Use generic functions in zones.

Use generic functions in zones.

Migrated to Gerrit: https://dart-review.googlesource.com/c/sdk/+/4942

[vsm, 2017-06-16 13:05:58]

vsm@google.com changed reviewers:
+ vsm@google.com

[vsm, 2017-06-16 13:05:59]

https://codereview.chromium.org/2893893002/diff/140001/sdk/lib/async/zone.dart
File sdk/lib/async/zone.dart (right):

https://codereview.chromium.org/2893893002/diff/140001/sdk/lib/async/zone.dar...
sdk/lib/async/zone.dart:1495: assert(onError is! ZoneUnaryCallback<R, Object>);
This assert is failing in DDC on lib/async/run_zoned5_test.

Is it really supposed to be "is!"?

[floitsch, 2017-06-16 19:54:17]

https://codereview.chromium.org/2893893002/diff/140001/sdk/lib/async/zone.dart
File sdk/lib/async/zone.dart (right):

https://codereview.chromium.org/2893893002/diff/140001/sdk/lib/async/zone.dar...
sdk/lib/async/zone.dart:1495: assert(onError is! ZoneUnaryCallback<R, Object>);
On 2017/06/16 13:05:59, vsm wrote:
> This assert is failing in DDC on lib/async/run_zoned5_test.
> 
> Is it really supposed to be "is!"?

Good catch. thanks.
done.

[ahe, 2017-07-05 13:43:54]

As far as I can tell, this no longer breaks Fasta. But Zones don't work either,
so our unit tests are broken.

[floitsch, 2017-07-05 14:00:41]

On 2017/07/05 13:43:54, ahe wrote:
> As far as I can tell, this no longer breaks Fasta. But Zones don't work
either,
> so our unit tests are broken.

Are you using a third-party package for your tests?
There are a few third-party packages that need patching:
stack_trace: https://codereview.chromium.org//2889993003
pool: https://codereview.chromium.org//2891093002
maybe some more, but I believe these are the most important ones.

[ahe, 2017-07-05 14:23:50]

On 2017/07/05 14:00:41, floitsch wrote:
> On 2017/07/05 13:43:54, ahe wrote:
> > As far as I can tell, this no longer breaks Fasta. But Zones don't work
> either,
> > so our unit tests are broken.
> 
> Are you using a third-party package for your tests?
> There are a few third-party packages that need patching:
> stack_trace: https://codereview.chromium.org//2889993003
> pool: https://codereview.chromium.org//2891093002
> maybe some more, but I believe these are the most important ones.

Yes. All the unit tests that are failing uses package:pool.

However, I ran more tests and found that Fasta is still causing problems in
these two tests:

    lib/async/zone_run_test: Pass -> RuntimeError
    lib/async/zone_run_unary_test: Pass -> RuntimeError

And those have warnings they shouldn't have. I'll let you know when I've fixed
the problems with the lib/async tests.

[ahe, 2017-07-05 14:27:01]

On 2017/07/05 14:23:50, ahe wrote:
> On 2017/07/05 14:00:41, floitsch wrote:
> > On 2017/07/05 13:43:54, ahe wrote:
> > > As far as I can tell, this no longer breaks Fasta. But Zones don't work
> > either,
> > > so our unit tests are broken.
> > 
> > Are you using a third-party package for your tests?
> > There are a few third-party packages that need patching:
> > stack_trace: https://codereview.chromium.org//2889993003
> > pool: https://codereview.chromium.org//2891093002
> > maybe some more, but I believe these are the most important ones.
> 
> Yes. All the unit tests that are failing uses package:pool.
> 
> However, I ran more tests and found that Fasta is still causing problems in
> these two tests:
> 
>     lib/async/zone_run_test: Pass -> RuntimeError
>     lib/async/zone_run_unary_test: Pass -> RuntimeError
> 
> And those have warnings they shouldn't have. I'll let you know when I've fixed
> the problems with the lib/async tests.

FWIW, it works for me to mark these two tests as failing in dartk and dartkp, if
you're ready to land this.
I think I've laid all the ground work and should be able to implement generic
local functions relatively quickly.

