coverage reports with forceCompile are broken in Dart 2 mode

[mraleph]

Underlying issue is that compiler breaks when it tries to force-compile redirecting factory because they have a "special" representation instead of a real body.

Note: this completely breaks Flutter --coverage flag.

There is a workaround we can apply to temporary unbreak things - we can replace UNREACHABLE() with ReportError. But I am hesitant to apply it because it just hides underlying issue and might lead to other confusing situations down the road.

Add a test case testing this:

diff --git a/runtime/observatory/tests/service/get_source_report_test.dart b/runtime/observatory/tests/service/get_source_report_test.dart
index 75f1e06331..9b2fa15522 100644
--- a/runtime/observatory/tests/service/get_source_report_test.dart
+++ b/runtime/observatory/tests/service/get_source_report_test.dart
@@ -119,6 +119,17 @@ var tests = <IsolateTest>[
     expect(coverage['ranges'].length, greaterThan(1));
     expect(coverage['scripts'].length, greaterThan(1));

+    // Full isolate
+    params = {
+      'reports': ['Coverage'],
+      'forceCompile': true
+    };
+    coverage = await isolate.invokeRpcNoUpgrade('getSourceReport', params);
+    expect(coverage['type'], equals('SourceReport'));
+    expect(coverage['ranges'].length, greaterThan(1));
+    expect(coverage['scripts'].length, greaterThan(1));
+
+
     // Multiple reports (make sure enum list parameter parsing works).
     params = {
       'reports': ['_CallSites', 'Coverage', 'PossibleBreakpoints'],

Run it

╰─$ tools/test.py -c dartk -m release -a x64 --strong service/get_source_report_test
Test configuration: dartk_vm_release_x64_strong

FAILED: dartk-vm release_x64 service/get_source_report_test
Expected: Pass
Actual: RuntimeError

--- Command "vm" (took 03.000145s):
DART_CONFIGURATION=ReleaseX64 pkg/vm/tool/dart2 --error_on_bad_type --error_on_bad_override --ignore-unrecognized-flags --packages=/usr/local/google/home/vegorov/src/dart/sdk/.packages /usr/local/google/home/vegorov/src/dart/sdk/runtime/observatory/tests/service/get_source_report_test.dart

