Support for line-level error suppression (#25685).

Support for line-level error suppression (#25685).

Adds filtering logic to apply source-level error suppression using a simple comment convention.  For example, suppressing an invalid assignment would look like this:

```
//# ignore: invalid_assignment
int x = '';
```

Lists are supported as well:

```
//# ignore: invalid_assignment, const_initialized_with_non_constant_value
const String y = x;
```

Conversation on final format continues (https://github.com/dart-lang/sdk/issues/25685), so this can be treated as provisional but proves out the mechanics.  Comments and concerns most welcome.

BUG=
R=brianwilkerson@google.com

Committed: https://github.com/dart-lang/sdk/commit/75b1379a0f659284dad268ec6a9d69e828fee9a3

[pquitslund, 2016-02-16 20:13:03]

pquitslund@google.com changed reviewers:
+ brianwilkerson@google.com

[Brian Wilkerson, 2016-02-16 21:39:05]

LGTM

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/lib/src/task/d...
File pkg/analyzer/lib/src/task/dart.dart (right):

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/lib/src/task/d...
pkg/analyzer/lib/src/task/dart.dart:2228: static const String
_normaledIgnorePrefix = '//#ignore:';
"normaled"?!? :-) Did you mean "normalized"?

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/lib/src/task/d...
pkg/analyzer/lib/src/task/dart.dart:2284: LineInfo lineInfo = new
LineInfo(scanner.lineStarts);
Ah! I didn't realize when I looked at this before that we are inside a task. The
cleaner way of doing this is to make the task request the TOKEN_STREAM and
LINE_INFO for the source as inputs. They should already exist by the time we get
here, so there's no reason to duplicate the work.

There's a possibility, though, that the token stream will have already been
flushed, so it might be safer (though not as obvious) to ask for the PARSED_UNIT
for the source and ask the resulting CompilationUnit for its beginning token.

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/lib/src/task/d...
pkg/analyzer/lib/src/task/dart.dart:2315: filtered.add(currentError);
Or just reverse the condition and put this in the then block.

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/test/generated...
File pkg/analyzer/test/generated/error_suppression_test.dart (right):

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/test/generated...
pkg/analyzer/test/generated/error_suppression_test.dart:22: class
ErrorSuppressionTest extends EngineTestCase {
A lot of the support code in this class is already implemented in
ResolverTestCase. Might be better to change the superclass.

[pquitslund, 2016-02-16 21:51:42]

Thanks!

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/lib/src/task/d...
File pkg/analyzer/lib/src/task/dart.dart (right):

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/lib/src/task/d...
pkg/analyzer/lib/src/task/dart.dart:2228: static const String
_normaledIgnorePrefix = '//#ignore:';
On 2016/02/16 21:39:05, Brian Wilkerson wrote:
> "normaled"?!? :-) Did you mean "normalized"?

:)

Done.

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/lib/src/task/d...
pkg/analyzer/lib/src/task/dart.dart:2284: LineInfo lineInfo = new
LineInfo(scanner.lineStarts);
On 2016/02/16 21:39:05, Brian Wilkerson wrote:
> Ah! I didn't realize when I looked at this before that we are inside a task.
The
> cleaner way of doing this is to make the task request the TOKEN_STREAM and
> LINE_INFO for the source as inputs. They should already exist by the time we
get
> here, so there's no reason to duplicate the work.
> 
> There's a possibility, though, that the token stream will have already been
> flushed, so it might be safer (though not as obvious) to ask for the
PARSED_UNIT
> for the source and ask the resulting CompilationUnit for its beginning token.

Ah!  This is great.  I'll follow-up with a CL to refine.

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/lib/src/task/d...
pkg/analyzer/lib/src/task/dart.dart:2315: filtered.add(currentError);
On 2016/02/16 21:39:05, Brian Wilkerson wrote:
> Or just reverse the condition and put this in the then block.

Done.

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/test/generated...
File pkg/analyzer/test/generated/error_suppression_test.dart (right):

https://codereview.chromium.org/1702733002/diff/1/pkg/analyzer/test/generated...
pkg/analyzer/test/generated/error_suppression_test.dart:22: class
ErrorSuppressionTest extends EngineTestCase {
On 2016/02/16 21:39:05, Brian Wilkerson wrote:
> A lot of the support code in this class is already implemented in
> ResolverTestCase. Might be better to change the superclass.

Funny.  I started that way and then convinced myself that I needed to do
something extra (in setUp() maybe?)  In any case, that's not true anymore (if it
ever was).  Updated accordingly.

[pquitslund, 2016-02-16 21:54:03]

Description was changed from

==========
Support for line-level error suppression (#25685).

Adds filtering logic to apply source-level error suppression using a simple
comment convention.  For example, suppressing an invalid assignment would look
like this:

```
//# ignore: invalid_assignment
int x = '';
```

Lists are supported as well:

```
//# ignore: invalid_assignment, const_initialized_with_non_constant_value
const String y = x;
```

Conversation on final format continues
(https://github.com/dart-lang/sdk/issues/25685), so this can be treated as
provisional but proves out the mechanics.  Comments and concerns most welcome.

BUG=
==========

to

==========
Support for line-level error suppression (#25685).

Adds filtering logic to apply source-level error suppression using a simple
comment convention.  For example, suppressing an invalid assignment would look
like this:

```
//# ignore: invalid_assignment
int x = '';
```

Lists are supported as well:

```
//# ignore: invalid_assignment, const_initialized_with_non_constant_value
const String y = x;
```

Conversation on final format continues
(https://github.com/dart-lang/sdk/issues/25685), so this can be treated as
provisional but proves out the mechanics.  Comments and concerns most welcome.

BUG=
R=brianwilkerson@google.com

Committed:
https://github.com/dart-lang/sdk/commit/75b1379a0f659284dad268ec6a9d69e828fee9a3
==========

[pquitslund, 2016-02-16 21:54:06]

Committed patchset #2 (id:20001) manually as
75b1379a0f659284dad268ec6a9d69e828fee9a3 (presubmit successful).