Allow binding captureless lambdas into base::Callback by base::Bind

Allow binding captureless lambdas into base::Callback by base::Bind

This CL adds FunctorTraits for captureless lambdas, which is used by
base::Bind impl, so that base::Base accepts captureless lambda as the
target function. Capturing lambdas are still not allowed.

Committed: https://crrev.com/c1db726538e5b85efac5994bf5e90320800b894d
Cr-Commit-Position: refs/heads/master@{#404334}

[tzik, 2016-07-01 05:21:09]

Description was changed from

==========
Allow binding captureless lambdas into base::Callback by base::Bind

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

to

==========
Allow binding captureless lambdas into base::Callback by base::Bind

This CL adds FunctorTraits for captureless lambdas, which is used by
base::Bind impl, makes base::Bind accept captureless lambdas.
==========

[tzik, 2016-07-01 05:21:10]

tzik@chromium.org changed reviewers:
+ danakj@chromium.org, dcheng@chromium.org, yutak@chromium.org

[tzik, 2016-07-01 05:21:40]

PTAL

[Yuta Kitamura, 2016-07-01 09:02:33]

Functionality-wise, it looks okay, so (non-owner) LGTM, but
the necessity of this patch is a bit unclear. We forbid
capturing lambdas, don't we?

https://codereview.chromium.org/2115533002/diff/140001/base/bind_internal.h
File base/bind_internal.h (right):

https://codereview.chromium.org/2115533002/diff/140001/base/bind_internal.h#n...
base/bind_internal.h:55: // Unlike to the original version, we need |make_void|
as a helper struct to
nit: Remove "to" after "Unlike"

https://codereview.chromium.org/2115533002/diff/140001/base/bind_internal.h#n...
base/bind_internal.h:70: // Evaluated to RunType of the given C++11 lambda
expressien type.
nit: expressien

[tzik, 2016-07-01 09:57:14]

Description was changed from

==========
Allow binding captureless lambdas into base::Callback by base::Bind

This CL adds FunctorTraits for captureless lambdas, which is used by
base::Bind impl, makes base::Bind accept captureless lambdas.
==========

to

==========
Allow binding captureless lambdas into base::Callback by base::Bind

1234567890123456789012345678901234567890123456789012345678901234567890

This CL adds FunctorTraits for captureless lambdas, which is used by
base::Bind impl, so that base::Base accepts captureless lambda as the
target function. Capturing lambdas are still not allowed.
==========

[tzik, 2016-07-01 09:57:50]

Description was changed from

==========
Allow binding captureless lambdas into base::Callback by base::Bind

1234567890123456789012345678901234567890123456789012345678901234567890

This CL adds FunctorTraits for captureless lambdas, which is used by
base::Bind impl, so that base::Base accepts captureless lambda as the
target function. Capturing lambdas are still not allowed.
==========

to

==========
Allow binding captureless lambdas into base::Callback by base::Bind

This CL adds FunctorTraits for captureless lambdas, which is used by
base::Bind impl, so that base::Base accepts captureless lambda as the
target function. Capturing lambdas are still not allowed.
==========

[tzik, 2016-07-01 09:58:08]

https://codereview.chromium.org/2115533002/diff/140001/base/bind_internal.h
File base/bind_internal.h (right):

https://codereview.chromium.org/2115533002/diff/140001/base/bind_internal.h#n...
base/bind_internal.h:55: // Unlike to the original version, we need |make_void|
as a helper struct to
On 2016/07/01 09:02:33, Yuta Kitamura wrote:
> nit: Remove "to" after "Unlike"

Done.

https://codereview.chromium.org/2115533002/diff/140001/base/bind_internal.h#n...
base/bind_internal.h:70: // Evaluated to RunType of the given C++11 lambda
expressien type.
On 2016/07/01 09:02:33, Yuta Kitamura wrote:
> nit: expressien

Done.

[dcheng, 2016-07-01 13:29:48]

https://codereview.chromium.org/2115533002/diff/150001/base/bind_internal.h
File base/bind_internal.h (right):

https://codereview.chromium.org/2115533002/diff/150001/base/bind_internal.h#n...
base/bind_internal.h:79: // captureless lambda expression type.
Nit: it's a bit more accurate to say "callable type that's convertible to a
function pointer" and then document that this is important to us because lambdas
with captures are not convertible to function pointers.

(We could try naming the template to reflect that as well, but I'm not sure what
a good name would be... CallableConvertsToFunctionPointer?)

