I have a program and a static library:
// main.cpp
int main() {}
// mylib.cpp
#include <iostream>
struct S {
S() { std::cout << "Hello World\n";}
};
S s;
I want to link the static library (libmylib.a
) to the program object (main.o
), although the latter does not use any symbol of the former directly.
The following commands do not seem to the job with g++ 4.7
. They will run without any errors or warnings, but apparently libmylib.a
will not be linked:
g++ -o program main.o -Wl,--no-as-needed /path/to/libmylib.a
or
g++ -o program main.o -L/path/to/ -Wl,--no-as-needed -lmylib
Do you have any better ideas?
Use --whole-archive
linker option.
Libraries that come after it in the command line will not have unreferenced symbols discarded. You can resume normal linking behaviour by adding --no-whole-archive
after these libraries.
In your example, the command will be:
g++ -o program main.o -Wl,--whole-archive /path/to/libmylib.a
In general, it will be:
g++ -o program main.o \
-Wl,--whole-archive -lmylib \
-Wl,--no-whole-archive -llib1 -llib2