how to set CC, CFLAGS, CXXFLAGS in bazel

[Ghilas BELHADJ]

I'd like to use obfuscator-llvm with bazel.

So, I have to set a special clang, and some flags to get this works.

$ CC=path_to_the/build/bin/clang
$ CFLAGS+="-mllvm -fla" or CXXFLAGS+="-mllvm -fla" (or any other obfuscation-related flags)
$ ./configure
$ make

how can I do that in bazel ?

[Damien Martin-guillerez]

CC is set the same way. We do not parse CFLAGS or CXXFLAGS currently but I think this is an acceptable contribution. See https://github.com/bazelbuild/bazel/blob/master/tools/cpp/cc_configure.bzl for the file that does it.

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[Ghilas BELHADJ]

@Damien Thank you for your answer.

For CFLAGS and CXXFLAGS I can set them with --copt and --cxxopt ?

[Damien Martin-guillerez]

Just --copt yes.

I don't think we separate C++ and C unfortunately.

On Mon, Dec 12, 2016 at 11:51 AM Ghilas BELHADJ <ghilas...@gmail.com> wrote:

@Damien Thank you for your answer.

For CFLAGS and CXXFLAGS I can set them with --copt and --cxxopt ?

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[Ghilas BELHADJ]

I have set CC the same way. and put the flags CFLAGS and CXXFLAGS like this in the bazel build command

'--cxxopt=-mllvm -fla','--copt=-mllvm -fla',

And I got this error

 arm-linux-androideabi-gcc: error: unrecognized command line option '-mllvm -fla'

[Damien Martin-guillerez]

+Alex Humesky Why does --copt propagate to Android NDK?

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[Ghilas BELHADJ]

Maybe I'm doing it wrong.

Here is the list of complete options I'm using to build if it can help.

bazel build -c opt
  --cxxopt=-mllvm -fla
  --copt=-mllvm -fla
  //:libfoo.so
  --crosstool_top=//external:android/crosstool
  --cpu=armeabi-v7a
  --host_crosstool_top=@bazel_tools//tools/cpp:toolchain
  --verbose_failures
  --genrule_strategy=standalone
  --spawn_strategy=standalone

[Damien Martin-guillerez]

Oh you need to use --host_copt instead --copt because you want it to apply to the host C++ toolchain, not the target one

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[Ghilas BELHADJ]

The error has changed, now it's:

clang: error: unknown argument: '-mllvm -fla'

I think bazel il always using the default clang.

[Damien Martin-guillerez]

Can you try --host_copt="-mllvm -fla" and --host_copt=-mllvm --host_copt=-fla? I don't rememebr the exact syntax. Also add --verbose_failures for more help.

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[Ghilas BELHADJ]

With

--host_copt=-mllvm --host_copt=-fla --verbose_failures

I have this error:

clang (LLVM option parsing): Unknown command line argument '-fla'.  Try: 'clang (LLVM option parsing) -help'
clang (LLVM option parsing): Did you mean '-help'?

With:

--host_copt="-mllvm -fla" --verbose_failures

I have this one

[Ghilas BELHADJ]

setting a wrong clang path does not affect bazel build.

CC=wrong_path_to_the/build/bin/clang

I think the CC variable is not parsed in bazel.

Maybe I should create a custom toolchain to do this ?

[Ghilas BELHADJ]

It works when I run 

bazel clean

But now standard libraries are not recognised.

external/protobuf/src/google/protobuf/stubs/common.h:38:10: fatal error: 'string' file not found
#include <string>
         ^
1 error generated.

[Ghilas BELHADJ]

I've added -s parameter to bazel build. and now I can see that some paths are not included when I set CC to a new clang.

with original clang

-isystem external/protobuf/src
-isystem bazel-out/arm-linux-androideabi-4.9-v7a-gnu-libstdcpp-opt/genfiles/external/protobuf/src
-isystem external/bazel_tools/tools/cpp/gcc3
-isystem external/eigen_archive
-isystem bazel-out/arm-linux-androideabi-4.9-v7a-gnu-libstdcpp-opt/genfiles/external/eigen_archive
-isystem external/androidndk/ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/include

-isystem external/androidndk/ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/include-fixed
-isystem external/androidndk/ndk/sources/cxx-stl/gnu-libstdc++/4.9/include
-isystem external/androidndk/ndk/sources/cxx-stl/gnu-libstdc++/4.9/libs/armeabi-v7a/include
-isystem external/androidndk/ndk/sources/cxx-stl/gnu-libstdc++/4.9/include/backward

with new clang

-isystem external/protobuf/src
-isystem bazel-out/host/genfiles/external/protobuf/src
-isystem external/bazel_tools/tools/cpp/gcc3

any help  to fix that ?