Don't ICE on mutable zst slices

[oli-obk]

fixes #62045

[rust-highfive]

r? @estebank

(rust_highfive has picked a reviewer for you, use r? to override)

[oli-obk]

r? @RalfJung @eddyb

[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:307074a0:start=1561383579154496625,finish=1561383580046512124,duration=892015499
$ 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
$ export AWS_ACCESS_KEY_ID=AKIA46X5W6CZEJZ6XT55
---

[00:03:52] travis_fold:start:tidy
travis_time:start:tidy
tidy check
[00:03:53] tidy error: /checkout/src/test/ui/consts/issue-62045.rs: too many trailing newlines (2)
[00:03:53] tidy error: /checkout/src/test/ui/consts/miri_unleashed/mutable_references_ice.rs:6: line longer than 100 chars
[00:03:54] some tidy checks failed
[00:03:54] 
[00:03:54] 
[00:03:54] 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"
[00:03:54] 
[00:03:54] 
[00:03:54] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
[00:03:54] Build completed unsuccessfully in 0:01:08
---
travis_time:end:1a816260:start=1561383825352390344,finish=1561383825356783691,duration=4393347
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:17d7fafa
$ 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:236863e7
travis_time:start:236863e7
$ 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:0536828d
$ 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)

[eddyb]

@bors r+

[bors]

📌 Commit 91a15e2 has been approved by eddyb

[bors]

⌛ Testing commit 91a15e2 with merge 10deeae...

[bors]

☀️ Test successful - checks-travis, status-appveyor
Approved by: eddyb
Pushing 10deeae to master...