[regis, 2017-07-24 18:21:09]

regis@google.com changed reviewers:
+ regis@google.com

[regis, 2017-07-24 18:21:10]

https://codereview.chromium.org/2893893002/diff/240001/sdk/lib/async/zone.dart
File sdk/lib/async/zone.dart (right):

https://codereview.chromium.org/2893893002/diff/240001/sdk/lib/async/zone.dar...
sdk/lib/async/zone.dart:802: _ZoneFunction<RunHandler> get _run;
It was pointed to me that generic function types are not allowed as type
arguments (or as bound).

[floitsch, 2017-07-27 14:11:36]

https://codereview.chromium.org/2893893002/diff/240001/sdk/lib/async/zone.dart
File sdk/lib/async/zone.dart (right):

https://codereview.chromium.org/2893893002/diff/240001/sdk/lib/async/zone.dar...
sdk/lib/async/zone.dart:802: _ZoneFunction<RunHandler> get _run;
On 2017/07/24 18:21:10, regis wrote:
> It was pointed to me that generic function types are not allowed as type
> arguments (or as bound).

I am not aware of such a restriction.

[regis, 2017-07-27 16:30:21]

On 2017/07/27 14:11:36, floitsch wrote:
> https://codereview.chromium.org/2893893002/diff/240001/sdk/lib/async/zone.dart
> File sdk/lib/async/zone.dart (right):
> 
>
https://codereview.chromium.org/2893893002/diff/240001/sdk/lib/async/zone.dar...
> sdk/lib/async/zone.dart:802: _ZoneFunction<RunHandler> get _run;
> On 2017/07/24 18:21:10, regis wrote:
> > It was pointed to me that generic function types are not allowed as type
> > arguments (or as bound).
> 
> I am not aware of such a restriction.

I was not either until I filed an issue against the analyzer last week:
https://github.com/dart-lang/sdk/issues/30207
I was told my test violates this restriction (see Erik's comment). So I fixed
the test and made the VM check for that restriction:
https://codereview.chromium.org/2989513002/

[floitsch, 2017-08-02 15:27:52]

https://codereview.chromium.org/2893893002/diff/240001/sdk/lib/async/zone.dart
File sdk/lib/async/zone.dart (right):

https://codereview.chromium.org/2893893002/diff/240001/sdk/lib/async/zone.dar...
sdk/lib/async/zone.dart:802: _ZoneFunction<RunHandler> get _run;
On 2017/07/27 14:11:35, floitsch wrote:
> On 2017/07/24 18:21:10, regis wrote:
> > It was pointed to me that generic function types are not allowed as type
> > arguments (or as bound).
> 
> I am not aware of such a restriction.

Changed the code.

[regis, 2017-08-08 20:31:21]

https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dart
File sdk/lib/async/zone.dart (right):

https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dar...
sdk/lib/async/zone.dart:1242: _ZoneFunction<RunHandler> get _run =>
The same restriction applies here. RunHandler is a generic function type not
allowed as a type argument.

[regis, 2017-08-09 00:53:30]

On 2017/08/08 20:31:21, regis wrote:
> https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dart
> File sdk/lib/async/zone.dart (right):
> 
>
https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dar...
> sdk/lib/async/zone.dart:1242: _ZoneFunction<RunHandler> get _run =>
> The same restriction applies here. RunHandler is a generic function type not
> allowed as a type argument.

I am getting a few type errors in zone tests with this patch. Here are some
examples:

FAILED: none-vm-checked debug_x64 lib/async/zone_register_callback_unary_test
Expected: Pass 
Actual: RuntimeError
CommandOutput[vm]:

stderr:
Unhandled exception:
type '<R>(Zone, ZoneDelegate, Zone, (dynamic) => R) => dynamic' is not a subtype
of type 'RegisterUnaryCallbackHandler' of 'registerUnaryCallback'
#0      new _ZoneSpecification (dart:async/zone.dart:158)
#1      main
(file:///usr/local/google/home/regis/dart2/sdk/tests/lib/async/zone_register_callback_unary_test.dart:16:54)
#2      _startIsolate.<anonymous closure>
(dart:isolate-patch/isolate_patch.dart:265)
#3      _RawReceivePortImpl._handleMessage
(dart:isolate-patch/isolate_patch.dart:151)


