VM nnbd sdk errors

[johnniwinther]

Enabling CFE warning/error reporting for NNBD shows various warnings.

The easiest way to enable the warning/error reporting while building the nnbd sdk is to change performNnbdChecks in pkg/front_end/lib/src/base/processed_options.dart to always return true, and run the compile_platform script directly:

tools/sdks/dart-sdk/bin/dart --packages=.packages --dfe=tools/sdks/dart-sdk/bin/snapshots/kernel-service.dart.snapshot pkg/front_end/tool/_fasta/compile_platform.dart dart:core -Ddart.vm.product=false -Ddart.developer.causal_async_stacks=true -Ddart.isVM=true --enable-experiment=non-nullable --single-root-scheme=org-dartlang-sdk --single-root-base=. org-dartlang-sdk:///sdk_nnbd/lib/libraries.json out/ReleaseX64NNBD/vm_outline_strong.dill out/ReleaseX64NNBD/vm_platform_strong.dill out/ReleaseX64NNBD/vm_outline_strong.dill

The current warnings are:

org-dartlang-sdk:///sdk_nnbd/lib/_internal/vm/lib/developer.dart:21:40: Warning: Optional parameter 'message' doesn't have a default value and its type 'String' doesn't allow null.
bool debugger({bool when: true, String message}) native "Developer_debugger";
                                       ^^^^^^^
org-dartlang-sdk:///sdk_nnbd/lib/_internal/vm/lib/developer.dart:28:15: Warning: Optional parameter 'time' doesn't have a default value and its type 'DateTime' doesn't allow null.
 - 'DateTime' is from 'dart:core'.
    {DateTime time,
              ^^^^
org-dartlang-sdk:///sdk_nnbd/lib/_internal/vm/lib/developer.dart:29:9: Warning: Optional parameter 'sequenceNumber' doesn't have a default value and its type 'int' doesn't allow null.
    int sequenceNumber,
        ^^^^^^^^^^^^^^
org-dartlang-sdk:///sdk_nnbd/lib/_internal/vm/lib/developer.dart:32:10: Warning: Optional parameter 'zone' doesn't have a default value and its type 'Zone' doesn't allow null.
 - 'Zone' is from 'dart:async'.
    Zone zone,
         ^^^^
org-dartlang-sdk:///sdk_nnbd/lib/_internal/vm/lib/developer.dart:33:12: Warning: Optional parameter 'error' doesn't have a default value and its type 'Object' doesn't allow null.
 - 'Object' is from 'dart:core'.
    Object error,
           ^^^^^
org-dartlang-sdk:///sdk_nnbd/lib/_internal/vm/lib/developer.dart:34:16: Warning: Optional parameter 'stackTrace' doesn't have a default value and its type 'StackTrace' doesn't allow null.
 - 'StackTrace' is from 'dart:core'.
    StackTrace stackTrace}) {
               ^^^^^^^^^^
org-dartlang-sdk:///sdk_nnbd/lib/_internal/vm/lib/ffi_patch.dart:86:15: Warning: Optional parameter 'exceptionalReturn' doesn't have a default value and its type 'Object' doesn't allow null.
 - 'Object' is from 'dart:core'.
      [Object exceptionalReturn]) {
              ^^^^^^^^^^^^^^^^^
org-dartlang-sdk:///sdk_nnbd/lib/ffi/ffi.dart:57:15: Warning: Optional parameter 'exceptionalReturn' doesn't have a default value and its type 'Object' doesn't allow null.
 - 'Object' is from 'dart:core'.
      [Object exceptionalReturn]);
              ^^^^^^^^^^^^^^^^^
org-dartlang-sdk:///sdk_nnbd/lib/isolate/isolate.dart:340:15: Warning: Optional parameter 'packageRoot' doesn't have a default value and its type 'Uri' doesn't allow null.
 - 'Uri' is from 'dart:core'.
          Uri packageRoot,
              ^^^^^^^^^^^
org-dartlang-sdk:///sdk_nnbd/lib/isolate/isolate.dart:525:15: Warning: Optional parameter 'response' doesn't have a default value and its type 'Object' doesn't allow null.
 - 'Object' is from 'dart:core'.
      {Object response, int priority = immediate});
              ^^^^^^^^
org-dartlang-sdk:///sdk_nnbd/lib/ffi/struct.dart:27:25: Warning: Assigning value of type 'Pointer<Null?>' to a variable of type 'Pointer<Struct>'.
 - 'Pointer' is from 'dart:ffi'.
 - 'Struct' is from 'dart:ffi'.
  Struct() : _addressOf = nullptr;
                        ^
