`root`

- Specifies root directory of the compiler installation. This option is necessary only if it's not possible to detect this information from the compiler command—for example if the specified compiler command is a user script.

`cflags`

- Specifies additional compiler flags that will be used when compiling C sources.

`cxxflags`

- Specifies additional compiler flags that will be used when compiling C++ sources.

`compileflags`

- Specifies additional compiler flags that will be used when compiling both C and C++ sources.

`linkflags`

- Specifies additional command line options that will be passed to the linker.