This option enables you to change the filename extension for object files from the default extension (.o) to an extension of your choice.
The following example creates an object file called test.obj, instead of test.o:
armcc ‑‑default_extension=obj ‑c test.c
Note
The ‑o filename option overrides this. For example, the following command results in an object file named test.o:
armcc ‑‑default_extension=obj ‑o test.o ‑c test.c