foo.c: In function 'main':
foo.c:7:9: warning: implicit declaration of function 'print_f'; did you mean 'printf'? [-Wimplicit-function-declaration]
    7 |         print_f("c=%d\n",c=a+b);
      |         ^~~~~~~
      |         printf
/nix/store/jfkmqz20q8fsaqizcml86adxqyzlwllx-binutils-2.38/bin/ld: /tmp/cc0Xrd9r.o: in function `main':
foo.c:(.text.startup+0x2a): undefined reference to `print_f'
/nix/store/jfkmqz20q8fsaqizcml86adxqyzlwllx-binutils-2.38/bin/ld: foo.c:(.text.startup+0x3f): undefined reference to `print_f'
/nix/store/jfkmqz20q8fsaqizcml86adxqyzlwllx-binutils-2.38/bin/ld: foo.c:(.text.startup+0x56): undefined reference to `print_f'
collect2: error: ld returned 1 exit status

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