org-dartlang-sdk:///sdk_nnbd/lib/_internal/vm/bin/vmservice_io.dart:48:5: Warning: Assigning value of type 'Server?' to a variable of type 'Server'.
 - 'Server' is from 'dart:vmservice_io'.
    return server;
    ^
org-dartlang-sdk:///sdk_nnbd/lib/vmservice/message.dart:163:15: Warning: Assigning value of type 'int' to a variable of type 'Null?'.
      ..[0] = 0 // Make room for OOB message type.
              ^
org-dartlang-sdk:///sdk_nnbd/lib/vmservice/message.dart:164:27: Warning: Assigning value of type 'SendPort' to a variable of type 'Null?'.
 - 'SendPort' is from 'dart:isolate'.
      ..[1] = receivePort.sendPort
                          ^
org-dartlang-sdk:///sdk_nnbd/lib/vmservice/message.dart:166:15: Warning: Assigning value of type 'String?' to a variable of type 'Null?'.
      ..[3] = method
              ^
org-dartlang-sdk:///sdk_nnbd/lib/vmservice/message.dart:167:15: Warning: Assigning value of type 'List<String>' to a variable of type 'Null?'.
 - 'List' is from 'dart:core'.
      ..[4] = keys
              ^
org-dartlang-sdk:///sdk_nnbd/lib/vmservice/message.dart:168:15: Warning: Assigning value of type 'List<String>' to a variable of type 'Null?'.
 - 'List' is from 'dart:core'.
      ..[5] = values;
              ^
org-dartlang-sdk:///sdk_nnbd/lib/vmservice/message.dart:211:15: Warning: Assigning value of type 'int' to a variable of type 'Null?'.
      ..[0] = 0 // Make room for OOB message type.
              ^
org-dartlang-sdk:///sdk_nnbd/lib/vmservice/message.dart:212:27: Warning: Assigning value of type 'SendPort' to a variable of type 'Null?'.
 - 'SendPort' is from 'dart:isolate'.
      ..[1] = receivePort.sendPort
                          ^
org-dartlang-sdk:///sdk_nnbd/lib/vmservice/message.dart:214:15: Warning: Assigning value of type 'String?' to a variable of type 'Null?'.
      ..[3] = method
              ^
org-dartlang-sdk:///sdk_nnbd/lib/vmservice/message.dart:215:15: Warning: Assigning value of type 'List<String>' to a variable of type 'Null?'.
 - 'List' is from 'dart:core'.
      ..[4] = keys
              ^
org-dartlang-sdk:///sdk_nnbd/lib/vmservice/message.dart:216:15: Warning: Assigning value of type 'List<dynamic>' to a variable of type 'Null?'.
 - 'List' is from 'dart:core'.
      ..[5] = values;
              ^
org-dartlang-sdk:///sdk_nnbd/lib/cli/wait_for.dart:63:25: Warning: Method 'call' is called on 'void Function(int)?' which is potentially null.
Try calling using ?. instead.
    _waitForEventClosure(timeout == null ? 0 : max(1, timeout.inMilliseconds));
                        ^
org-dartlang-sdk:///sdk_nnbd/lib/cli/wait_for.dart:63:25: Warning: Expression of type 'void Function(int)?' is used as a function, but it's potentially null.
Try calling using ?.call instead.
    _waitForEventClosure(timeout == null ? 0 : max(1, timeout.inMilliseconds));
                        ^

[a-siva]

Landed https://dart-review.googlesource.com/c/sdk/+/137250 to fix all errors reported by CFE when performNnbdChecks is turned on.
There is one remaining error which is a CFE issue -

output: org-dartlang-sdk:///sdk_nnbd/lib/_internal/vm/bin/socket_patch.dart:365:24: Warning: This constructor doesn't initialize field 'localAddress' and its type 'InternetAddress' doesn't allow null.
 - 'InternetAddress' is from 'dart:io'.
  late InternetAddress localAddress;
                       ^^^^^^^^^^^^

[a-siva]

Transferring issue back to CFE to close once the CFE fix lands.

[chloestefantsova]

I think with https://dart-review.googlesource.com/c/sdk/+/137787 landed, the issue is fixed.

[a-siva]

Now that all the errors found while compiling the SDK have been fixed, does the CFE turn on performNnbdChecks to true by default when --enable-experiment=non-nullable is specified?

[johnniwinther]

It's the plan. I've created #40980 for this.