Forcing compile time error for "undefined symbol" in scons - c

Question

I am having a problem where I get this error: "undefined symbol: someVar" at runtime. I would like to get that error at link time.
I would like to force a link error similar to this issue:
Easy check for unresolved symbols in shared libraries?
I am using scons, so I am looking for an scons specific answer.
My scons rule looks like this:
def create_objs(SRCS):
return [env.Object(src) for src in SRCS]
object_mylib = ['mylib.c'
,'one.c'
,'two.c'
]
env.SharedLibrary('#/lib/mylib', create_objs(object_mylib))
I found this issue for adding linker flags in scons:
How do I add --whole-archive linker option in scons?
A) Is my best option to pattern a solution after those two issues to add the proper flag?
B) Is there a better way?
It seems that some doubt that I am getting this error at runtime, so I am adding this detail:
I get this error:
could not load /somepath/libmylib.so for /somepath/libmylib.so: undefined symbol: someVar
On this code:
char *libFile = "/somepath/libmylib.so";
Handle = dlopen(libFile, RTLD_LAZY);
if (!Handle)
{
printf("could not load %s for %s", libFile, dlerror());
}
during runtime.
My backup plan is to write a small program that does the dlopen and add that to the SConscript.

Answer 1

Here is the answer I (the OP) came up with:
Add
env.Append(LINKFLAGS=['-Wl,-z,defs'])
to SConstruct
Now this command runs:
gcc -o lib/libmylib.so -Wl,-z,defs -shared build/mylib.o build/one.o build/two.o
Which outputs this error:
build/one.o: In function `somefunc':
/home/.../src/one.c:34: undefined reference to `someVar'
This works for me. I will wait while before accepting this answer to see if anyone comes up with a better technique or improvements to this technique.