^CMake Error at ConfigCase.cmake:[0-9]+ \(add_library\):
  Target "impl" links to target "config::impl-Debug" but the target was not
  found.  Perhaps a find_package\(\) call is missing for an IMPORTED target, or
  an ALIAS target is missing\?
Call Stack \(most recent call first\):
  CMakeLists.txt:[0-9]+ \(include\)
+
CMake Error at ConfigCase.cmake:[0-9]+ \(add_library\):
  Target "impl" links to target "config::iface-Debug" but the target was not
  found.  Perhaps a find_package\(\) call is missing for an IMPORTED target, or
  an ALIAS target is missing\?
Call Stack \(most recent call first\):
  CMakeLists.txt:[0-9]+ \(include\)