code for type `arena::TypedArena`\n\n"}
[01:21:43] {"message":"For more information about this error, try `rustc --explain E0597`.","code":null,"level":"","spans":[],"children":[],"rendered":"For more information about this error, try `rustc --explain E0597`.\n"}
[01:21:43] 
[01:21:43] ------------------------------------------
[01:21:43] 
[01:21:43] 
[01:21:43] thread '[ui] ui-fulldeps/dropck_tarena_unsound_drop.rs' panicked at 'explicit panic', src/tools/compiletest/src/runtest.rs:3326:9
[01:21:43] note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
[01:21:43] 
[01:21:43] ---- [ui] ui-fulldeps/dropck_tarena_cycle_checked.rs stdout ----
[01:21:43] diff of stderr:
[01:21:43] 
[01:21:43] 1 error[E0597]: `arena` does not live long enough
[01:21:43] +   --> $DIR/dropck_tarena_cycle_checked.rs:116:7
[01:21:43] 3    |
[01:21:43] 3    |
[01:21:43] 4 LL |     f(&arena);
[01:21:43] -    |        ^^^^^ borrowed value does not live long enough
[01:21:43] +    |       ^^^^^^ borrowed value does not live long enough
[01:21:43] 6 LL | }
[01:21:43] -    | - `arena` dropped here while still borrowed
[01:21:43] -    |
[01:21:43] -    = note: values in a scope are dropped in the opposite order they are created
[01:21:43] +    | |
[01:21:43] +    | |
[01:21:43] +    | `arena` dropped here while still borrowed
[01:21:43] +    | borrow might be used here, when `arena` is dropped and runs the `Drop` code for type `arena::TypedArena`
[01:21:43] 11 error: aborting due to previous error
[01:21:43] 12 
[01:21:43] 
[01:21:43] 
[01:21:43] 
[01:21:43] The actual stderr differed from the expected stderr.
[01:21:43] Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui-fulldeps/dropck_tarena_cycle_checked/dropck_tarena_cycle_checked.stderr
[01:21:43] To update references, rerun the tests and pass the `--bless` flag
[01:21:43] To only update this specific test, also pass `--test-args dropck_tarena_cycle_checked.rs`
[01:21:43] error: 1 errors occurred comparing output.
[01:21:43] status: exit code: 1
[01:21:43] status: exit code: 1
[01:21:43] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui-fulldeps/dropck_tarena_cycle_checked.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui-fulldeps/dropck_tarena_cycle_checked/a" "-Crpath" "-O" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui-fulldeps/dropck_tarena_cycle_checked/auxiliary" "-A" "unused"
[01:21:43] ------------------------------------------
[01:21:43] 
[01:21:43] ------------------------------------------
[01:21:43] stderr:
[01:21:43] stderr:
[01:21:43] ------------------------------------------
[01:21:43] {"message":"`arena` does not live long enough","code":{"code":"E0597","explanation":"\nThis error occurs because a value was dropped while it was still borrowed\n\nExample of erroneous code:\n\n```compile_fail,E0597\nstruct Foo<'a> {\n    x: Option<&'a u32>,\n}\n\nlet mut x = Foo { x: None };\n{\n    let y = 0;\n    x.x = Some(&y); // error: `y` does not live long enough\n}\nprintln!(\"{:?}\", x.x);\n```\n\nIn here, `y` is dropped at the end of the inner scope, but it is borrowed by\n`x` until the `println`. To fix the previous example, just remove the scope\nso that `y` isn't dropped until after the println\n\n```\nstruct Foo<'a> {\n    x: Option<&'a u32>,\n}\n\nlet mut x = Foo { x: None };\n\nlet y = 0;\nx.x = Some(&y);\n\nprintln!(\"{:?}\", x.x);\n```\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui-fulldeps/dropck_tarena_cycle_checked.rs","byte_start":2531,"byte_end":2537,"line_start":116,"line_end":116,"column_start":7,"column_end":13,"is_primary":true,"text":[{"text":"    f(&arena);","highlight_start":7,"highlight_end":13}],"label":"borrowed value does not live long enough","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui-fulldeps/dropck_tarena_cycle_checked.rs","byte_start":2540,"byte_end":2541,"line_start":117,"line_end":117,"column_start":1,"column_end":2,"is_primary":false,"text":[{"text":"} //~^ ERROR `arena` does not live long enough","highlight_start":1,"highlight_end":2}],"label":"`arena` dropped