Linking a static library to an interface library -> no such library when used outside

This issue was created automatically from an original Mantis Issue. Further discussion may take place here.

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First, there is no error with the following:

add_library(a INTERFACE)
add_library(b STATIC)
target_link_libraries(b PRIVATE a)
install(TARGETS b EXPORT foo)

which generates

    set_target_properties(b PROPERTIES INTERFACE_LINK_LIBRARIES "$<LINK_ONLY:a>")

in the targets file which causes users of b to not be able to find 'a'.

However, I would like for 'a' to just not show up at all in the export file (which I think makes sense for INTERFACE libraries linked to via PRIVATE).