EXTERNAL_OBJECT

If set to true then this is an object file.

If this property is set to true then the source file is really an object file and should not be compiled. It will still be linked into the target though.

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© 2000–2011 Insight Software Consortium
Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.5/prop_sf/EXTERNAL_OBJECT.html