Re-commit "win: Set is_clang=true by default" over the weekend.

Re-commit "win: Set is_clang=true by default" over the weekend.

This relands https://codereview.chromium.org/2870543003

To figure out unknown problems. If this inconveniences you in any way, please
do let us know (ideally on crbug.com) – finding annoying things are part of the
motivation for this change.

If this breaks anything, please revert with prejudice -- but file a bug for
us about what went wrong. We intend to revert this on Sunday afternoon if it's not
reverted earlier due to breaking something.

This also switches win_clang to use MSVC as compiler, to make sure things stay
compilable with both compilers even while this is in.

Known problems:
* build times without goma are slower (but you can do goma builds with debug
  info, which are faster)
* incremental linking of webcore.dll doesn't work, so if you work on blink
  on windows links will be slow. If this affects you, please star
  https://crbug.com/717207 and make yourself heard.

This doesn't affect what we ship, which is currently off an PGO builder.

BUG=709690, 82385
Review-Url: https://codereview.chromium.org/2916933002
Cr-Commit-Position: refs/heads/master@{#476884}
Committed: https://chromium.googlesource.com/chromium/src/+/8476c55fd44915447233200c063fcd426dfe9807

[Nico, 2017-06-01 17:15:39]

Description was changed from

==========
Re-commit "win: Set is_clang=true by default" over the weekend.

To figure out unknown problems. If this inconveniences you in any way, please
do let us know (ideally on crbug.com) – finding annoying things are part of the
motivation for this change.

If this breaks anything, please revert with prejudice -- but file a bug for
us about what went wrong. We intend to revert this on Sunday afternoon if it's
not
reverted earlier due to breaking something.

This also switches win_clang to use MSVC as compiler, to make sure things stay
compilable with both compilers even while this is in.

Known problems:
* build times without goma are slower (but you can do goma builds with debug
  info, which are faster)
* incremental linking of webcore.dll doesn't work, so if you work on blink
  on windows links will be slow. If this affects you, please star
  https://crbug.com/717207 and make yourself heard.

This doesn't affect what we ship, which is currently off an PGO builder.

BUG=709690, 82385
==========

to

==========
Re-commit "win: Set is_clang=true by default" over the weekend.

This relands https://codereview.chromium.org/2870543003

To figure out unknown problems. If this inconveniences you in any way, please
do let us know (ideally on crbug.com) – finding annoying things are part of the
motivation for this change.

If this breaks anything, please revert with prejudice -- but file a bug for
us about what went wrong. We intend to revert this on Sunday afternoon if it's
not
reverted earlier due to breaking something.

This also switches win_clang to use MSVC as compiler, to make sure things stay
compilable with both compilers even while this is in.

Known problems:
* build times without goma are slower (but you can do goma builds with debug
  info, which are faster)
* incremental linking of webcore.dll doesn't work, so if you work on blink
  on windows links will be slow. If this affects you, please star
  https://crbug.com/717207 and make yourself heard.

This doesn't affect what we ship, which is currently off an PGO builder.

BUG=709690, 82385
==========

[Nico, 2017-06-01 17:18:16]

thakis@chromium.org changed reviewers:
+ thakis@chromium.org

[Nico, 2017-06-01 17:18:17]

lgtm

[hans, 2017-06-01 17:22:15]

hans@chromium.org changed reviewers:
+ brettw@chromium.org, brucedawson@chromium.org, jam@chromium.org

[hans, 2017-06-01 17:22:16]

brettw, jam, brucedawson: Please take a look.

(I'm also planning to add baselines for the layout tests we saw small diffs in
when this landed previously.)

[Nico, 2017-06-01 17:29:42]

thakis@chromium.org changed reviewers:
- brucedawson@chromium.org, jam@chromium.org

[Nico, 2017-06-01 17:29:43]

jam and bruce to cc
brettw: this is just a (again, temporary) rebasedreland of last week's switch cl

[brucedawson, 2017-06-01 18:49:19]

On 2017/06/01 17:29:43, Nico (vacation Jun 3-11) wrote:
> jam and bruce to cc
> brettw: this is just a (again, temporary) rebasedreland of last week's switch
cl

lgtm.

