This deals with the configure phase. It provides the configure action which is given the package description and configure flags. It then tries to: configure the compiler; resolves any conditionals in the package description; resolve the package dependencies; check if all the extensions used by this package are supported by the compiler; check that all the build tools are available (including version checks if appropriate); checks for any required pkg-config packages (updating the BuildInfo with the results)

Then based on all this it saves the info in the LocalBuildInfo and writes it out to the dist/setup-config file. It also displays various details to the user, the amount of information displayed depending on the verbosity level.