Allow NOLINT to skip the std::abs PRESUBMIT check.

Allow NOLINT to skip the std::abs PRESUBMIT check.

shader code is one example where abs() without std:: is acceptable.
But we still would like to generally keep the PRESUBMIT check that
enforces all uses of abs() and related functions must be prefixed
with "std::"

So in order to prevent PRESUBMIT annoyances when we modify shader
code or other similar situations, the regular expression for the
presubmit is modified to recognize a "// NOLINT" comment. In that
case, it ignores any un-prefixed abs() usage.

BUG=261900
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=221607

[shawnsingh, 2013-09-05 00:40:24]

PTAL, thanks in advance.

I had to split the regex into pieces to abide by 80 column limit.  The only new
piece of the regex is "no_nolint", which matches if there exists no "// NOLINT"
on the same line.

Put literally, the new part of the regex says: "The string is NOT a match if
there is any arbitrary text except no \n character, followed by '// NOLINT' " 
... which is how it checks for // NOLINT only on the same line.

[enne (OOO), 2013-09-05 01:00:39]

https://codereview.chromium.org/23591027/diff/1/cc/PRESUBMIT.py
File cc/PRESUBMIT.py (right):

https://codereview.chromium.org/23591027/diff/1/cc/PRESUBMIT.py#newcode86
cc/PRESUBMIT.py:86: no_nolint = "(?![^\\n]*// NOLINT)"
Maybe \s+ instead of the space in NOLINT?

https://codereview.chromium.org/23591027/diff/1/cc/PRESUBMIT.py#newcode87
cc/PRESUBMIT.py:87: expression = re.compile("%s|%s%s" % (no_abs, no_fabs,
no_nolint))
If you're going to put an | outside of the strings, can you also put the
surrounding parentheses too?  It took me a second to realize there wasn't a typo
in the strings or the final regular expression.

If you didn't know, you can do implicit line continuation in Python using
parentheses if you wanted to keep this all in one statement.

https://codereview.chromium.org/23591027/diff/1/cc/output/shader.cc
File cc/output/shader.cc (right):

https://codereview.chromium.org/23591027/diff/1/cc/output/shader.cc#newcode1600
cc/output/shader.cc:1600: float picker = abs(coord.x - coord.y); // NOLINT
optional style nit: two spaces before the comment to match clang-format / most
of cc.

[shawnsingh, 2013-09-05 22:29:26]

PTAL, feedback addressed, should be good to go.

[enne (OOO), 2013-09-05 23:29:38]

lgtm

[commit-bot: I haz the power, 2013-09-05 23:30:55]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/shawnsingh@chromium.org/23591027/10001

[commit-bot: I haz the power, 2013-09-06 06:33:35]

Change committed as 221607