Unkown warning option '-Wunused-but-set-parameter' when using clang

[RenatoUtsch]

All my C++ projects started throwing the following two warning lines after I updated Bazel to the latest version:

warning: unknown warning option '-Wunused-but-set-parameter'; did you mean '-Wunused-parameter'? [-Wunknown-warning-option]
warning: unknown warning option '-Wno-free-nonheap-object'; did you mean '-Wno-sequence-point'? [-Wunknown-warning-option]

These warnings are extremely irritating, because they appear for all source files and clutter the terminal. Even more, as I use -Werror, these warnings break my build.

This happens with every C++ library/binary I try to build. For example, upon inspecting the build commands of one of these libraries with the -s option, you can see that Bazel adds these two warning options when it shouldn't:

>>>>> # //herakles/vulkan:utils [action 'Compiling herakles/vulkan/utils.cpp']                           
(cd /home/renato/.cache/bazel/_bazel_renato/a009e38a5efb52dabc3a2546ba473f66/execroot/com_github_renatoutsch_herakles && \
  exec env - \            
    PATH=/usr/local/bin:/usr/local/bin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/home/renato/go/bin:/home/renato/.npm-global/bin:/home/renato/go/bin:/home/renato/.npm-global/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/home/renato/go/bin:/home/renato/.npm-global/bin \
    PWD=/proc/self/cwd \  
  /usr/bin/clang -U_FORTIFY_SOURCE -fstack-protector -Wall -B/usr/bin -B/usr/bin -Wunused-but-set-parameter -Wno-free-nonheap-object -fcolor-diagnostics -fno-omit-frame-pointer '-std=c++0x' -MD -MF bazel-out/local-fastbuild/bin/herakles/vulkan/_objs/utils/herakles/vulkan/utils.pic.d '-frandom-seed=bazel-out/local-fastbuild/bin/herakles/vulkan/_objs/utils/herakles/vulkan/utils.pic.o' -fPIC -iquote . -iquote bazel-out/local-fastbuild/genfiles -iquote external/glog -iquote bazel-out/local-fastbuild/genfiles/external/glog -iquote external/bazel_tools -iquote bazel-out/local-fastbuild/genfiles/external/bazel_tools -isystem external/glog -isystem bazel-out/local-fastbuild/genfiles/external/glog -isystem external/bazel_tools/tools/cpp/gcc3 -Wno-builtin-macro-redefined '-D__DATE__="redacted"' '-D__TIMESTAMP__="redacted"' '-D__TIME__="redacted"' -c herakles/vulkan/utils.cpp -o bazel-out/local-fastbuild/bin/herakles/vulkan/_objs/utils/herakles/vulkan/utils.pic.o)
INFO: From Compiling herakles/vulkan/utils.cpp:     
warning: unknown warning option '-Wunused-but-set-parameter'; did you mean '-Wunused-parameter'? [-Wunknown-warning-option]
warning: unknown warning option '-Wno-free-nonheap-object'; did you mean '-Wno-sequence-point'? [-Wunknown-warning-option]
2 warnings generated.

Just to be clear, I am not adding these two flags to the command line.

I'm using clang in ArchLinux, with bazel release 0.5.3.- (@non-git). I installed Bazel using pacman, so I don't know why it shows (@non-git).

It seems some people on Tensorflow are also having the same problem:
tensorflow/tensorflow#12123

[RenatoUtsch]

Upon digging some more, this in fact does not seem to be related to Bazel's version. I discovered what is triggering these warnings.

It seems that these warnings appear if the CC environment variable is set to clang. If I change the CC environment variable to gcc, the warnings disappear.

Also, while changing the CC environment variable seems to reproduce this bug on Linux, I can't reproduce it on Mac OS.

[luchensk]

Thanks @RenatoUtsch .

