I am trying to compile a code that is written in Fortran and then linked through the C compiler. The problem comes when I try the Intel compilers, ifort + icc. If I do the same with GNU compilers, gfortran + gcc, it works.
Bellow we can see their outputs.
ICC, not working:
ifort -c -o fonts/pgpack.o -g -fno-automatic -fPIC fonts/pgpack.f ifort: command line warning #10006: ignoring unknown option '-fno-automatic'
icc -o pgpack fonts/pgpack.o -O2 -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/../compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/mkl/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/tbb/lib/intel64/gcc4.4 -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/ -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/ -L/lib/../lib64 -L/lib/../lib64/ -L/usr/lib/../lib64 -L/usr/lib/../lib64/ -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64/ -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/../compiler/lib/intel64/ -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/lib/intel64/ -L/opt/intel/composer_xe_2013_sp1.0.080/mkl/lib/intel64/ -L/opt/intel/composer_xe_2013_sp1.0.080/tbb/lib/intel64/gcc4.4/ -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../ -L/lib64 -L/lib/ -L/usr/lib64 -L/usr/lib -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/../compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/mkl/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/tbb/lib/intel64/gcc4.4 -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/ -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/ -L/lib/../lib64 -L/lib/../lib64/ -L/usr/lib/../lib64 -L/usr/lib/../lib64/ -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64/ -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/../compiler/lib/intel64/ -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/lib/intel64/ -L/opt/intel/composer_xe_2013_sp1.0.080/mkl/lib/intel64/ -L/opt/intel/composer_xe_2013_sp1.0.080/tbb/lib/intel64/gcc4.4/ -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../ -L/lib64 -L/lib/ -L/usr/lib64 -L/usr/lib -lifport -lifcore -limf -lsvml -lm -lipgo -lirc -lpthread -lsvml -lc -lgcc -lgcc_s -lirc_s -ldl -lc
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crt1.o: In function '_start':
(.text+0x20): undefined reference to `main'
Note: it is strange to me that icc is linking against gcc libraries (/usr/lib/gcc/...). Is this normal/right?
GCC, working:
gfortran -c -o fonts/pgpack.o -O2 -Wall -fno-second-underscore -g -fno-automatic -fPIC fonts/pgpack.f
Warning: Nonconforming tab character in column 6 of line 15
Warning: Nonconforming tab character in column 6 of line 16
Warning: Nonconforming tab character in column 6 of line 17
Warning: Nonconforming tab character in column 2 of line 19
Warning: Nonconforming tab character in column 2 of line 20
Warning: Nonconforming tab character in column 2 of line 21
Warning: Nonconforming tab character in column 2 of line 24
Warning: Nonconforming tab character in column 2 of line 25
gcc -o pgpack fonts/pgpack.o -O2 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/../compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/mkl/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/tbb/lib/intel64/gcc4.4 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../.. -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/../compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/ipp/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/compiler/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/mkl/lib/intel64 -L/opt/intel/composer_xe_2013_sp1.0.080/tbb/lib/intel64/gcc4.4 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../.. -lgfortranbegin -lgfortran -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc
: pgpack
I notice that some libraries being linked changed (e.g, libgfortranbegin), but that is automatically added/changed by the make system.
I already tried solutions offered by other posts, for similar errors, like use the flag (ifort)-nofor-main and (icc)-nostartfiles, but it keeps failing.
What am I missing? Thanks.
In the icc case, none of the modules you are linking provides a function main() to be the entry point of the program. That gcc nevertheless links the program successfully is probably due in part to the inclusion of -lgfortranbegin in the link. That will provide a standard (for gfortran) main() function that sets up the Fortran environment before handing off control to a differently-named routine corresponding to the PROGRAM subunit defined in pgpack.f.
It is likely possible to link an ifort-compiled object file into a complete program via icc, but apparently you need an ifort-specific starting point routine, and none of the libraries you specified provides one. In any event, it is likely wrong that you are including GCC libraries in the icc link. I presume that your build system is identifying and including those, but it is incorrect in doing so.
In any event, it is surpassingly strange that you are linking with gcc / icc when you have only a single object file derived from a Fortran source. You should be linking with the Fortran linker driver, which in both cases is the same as the Fortran compiler driver (gfortran / ifort). In that case you probably do not need any of the -L or -l options you are currently specifying.
Even if you were linking in some C routines, too, generally you should use the linker driver for the language in which the main routine is written. There are caveats, and it gets more complicated if you roll some other languages into the mix (e.g. C++), but your particular case looks very simple.