dart2js compiler crashing due to visiting properties with value child of null

[sstrickl]

I'm getting the following assert crash on two very large codesets, so unfortunately I don't have a smaller or external-friendly reproduction source set to provide alongside the error.

Here's the output from the compiler:

---

Internal Error: The compiler crashed when compiling this element.

The compiler is broken.

When compiling the above element, the compiler crashed. It is not
possible to tell if this is caused by a problem in your program or
not. Regardless, the compiler should not crash.

The Dart team would greatly appreciate if you would take a moment to
report this problem at http://dartbug.com/new.

Please include the following information:

• the name and version of your operating system,

• the Dart SDK build number (2.2.1-edge.7f5ed18ffc5bb4f11768c0315e88844b8d46b3ac), and

• the entire message you see here (including the full stack trace
  below as well as the source location above).

The compiler crashed: NoSuchMethodError: The method 'accept' was called on null.
Receiver: null
Tried calling: accept(Instance of 'TokenCounter')
#0 Object.noSuchMethod (dart:core-patch/object_patch.dart:50:5)
#1 Property.visitChildren (package:js_ast/src/nodes.dart:1765:11)
#2 BaseVisitor.visitNode (package:js_ast/src/nodes.dart:89:10)
#3 TokenCounter.visitNode (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js/js.dart:114:13)
#4 BaseVisitor.visitProperty (package:js_ast/src/nodes.dart:175:37)
#5 Property.accept (package:js_ast/src/nodes.dart:1758:50)
#6 ObjectInitializer.visitChildren (package:js_ast/src/nodes.dart:1739:44)
#7 BaseVisitor.visitNode (package:js_ast/src/nodes.dart:89:10)
#8 TokenCounter.visitNode (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js/js.dart:114:13)
#9 BaseVisitor.visitExpression (package:js_ast/src/nodes.dart:121:41)
#10 BaseVisitor.visitObjectInitializer (package:js_ast/src/nodes.dart:174:55)
#11 ObjectInitializer.accept (package:js_ast/src/nodes.dart:1733:50)
#12 Assignment.visitChildren (package:js_ast/src/nodes.dart:1133:30)
#13 BaseVisitor.visitNode (package:js_ast/src/nodes.dart:89:10)
#14 TokenCounter.visitNode (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js/js.dart:114:13)
#15 BaseVisitor.visitExpression (package:js_ast/src/nodes.dart:121:41)
#16 BaseVisitor.visitAssignment (package:js_ast/src/nodes.dart:127:41)
#17 Assignment.accept (package:js_ast/src/nodes.dart:1126:50)
#18 ExpressionStatement.visitChildren (package:js_ast/src/nodes.dart:514:16)
#19 BaseVisitor.visitNode (package:js_ast/src/nodes.dart:89:10)
#20 TokenCounter.visitNode (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js/js.dart:114:13)
#21 BaseVisitor.visitStatement (package:js_ast/src/nodes.dart:95:39)
#22 BaseVisitor.visitExpressionStatement (package:js_ast/src/nodes.dart:100:59)
#23 ExpressionStatement.accept (package:js_ast/src/nodes.dart:508:50)
#24 Block.visitChildren (package:js_ast/src/nodes.dart:491:55)
#25 BaseVisitor.visitNode (package:js_ast/src/nodes.dart:89:10)
#26 TokenCounter.visitNode (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js/js.dart:114:13)
#27 BaseVisitor.visitStatement (package:js_ast/src/nodes.dart:95:39)
#28 BaseVisitor.visitBlock (package:js_ast/src/nodes.dart:99:31)
#29 Block.accept (package:js_ast/src/nodes.dart:485:50)
#30 Fun.visitChildren (package:js_ast/src/nodes.dart:1460:10)
#31 BaseVisitor.visitNode (package:js_ast/src/nodes.dart:89:10)
#32 TokenCounter.visitNode (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js/js.dart:114:13)
#33 BaseVisitor.visitExpression (package:js_ast/src/nodes.dart:121:41)
#34 BaseVisitor.visitFun (package:js_ast/src/nodes.dart:151:27)
#35 Fun.accept (package:js_ast/src/nodes.dart:1453:50)
#36 TokenCounter.countTokens (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js/js.dart:118:39)
#37 Iterable.forEach (dart:core/iterable.dart:277:30)
#38 ModelEmitter.emitProgram (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js_emitter/startup_emitter/model_emitter.dart:195:34)
#39 Emitter.emitProgram (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js_emitter/startup_emitter/emitter.dart:69:21)
#40 CodeEmitterTask.assembleProgram. (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js_emitter/code_emitter_task.dart:199:26)
#41 CompilerTask.measure (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/common/tasks.dart:64:51)
#42 CodeEmitterTask.assembleProgram (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js_emitter/code_emitter_task.dart:169:12)
#43 JavaScriptBackend.assembleProgram (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/js_backend/backend.dart:702:31)
#44 Compiler.generateJavaScriptCode (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/compiler.dart:388:31)
#45 Compiler.compileFromKernel. (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/compiler.dart:429:9)
#46 CompilerTask.measureSubtask (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/common/tasks.dart:179:35)
#47 Compiler.compileFromKernel (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/compiler.dart:403:14)
#48 Compiler.runInternal (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/compiler.dart:272:13)

#49 Compiler.run.. (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/compiler.dart:223:38)
#50 new Future.sync (dart:async/future.dart:224:31)
#51 Compiler.run. (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/compiler.dart:223:20)
#52 CompilerTask.measureSubtask (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/common/tasks.dart:179:35)
#53 Compiler.run (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/compiler.dart:220:41)
#54 CompilerImpl.run.. (file:///usr/local/google/home/sstrickl/dart/sdk/pkg/compiler/lib/src/apiimpl.dart:91:22)
#55 _RootZone.runUnary (dart:async/zone.dart:1379:54)
#56 _FutureListener.handleValue (dart:async/future_impl.dart:126:18)
#57 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:639:45)
#58 Future._propagateToListeners (dart:async/future_impl.dart:668:32)
#59 Future._completeWithValue (dart:async/future_impl.dart:483:5)
#60 Future._asyncComplete. (dart:async/future_impl.dart:513:7)
#61 _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
#62 _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)
#63 _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:115:13)
#64 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:172:5)

[sstrickl]

Tested a few release versions, and found this was introduced between 2.2.1-dev.1.1 and 2.2.1-dev.2.0. Bisected from there, and the first bad commit is 231c5c1.

[sstrickl]

Given that, and the fact that I had already been talking to him about this last week, assigning this to @johnniwinther.

[johnniwinther]

Thanks for the bisect!

[johnniwinther]

This happens because the codegen enqueuer doesn't honour the static types, leading to dead getters and setters being required by the emitted.

https://dart-review.googlesource.com/c/sdk/+/98852 contains temporary work-around.