As you said, it is not working by changing the CC environment to gcc on MAC OS, and these are some env info on my MAC, as below:

$ sw_vers
ProductName: Mac OS X
ProductVersion: 10.12.4
BuildVersion: 16E195

$ gcc --version
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 8.1.0 (clang-802.0.42)
Target: x86_64-apple-darwin16.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

$ clang -v
Apple LLVM version 8.1.0 (clang-802.0.42)
Target: x86_64-apple-darwin16.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

$ bazel version
Build label: 0.5.3-homebrew
Build target: bazel-out/darwin_x86_64-opt/bin/src/main/java/com/google/devtools/build/lib/bazel/BazelServer_deploy.jar
Build time: Thu Jul 27 19:30:37 2017 (1501183837)
Build timestamp: 1501183837
Build timestamp as int: 1501183837

[gunan]

I don't think we do any autoconf with cc. We just check operating system and set flags.
@damienmg to confirm if we have a mechanism to pick compilers in an OS.

[luchensk]

Thanks @gunan . For the detail of the error on TF, I post here just in case you need it:

ERROR: /private/var/tmp/_bazel_sunkai/f32adcfaaeaeed39ed3812ab214ba306/external/boringssl/BUILD:131:1: C++ compilation of rule '@boringssl//:ssl' failed (Exit 1): cc_wrapper.sh failed: error executing command (exec env - \ PATH=/Users/sunkai/work/workspace/project/tf-env/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/mysql/bin:/Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home:/Users/sunkai/ali-dev-env/apache-maven-3.5.0/bin \ PWD=/proc/self/cwd \ PYTHON_BIN_PATH=/Users/sunkai/work/workspace/project/tf-env/bin/python \ PYTHON_LIB_PATH=/Users/sunkai/work/workspace/project/tf-env/lib/python2.7/site-packages \ TF_NEED_CUDA=0 \ TF_NEED_OPENCL=0 \ TMPDIR=/var/folders/sn/j9d72mw55fv9wqd3sn55sn8c0000gn/T/ \ external/local_config_cc/cc_wrapper.sh -U_FORTIFY_SOURCE -fstack-protector -Wall -Wthread-safety -Wself-assign -Wunused-but-set-parameter -Wno-free-nonheap-object -fcolor-diagnostics -fno-omit-frame-pointer -g0 -O2 '-D_FORTIFY_SOURCE=1' -DNDEBUG -ffunction-sections -fdata-sections '-march=native' -MD -MF bazel-out/local-opt/bin/external/boringssl/_objs/ssl/external/boringssl/src/ssl/s3_pkt.pic.d -fPIC -iquote external/boringssl -iquote bazel-out/local-opt/genfiles/external/boringssl -iquote external/bazel_tools -iquote bazel-out/local-opt/genfiles/external/bazel_tools -isystem external/boringssl/src/include -isystem bazel-out/local-opt/genfiles/external/boringssl/src/include -isystem external/bazel_tools/tools/cpp/gcc3 -Wa,--noexecstack '-D_XOPEN_SOURCE=700' -Wall -Werror '-Wformat=2' -Wsign-compare -Wmissing-field-initializers -Wwrite-strings -Wshadow -fno-common '-std=c11' -Wmissing-prototypes -Wold-style-definition -Wstrict-prototypes -Wno-builtin-macro-redefined '-D__DATE__="redacted"' '-D__TIMESTAMP__="redacted"' '-D__TIME__="redacted"' -c external/boringssl/src/ssl/s3_pkt.c -o bazel-out/local-opt/bin/external/boringssl/_objs/ssl/external/boringssl/src/ssl/s3_pkt.pic.o). error: unknown warning option '-Wunused-but-set-parameter'; did you mean '-Wunused-parameter'? [-Werror,-Wunknown-warning-option] error: unknown warning option '-Wno-free-nonheap-object'; did you mean '-Wno-sequence-point'? [-Werror,-Wunknown-warning-option] Target //tensorflow/tools/pip_package:build_pip_package failed to build

[luchensk]

For the error on TF, refer to tensorflow/tensorflow#12123 and it works now, thanks.

[damienmg]

/cc @mhlopko

We do auto config in Bazel itself.