exit code:
255

stdout:
** Launching SERVICE_TEST_TESTEE=true /usr/local/google/home/vegorov/src/dart/sdk/pkg/vm/tool/../../../out/ReleaseX64/dart -DDART_SERVICE_USE_AUTH=false --profiler --preview_dart_2 --strong --reify-generic-functions --limit-ints-to-64-bits --error_on_bad_type --error_on_bad_override --ignore-unrecognized-flags --packages=/usr/local/google/home/vegorov/s
rc/dart/sdk/.packages --enable-vm-service:0 /usr/local/google/home/vegorov/src/dart/sdk/runtime/observatory/tests/service/get_source_report_test.dart
>testee>out> Observatory listening on http://127.0.0.1:39819/
** Signaled to run test queries on http://127.0.0.1:39819/
>testee>out>
Loading VM...
>testee>out> otherFunction <
>testee>out> positive
Done loading VM
Running get_source_report_test.dart [1/2]
Paused with PauseBreakpoint
Running get_source_report_test.dart [2/2]
>testee>err> ../../runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc: 6763: error: unimplemented code
>testee>err> Dumping native stack trace for thread 32d3f
>testee>err>   [0x00000000009ea897] dart::Profiler::DumpStackTrace(bool)
>testee>err>   [0x00000000009ea897] dart::Profiler::DumpStackTrace(bool)
>testee>err>   [0x0000000000c140b9] dart::DynamicAssertionHelper::Fail(char const*, ...)
>testee>err>   [0x0000000000b743be] dart::kernel::StreamingFlowGraphBuilder::BuildStaticGet(dart::TokenPosition*)
>testee>err>   [0x0000000000b6c577] dart::kernel::StreamingFlowGraphBuilder::BuildExpression(dart::TokenPosition*)
>testee>err>   [0x0000000000b7f5c6] dart::kernel::StreamingFlowGraphBuilder::BuildVariableDeclaration()
>testee>err>   [0x0000000000b6c829] dart::kernel::StreamingFlowGraphBuilder::BuildExpression(dart::TokenPosition*)
>testee>err>   [0x0000000000b6e862] dart::kernel::StreamingFlowGraphBuilder::BuildStatement()
>testee>err>   [0x0000000000b710b2] dart::kernel::StreamingFlowGraphBuilder::BuildGraphOfFunction(bool)
>testee>err>   [0x0000000000b71e47] dart::kernel::StreamingFlowGraphBuilder::BuildGraph(long)
>testee>err>   [0x0000000000b93d8b] dart::kernel::FlowGraphBuilder::BuildGraph()
>testee>err>   [0x0000000000bbb2ca] dart::DartCompilationPipeline::BuildFlowGraph(dart::Zone*, dart::ParsedFunction*, dart::ZoneGrowableArray<dart::ICData const*> const&, long, bool)
>testee>err>   [0x0000000000bbdddb] dart::CompileParsedFunctionHelper::Compile(dart::CompilationPipeline*)
>testee>err>   [0x0000000000bbf796] Unknown symbol
>testee>err>   [0x0000000000bc0338] dart::Compiler::EnsureUnoptimizedCode(dart::Thread*, dart::Function const&)
>testee>err>   [0x0000000000a701a8] dart::SourceReport::VisitFunction(dart::JSONArray*, dart::Function const&)
>testee>err>   [0x0000000000a706e7] dart::SourceReport::VisitLibrary(dart::JSONArray*, dart::Library const&)
>testee>err>   [0x0000000000a70d0f] dart::SourceReport::PrintJSON(dart::JSONStream*, dart::Script const&, dart::TokenPosition, dart::TokenPosition)
>testee>err>   [0x0000000000a5e25b] Unknown symbol
>testee>err>   [0x0000000000a57638] dart::Service::InvokeMethod(dart::Isolate*, dart::Array const&, bool)
>testee>err>   [0x0000000000a57d07] dart::Service::HandleIsolateMessage(dart::Isolate*, dart::Array const&)
>testee>err>   [0x00000000008cdec0] dart::IsolateMessageHandler::HandleMessage(dart::Message*)
>testee>err>   [0x00000000008f683e] dart::MessageHandler::HandleMessages(dart::MonitorLocker*, bool, bool)
>testee>err>   [0x00000000008f6ac0] dart::MessageHandler::HandleOOBMessages()
>testee>err>   [0x0000000000be6e28] Dart_HandleServiceMessages
>testee>err>   [0x00000000008d4a80] dart::Isolate::PauseEventHandler()
>testee>err>   [0x00000000008a3777] dart::Debugger::Pause(dart::ServiceEvent*)
>testee>err>   [0x00000000008af396] dart::Debugger::PauseStepping()
>testee>err>   [0x0000000000a434ab] dart::DRT_SingleStepHandler(dart::NativeArguments)
>testee>err>   [0x00007fc641d8063b] Unknown symbol
>testee>err>   [0x00007fc641d80b1b] Unknown symbol
>testee>err>   [0x00007fc62ef80495] Unknown symbol
>testee>err>   [0x00007fc63c53ff57] Unknown symbol
>testee>err>   [0x00007fc62ef80177] Unknown symbol
>testee>err>   [0x00007fc63c531a92] Unknown symbol
>testee>err>   [0x00007fc63c53f181] Unknown symbol
>testee>err>   [0x00007fc63c531a92] Unknown symbol
>testee>err>   [0x00007fc63c532640] Unknown symbol
>testee>err>   [0x00007fc63c531a92] Unknown symbol
>testee>err>   [0x00007fc63c5322df] Unknown symbol
>testee>err>   [0x00007fc63c531d7c] Unknown symbol
>testee>err>   [0x00007fc63c531bf7] Unknown symbol
>testee>err>   [0x00007fc63c531a92] Unknown symbol
>testee>err>   [0x00007fc63c531993] Unknown symbol
>testee>err>   [0x00007fc63c52c8d4] Unknown symbol
>testee>err>   [0x00007fc641d80a83] Unknown symbol
>testee>err>   [0x000000000089cff3] dart::DartEntry::InvokeFunction(dart::Function const&, dart::Array const&, dart::Array const&, unsigned long)
>testee>err>   [0x00000000008a068a] dart::DartLibraryCalls::HandleMessage(dart::Object const&, dart::Instance const&)
>testee>err>   [0x00000000008cdca0] dart::IsolateMessageHandler::HandleMessage(dart::Message*)
>testee>err>   [0x00000000008f676a] dart::MessageHandler::HandleMessages(dart::MonitorLocker*, bool, bool)
>testee>err>   [0x00000000008f6eec] dart::MessageHandler::TaskCallback()
>testee>err>   [0x0000000000a85d9d] dart::ThreadPool::Worker::Loop()
>testee>err>   [0x0000000000a85c26] dart::ThreadPool::Worker::Main(unsigned long)

