Stabilize min_const_unsafe_fn in 1.33

[Centril]

Fixes #55607

r? @oli-obk

[Centril]

Not entirely sure about the stage0 stuff...

[Centril]

Not entirely sure about the stage0 stuff...

[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:04637f34:start=1545502198099955332,finish=1545502254132288765,duration=56032333433
$ 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
Setting environment variables from .travis.yml
$ export IMAGE=x86_64-gnu-llvm-6.0
---
[00:56:27] .................................................................................................... 400/5192
[00:56:31] .................................................................................................... 500/5192
[00:56:34] ..............................i..................................................................... 600/5192
[00:56:37] .................................................................................................... 700/5192
[00:56:43] ....................................................F............................................... 800/5192
[00:56:50] ..............................iiiii................................................................. 1000/5192
[00:56:53] .................................................................................................... 1100/5192
[00:56:55] .................................................................................................... 1200/5192
[00:56:57] .................................................................................................... 1300/5192
---
[00:59:07] diff of stderr:
[00:59:07] 
[00:59:07] 5    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^
[00:59:07] 6    |
[00:59:07] 7 note: ...which requires const-evaluating `Foo::bytes::{{constant}}`...
[00:59:07] +   --> $SRC_DIR/libcore/mem.rs:LL:COL
[00:59:07] +    |
[00:59:07] + LL |     intrinsics::size_of::<T>()
[00:59:07] +    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
[00:59:07] 8 note: ...which requires computing layout of `Foo`...
[00:59:07] 9 note: ...which requires normalizing `ParamEnvAnd { param_env: ParamEnv { caller_bounds: [], reveal: All }, value: [u8; _] }`...
[00:59:07] 10 note: ...which requires const-evaluating + checking `Foo::bytes::{{constant}}`...
[00:59:07] 
[00:59:07] The actual stderr differed from the expected stderr.
[00:59:07] Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/consts/const-size_of-cycle/const-size_of-cycle.stderr
[00:59:07] Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/consts/const-size_of-cycle/const-size_of-cycle.stderr
[00:59:07] To update references, rerun the tests and pass the `--bless` flag
[00:59:07] To only update this specific test, also pass `--test-args consts/const-size_of-cycle.rs`
[00:59:07] error: 1 errors occurred comparing output.
[00:59:07] status: exit code: 1
[00:59:07] status: exit code: 1
[00:59:07] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/consts/const-size_of-cycle.rs" "--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/consts/const-size_of-cycle/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/consts/const-size_of-cycle/auxiliary" "-A" "unused"
[00:59:07] ------------------------------------------
[00:59:07] 
[00:59:07] ------------------------------------------
[00:59:07] stderr:
[00:59:07] stderr:
[00:59:07] ------------------------------------------
[00:59:07] {"message":"cycle detected when const-evaluating + checking `Foo::bytes::{{constant}}`","code":{"code":"E0391","explanation":"\nThis error indicates that some types or traits depend on each other\nand therefore cannot be constructed.\n\nThe following example contains a circular dependency between two traits:\n\n```compile_fail,E0391\ntrait FirstTrait : SecondTrait {\n\n}\n\ntrait SecondTrait : FirstTrait {\n\n}\n```\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/consts/const-size_of-cycle.rs","byte_start":559,"byte_end":585,"line_start":16,"line_end":16,"column_start":17,"column_end":43,"is_primary":true,"text":[{"text":"    bytes: [u8; std::mem::size_of::<Foo>()]","highlight_start":17,"highlight_end":43}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"...which requires const-evaluating `Foo::bytes::{{constant}}`...","code":null,"level":"note","spans":[{"file_name":"/checkout/src/libcore/mem.rs","byte_start":9866,"byte_end":9892,"line_start":301,"line_end":301,"column_start":5,"column_end":31,"is_primary":true,"text":[{"text":"    intrinsics::size_of::<T>()","highlight_start":5,"highlight_end":31}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":null},{"message":"...which requires computing layout of `Foo`...","code":null,"level":"note","spans":[{"file_name":"/checkout/src/test/ui/consts/const-size_of-cycle.rs","byte_start":0,"byte_end":0,"line_start":1,"line_end":1,"column_start":1,"column_end":1,"is_primary":true,"text":[{"text":"// Copyright 2017 The Rust Project Developers. See the COPYRIGHT","highlight_start":1,"highlight_end":1}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":null},{"message":"...which requires normalizing `ParamEnvAnd { param_env: ParamEnv { caller_bounds: [], reveal: All }, value: [u8; _] }`...","code":null,"level":"note","spans":[{"file_name":"/checkout/src/test/ui/consts/const-size_of-cycle.rs","byte_start":0,"byte_end":0,"line_start":1,"line_end":1,"column_start":1,"column_end":1,"is_primary":true,"text":[{"text":"// Copyright 2017 The Rust Project Developers. See the COPYRIGHT","highlight_start":1,"highlight_end":1}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":null},{"message":"...which requires const-evaluating + checking `Foo::bytes::{{constant}}`...","code":null,"level":"note","spans":[{"file_name":"/checkout/src/test/ui/consts/const-size_of-cycle.rs","byte_start":559,"byte_end":585,"line_start":16,"line_end":16,"column_start":17,"column_end":43,"is_primary":true,"text":[{"text":"    bytes: [u8; std::mem::size_of::<Foo>()]","highlight_start":17,"highlight_end":43}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":null},{"message":"...which again requires const-evaluating + checking `Foo::bytes::{{constant}}`, completing the cycle","code":null,"level":"note","spans":[],"children":[],"rendered":null},{"message":"cycle used when processing `Foo`","code":null,"level":"note","spans":[{"file_name":"/checkout/src/test/ui/consts/const-size_of-cycle.rs","byte_start":530,"byte_end":540,"line_start":15,"line_end":15,"column_start":1,"column_end":11,"is_primary":true,"text":[{"text":"struct Foo {","highlight_start":1,"highlight_end":11}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":null}],"rendered":"error[E0391]: cycle detected when const-evaluating + checking `Foo::bytes::{{constant}}`\n  --> /checkout/src/test/ui/consts/const-size_of-cycle.rs:16:17\n   |\nLL |     bytes: [u8; std::mem::size_of::<Foo>()]\n   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^\n   |\nnote: ...which requires const-evaluating `Foo::bytes::{{constant}}`...\n  --> /checkout/src/libcore/mem.rs:301:5\n   |\nLL |     intrinsics::size_of::<T>()\n   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^\nnote: ...which requires computing layout of `Foo`...\nnote: ...which requires normalizing `ParamEnvAnd { param_env: ParamEnv { caller_bounds: [], reveal: All }, value: [u8; _] }`...\nnote: ...which requires const-evaluating + checking `Foo::bytes::{{constant}}`...\n  --> /checkout/src/test/ui/consts/const-size_of-cycle.rs:16:17\n   |\nLL |     bytes: [u8; std::mem::size_of::<Foo>()]\n   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^\n   = note: ...which again requires const-evaluating + checking `Foo::bytes::{{constant}}`, completing the cycle\nnote: cycle used when processing `Foo`\n  --> /checkout/src/test/ui/consts/const-size_of-cycle.rs:15:1\n   |\nLL | struct Foo {\n   | ^^^^^^^^^^\n\n"}
[00:59:07] {"message":"aborting due to previous error","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to previous error\n\n"}
[00:59:07] {"message":"For more information about this error, try `rustc --explain E0391`.","code":null,"level":"","spa4-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"
[00:59:07] 
[00:59:07] 
[00:59:07] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[00:59:07] Build completed unsuccessfully in 0:03:49
[00:59:07] Build completed unsuccessfully in 0:03:49
[00:59:07] make: *** [check] Error 1
[00:59:07] Makefile:58: recipe for target 'check' failed
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:1bc0e430
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
Sat Dec 22 19:10:10 UTC 2018

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)

[oli-obk]

We need to update the docs, too. At least that's an open point in the issue, so this PR doesn't fix the issue as described in the PR message

[bors]

☔️ The latest upstream changes (presumably #57063) made this pull request unmergeable. Please resolve the merge conflicts.

[Centril]

@oli-obk Rebased. I've also filed documentation issue (rust-lang-nursery/reference#482) for the reference; we can track needed documentation changes from there. :)

[oli-obk]

@bors r+

[bors]

📌 Commit 7ae6fb2 has been approved by oli-obk

[jethrogb]

I'm slightly confused as to why this feature was stabilized after being in master for only 18 days. Surely it could've been insta-stable or there should've been an FCP?