Cancel async generator only when it yields

Cancel async generator only when it yields

Async generators should only react to a cancellation when they
yield a value. Otherwise, the cancellation is ignored.

The example in dartbug.com/23436 should therefore never terminate,
because the generator function contains no yield statement.

This CL fixes bug 23436 by implementing the expected behavior, i.e.
not terminating the generator. If a yield statement is added to the
generator, the finally clause is executed once only, as expected.

BUG=23436
R=floitsch@google.com

Committed: https://github.com/dart-lang/sdk/commit/4b6ef00d5996471274a1e685eb32c55419482cf7

[hausner, 2016-02-09 18:20:58]

Description was changed from

==========
Cancel async generator only when it yields

Async generators should only react to a cancellation when they
yield a value. Otherwise, the cancellation is ignored.

The example in dartbug.com/23436 should therefore never terminate,
because the generator function contains no yield statement.

This CL fixes bug 23436 by implementing the expected behavior, i.e.
not terminating the generator. If a yield statement is added to the
generator, the finally clause is executed once only, as expected.

BUG=23436
==========

to

==========
Cancel async generator only when it yields

Async generators should only react to a cancellation when they
yield a value. Otherwise, the cancellation is ignored.

The example in dartbug.com/23436 should therefore never terminate,
because the generator function contains no yield statement.

This CL fixes bug 23436 by implementing the expected behavior, i.e.
not terminating the generator. If a yield statement is added to the
generator, the finally clause is executed once only, as expected.

BUG=23436
==========

[hausner, 2016-02-09 18:20:58]

hausner@google.com changed reviewers:
+ floitsch@google.com

[floitsch, 2016-02-09 18:23:31]

LGTM.

Tests will come with my CL (https://chromiumcodereview.appspot.com/1677063003/)

Please make sure that they pass (and I will revert the status-file change in my
CL before submitting).

[hausner, 2016-02-09 18:45:19]

Description was changed from

==========
Cancel async generator only when it yields

Async generators should only react to a cancellation when they
yield a value. Otherwise, the cancellation is ignored.

The example in dartbug.com/23436 should therefore never terminate,
because the generator function contains no yield statement.

This CL fixes bug 23436 by implementing the expected behavior, i.e.
not terminating the generator. If a yield statement is added to the
generator, the finally clause is executed once only, as expected.

BUG=23436
==========

to

==========
Cancel async generator only when it yields

Async generators should only react to a cancellation when they
yield a value. Otherwise, the cancellation is ignored.

The example in dartbug.com/23436 should therefore never terminate,
because the generator function contains no yield statement.

This CL fixes bug 23436 by implementing the expected behavior, i.e.
not terminating the generator. If a yield statement is added to the
generator, the finally clause is executed once only, as expected.

BUG=23436
R=floitsch@google.com

Committed:
https://github.com/dart-lang/sdk/commit/4b6ef00d5996471274a1e685eb32c55419482cf7
==========

[hausner, 2016-02-09 18:45:20]

Committed patchset #2 (id:20001) manually as
4b6ef00d5996471274a1e685eb32c55419482cf7 (presubmit successful).

[hausner, 2016-02-09 18:47:07]

Your new tests pass. Thank you for the review and the tests.