Assertion failures related to line_starts_data

[rmacnak-google]

The tests

vm/dart/regress_48523_test RuntimeError (expected Pass)

are failing on configurations

vm-linux-debug-x64
vm-mac-debug-arm64
vm-mac-debug-x64
vm-win-debug-x64

--- Command "vm" (took 14.000320s):
DART_CONFIGURATION=DebugX64 out/DebugX64/dart --sound-null-safety -Dtest_runner.configuration=vm-linux-debug-x64 --ignore-unrecognized-flags --packages=/b/s/w/ir/.dart_tool/package_config.json /b/s/w/ir/runtime/tests/vm/dart/regress_48523_test.dart

exit code:
255

stdout:
Launching out/DebugX64/dart --packages=.dart_tool/package_config.json --snapshot-kind=kernel --snapshot=/b/s/w/itv559pxxg/DMYVEO/test.dart.0.dill /b/s/w/itv559pxxg/DMYVEO/test.dart
Launching out/DebugX64/dart --packages=.dart_tool/package_config.json --snapshot-kind=kernel --snapshot=/b/s/w/itv559pxxg/DMYVEO/test.dart.1.dill /b/s/w/itv559pxxg/DMYVEO/test.dart
Launching out/DebugX64/dart --packages=.dart_tool/package_config.json --snapshot-kind=kernel --snapshot=/b/s/w/itv559pxxg/DMYVEO/test.dart.2.dill /b/s/w/itv559pxxg/DMYVEO/test.dart
Launching out/DebugX64/dart --enable-vm-service:0 --disable-dart-dev --disable-service-auth-codes file:///b/s/w/itv559pxxg/DMYVEO/test.dart.0.dill
stdout: [testee] helper isolate is ready
stdout: The Dart VM service is listening on http://127.0.0.1:45555/
stderr: ../../runtime/vm/object.cc: 13110: error: expected: last_token_index->Serialize() <= source_length
stderr: version=3.1.0-edge.46086e908cbea8ccf6a0d2280adeb1b3d48eaa06 (be) (Fri Jul 21 11:08:48 2023 +0000) on "linux_x64"
stderr: pid=67565, thread=67576, isolate_group=main(0x55d072c531b0), isolate=helper-isolate(0x7f0c64000cd0)
stderr: os=linux, arch=x64, comp=no, sim=no
stderr: isolate_instructions=55d0706dbca0, vm_instructions=55d0706dbca0
stderr: fp=7f0c772fc960, sp=7f0c772fc828, pc=55d070acadec
stderr:   pc 0x000055d070acadec fp 0x00007f0c772fc960 dart::Profiler::DumpStackTrace(void*)+0x7c
stderr:   pc 0x000055d0706dbe94 fp 0x00007f0c772fca40 dart::Assert::Fail(char const*, ...) const+0x84
stderr:   pc 0x000055d070a0fd1b fp 0x00007f0c772fcaa0 out/DebugX64/dart+0x2642d1b
stderr:   pc 0x000055d070931d48 fp 0x00007f0c772fcb50 dart::Debugger::BreakpointLocationAtLineCol(dart::String const&, long, long)+0x1f8
stderr:   pc 0x000055d070931fe3 fp 0x00007f0c772fcb80 dart::Debugger::SetBreakpointAtLineCol(dart::String const&, long, long)+0x23
stderr:   pc 0x000055d070b61bc6 fp 0x00007f0c772fcbe0 out/DebugX64/dart+0x2794bc6
stderr:   pc 0x000055d070b52248 fp 0x00007f0c772fd3f0 dart::Service::InvokeMethod(dart::Isolate*, dart::Array const&, bool)+0x4d8
stderr:   pc 0x000055d070b52cba fp 0x00007f0c772fd420 dart::Service::HandleIsolateMessage(dart::Isolate*, dart::Array const&)+0x1a
stderr:   pc 0x000055d070958083 fp 0x00007f0c772fdbb0 dart::IsolateMessageHandler::HandleMessage(std::__2::unique_ptr<dart::Message, std::__2::default_delete<dart::Message>>)+0x273
stderr:   pc 0x000055d070996345 fp 0x00007f0c772fdc40 dart::MessageHandler::HandleMessages(dart::MonitorLocker*, bool, bool)+0x1d5
stderr:   pc 0x000055d070996fe7 fp 0x00007f0c772fdcc0 dart::MessageHandler::TaskCallback()+0x307
stderr:   pc 0x000055d070b91760 fp 0x00007f0c772fdd50 dart::ThreadPool::WorkerLoop(dart::ThreadPool::Worker*)+0x180
stderr:   pc 0x000055d070b9208b fp 0x00007f0c772fdda0 dart::ThreadPool::Worker::Main(unsigned long)+0x12b
stderr:   pc 0x000055d070ac38e3 fp 0x00007f0c772fdef0 out/DebugX64/dart+0x26f68e3
stderr: -- End of DumpStackTrace

stderr:
Unhandled exception:
Bad state: The client closed with pending request "addBreakpoint".

--- Re-run this test:
python3 tools/test.py -n vm-linux-debug-x64 vm/dart/regress_48523_test

This test appears to have been flaky failing for a long time and recently switched to consistently failing.

[a-siva]

//cc @derekxu16

[dcharkes]

Also the dart_2 version of this test https://dart-ci.appspot.com/log/vm-kernel-linux-debug-x64/dartk-linux-debug-x64/21501/vm/dart_2/regress_48523_test

[derekxu16]

What I'm observing is:

The test loads a program from a dill here

sdk/runtime/tests/vm/dart/regress_48523_test.dart

Line 17 in 293d32f

final reloader = await launchOn(dills[0]);

and then calling HasSource() on the Script corresponding to the program returns true, making it enter this branch

sdk/runtime/vm/object.cc

Lines 13108 to 13109 in 293d32f

	const String& source = String::Handle(zone, Source());
	source_length = source.Length();

but source is an empty string in that branch

Is this expected?

cc @mkustermann, @johnniwinther

[mkustermann]

This was probably introduced by my change in 8d802dd. Made cl/316581 to fix it.