Make the output file have the same extension as the source file.
If this property is set then the file extension of the output file will be the same as that of the source file. Normally the output file extension is computed based on the language of the source file, for example .cxx will go to a .o extension.
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Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.19/prop_sf/KEEP_EXTENSION.html