[RenatoUtsch]

cc_autoconf sets these two offending flags conditionally depending on if the compiler supports them. My guess is that it is doing it wrongly on linux, but I couldn't figure out why. I'll update to 0.5.4 later and see if this still persists.

…

On Mon, Aug 28, 2017, 06:05 Damien Martin-Guillerez < ***@***.***> wrote: /cc @mhlopko <https://github.com/mhlopko> We do auto config in Bazel itself. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#3622 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAzC7as27qjg0c9yLkiWCCo6o_aov5G3ks5scoLVgaJpZM4PC6Y_> .

[hlopko]

We do have an ability to specify/detect which compiler should be used by bazel. It all happens in
https://github.com/bazelbuild/bazel/blob/master/tools/cpp/cc_configure.bzl.

This is where we check for flags in question:
https://github.com/bazelbuild/bazel/blob/master/tools/cpp/unix_cc_configure.bzl#L229

So it's running something like:

clang -Wunused-but-set-parameter -o /dev/null -c empty.cc

and searching for -Wunused-but-set-parameter in stderr. Any idea what is wrong there? My clang returns:

warning: unknown warning option '-Wunused-but-set-parameter'; did you mean '-Wunused-parameter'? [-Wunknown-warning-option]
1 warning generated.

@RenatoUtsch do I understand correctly that this was working correctly with older bazel? Or with the upgrade you also changed the value of CC env var?

@luchensk CC fix doesn't work for you because your gcc is actually clang.

[luchensk]

@mhlopko got it, thanks:), let's wait for the result from @RenatoUtsch with update to 0.5.4.

[pcj]

This is also breaks rules_protobuf with bazel 0.5.3 on darwin due to boringssl compilation failure.

pcj:~/github/rules_protobuf*master$ bazel build @boringssl//:ssl 
INFO: Found 1 target...
ERROR: /private/var/tmp/_bazel_pcj/63330772b4917b139280caef8bb81867/external/boringssl/BUILD:92:1: C++ compilation of rule '@boringssl//:crypto' failed (Exit 1).
error: unknown warning option '-Wunused-but-set-parameter'; did you mean '-Wunused-parameter'? [-Werror,-Wunknown-warning-option]
error: unknown warning option '-Wno-free-nonheap-object'; did you mean '-Wno-sequence-point'? [-Werror,-Wunknown-warning-option]
Target @boringssl//:ssl failed to build
Use --verbose_failures to see the command lines of failed build steps.
INFO: Elapsed time: 26.306s, Critical Path: 0.18s

pcj:~/github/rules_protobuf*master$ bazel version
Build label: 0.5.3
Build target: bazel-out/darwin_x86_64-fastbuild/bin/src/main/java/com/google/devtools/build/lib/bazel/BazelServer_deploy.jar
Build time: Fri Jul 28 08:34:35 2017 (1501230875)
Build timestamp: 1501230875
Build timestamp as int: 1501230875

Issue is resolved on 0.5.4:

pcj:~/github/rules_protobuf*master$ bazel build @boringssl//:ssl
INFO: Found 1 target...
Target @boringssl//:ssl up-to-date:
  bazel-bin/external/boringssl/libssl.a
  bazel-bin/external/boringssl/libssl.so
INFO: Elapsed time: 40.195s, Critical Path: 1.59s

pcj:~/github/rules_protobuf*master$ bazel version
Build label: 0.5.4
Build target: bazel-out/darwin_x86_64-fastbuild/bin/src/main/java/com/google/devtools/build/lib/bazel/BazelServer_deploy.jar
Build time: Fri Aug 25 09:57:39 2017 (1503655059)
Build timestamp: 1503655059
Build timestamp as int: 1503655059

[RenatoUtsch]

I updated to 0.5.4 and the issue is resolved. This was an issue on 0.5.3 only.

I'll close the issue as it was resolved already.

[hlopko]

Hi @pcj, can you also verify it works with 0.5.4 please?

[RenatoUtsch]

He edited his last comment to say that it was resolved with 0.5.4.

[hlopko]

Oh I haven't noticed. Thanks. So this really is resolved. Thanks everybody!