Command[vm]: DART_CONFIGURATION=DebugX64 out/DebugX64/dart --enable_asserts
--enable_type_checks --ignore-unrecognized-flags
--packages=/usr/local/google/home/regis/dart2/sdk/.packages
/usr/local/google/home/regis/dart2/sdk/tests/lib/async/zone_register_callback_unary_test.dart
Took 0:00:01.858181

Short reproduction command (experimental):
    python tools/test.py --checked lib/async/zone_register_callback_unary_test

[05:01 |  35% | + 5650 | -    7]
FAILED: none-vm-checked debug_x64 lib/async/zone_error_callback_test
Expected: Pass 
Actual: RuntimeError
CommandOutput[vm]:

stdout:
unittest-suite-wait-for-done


stderr:
Unhandled exception:
type '(dynamic, dynamic) => void' is not a subtype of type '(Object, StackTrace)
=> bool' of 'callback'
#0      _CustomZone.registerBinaryCallback (dart:async/zone.dart:1057)
#1      _registerErrorHandler (dart:async/async_error.dart:19)
#2      _Future.catchError (dart:async/future_impl.dart:258)
#3      testThrownErrors
(file:///usr/local/google/home/regis/dart2/sdk/tests/lib/async/zone_error_callback_test.dart:226:50)
#4      testNoChange.testTransparent
(file:///usr/local/google/home/regis/dart2/sdk/tests/lib/async/zone_error_callback_test.dart:287:5)
#5      _rootRun (dart:async/zone.dart:1124)
#6      _CustomZone.run (dart:async/zone.dart:1021)
#7      runZoned (dart:async/zone.dart:1502)
#8      testNoChange
(file:///usr/local/google/home/regis/dart2/sdk/tests/lib/async/zone_error_callback_test.dart:294:3)
#9      main
(file:///usr/local/google/home/regis/dart2/sdk/tests/lib/async/zone_error_callback_test.dart:11:3)
#10     _startIsolate.<anonymous closure>
(dart:isolate-patch/isolate_patch.dart:265)
#11     _RawReceivePortImpl._handleMessage
(dart:isolate-patch/isolate_patch.dart:151)


Command[vm]: DART_CONFIGURATION=DebugX64 out/DebugX64/dart --enable_asserts
--enable_type_checks --ignore-unrecognized-flags
--packages=/usr/local/google/home/regis/dart2/sdk/.packages
/usr/local/google/home/regis/dart2/sdk/tests/lib/async/zone_error_callback_test.dart
Took 0:00:02.694942

Short reproduction command (experimental):
    python tools/test.py --checked lib/async/zone_error_callback_test

[05:09 |  36% | + 5800 | -    8]
FAILED: none-vm-checked debug_x64 lib/async/zone_debug_test
Expected: Pass 
Actual: CompileTimeError
CommandOutput[vm]:

stderr:
Unhandled exception:
Unhandled exception:
type '(Zone, ZoneDelegate, Zone, () => dynamic) => dynamic' is not a subtype of
type 'RunHandler' of 'run'
#0      new _ZoneSpecification (dart:async/zone.dart:154)
#1      _startIsolate.<anonymous closure>
(dart:isolate-patch/isolate_patch.dart:265)
#2      _RawReceivePortImpl._handleMessage
(dart:isolate-patch/isolate_patch.dart:151)
'file:///usr/local/google/home/regis/dart2/sdk/tests/lib/async/zone_debug_test.dart':
error: line 58 pos 35: error while evaluating const constructor
const DEBUG_SPECIFICATION = const ZoneSpecification(
                                  ^

#0      _startIsolate.<anonymous closure>
(dart:isolate-patch/isolate_patch.dart:265)
#1      _RawReceivePortImpl._handleMessage
(dart:isolate-patch/isolate_patch.dart:151)


Command[vm]: DART_CONFIGURATION=DebugX64 out/DebugX64/dart --enable_asserts
--enable_type_checks --ignore-unrecognized-flags
--packages=/usr/local/google/home/regis/dart2/sdk/.packages
/usr/local/google/home/regis/dart2/sdk/tests/lib/async/zone_debug_test.dart
Took 0:00:01.867135

