is there a GCC compiler/linker option to change the name of main? [duplicate]

Answer 1

I had the same problem today: m1.c and m2.c both had a main function but needed to be linked and run one of them. Solution: user STRIP to remove the main symbol from one of them after compilation but before linking:

gcc -c m1.c m2.c;  strip --strip-symbol main m1.o; gcc m1.o m2.o; ./a.out

will run main from m2

gcc -c m1.c m2.c;  strip --strip-symbol main m2.o; gcc m1.o m2.o; ./a.out

will run main from m1

Without strip:

gcc - m1.c m2.c
m2.o: In function `main':
m2.c:(.text+0x0): multiple definition of `main'
m1.o:m1.c:(.text+0x0): first defined here
collect2: ld returned 1 exit status

Answer 2

Put them in separate files, and specify one .c file for normal use, and one .c file for testing.

Alternately, #define testing on the commandline using test builds and use something like:

int main(int argc, char *argv[])
{
#ifdef TESTING
    return TestMain(argc, argv);
#else
    return NormalMain(argc, argv);
#endif
}

int TestMain(int argc, char *argv[])
{
    // Do testing in here
}

int NormalMain(int argc, char *argv[])
{
    //Do normal stuff in here
}

Answer 3

#ifdef TESTING

int main()

{

/* testing code here */

}

#else

int main()

{

/* normal code here */

}

#endif

$ gcc -DTESTING=1 -o a.out filename.c #building for testing

$ gcc -UTESTING -o a.out filename.c #building for normal purposes

man gcc showed me the -D and -U

Answer 4

First of all, you can't have two functions named main in one compilation, so either the sources are in different files or you're using conditional compilation. Either way you've got to get two different .o files out. Therefore, you don't need a linker option; you just pass the .o file that you want in as an argument.

If you don't like that, you can do fancy things with dlopen() to pull main from any object file you name dynamically. I can imagine circumstances where this might be useful—say, you take a systematic approach to unit tests, just put them all in a directory, and your code walks the directory, grabbing each object file, dynamically loading it, and running its tests. But to get started, something simpler is probably indicated.

Answer 5

You may have to run ld separately to use them, but ld supports scripts to define many aspects of the output file (including the entry point).