[a-siva]

@kmillikin it might be a good idea to have somebody in your team run 'out/DebugX64/dart --preview-dart-2 --compile-all tests/language_2/first_test.dart' and shake out any crashes they see.

I found another stack trace running the --compile-all on first_test.dart which might be related

`../../runtime/vm/compiler/frontend/kernel_to_il.cc: 469: error: expected: IsProcedure(procedure)
Dumping native stack trace for thread 88a8
  [0x0000000000b18de7] dart::Profiler::DumpStackTrace(bool)
  [0x0000000000b18de7] dart::Profiler::DumpStackTrace(bool)
  [0x0000000000ded839] dart::DynamicAssertionHelper::Fail(char const*, ...)
  [0x0000000000d431ca] dart::kernel::TranslationHelper::DartProcedureName(dart::kernel::NameIndex)
  [0x0000000000d43afb] dart::kernel::TranslationHelper::LookupStaticMethodByKernelProcedure(dart::kernel::NameIndex)
  [0x0000000000d2d642] dart::kernel::StreamingFlowGraphBuilder::BuildStaticGet(dart::TokenPosition*)
  [0x0000000000d25b04] dart::kernel::StreamingFlowGraphBuilder::BuildExpression(dart::TokenPosition*)
  [0x0000000000d37e4d] dart::kernel::StreamingFlowGraphBuilder::BuildVariableDeclaration()
  [0x0000000000d25d3b] dart::kernel::StreamingFlowGraphBuilder::BuildExpression(dart::TokenPosition*)
  [0x0000000000d27b7d] dart::kernel::StreamingFlowGraphBuilder::BuildStatement()
  [0x0000000000d2a017] dart::kernel::StreamingFlowGraphBuilder::BuildGraphOfFunction(bool)
  [0x0000000000d2b2ff] dart::kernel::StreamingFlowGraphBuilder::BuildGraph(long)
  [0x0000000000d4ec07] dart::kernel::FlowGraphBuilder::BuildGraph()
  [0x0000000000d857c4] dart::DartCompilationPipeline::BuildFlowGraph(dart::Zone*, dart::ParsedFunction*, dart::ZoneGrowableArray<dart::ICData const*> const&, long, bool)
  [0x0000000000d88eb4] dart::CompileParsedFunctionHelper::Compile(dart::CompilationPipeline*)
  [0x0000000000d8b91c] Unknown symbol
  [0x0000000000d8b268] dart::Compiler::CompileFunction(dart::Thread*, dart::Function const&)
`

[mraleph]

This failure is the same one. Compile-all was crashing ever since we started to use this "invalid-expression" representation for redirecting factories.

[kmillikin]

There are things in the Kernel file that are not intended to be compiled, so "compile all" isn't ever what you want.

We will solve this by adding a bit that allows you to skip them.