Short reproduction command (experimental):
    python tools/test.py --checked lib/async/zone_debug_test

[06:16 |  40% | + 6400 | -    9]
FAILED: none-vm-checked debug_x64 standalone/io/test_runner_test
Expected: Pass 
Actual: RuntimeError
CommandOutput[vm]:

stderr:
Unhandled exception:
type '<T extends num>(T, T) => T' is not a subtype of type '(dynamic, dynamic)
=> dynamic' of 'combine'
#0      ListIterable.fold (dart:_internal/iterable.dart:190)
#1      CommandQueue._tryRunNextCommand
(file:///usr/local/google/home/regis/dart2/sdk/tools/testing/dart/test_runner.dart:1023:58)
#2      new CommandQueue.<anonymous closure>.<anonymous closure>
(file:///usr/local/google/home/regis/dart2/sdk/tools/testing/dart/test_runner.dart:980:25)
#3      Timer._createTimer.<anonymous closure>
(dart:async-patch/timer_patch.dart:21)
#4      _Timer._runTimers (dart:isolate-patch/timer_impl.dart:366)
#5      _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:394)
#6      _RawReceivePortImpl._handleMessage
(dart:isolate-patch/isolate_patch.dart:151)


Command[vm]: DART_CONFIGURATION=DebugX64 out/DebugX64/dart --enable_asserts
--enable_type_checks --ignore-unrecognized-flags
--packages=/usr/local/google/home/regis/dart2/sdk/.packages
/usr/local/google/home/regis/dart2/sdk/tests/standalone/io/test_runner_test.dart
Took 0:00:06.739522

Short reproduction command (experimental):
    python tools/test.py --checked standalone/io/test_runner_test

[07:05 |  46% | + 7422 | -   10]
FAILED: none-vm-checked debug_x64
co19/LibTest/async/Zone/registerBinaryCallback_A01_t01
Expected: Pass 
Actual: RuntimeError
CommandOutput[vm]:

stderr:
Unhandled exception:
type '(Zone, ZoneDelegate, Zone, (dynamic, dynamic) => dynamic) => dynamic' is
not a subtype of type 'RegisterBinaryCallbackHandler' of
'registerBinaryCallback'
#0      new _ZoneSpecification (dart:async/zone.dart:159)
#1      main
(file:///usr/local/google/home/regis/dart2/sdk/tests/co19/src/LibTest/async/Zone/registerBinaryCallback_A01_t01.dart:38:29)
#2      _startIsolate.<anonymous closure>
(dart:isolate-patch/isolate_patch.dart:265)
#3      _RawReceivePortImpl._handleMessage
(dart:isolate-patch/isolate_patch.dart:151)


Command[vm]: DART_CONFIGURATION=DebugX64 out/DebugX64/dart --enable_asserts
--enable_type_checks --ignore-unrecognized-flags
--packages=/usr/local/google/home/regis/dart2/sdk/.packages
/usr/local/google/home/regis/dart2/sdk/tests/co19/src/LibTest/async/Zone/registerBinaryCallback_A01_t01.dart
Took 0:00:02.278749

Short reproduction command (experimental):
    python tools/test.py --checked
co19/LibTest/async/Zone/registerBinaryCallback_A01_t01

[07:05 |  46% | + 7425 | -   11]
FAILED: none-vm-checked debug_x64
co19/LibTest/async/Zone/registerCallback_A01_t01
Expected: Pass 
Actual: RuntimeError
CommandOutput[vm]:

stderr:
Unhandled exception:
type '(Zone, ZoneDelegate, Zone, () => dynamic) => dynamic' is not a subtype of
type 'RegisterCallbackHandler' of 'registerCallback'
#0      new _ZoneSpecification (dart:async/zone.dart:157)
#1      main
(file:///usr/local/google/home/regis/dart2/sdk/tests/co19/src/LibTest/async/Zone/registerCallback_A01_t01.dart:37:29)
#2      _startIsolate.<anonymous closure>
(dart:isolate-patch/isolate_patch.dart:265)
#3      _RawReceivePortImpl._handleMessage
(dart:isolate-patch/isolate_patch.dart:151)


