Safe numeric library: base/numerics (copied from Chromium)

webrtc/base/numerics/BUILD.gn

Index: webrtc/base/numerics/BUILD.gn
diff --git a/BUILD.gn b/webrtc/base/numerics/BUILD.gn
similarity index 54%
copy from BUILD.gn
copy to webrtc/base/numerics/BUILD.gn
index b7f7a0619a9a73591c070aee611224ec6a544f79..d3edd1f91e68fb0dda2242db242c440d004728b3 100644
--- a/BUILD.gn
+++ b/webrtc/base/numerics/BUILD.gn
@@ -1,4 +1,4 @@
-# Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
+# Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
@@ -6,9 +6,12 @@
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
-# This file is copied and modified from Chromium (src/BUILD.gn).
-group("root") {
-  deps = [
-    "//webrtc",
+# GYP version: webrtc/base/numerics/safe_numerics.gyp:safe_numerics
+source_set("safe_numerics") {
+  sources = [
+    "safe_conversions.h",
+    "safe_conversions_impl.h",
+    "safe_math.h",
+    "safe_math_impl.h",
   ]

[hbos, 2016/03/02 15:46:51]

Is this correct (and similar in GYP as a static_library)?

What I'm wondering about is this uses some of the stuff from base
(checks.h/logging.h), so there is a dependency on base. It compiles as a part of
base (is a dependency of it) though so this works fine.
However as a stand-alone target we would have to add a dependency on base, which
would result in a circular dependency base -> safe_numerics -> base.

If this is wrong and a dep on base is needed but not allowed due to circularity,
then I suggest we create a .gypi variable for the sources and reference it from
the base target as to not have to work on breaking this free from base (not have
a stand-alone build target), at least not in this CL.

(Or perhaps I mean base_approved when I say base, same concern...)

[tommi, 2016/03/02 16:13:53]

Can we make this depend on base and base not depend on this?

[kjellander_webrtc, 2016/03/02 18:40:05]

Please don't add a new BUILD.gn file, add a new target in webrtc/base/BUILD.gn
instead.
We talked about removing the base/logging.h dependency from the source, right? 
Changing it to webrtc/base/logging.h would also work as long as you don't plan
to introduce a dependency from the other base source to base/numerics - or is
that something you plan to do?

[kwiberg-webrtc, 2016/03/02 20:14:12]

Specifically, can we have base depend on numerics which in turn depends on
base_approved?

[kjellander_webrtc, 2016/03/03 10:25:20]

I guess that would work since it's not a cycle.

[hbos, 2016/03/03 14:17:06]

I changed it to webrtc/base/logging.h but it turns out its not event used.

[hbos, 2016/03/03 14:17:06]

Oh, nice. Yes that works. Now we have rtc_base -> safe_numerics ->
rtc_base_approved (and I verified that this compiles and can link into an
executable).

 }