T10279.hs:10:9: error:
    • Failed to load interface for ‘A’
      no unit id matching ‘rts-1.0’ was found
      (This unit ID looks like the source package ID;
       the real unit ID is ‘rts’)
    • In the expression: rts-1.0:A.Foo
      In an equation for ‘blah’: blah = (rts-1.0:A.Foo)