Fix build when emma_coverage changes from false->true

Fix build when emma_coverage changes from false->true

by explicitly clearing out hardlinked output file.

BUG=571642
Committed: https://crrev.com/89572b9c9defce673e0ec094b14a0bc9bbe9b8db
Cr-Commit-Position: refs/heads/master@{#366675}

[agrieve, 2015-12-22 19:22:09]

Description was changed from

==========
Fix build when emma_coverage changes from false->true

by explicitly clearing out hardlinked output file.

BUG=571642
==========

to

==========
Fix build when emma_coverage changes from false->true

by explicitly clearing out hardlinked output file.

BUG=571642
==========

[agrieve, 2015-12-22 19:22:09]

agrieve@chromium.org changed reviewers:
+ jbudorick@chromium.org

[agrieve, 2015-12-22 19:22:18]

On 2015/12/22 19:22:09, agrieve wrote:
> mailto:agrieve@chromium.org changed reviewers:
> + mailto:jbudorick@chromium.org

🎅

[jbudorick, 2015-12-22 19:34:44]

https://codereview.chromium.org/1542173002/diff/1/build/android/gyp/emma_inst...
File build/android/gyp/emma_instr.py (right):

https://codereview.chromium.org/1542173002/diff/1/build/android/gyp/emma_inst...
build/android/gyp/emma_instr.py:185: # input_path is a hardlink to output_path.
http://crbug.com/571642
I'm confused about how this fixes 571642. That failure appears to appear at emma
time up at line 176?

[agrieve, 2015-12-22 20:10:00]

https://codereview.chromium.org/1542173002/diff/1/build/android/gyp/emma_inst...
File build/android/gyp/emma_instr.py (right):

https://codereview.chromium.org/1542173002/diff/1/build/android/gyp/emma_inst...
build/android/gyp/emma_instr.py:185: # input_path is a hardlink to output_path.
http://crbug.com/571642
On 2015/12/22 19:34:44, jbudorick wrote:
> I'm confused about how this fixes 571642. That failure appears to appear at
emma
> time up at line 176?

1. Build once without coverage enabled, and there's a GN copy() target with
src=input_path dst=output_path. This results in a hardlink
2. Build once with coverage enabled. It succeeds, but since output_path is the
same inode as input_path, writing to output_path actually causes input_path to
get updated as well (they still point to the same inode after this runs)
3. Build again, and emma complains that input_path is already instrumented
(since it was wrongly modified by the previous run)

[jbudorick, 2015-12-22 20:42:36]

🌮

https://codereview.chromium.org/1542173002/diff/1/build/android/gyp/emma_inst...
File build/android/gyp/emma_instr.py (right):

https://codereview.chromium.org/1542173002/diff/1/build/android/gyp/emma_inst...
build/android/gyp/emma_instr.py:185: # input_path is a hardlink to output_path.
http://crbug.com/571642
On 2015/12/22 20:10:00, agrieve wrote:
> On 2015/12/22 19:34:44, jbudorick wrote:
> > I'm confused about how this fixes 571642. That failure appears to appear at
> emma
> > time up at line 176?
> 
> 1. Build once without coverage enabled, and there's a GN copy() target with
> src=input_path dst=output_path. This results in a hardlink
> 2. Build once with coverage enabled. It succeeds, but since output_path is the
> same inode as input_path, writing to output_path actually causes input_path to
> get updated as well (they still point to the same inode after this runs)
> 3. Build again, and emma complains that input_path is already instrumented
> (since it was wrongly modified by the previous run)

ah, ok. lgtm

[agrieve, 2015-12-22 21:30:33]

The CQ bit was checked by agrieve@chromium.org

[commit-bot: I haz the power, 2015-12-22 21:32:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1542173002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1542173002/1

[commit-bot: I haz the power, 2015-12-22 22:45:52]

Description was changed from

==========
Fix build when emma_coverage changes from false->true

by explicitly clearing out hardlinked output file.

BUG=571642
==========

to

==========
Fix build when emma_coverage changes from false->true

by explicitly clearing out hardlinked output file.

BUG=571642
==========

[commit-bot: I haz the power, 2015-12-22 22:45:53]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-12-22 22:47:07]

Description was changed from

==========
Fix build when emma_coverage changes from false->true

by explicitly clearing out hardlinked output file.

BUG=571642
==========

to

==========
Fix build when emma_coverage changes from false->true

by explicitly clearing out hardlinked output file.

BUG=571642

Committed: https://crrev.com/89572b9c9defce673e0ec094b14a0bc9bbe9b8db
Cr-Commit-Position: refs/heads/master@{#366675}
==========

[commit-bot: I haz the power, 2015-12-22 22:47:09]

Patchset 1 (id:??) landed as
https://crrev.com/89572b9c9defce673e0ec094b14a0bc9bbe9b8db
Cr-Commit-Position: refs/heads/master@{#366675}