DDC does not support map assignment operators with += in cascaded invocations

[corwinsheahan-wf]

ATTN: This appears to be fixed in build_web_compilers 2.x. Sorry for any confusion. Feel free to close at your discretion.

Dart 2.3.0
build_web_compilers: 1.2.2

Hi there,

I was getting the generic We're sorry, you've found a bug in our compiler error message, and tracked it down to the source of the problem. Here is an example of the offending code, which breaks compilation only in ddc and not dart2js:

  final map = {'key': 0}..['key'] += 3;

The breaking part here seems to be the += assignment in combination with the cascade. Either one separately does not break compilation. I checked out the dart-lang spec, and afaict this syntax should be supported.

Here is the full error traceback:

[SEVERE] build_web_compilers:ddc on lib/entrypoint.dartdevc.module:
Error compiling dartdevc module:breaking|lib/entrypoint.ddc.js

We're sorry, you've found a bug in our compiler.
You can report this bug at:
    https://github.com/dart-lang/sdk/issues/labels/area-dev-compiler
Please include the information below in your report, along with
any other information that may help us track it down. Thanks!
    dartdevc arguments: --dart-sdk=/usr/local/Cellar/dart/2.3.0/libexec --dart-sdk-summary=/usr/local/Cellar/dart/2.3.0/libexec/lib/_internal/ddc_sdk.sum --modules=amd -o packages/breaking/entrypoint.ddc.js --module-root=. --library-root=/lib --summary-extension=dartdevc.linked.sum --no-summarize --options=packages/build_modules/src/analysis_options.default.yaml --source-map --source-map-comment --inline-source-map --url-mapping=package:breaking/entrypoint.dart,packages/breaking/entrypoint.dart --url-mapping=package:breaking/src/breaking.dart,packages/breaking/src/breaking.dart package:breaking/entrypoint.dart package:breaking/src/breaking.dart
    dart --version: 2.3.0 (Fri May 3 10:32:31 2019 +0200) on "macos_x64"