Note that a fix/workaround for 717207 is available - VS 2017 Update 3 Preview 1
fixes it. I commented on the bug.

I am exclusively using VS 2017 Update 3 Preview 1 so I am immune to the bug.

[brettw, 2017-06-01 20:23:03]

lgtm

[hans, 2017-06-01 21:15:48]

The CQ bit was checked by hans@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-06-01 21:16:20]

Dry run: 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, 2017-06-01 23:11:36]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-06-01 23:11:38]

Dry run: Try jobs failed on following builders:
  ios-simulator on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-simulator/bui...)

[hans, 2017-06-01 23:12:25]

The CQ bit was checked by hans@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-06-01 23:13:40]

Dry run: 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, 2017-06-02 00:05:26]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-06-02 00:05:28]

Dry run: This issue passed the CQ dry run.

[hans, 2017-06-03 00:35:38]

The CQ bit was checked by hans@chromium.org

[hans, 2017-06-03 00:35:40]

The patchset sent to the CQ was uploaded after l-g-t-m from thakis@chromium.org,
brettw@chromium.org, brucedawson@chromium.org
Link to the patchset: https://codereview.chromium.org/2916933002/#ps20001
(title: "third_party/WebKit/Tools/Scripts/webkit-patch rebaseline-cl")

[commit-bot: I haz the power, 2017-06-03 00:36:20]

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, 2017-06-03 03:58:20]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1496450138645500,
"parent_rev": "7486e37f46e1960620a8ea832cdbad356ae84916", "commit_rev":
"8476c55fd44915447233200c063fcd426dfe9807"}

[commit-bot: I haz the power, 2017-06-03 03:58:30]

Description was changed from

==========
Re-commit "win: Set is_clang=true by default" over the weekend.

This relands https://codereview.chromium.org/2870543003

To figure out unknown problems. If this inconveniences you in any way, please
do let us know (ideally on crbug.com) – finding annoying things are part of the
motivation for this change.

If this breaks anything, please revert with prejudice -- but file a bug for
us about what went wrong. We intend to revert this on Sunday afternoon if it's
not
reverted earlier due to breaking something.

This also switches win_clang to use MSVC as compiler, to make sure things stay
compilable with both compilers even while this is in.

Known problems:
* build times without goma are slower (but you can do goma builds with debug
  info, which are faster)
* incremental linking of webcore.dll doesn't work, so if you work on blink
  on windows links will be slow. If this affects you, please star
  https://crbug.com/717207 and make yourself heard.

This doesn't affect what we ship, which is currently off an PGO builder.

BUG=709690, 82385
==========

to

==========
Re-commit "win: Set is_clang=true by default" over the weekend.

This relands https://codereview.chromium.org/2870543003

To figure out unknown problems. If this inconveniences you in any way, please
do let us know (ideally on crbug.com) – finding annoying things are part of the
motivation for this change.

If this breaks anything, please revert with prejudice -- but file a bug for
us about what went wrong. We intend to revert this on Sunday afternoon if it's
not
reverted earlier due to breaking something.

This also switches win_clang to use MSVC as compiler, to make sure things stay
compilable with both compilers even while this is in.

Known problems:
* build times without goma are slower (but you can do goma builds with debug
  info, which are faster)
* incremental linking of webcore.dll doesn't work, so if you work on blink
  on windows links will be slow. If this affects you, please star
  https://crbug.com/717207 and make yourself heard.

This doesn't affect what we ship, which is currently off an PGO builder.

BUG=709690, 82385

Review-Url: https://codereview.chromium.org/2916933002
Cr-Commit-Position: refs/heads/master@{#476884}
Committed:
https://chromium.googlesource.com/chromium/src/+/8476c55fd44915447233200c063f...
==========

[commit-bot: I haz the power, 2017-06-03 03:58:34]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/chromium/src/+/8476c55fd44915447233200c063f...

[hans, 2017-06-04 22:18:56]

The revert button just gives a 500 error. Doing it manually here:
https://codereview.chromium.org/2919313002/