Add a target in GN that generates a last_change.h file for the SVN revision.

Add a target in GN that generates a last_change.h file for the SVN revision.

This is GN-only so the GYP build currently sets this to 0.

This adds the root generated file directory to all targets, so you can do #include "foo/bar.h" and get a generated file "bar.h" generated in directory "foo". This basically matches the internal Google build, and I use it here.

BUG=
R=viettrungluu@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=233969

[brettw, 2013-10-25 23:05:47]

Closed in favor of https://codereview.chromium.org/46003002

[brettw, 2013-10-25 23:06:26]

This replaces these changes with a new approach:
https://codereview.chromium.org/46003002/
https://codereview.chromium.org/40833003/

[brettw, 2013-10-25 23:08:04]

I kept "--version" as just a check for the switches rather than a command. This
matches most command line tools.  For example, "svn --version" but not "svn
version". Git provides both but I think this is uncommon.

The help this is a command because its the entrypoint to the help system. I just
added a hardcoded "--help" alias since people often expect "foo --help" to work.

[viettrungluu, 2013-11-06 18:39:21]

https://codereview.chromium.org/46003002/diff/1/build/util/lastchange.py
File build/util/lastchange.py (right):

https://codereview.chromium.org/46003002/diff/1/build/util/lastchange.py#newc...
build/util/lastchange.py:184: return guard.replace('/', '_').replace('.',
'_').replace('\\', '_') + '_'
Maybe it'd be better to just replace all non-alphanumeric characters with
'_'.... <shrug>

https://codereview.chromium.org/46003002/diff/1/build/util/lastchange.py#newc...
build/util/lastchange.py:231: parser.add_option("", "--define",
Maybe this should be "--version-macro" or "--version-macro-name", instead of
"--define", which is a little vague. <shrug>

https://codereview.chromium.org/46003002/diff/1/build/util/lastchange.py#newc...
build/util/lastchange.py:234: default="LASTCHANGE")
Why is your default ("LASTCHANGE") something other than what you actually use
("LAST_CHANGE")?

https://codereview.chromium.org/46003002/diff/1/tools/gn/gn_main.cc
File tools/gn/gn_main.cc (right):

https://codereview.chromium.org/46003002/diff/1/tools/gn/gn_main.cc#newcode13
tools/gn/gn_main.cc:13: // Only the GN-generated build makes this header for
now.
Is this a TODO?

[brettw, 2013-11-07 18:47:33]

I did the other stuff

https://codereview.chromium.org/46003002/diff/1/build/util/lastchange.py
File build/util/lastchange.py (right):

https://codereview.chromium.org/46003002/diff/1/build/util/lastchange.py#newc...
build/util/lastchange.py:184: return guard.replace('/', '_').replace('.',
'_').replace('\\', '_') + '_'
I didn't do this because it doesn't come up, it's more work, and I'm lazy. Feel
free to argue if you feel strongly.

[viettrungluu, 2013-11-08 17:17:48]

lgtm

[brettw, 2013-11-08 20:31:52]

Committed patchset #2 manually as r233969 (presubmit successful).