NoSuchMethodError: The getter 'staticType' was called on null.
Receiver: null
Tried calling: staticType
#0 Object.noSuchMethod (dart:core-patch/object_patch.dart:50:5)
#1 getStaticType (package:dev_compiler/src/analyzer/element_helpers.dart:117:7)
#2 CodeGenerator._bindValue (package:dev_compiler/src/analyzer/code_generator.dart:4994:36)
#3 CodeGenerator._bindLeftHandSide (package:dev_compiler/src/analyzer/code_generator.dart:4949:11)
#4 CodeGenerator._emitOpAssign (package:dev_compiler/src/analyzer/code_generator.dart:3415:15)
#5 CodeGenerator.visitAssignmentExpression (package:dev_compiler/src/analyzer/code_generator.dart:3388:12)
#6 AssignmentExpressionImpl.accept (package:analyzer/src/dart/ast/ast.dart:748:49)
#7 CodeGenerator._visitExpression (package:dev_compiler/src/analyzer/code_generator.dart:5779:18)
#8 MappedListIterable.elementAt (dart:_internal/iterable.dart:414:29)
#9 ListIterable.toList (dart:_internal/iterable.dart:219:19)
#10 CodeGenerator._visitExpressionList (package:dev_compiler/src/analyzer/code_generator.dart:5786:42)
#11 CodeGenerator.visitCascadeExpression (package:dev_compiler/src/analyzer/code_generator.dart:5113:20)
#12 CascadeExpressionImpl.accept (package:analyzer/src/dart/ast/ast.dart:1279:49)
#13 CodeGenerator._visitExpression (package:dev_compiler/src/analyzer/code_generator.dart:5779:18)
#14 CodeGenerator.visitVariableDeclarationStatement (package:dev_compiler/src/analyzer/code_generator.dart:4231:19)
#15 VariableDeclarationStatementImpl.accept (package:analyzer/src/dart/ast/ast.dart:10529:15)
#16 CodeGenerator._visitStatement (package:dev_compiler/src/analyzer/code_generator.dart:5793:18)
#17 MappedListIterable.elementAt (dart:_internal/iterable.dart:414:29)
#18 ListIterable.toList (dart:_internal/iterable.dart:219:19)
#19 CodeGenerator._visitStatementList (package:dev_compiler/src/analyzer/code_generator.dart:5800:41)
#20 CodeGenerator.visitBlockFunctionBody (package:dev_compiler/src/analyzer/code_generator.dart:3601:21)
#21 BlockFunctionBodyImpl.accept (package:analyzer/src/dart/ast/ast.dart:1072:49)
#22 CodeGenerator._emitFunctionScopedBody (package:dev_compiler/src/analyzer/code_generator.dart:2824:22)
#23 CodeGenerator._emitSyncFunctionBody (package:dev_compiler/src/analyzer/code_generator.dart:2773:17)
#24 CodeGenerator._emitFunction (package:dev_compiler/src/analyzer/code_generator.dart:2756:11)
#25 CodeGenerator._emitMethodDeclaration (package:dev_compiler/src/analyzer/code_generator.dart:2552:12)
#26 CodeGenerator._emitClassMethods (package:dev_compiler/src/analyzer/code_generator.dart:1464:23)
#27 CodeGenerator._emitClassDeclaration (package:dev_compiler/src/analyzer/code_generator.dart:810:21)
#28 CodeGenerator.visitClassDeclaration (package:dev_compiler/src/analyzer/code_generator.dart:769:12)
#29 ClassDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:1560:49)
#30 CodeGenerator._emitTypeDeclaration (package:dev_compiler/src/analyzer/code_generator.dart:502:26)
#31 CodeGenerator.visitCompilationUnit (package:dev_compiler/src/analyzer/code_generator.dart:556:9)
#32 List.forEach (dart:core-patch/array.dart:106:8)
#33 CodeGenerator.compile (package:dev_compiler/src/analyzer/code_generator.dart:313:22)
#34 compileWithAnalyzer (package:dev_compiler/src/analyzer/module_compiler.dart:108:33)
#35 _compile (package:dev_compiler/src/analyzer/command.dart:152:16)
#36 compile (package:dev_compiler/src/analyzer/command.dart:56:18)
#37 compile (package:dev_compiler/src/compiler/shared_command.dart:405:18)
#38 _CompilerWorker.performRequest. (file:///b/s/w/ir/cache/builder/sdk/pkg/dev_compiler/bin/dartdevc.dart:54:39)
#39 _rootRun (dart:async/zone.dart:1124:13)
#40 _CustomZone.run (dart:async/zone.dart:1021:19)
#41 _runZoned (dart:async/zone.dart:1516:10)
#42 runZoned (dart:async/zone.dart:1463:12)
#43 _CompilerWorker.performRequest (file:///b/s/w/ir/cache/builder/sdk/pkg/dev_compiler/bin/dartdevc.dart:54:24)

#44 AsyncWorkerLoop.run. (package:bazel_worker/src/worker/async_worker_loop.dart:33:41)
#45 _rootRun (dart:async/zone.dart:1124:13)
#46 _CustomZone.run (dart:async/zone.dart:1021:19)
#47 _runZoned (dart:async/zone.dart:1516:10)
#48 runZoned (dart:async/zone.dart:1463:12)
#49 AsyncWorkerLoop.run (package:bazel_worker/src/worker/async_worker_loop.dart:33:26)

#50 main (file:///b/s/w/ir/cache/builder/sdk/pkg/dev_compiler/bin/dartdevc.dart:28:57)

#51 _startIsolate. (dart:isolate-patch/isolate_patch.dart:296:32)
#52 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:171:12)

[corwinsheahan-wf]

NVM, this appears to be fixed in build_web_compilers 2.x. Sorry for any confusion. Feel free to close at your discretion.

[jakemac53]

cc @vsmenon worth fixing analyzer based DDC for this or no?

[vsmenon]

@jakemac53 - probably not - as long as we can switch everyone. :-)

[jakemac53]

Closing manually, transfer seemed to partially fail

[jakemac53]

(btw, I transferred to the sdk dart-lang/sdk#37286)