[tzik, 2016-07-01 14:34:58]

https://codereview.chromium.org/2115533002/diff/150001/base/bind_internal.h
File base/bind_internal.h (right):

https://codereview.chromium.org/2115533002/diff/150001/base/bind_internal.h#n...
base/bind_internal.h:79: // captureless lambda expression type.
On 2016/07/01 13:29:47, dcheng wrote:
> Nit: it's a bit more accurate to say "callable type that's convertible to a
> function pointer" and then document that this is important to us because
lambdas
> with captures are not convertible to function pointers.
> 
> (We could try naming the template to reflect that as well, but I'm not sure
what
> a good name would be... CallableConvertsToFunctionPointer?)

OK, updated the names and comments. WDYT?

[dcheng, 2016-07-04 05:14:02]

LGTM

https://codereview.chromium.org/2115533002/diff/190001/base/bind_internal.h
File base/bind_internal.h (right):

https://codereview.chromium.org/2115533002/diff/190001/base/bind_internal.h#n...
base/bind_internal.h:139: // to the function type while capturing lambda can't.
Nit: capturing lambdas (for consistency with captureless lambdas)

[tzik, 2016-07-04 08:15:48]

https://codereview.chromium.org/2115533002/diff/190001/base/bind_internal.h
File base/bind_internal.h (right):

https://codereview.chromium.org/2115533002/diff/190001/base/bind_internal.h#n...
base/bind_internal.h:139: // to the function type while capturing lambda can't.
On 2016/07/04 05:14:01, dcheng wrote:
> Nit: capturing lambdas (for consistency with captureless lambdas)

Done.

[tzik, 2016-07-07 21:15:47]

Dana: Could you take a look to this as an OWNER of //styleguide?

[danakj, 2016-07-07 21:18:49]

On 2016/07/07 21:15:47, tzik wrote:
> Dana: Could you take a look to this as an OWNER of //styleguide?

LGTM

[tzik, 2016-07-08 02:09:15]

The CQ bit was checked by tzik@chromium.org

[tzik, 2016-07-08 02:09:15]

The patchset sent to the CQ was uploaded after l-g-t-m from yutak@chromium.org,
dcheng@chromium.org
Link to the patchset: https://codereview.chromium.org/2115533002/#ps230001
(title: "rebase")

[commit-bot: I haz the power, 2016-07-08 02:09:43]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[tzik, 2016-07-08 04:09:45]

The CQ bit was unchecked by tzik@chromium.org

[tzik, 2016-07-08 04:10:26]

The CQ bit was checked by tzik@chromium.org

[commit-bot: I haz the power, 2016-07-08 04:10:52]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-08 09:42:51]

Description was changed from

==========
Allow binding captureless lambdas into base::Callback by base::Bind

This CL adds FunctorTraits for captureless lambdas, which is used by
base::Bind impl, so that base::Base accepts captureless lambda as the
target function. Capturing lambdas are still not allowed.
==========

to

==========
Allow binding captureless lambdas into base::Callback by base::Bind

This CL adds FunctorTraits for captureless lambdas, which is used by
base::Bind impl, so that base::Base accepts captureless lambda as the
target function. Capturing lambdas are still not allowed.
==========

[commit-bot: I haz the power, 2016-07-08 09:42:52]

Committed patchset #13 (id:230001)

[commit-bot: I haz the power, 2016-07-08 09:43:06]

CQ bit was unchecked.

[commit-bot: I haz the power, 2016-07-08 09:47:03]

Description was changed from

==========
Allow binding captureless lambdas into base::Callback by base::Bind

This CL adds FunctorTraits for captureless lambdas, which is used by
base::Bind impl, so that base::Base accepts captureless lambda as the
target function. Capturing lambdas are still not allowed.
==========

to

==========
Allow binding captureless lambdas into base::Callback by base::Bind

This CL adds FunctorTraits for captureless lambdas, which is used by
base::Bind impl, so that base::Base accepts captureless lambda as the
target function. Capturing lambdas are still not allowed.

Committed: https://crrev.com/c1db726538e5b85efac5994bf5e90320800b894d
Cr-Commit-Position: refs/heads/master@{#404334}
==========

[commit-bot: I haz the power, 2016-07-08 09:47:04]

Patchset 13 (id:??) landed as
https://crrev.com/c1db726538e5b85efac5994bf5e90320800b894d
Cr-Commit-Position: refs/heads/master@{#404334}