Handle differences in math headers compiling with Clang

[metcalf]

Problem

Attempting to compile for unit testing using Clang fails due to differences in the math headers with the errors below.

ERROR: /Users/andrew/code/arduino-particle-bazel-demo/particle/src/BUILD:3:17: Compiling src/particle-bazel-demo.cpp failed: (Aborted): wrapped_clang failed: error executing command external/local_config_cc/wrapped_clang '-D_FORTIFY_SOURCE=1' -fstack-protector -fcolor-diagnostics -Wall -Wthread-safety -Wself-assign -fno-omit-frame-pointer -O0 -DDEBUG '-std=c++11' ... (remaining 143 argument(s) skipped)

Use --sandbox_debug to see verbose messages from the sandbox
In file included from src/particle-bazel-demo.cpp:10:
In file included from bazel-out/darwin_arm64-fastbuild/bin/lib/_virtual_includes/Adafruit_GFX_RK/Adafruit_GFX.h:11:
In file included from bazel-out/darwin_arm64-fastbuild/bin/external/io_particle_device_os/_virtual_includes/user/WProgram.h:1:
bazel-out/darwin_arm64-fastbuild/bin/external/io_particle_device_os/_virtual_includes/user/Arduino.h:197:7: error: no member named 'isnan' in namespace 'std'; did you mean '::isnan'?
using std::isnan;
      ^~~~~~~~~~
      ::isnan
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk/usr/include/c++/v1/math.h:523:1: note: '::isnan' declared here
isnan(_A1 __lcpp_x) _NOEXCEPT
^
In file included from src/particle-bazel-demo.cpp:10:
In file included from bazel-out/darwin_arm64-fastbuild/bin/lib/_virtual_includes/Adafruit_GFX_RK/Adafruit_GFX.h:11:
In file included from bazel-out/darwin_arm64-fastbuild/bin/external/io_particle_device_os/_virtual_includes/user/WProgram.h:1:
bazel-out/darwin_arm64-fastbuild/bin/external/io_particle_device_os/_virtual_includes/user/Arduino.h:201:7: error: no member named 'isinf' in namespace 'std'; did you mean '::isinf'?
using std::isinf;
      ^~~~~~~~~~
      ::isinf
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk/usr/include/c++/v1/math.h:473:1: note: '::isinf' declared here
isinf(_A1 __lcpp_x) _NOEXCEPT
^
2 errors generated.

ERROR: /private/var/tmp/_bazel_andrew/a4c7ff0b81f89f303b386f9cf19fd00e/external/io_particle_device_os/BUILD.bazel:1:11: Compiling wiring/src/spark_wiring_usbserial.cpp failed: (Aborted): wrapped_clang failed: error executing command external/local_config_cc/wrapped_clang '-D_FORTIFY_SOURCE=1' -fstack-protector -fcolor-diagnostics -Wall -Wthread-safety -Wself-assign -fno-omit-frame-pointer -O0 -DDEBUG '-std=c++11' ... (remaining 131 argument(s) skipped)

Use --sandbox_debug to see verbose messages from the sandbox
external/io_particle_device_os/wiring/src/spark_wiring_usbserial.cpp:68:14: error: no member named 'max' in namespace 'std'
        return std::max(-1, (int)HAL_USB_USART_Receive_Data(_serial, false));
               ~~~~~^
external/io_particle_device_os/wiring/src/spark_wiring_usbserial.cpp:73:15: error: no member named 'max' in namespace 'std'
  return std::max(0, (int)HAL_USB_USART_Available_Data_For_Write(_serial));
         ~~~~~^
external/io_particle_device_os/wiring/src/spark_wiring_usbserial.cpp:78:14: error: no member named 'max' in namespace 'std'
        return std::max(0, (int)HAL_USB_USART_Available_Data(_serial));
               ~~~~~^
external/io_particle_device_os/wiring/src/spark_wiring_usbserial.cpp:84:17: error: no member named 'max' in namespace 'std'
    return std::max(0, (int)HAL_USB_USART_Send_Data(_serial, byte));
           ~~~~~^
external/io_particle_device_os/wiring/src/spark_wiring_usbserial.cpp:101:14: error: no member named 'max' in namespace 'std'
        return std::max(-1, (int)HAL_USB_USART_Receive_Data(_serial, true));
               ~~~~~^
5 errors generated.

Solution

Add clang-specific preprocessor directives to handle these cases. There appears to be precedent for clang-specific directives in this project:
https://github.com/particle-iot/device-os/search?q=__clang__

Steps to Test

I wrote a demo project to use Bazel and Google Test with Particle for unit testing. To make it compile successfully, I had to include the changes from this PR as a patch:
https://github.com/metcalf/arduino-particle-bazel-demo/blob/main/tools/io_particle_device_os.patch

Example App

N/A

References

Links to the Community, Docs, Other Issues, etc..

---

Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)

[avtolstoy]

This does not need to be __clang__-specific.

[metcalf]

Fixed

[avtolstoy]

I would suggest also not using targeting __clang__ specifically and instead include <cmath> if compiling as __cplusplus and math.h otherwise, which should resolve the problem.

[metcalf]

Fixed. Note that my fix still includes math.h in all cases since I think that's required for backwards compatibility with user code as described in the new comment. My C experience is limited so I'm prepared to be wrong about that!

I also chose to put the conditional include of <cmath> adjacent to the include of math.h since I think it's clearer even though it requires a separate #ifndef __cplusplus guard.

[avtolstoy]

This is now included twice.

[metcalf]

Gah, sorry, I caught this locally but forgot to push. Fixed now.