Command[vm]: DART_CONFIGURATION=DebugX64 out/DebugX64/dart --enable_asserts
--enable_type_checks --ignore-unrecognized-flags
--packages=/usr/local/google/home/regis/dart2/sdk/.packages
/usr/local/google/home/regis/dart2/sdk/tests/co19/src/LibTest/async/Zone/registerCallback_A01_t01.dart
Took 0:00:01.863665

Short reproduction command (experimental):
    python tools/test.py --checked
co19/LibTest/async/Zone/registerCallback_A01_t01

[07:06 |  47% | + 7434 | -   12]
FAILED: none-vm-checked debug_x64
co19/LibTest/async/Zone/registerUnaryCallback_A01_t01
Expected: Pass 
Actual: RuntimeError
CommandOutput[vm]:

stderr:
Unhandled exception:
type '(Zone, ZoneDelegate, Zone, (dynamic) => dynamic) => dynamic' is not a
subtype of type 'RegisterUnaryCallbackHandler' of 'registerUnaryCallback'
#0      new _ZoneSpecification (dart:async/zone.dart:158)
#1      main
(file:///usr/local/google/home/regis/dart2/sdk/tests/co19/src/LibTest/async/Zone/registerUnaryCallback_A01_t01.dart:37:29)
#2      _startIsolate.<anonymous closure>
(dart:isolate-patch/isolate_patch.dart:265)
#3      _RawReceivePortImpl._handleMessage
(dart:isolate-patch/isolate_patch.dart:151)


Command[vm]: DART_CONFIGURATION=DebugX64 out/DebugX64/dart --enable_asserts
--enable_type_checks --ignore-unrecognized-flags
--packages=/usr/local/google/home/regis/dart2/sdk/.packages
/usr/local/google/home/regis/dart2/sdk/tests/co19/src/LibTest/async/Zone/registerUnaryCallback_A01_t01.dart
Took 0:00:02.226463

Short reproduction command (experimental):
    python tools/test.py --checked
co19/LibTest/async/Zone/registerUnaryCallback_A01_t01

[12:38 | 100% | +15829 | -   13]

[floitsch, 2017-08-09 10:34:32]

@Regis: thanks!
These failures were very helpful. I updated the tests and filed a bug against
co19: https://github.com/dart-lang/co19/issues/121

If you have more failures I would be happy to look at them.

https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dart
File sdk/lib/async/zone.dart (right):

https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dar...
sdk/lib/async/zone.dart:1242: _ZoneFunction<RunHandler> get _run =>
On 2017/08/08 20:31:21, regis wrote:
> The same restriction applies here. RunHandler is a generic function type not
> allowed as a type argument.

argh. Missed these ones.
done.

[regis, 2017-08-09 22:27:56]

On 2017/08/09 10:34:32, floitsch wrote:
> @Regis: thanks!
> These failures were very helpful. I updated the tests and filed a bug against
> co19: https://github.com/dart-lang/co19/issues/121
> 
> If you have more failures I would be happy to look at them.
> 
> https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dart
> File sdk/lib/async/zone.dart (right):
> 
>
https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dar...
> sdk/lib/async/zone.dart:1242: _ZoneFunction<RunHandler> get _run =>
> On 2017/08/08 20:31:21, regis wrote:
> > The same restriction applies here. RunHandler is a generic function type not
> > allowed as a type argument.
> 
> argh. Missed these ones.
> done.

I do not see any more failures. Thanks!

[regis, 2017-08-15 22:42:43]

On 2017/08/09 22:27:56, regis wrote:
> On 2017/08/09 10:34:32, floitsch wrote:
> > @Regis: thanks!
> > These failures were very helpful. I updated the tests and filed a bug
against
> > co19: https://github.com/dart-lang/co19/issues/121
> > 
> > If you have more failures I would be happy to look at them.
> > 
> >
https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dart
> > File sdk/lib/async/zone.dart (right):
> > 
> >
>
https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dar...
> > sdk/lib/async/zone.dart:1242: _ZoneFunction<RunHandler> get _run =>
> > On 2017/08/08 20:31:21, regis wrote:
> > > The same restriction applies here. RunHandler is a generic function type
not
> > > allowed as a type argument.
> > 
> > argh. Missed these ones.
> > done.
> 
> I do not see any more failures. Thanks!

