How to provide additional flags only to the native cc compiler? - bazel

Question

In our project team we applications for micro-controller targets with arm-none-eabi-gcc. For running our testrunner we compile using the native cc compiler.
In our project team most use a Linux os, but some us a windows os (for reasons). The issue we run into is that we use the C11 keyword _Static_assert. When compiling on Linux it works, but when compiling under windows we get the following error: error LNK2019: unresolved external symbol _Static_assert referenced in function {}
This is due to the reason that the default MSVC compiler implements ANSI C89 which doesn't support the _Static_assert symbol. MSVC - C standards support
It also specifies that adding the /std:c11 or /std:c17 compiler options enable the support for _Static_assert.
We already have enabled --enable_platform_specific_config for other reasons.
Simply adding the build:windows --copt="/std:c11" to the .bazelrc solves the issue but also breaks the normal application build because arm-none-eabi-gcc compiler doesn't support the /std:c11 compiler flag.
Question: How can i add the /std:c11 compiler flag so that it only propagates to the native msvc compiler and not to the rest of my build targets?

Answer 1

When using MSVC for host builds (when building a tool that emits source code which is then #include'd, for example protocol buffer compiler) add build:windows --host_copt="/std:c11". When using MSVC for test builds, add test:windows --host_copt="/std:c11". Don't put it in build:windows --copt because that will apply even when running builds to the target.