prebuilt_cxx_library has no flavors

[njlr]

A prebuilt_cxx_library has no flavors (according to buck audit). Internally, however, there seem to be various flavors for headers. How can I "build" these flavor from the command-line so that I can inspect the header-files on disk?

$ buck build //:foo#default,headers

One possible work-around: create an empty cxx_library that depends on the prebuilt_cxx_library and build that. You will find the headers in the buck-out folder.