dart2js: Forbid # placeholders in JS function bodies.

dart2js: Forbid # placeholders in JS function bodies.

This enforces one of the guidelines that is described in the documentation for 'JS' in js_runtime/lib/foreign_helper.dart

The JS code should be rewritten to explicitly capture the values in JS.

    // Dart 'a' might change after it is closed over.
    JS('', 'function(){return #;}', a);

-->

    // Immediately bind Dart 'a' to JS 'a' and then close over JS 'a':
    //
    JS('', '(function(a){return function(){return a;};})(#)', a);

R=sigmund@google.com

Committed: https://github.com/dart-lang/sdk/commit/77483ae5d34ed0c90355718f515d744f545c0181

[sra1, 2015-11-12 20:18:52]

Description was changed from

==========
Avoid JS functions capturing # placeholders
==========

to

==========
dart2js: Forbid # placeholders in JS function bodies.

This can lead to all kinds of capture problem.
The solution is to explicitly capture the values in JS.

JS('', 'function(){return #;}', a);

-->

JS('', '(function(a){return function(){return a;};})(#)', a);
==========

[sra1, 2015-11-12 20:18:52]

sra@google.com changed reviewers:
+ sigmund@google.com

[sra1, 2015-11-12 20:42:25]

Patchset #1 (id:1) has been deleted

[sra1, 2015-11-12 20:42:31]

Patchset #1 (id:20001) has been deleted

[sra1, 2015-11-12 20:51:23]

Description was changed from

==========
dart2js: Forbid # placeholders in JS function bodies.

This can lead to all kinds of capture problem.
The solution is to explicitly capture the values in JS.

JS('', 'function(){return #;}', a);

-->

JS('', '(function(a){return function(){return a;};})(#)', a);
==========

to

==========
dart2js: Forbid # placeholders in JS function bodies.

This can lead to capture problems.
The solution is to explicitly capture the values in JS.

    JS('', 'function(){return #;}', a);

-->

    // Immediately bind Dart 'a' to JS 'a' and then close over JS 'a':
    //
    JS('', '(function(a){return function(){return a;};})(#)', a);
==========

[sra1, 2015-11-12 20:52:17]

Description was changed from

==========
dart2js: Forbid # placeholders in JS function bodies.

This can lead to capture problems.
The solution is to explicitly capture the values in JS.

    JS('', 'function(){return #;}', a);

-->

    // Immediately bind Dart 'a' to JS 'a' and then close over JS 'a':
    //
    JS('', '(function(a){return function(){return a;};})(#)', a);
==========

to

==========
dart2js: Forbid # placeholders in JS function bodies.

This can lead to capture problems.
The solution is to explicitly capture the values in JS.

    // Dart 'a' might change after it is closed over.
    JS('', 'function(){return #;}', a);

-->

    // Immediately bind Dart 'a' to JS 'a' and then close over JS 'a':
    //
    JS('', '(function(a){return function(){return a;};})(#)', a);
==========

[sra1, 2015-11-12 20:56:29]

Description was changed from

==========
dart2js: Forbid # placeholders in JS function bodies.

This can lead to capture problems.
The solution is to explicitly capture the values in JS.

    // Dart 'a' might change after it is closed over.
    JS('', 'function(){return #;}', a);

-->

    // Immediately bind Dart 'a' to JS 'a' and then close over JS 'a':
    //
    JS('', '(function(a){return function(){return a;};})(#)', a);
==========

to

==========
dart2js: Forbid # placeholders in JS function bodies.

This enforces one of the guidelines that is described in the documentation for
'JS' in js_runtime/lib/foreign_helper.dart

The JS code should be rewritten to explicitly capture the values in JS.

    // Dart 'a' might change after it is closed over.
    JS('', 'function(){return #;}', a);

-->

    // Immediately bind Dart 'a' to JS 'a' and then close over JS 'a':
    //
    JS('', '(function(a){return function(){return a;};})(#)', a);
==========

[Siggi Cherem (dart-lang), 2015-11-12 21:21:29]

lgtm

https://codereview.chromium.org/1436263002/diff/40001/pkg/compiler/lib/src/ss...
File pkg/compiler/lib/src/ssa/builder.dart (right):

https://codereview.chromium.org/1436263002/diff/40001/pkg/compiler/lib/src/ss...
pkg/compiler/lib/src/ssa/builder.dart:4161: 'JS code must not use `#` inside
functions'});
maybe include your suggestion as well?

[sra1, 2015-11-12 22:23:26]

https://codereview.chromium.org/1436263002/diff/40001/pkg/compiler/lib/src/ss...
File pkg/compiler/lib/src/ssa/builder.dart (right):

https://codereview.chromium.org/1436263002/diff/40001/pkg/compiler/lib/src/ss...
pkg/compiler/lib/src/ssa/builder.dart:4161: 'JS code must not use `#` inside
functions'});
On 2015/11/12 21:21:29, Siggi Cherem (dart-lang) wrote:
> maybe include your suggestion as well?

I tried. Providing examples is confusing because they look just like the bad
code.

[Siggi Cherem (dart-lang), 2015-11-12 22:29:47]

On 2015/11/12 22:23:26, sra1 wrote:
>
https://codereview.chromium.org/1436263002/diff/40001/pkg/compiler/lib/src/ss...
> File pkg/compiler/lib/src/ssa/builder.dart (right):
> 
>
https://codereview.chromium.org/1436263002/diff/40001/pkg/compiler/lib/src/ss...
> pkg/compiler/lib/src/ssa/builder.dart:4161: 'JS code must not use `#` inside
> functions'});
> On 2015/11/12 21:21:29, Siggi Cherem (dart-lang) wrote:
> > maybe include your suggestion as well?
> 
> I tried. Providing examples is confusing because they look just like the bad
> code.

thanks. lgtm

[sra1, 2015-11-12 23:38:23]

Committed patchset #2 (id:60001) manually as
77483ae5d34ed0c90355718f515d744f545c0181 (presubmit successful).