What's the recommended way to use bazel with address/thread sanitizer?

[Ming Zhao]

I can use command line flags like this:
bazel build --copt -fsanitize=address --copt -O1

I guess I can potentially put these options into bazelrc, but what if
I need to dynamic switch compiler to clang when building with address
sanitizer? Is there recommended way to deal with that?

Thanks.

[Austin Schuh]

I've been putting it in the CROSSTOOL file.

  compilation_mode_flags {

    mode: DBG

    compiler_flag: '-fsanitize=address'

    linker_flag: '-fsanitize=address'

  }

is the stanza that I've been using.

Austin

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[Ming Zhao]

Thanks, that should work.

If we continue this approach, there are still two questions, how do we
allow the user to choose whether to enable address sanitizer or not? I
guess we can define the CROSSTOOL setting in another directory and use
--crosstool_top to select it, or since crosstool toolchain is selected
by the combination or cpu, compiler and glibc, we can probably give
the particular toolchain a special compiler name so that it can be
also chosen by using --compiler gcc_address_sanitizer, etc. It doesn't
seem to be perfect but it should work.

Then it comes to another problem, how to we manage toolchain settings
inside CROSSTOOL file. At the moment it seems like a lot copy pasting
is inevtiable because we can't inherit another toolchain stetting, so
that if I have a toolchain definition to use clang for normal build,
and I want to introduce another toolchain definition for address
sanitizer, I need to copy the most of clang normal build toolchain and
add a few settings just to turn on address sanitizer, which is
sub-optimimal.

[Ming Zhao]

Inspired by the link shared by Damien,
https://bazel-review.googlesource.com/#/c/1430/6/site/contributing.md

I think a better to do that is to define address/thread sanitzer
config in .bazel, for example:

build:asan --strip=never
build:asan --copt -fsanitize=address
build:asan --copt -O1
build:asan --copt -fno-omit-frame-pointer
build:asan --linkopt -fsanitize=address

Then I don't have to blow up the CROSSTOOL config with a lot of duplication.