generate .o files from compiler instead of .obj files

Usage
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#1

I am working in an embedded project.
target : ppc
compiler : windriver
Host environment : windows 10
build generator : cmake, MinGW makefiles

during compilation i see .c.obj getting generated.
I want .o instead of .c.obj.
from cmake side can we do this or it is compiler specific ?

#2

The extension is compiler-specific. Why does the extension matter in this case?

And the .c is always going to be there under CMake (some projects have foo.c and foo.cxx and CMake’s strategy avoids this conflict unconditionally).