Recompile with -fPIC option, but the option is already in the makefile

Question

I get this error when I do the make:

relocation R_X86_64_32 against `vtable for Torch::MemoryDataSet' can not be used  when making a shared object; recompile with -fPIC 

It says that I should recompile with the -fPIC option. I did that, adding the -fPIC option to CFLAGS and CXXFLAGS, but I still get the same error. Is there any way to solve this? I have seen that this problem is related with the use of a 64-bit machine, and it is true that I am using one.

Answer 1

I had this problem quite a while back and if I remember correctly, the fix was moving the placement of -fPIC just after gcc in the command line. Made absolutely no sense, and less so now, but as I remember, that fixed it.

Answer 2

I encountered the same problem, but it had an extra twist. The answer by @clintm solved it, but I thought I would describe my variation of the problem here for future reference...

Makefile on 32-bit machine:

CXX=g++ CXXFLAGS= -O3 -Wall ... ...    %.o:  %.c     $(CXX)  $(CXXFLAGS)  -fpic  -c  $<        libmylibrary.so: $(OBJECTS)     $(CXX) -shared -Wl,-soname,$@ -o $@   $(OBJECTS) 

This compiled correctly. But the same Makefile failed when I tried it on a 64-bit machine. I changed "-fpic" to "-fPIC" and it still failed. I changed the object rule to:

%.o:  %.c     $(CXX)  -fPIC  $(CXXFLAGS)  -c  $<  

and it still failed.

Finally, I placed "-fPIC" in the actual compiler variable (so that now "-fPIC" appears in the rule for each object and the rule for the shared library):

CXX=g++  -fPIC CXXFLAGS= -g -O3 -Wall ... %.o:  %.c         $(CXX)    $(CXXFLAGS)   -c      -o $@    $<     libalglib.so: $(OBJECTS)         $(CXX) -shared -Wl,-soname,$@  -o $@      $(OBJECTS) 

And it worked!