Name of the default command to call the preprocessor. If the CPP environment variable is set, use it; else use the built-in default from autoconf. Usually this is "gcc -C -E -I."

whether the preprocessor command is the one defined at configure time or the result of taking a CPP environment variable, in case it differs

whether the default preprocessor accepts the same options as gcc (i.e. is either gcc or clang). When this is the case, the default command line for preprocessing contains more options.

true if the default preprocessor selected during compilation is able to keep comments (hence ACSL annotations) in its output.

architecture-related options (e.g. -m32) known to be supported by the default preprocessor. Used to match preprocessor commands to selected machdeps.