foo.c: In function 'main':
foo.c:52:16: warning: implicit declaration of function 'Mul'; did you mean 'Mul1'? [-Wimplicit-function-declaration]
   52 |         len3 = Mul(d1, len1, d2, len2, d3);
      |                ^~~
      |                Mul1
/nix/store/74y3751gsixaz9797ib0hp7c658sp1y5-binutils-2.40/bin/ld: /tmp/ccAHSWC8.o: in function `main':
foo.c:(.text.startup+0x1ed): undefined reference to `Mul'
collect2: error: ld returned 1 exit status

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