Experiment with what gets compiled where

Experiment with what gets compiled where

BUG=

[manzagop (departed), 2016-12-07 22:15:53]

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

[commit-bot: I haz the power, 2016-12-07 22:16:27]

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, 2016-12-07 22:25:29]

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

[commit-bot: I haz the power, 2016-12-07 22:25:29]

Dry run: Try jobs failed on following builders:
  chromium_presubmit on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[manzagop (departed), 2016-12-07 23:02:55]

manzagop@chromium.org changed reviewers:
+ maruel@chromium.org

[manzagop (departed), 2016-12-07 23:02:56]

Hi M-A!

Question for you: is it expected that some bots build the "dont_depend_on_me"
target while others do not?

I have a similar CL where introducing a dependency from a non-win target in
build file A to a cross-platform target in build file B started causing
compilation of windows-only targets in file B (note these were never enclosed in
is_win).

Thanks!

P-A

[manzagop (departed), 2016-12-08 14:09:16]

manzagop@chromium.org changed reviewers:
+ dpranke@chromium.org
- maruel@chromium.org

[manzagop (departed), 2016-12-08 14:09:17]

Hi Dirk!

[manzagop (departed), 2016-12-08 14:12:08]

> Hi Dirk!

(Sorry, fat fingered "send".)

I'm trying to understand what determines which targets get built. In this case,
is it expected that some bots build the "dont_depend_on_me" executable target 
while others do not?

I have a similar CL where introducing a dependency from a non-win target in
build file A to a cross-platform target in build file B started causing
compilation of windows-only targets in file B (note these were never enclosed in
is_win).

Thanks,

Pierre

[Dirk Pranke, 2016-12-08 18:16:53]

On 2016/12/08 14:12:08, manzagop wrote:
> > Hi Dirk!
> 
> (Sorry, fat fingered "send".)
> 
> I'm trying to understand what determines which targets get built. In this
case,
> is it expected that some bots build the "dont_depend_on_me" executable target 
> while others do not?

Roughly speaking, yes :).

Most builders use the "chromium_trybot" build recipe, where each builder is
configured to potentially build some tests and some additional compile targets.
We take those targets and the list of affected files, and pass them to the
"analyze"
step to see which are impacted. 

In the current implementation of analyze, if the list of affected files contains
any .gn or .gni file, we can't easily determine which targets are actually
affected,
and so we conservatively assume that they all are.

Some builders (notably, some of the ios builders), work slightly differently.

If you point me at the actual CL where you had the problem, I can provide more
details on what happened and why.

[manzagop (departed), 2016-12-08 19:12:28]

On 2016/12/08 18:16:53, Dirk Pranke wrote:
> On 2016/12/08 14:12:08, manzagop wrote:
> > > Hi Dirk!
> > 
> > (Sorry, fat fingered "send".)
> > 
> > I'm trying to understand what determines which targets get built. In this
> case,
> > is it expected that some bots build the "dont_depend_on_me" executable
target 
> > while others do not?
> 
> Roughly speaking, yes :).
> 
> Most builders use the "chromium_trybot" build recipe, where each builder is
> configured to potentially build some tests and some additional compile
targets.
> We take those targets and the list of affected files, and pass them to the
> "analyze"
> step to see which are impacted. 
> 
> In the current implementation of analyze, if the list of affected files
contains
> any .gn or .gni file, we can't easily determine which targets are actually
> affected,
> and so we conservatively assume that they all are.
> 
> Some builders (notably, some of the ios builders), work slightly differently.
> 
> If you point me at the actual CL where you had the problem, I can provide more
> details on what happened and why.

Thanks for the explanation! For reference, my CL is
https://chromiumcodereview.appspot.com/2531123002/

I'll enclose the win only targets in some "if (is_win){}".