Only use /Gw in non-ASan builds on Windows

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index d1492320f727797ac8f4fb5c39ea091aba0eacf6..97ccb481f552370949315d597590615d426c8b4e 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -3372,11 +3372,14 @@
                 # "/Oy /Oy-" and warnings about overriding.
                 'AdditionalOptions': ['/Oy-'],
               }],
+              ['asan==0', {
+                # Put data in separate COMDATs, unless ASan is enabled.

[Nico, 2014/12/29 19:50:20]

nit: The "unless ASan is enabled" only repeats the conditional instead of saying
_why_ this is done. Maybe "Put data in separate COMDATs. This allows the linker
to put bit-identical constants at the same address even if they're unrelated
constants, which saves binary size – but it's incompatible with ASan which
tracks metadata for every address and assumes that every address belongs to only
one object" (there's probably a more concise phrasing of that)?

[Timur Iskhodzhanov, 2014/12/29 20:07:29]

Done (we came up with an even better version offline)

+                'AdditionalOptions': ['/Gw'],
+              }],
             ],
             'AdditionalOptions': [
                 '/d2Zi+',  # Improve debugging of Release builds.
                 '/Zc:inline',  # Remove unreferenced COMDAT (faster links).
-                '/Gw',  # Put data in separate COMDATs.
                 '<@(win_release_extra_cflags)',
             ],
           },