save-analysis: Fix ICE when processing associated constant

[Xanewok]

Closes #59134
Closes rust-lang/rls#1449

Thanks @swgillespie for helping tracking this down and fixing it!

r? @eddyb

[Xanewok]

@rust-lang/infra this fixes a widespread ICE (any crate that transitively depends on bitflags 1.0.5, which is quite a few, currently yanked for this reason) in the RLS - any chance this can be backported to stable or at least to beta?

cc @KodrAus

[KodrAus]

A back port to beta sounds good to me, I’m also happy to just sit on our current master branch in bitflags for a while until it is available on the latest stable.

[Centril]

cc @rust-lang/compiler @rust-lang/release

Beta & stable nominating based on #60649 (comment).

[pietroalbini]

Note that a point release is likely not going to happen. We're two weeks from the next release and since this isn't merged yet the most likely target is May 16th, one week before 1.35 is out.

[Xanewok]

@pietroalbini ah, my release math was way off, sorry. Assuming this will be merged soon, is beta backport still on the table?

[pietroalbini]

Yep, the deadline for beta backports to be merged is Sunday 19th.

[Xanewok]

Added a test for both ICEs (when processing const with associated type and when processing assoc const with bogus field access).
I tried to apply the patch from #60649 (comment) but it didn't fix the ICEs so didn't include it here.

[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:080c4090:start=1557404023920840570,finish=1557404110925580129,duration=87004739559
$ 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
---

[00:03:48] travis_fold:start:tidy
travis_time:start:tidy
tidy check
[00:03:49] tidy error: /checkout/src/test/ui/save-analysis/issue-59134-1.rs: missing trailing newline
[00:03:49] tidy error: /checkout/src/test/ui/save-analysis/issue-59134-0.rs: missing trailing newline
[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" "--quiet"
[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 0:01:05
[00:03:54] Build completed unsuccessfully in 0:01:05
[00:03:54] Makefile:67: recipe for target 'tidy' failed
[00:03:54] make: *** [tidy] Error 1
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:089ef8cc
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
Thu May  9 12:19:14 UTC 2019
---
travis_time:end:3cb30eb4:start=1557404355299172114,finish=1557404355304092990,duration=4920876
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travis_time:start:06c56d30
$ 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
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travis_time:start:30a0bdf8
travis_time:start:30a0bdf8
$ 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:0194b6e0
$ 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)

[nikomatsakis]

Discussed in compiler meeting. Marking as beta-accepted.

[nikomatsakis]

Seems like a point release won't happen, so we didn't discuss that.

[Xanewok]

I'll drop the stable-nominated label then

[mouse07410]

Pardon a naive question, but when can we hope to see this fix added to the stable...?

[tesuji]

@mouse07410 Probably next stable, 1.35.

[Xanewok]

@oli-obk what do you think?

EDIT: Feel like r+'ing so it has a chance to be backported in beta as well?

[oli-obk]

@bors r+

r? @oli-obk

[bors]

📌 Commit 0af18ee has been approved by oli-obk

[bors]

⌛ Testing commit 0af18ee with merge a9ec99f...

[bors]

☀️ Test successful - checks-travis, status-appveyor
Approved by: oli-obk
Pushing a9ec99f to master...