modifying radio.c does not take effect ?!

Hi, so i wanted to make some small modifications on the radio.c file but after i do when I build / make project it does not take effect. In fact I put some bad syntax errors in that file and the compiler doesn't even see it or complain. How can I make these changes take effect when building the firmware ?!

Start with the project’s make/build entry point and trace whether radio.c is included in the firmware target. Confirm that changes to radio.c, including an intentional syntax error, reach the compiler during a clean build; done means the modified source affects the resulting firmware.

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