Dart 2-dev.63 crashes: Segmentation fault

[chalin]

Environment

Dart VM version: 2.0.0-dev.61.0 to -dev.63.0 on "macos_x64"

Steps to reproduce

1. Clone https://github.com/chalin/linkcheck
2. Checkout the chalin-dart-2-runtime-0612 branch (Use master now.)
3. pub upgrade
4. dart --preview-dart-2 test/e2e_test.dart

Expected result

The tests should run, but instead dart crashes:

> dart --preview-dart-2 test/e2e_test.dart
00:00 +0: linkcheck e2e reports no errors or warnings for a site without issues
2018-06-12T14:17:40.675072  0:00:00.026956 GET     [200] /
2018-06-12T14:17:40.722348  0:00:00.001239 GET     [404] /robots.txt
2018-06-12T14:17:40.844328  0:00:00.000416 GET     [200] /main.css

===== CRASH =====
version=2.0.0-dev.61.0 (Mon Jun 11 15:46:09 2018 +0200) on "macos_x64"
si_signo=Segmentation fault: 11(11), si_code=1, si_addr=0x0
Dumping native stack trace for thread 2903
  [0x000000010c91f470] dart::Instance::CheckAndCanonicalizeFields(dart::Thread*, char const**) const

===== CRASH =====
version=2.0.0-dev.61.0 (Mon Jun 11 15:46:09 2018 +0200) on "macos_x64"
si_signo=Segmentation fault: 11(11), si_code=1, si_addr=0x0
Aborting re-entrant request for stack trace.
Abort trap: 6

cc @kwalrath @kevmoo @natebosch

[chalin]

FYI, it seems to run w/o issue under Linux as can be seen from this Travis log.

[chalin]

Oops, no, I take that back: test run fine w/o the --preview-dart-2 flag, but with --preview-dart-2 it crashes under Linux too, as can be seen from this Travis log.

[chalin]

FYI, it is still crashing under 2-dev.62, see this Travis log.

[chalin]

Just keeping y'all up-to-date: it is still crashing under 2-dev.63.

[kevmoo]

CC @dgrove @a-siva

[dgrove]

Initially assigning to @a-siva

[a-siva]

Seems to fail in dart::Instance::CheckAndCanonicalizeFields while reading an isolate message

#3  0x00005555570e6bf7 in dart::Assert::Fail (this=<optimized out>, 
    format=<optimized out>) at ../../runtime/platform/assert.cc:43
#4  0x0000555556d902d1 in dart::Instance::CheckAndCanonicalizeFields (
    this=0x555558d21600, thread=<optimized out>, error_str=<optimized out>)
    at ../../runtime/vm/object.cc:15938
#5  0x0000555556d90359 in dart::Instance::CheckAndCanonicalize (
    this=0x555558d21600, thread=0x555558392900, error_str=0x0)
    at ../../runtime/vm/object.cc:15972
#6  0x0000555556ee005d in dart::SnapshotReader::ReadInstance (
    this=<optimized out>, object_id=<optimized out>, tags=2, 
    as_reference=false) at ../../runtime/vm/snapshot.cc:582
#7  0x0000555556edca93 in ReadObjectImpl (as_reference=false, 
    patch_object_id=-1, patch_offset=0, this=<optimized out>)
    at ../../runtime/vm/snapshot.cc:448
#8  dart::SnapshotReader::ReadObject (this=0x7fffd84bea90)
    at ../../runtime/vm/snapshot.cc:226
#9  0x0000555556cd75a6 in dart::IsolateMessageHandler::HandleMessage (
    this=0x555557b86460, message=0x55555886ac40)
    at ../../runtime/vm/isolate.cc:533
#10 0x0000555556d0f91a in dart::MessageHandler::HandleMessages (
    this=0x555557b86460, ml=0x7fffd84bec40, allow_normal_messages=true, 
    allow_multiple_normal_messages=true)
    at ../../runtime/vm/message_handler.cc:231
#11 0x0000555556d104fc in dart::MessageHandler::TaskCallback (
    this=0x555557b86460) at ../../runtime/vm/message_handler.cc:426
#12 0x0000555556f0ce57 in dart::ThreadPool::Worker::Loop (this=0x555557b7a6e0)
    at ../../runtime/vm/thread_pool.cc:381
#13 0x0000555556f0cb78 in dart::ThreadPool::Worker::Main (args=93825032234720)
    at ../../runtime/vm/thread_pool.cc:436

[chalin]

Still crashing under 2.0.0-dev.64.1, as shown in this Travis log.

[a-siva]

@chalin we are investigating this crash and will update status here once it is fixed.

[a-siva]

The CL https://dart-review.googlesource.com/c/sdk/+/61721 fixes the crash.
Will open a separate bug for addressing the longer term issue of dealing with the interaction between
deferred canonicalization of type arguments and canonicalization of instances.

[dgrove]

Can this one be closed since https://dart-review.googlesource.com/c/sdk/+/61721 has landed?

[chalin]

In case you are wondering which two lines caused the crash in linkcheck, see https://github.com/filiph/linkcheck/pull/16/files#diff-e29ff10915c7af85fedd110a8cb724ef.

Essentially (and as a workaround while awaiting the fix), I changed two lines of this form:

const unrecognizedMessage = const {verbKey: unrecognizedVerb};

To this form:

final unrecognizedMessage = {verbKey: unrecognizedVerb};

(Well at least I've learned that const canonicalization is done lazily.) /cc @filiph