Florian, Vijay, do you have any estimate on when this cl will be committed? Any
road blocks remaining? It has been pending for almost 3 months and it would be
great if you can submit it. Note that reification of generic functions is not
yet enabled by default in the VM, so this should not be a concern to you.

Thanks,
Regis

[regis, 2017-09-25 20:13:12]

On 2017/08/15 22:42:43, regis wrote:
> On 2017/08/09 22:27:56, regis wrote:
> > On 2017/08/09 10:34:32, floitsch wrote:
> > > @Regis: thanks!
> > > These failures were very helpful. I updated the tests and filed a bug
> against
> > > co19: https://github.com/dart-lang/co19/issues/121
> > > 
> > > If you have more failures I would be happy to look at them.
> > > 
> > >
> https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dart
> > > File sdk/lib/async/zone.dart (right):
> > > 
> > >
> >
>
https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dar...
> > > sdk/lib/async/zone.dart:1242: _ZoneFunction<RunHandler> get _run =>
> > > On 2017/08/08 20:31:21, regis wrote:
> > > > The same restriction applies here. RunHandler is a generic function type
> not
> > > > allowed as a type argument.
> > > 
> > > argh. Missed these ones.
> > > done.
> > 
> > I do not see any more failures. Thanks!
> 
> Florian, Vijay, do you have any estimate on when this cl will be committed?
Any
> road blocks remaining? It has been pending for almost 3 months and it would be
> great if you can submit it. Note that reification of generic functions is not
> yet enabled by default in the VM, so this should not be a concern to you.
> 
> Thanks,
> Regis

Do I understand correctly that this cl is now obsolete, because it was patched
in as part of https://codereview.chromium.org/3014593002 ?

[floitsch, 2017-09-26 10:45:28]

On 2017/09/25 20:13:12, regis wrote:
> On 2017/08/15 22:42:43, regis wrote:
> > On 2017/08/09 22:27:56, regis wrote:
> > > On 2017/08/09 10:34:32, floitsch wrote:
> > > > @Regis: thanks!
> > > > These failures were very helpful. I updated the tests and filed a bug
> > against
> > > > co19: https://github.com/dart-lang/co19/issues/121
> > > > 
> > > > If you have more failures I would be happy to look at them.
> > > > 
> > > >
> >
https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dart
> > > > File sdk/lib/async/zone.dart (right):
> > > > 
> > > >
> > >
> >
>
https://codereview.chromium.org/2893893002/diff/260001/sdk/lib/async/zone.dar...
> > > > sdk/lib/async/zone.dart:1242: _ZoneFunction<RunHandler> get _run =>
> > > > On 2017/08/08 20:31:21, regis wrote:
> > > > > The same restriction applies here. RunHandler is a generic function
type
> > not
> > > > > allowed as a type argument.
> > > > 
> > > > argh. Missed these ones.
> > > > done.
> > > 
> > > I do not see any more failures. Thanks!
> > 
> > Florian, Vijay, do you have any estimate on when this cl will be committed?
> Any
> > road blocks remaining? It has been pending for almost 3 months and it would
be
> > great if you can submit it. Note that reification of generic functions is
not
> > yet enabled by default in the VM, so this should not be a concern to you.
> > 
> > Thanks,
> > Regis
> 
> Do I understand correctly that this cl is now obsolete, because it was patched
> in as part of https://codereview.chromium.org/3014593002 ?

Yes: this CL is obsolete.
No: https://codereview.chromium.org/3014593002 was just a CL for dartium.
  The CL that made this one obsolete was:
https://dart-review.googlesource.com/c/sdk/+/4942

Will update the description.

[floitsch, 2017-09-26 10:45:48]

Description was changed from

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Use generic functions in zones.
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to

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Use generic functions in zones.

Migrated to Gerrit: https://dart-review.googlesource.com/c/sdk/+/4942
==========