Thank you for filing this bug Manoj. 

To reiterate the idea discussed in the meeting: is it would be possible to build an entire fuzzer build with a special "compiler" that is really a wrapper around clang? The purpose of the wrapper is to pass the sanitizer flags we want to the actual clang.

This approach is similar to afl-gcc (https://github.com/mcarpenter/afl/blob/master/afl-gcc.c) which is probably the most popular method for building targets for coverage guided fuzzing.

or just add them to our existing CFLAGS/CXXFLAGS variables in the profile.  no need for yet another wrapper.

Yes, see https://chromium-review.googlesource.com/c/chromiumos/overlays/board-overlays/+/1050914

It is also going to break the unit tests. Probably lets disable them for now in builder and see if they can be selectively enabled later on.

+1 I don't think the unittests is an issue. We don't do this in chrome.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/bec012932b078920fdb16d2288ed9859f57bd4f4

commit bec012932b078920fdb16d2288ed9859f57bd4f4
Author: Manoj Gupta <manojgupta@google.com>
Date: Thu May 10 22:09:55 2018

profile.bashrc: Add helper function to filter sanitizers.

Some packages can't or shouldn't be built with sanitizer flags.
Add a helper function filter_sanitizers that can be called in
ebuilds to filter sanitizer flags.

BUG= chromium:840995 
TEST="-fsanitize=*" flags were filtered out by calling this in ebuild.

Change-Id: I2dc8c140e5b3ff1f25b4581aea604287aca8fe6d
Reviewed-on: https://chromium-review.googlesource.com/1052678
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Caroline Tice <cmtice@chromium.org>
Reviewed-by: Jonathan Metzman <metzman@chromium.org>

[modify] https://crrev.com/bec012932b078920fdb16d2288ed9859f57bd4f4/profiles/base/profile.bashrc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/board-overlays/+/c44090385694e44c6041f5397986ec2187f7329c

commit c44090385694e44c6041f5397986ec2187f7329c
Author: Manoj Gupta <manojgupta@google.com>
Date: Wed May 16 19:42:39 2018

fuzzing: Add sanitizer flags to {C,CXX,LD}FLAGS.

Add sanitizer flags to make.defaults.
This will force all packages to be built with libfuzzer + address
sanitizer.

BUG= chromium:840995 
TEST=Can succesfully run a fuzzer with the sysroot uploaded by tryjob.

Change-Id: I0733ddc51c2d2a513b67a0c21d1d728c5b6b2712
Reviewed-on: https://chromium-review.googlesource.com/1050914
Commit-Ready: Manoj Gupta <manojgupta@chromium.org>
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>

[modify] https://crrev.com/c44090385694e44c6041f5397986ec2187f7329c/overlay-amd64-generic/profiles/fuzzer/make.defaults