I'm using 0.28.0-insiders3 and it doesn't work with ARMClang. I get incorrect code highlighting until I add some defines, which usually the compiler would provide. Also includes are handled wrongly, it still tries to resolve stdint.h from the c stdlib instead of from the ARMClang toolchain directory.

@aelray, could you create a new issue and provide your c_cpp_properties.json and the C/C++ language server logging when opening the project? The defines should have been queried from the compiler. Perhaps the extension failed to query the compiler so it could not get the defines and relative paths of the library header files.