here while still borrowed","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui-fulldeps/dropck_tarena_cycle_checked.rs","byte_start":2540,"byte_end":2541,"line_start":117,"line_end":117,"column_start":1,"column_end":2,"is_primary":false,"text":[{"text":"} //~^ ERROR `arena` does not live long enough","highlight_start":1,"highlight_end":2}],"label":"borrow might be used here, when `arena` is dropped and runs the `Drop` code for type `arena::TypedArena`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0597]: `arena` does not live long enough\n  --> /checkout/src/test/ui-fulldeps/dropck_tarena_cycle_checked.rs:116:7\n   |\nLL |     f(&arena);\n   |       ^^^^^^ borrowed value does not live long enough\nLL | } //~^ ERROR `arena` does not live long enough\n   | -\n   | |\n   | `arena` dropped here while still borrowed\n   | borrow might be used here, when `arena` is dropped and runs the `Drop` code for type `arena::TypedArena`\n\n"}
[01:21:43] {"message":"aborting due to previous error","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to previous error\n\n"}
[01:21:43] {"message":"For more information about this error, try `rustc --explain E0597`.","code":null,"level":"","spans":[],"children":[],"rendered":"For more information about this error, try `rustc --explain E0597`.\n"}
[01:21:43] 
[01:21:43] ------------------------------------------
---
[01:21:43] test result: FAILED. 18 passed; 2 failed; 0 ignored; 0 measured; 0 filtered out
[01:21:43] 
[01:21:43] 
[01:21:43] 
[01:21:43] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/compiletest" "--compile-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" "--run-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "--rustc-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "--src-base" "/checkout/src/test/ui-fulldeps" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui-fulldeps" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--mode" "ui" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/usr/lib/llvm-6.0/bin/FileCheck" "--host-rustcflags" "-Crpath -O -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target-rustcflags" "-Crpath -O -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--docck-python" "/usr/bin/python2.7" "--lldb-python" "/usr/bin/python2.7" "--gdb" "/usr/bin/gdb" "--quiet" "--llvm-version" "6.0.0\n" "--system-llvm" "--cc" "" "--cxx" "" "--cflags" "" "--llvm-components" "" "--llvm-cxxflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
[01:21:43] 
[01:21:43] 
[01:21:43] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[01:21:43] Build completed unsuccessfully in 0:12:25
[01:21:43] Build completed unsuccessfully in 0:12:25
[01:21:43] make: *** [check] Error 1
[01:21:43] Makefile:48: recipe for target 'check' failed
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:025555c2
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
Tue Mar 12 21:52:35 UTC 2019
---
travis_time:end:05e85a84:start=1552427556937398663,finish=1552427556941921642,duration=4522979
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:194b913a
$ 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 --batch -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
travis_fold:start:after_failure.5
travis_time:start:2af241f4
travis_time:start:2af241f4
$ 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:2a50a234
$ 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)

[pnkfelix]

might as well fix the comment to not refer to AST mode any more

[pnkfelix]

are we supposed to be revising the text associated with error diagnostic codes in this manner? Was this an expected outcome of this change?

[matthewjasper]

This is a drive by fix since the documentation for this error is very outdated. The current example gives E0524.

[pnkfelix]

Ah this is so exciting!

[pnkfelix]

r=me once this is unblocked by PR #58739

[bors]

☔ The latest upstream changes (presumably #59120) made this pull request unmergeable. Please resolve the merge conflicts.