crt1.o: In function `_start': - undefined reference to `main' in Linux

Question

I am porting an application from Solaris to Linux

The object files which are linked do not have a main() defined. But compilation and linking is done properly in Sol

Answer 1

I had a similar result when compiling a Fortran program that had C++ components linked in. In my case, CMake failed to detect that Fortran should be used for the final linking. The messages returned by make then ended with

[100%] Linking CXX executable myprogram
/lib/../lib64/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
make[3]: *** [myprogram] Error 1
make[2]: *** [CMakeFiles/myprogram.dir/all] Error 2
make[1]: *** [CMakeFiles/myprogram.dir/rule] Error 2
make: *** [myprogram] Error 2

The solution was to add

set_target_properties(myprogram PROPERTIES LINKER_LANGUAGE Fortran) 

to the CMakeLists.txt, so that make prints out:

[100%] Linking Fortran executable myprogram
[100%] Built target myprogram