如何强制gcc链接静态库？

Question

I write a static library: libA.a. I have another application called BoBo doesn't used any functions in libA.a. I want to combine libA.o into Bo, then I could call some stuff in libA.a by other methods, when Bo is running.

I write makefile like this: gcc Bc -o Bo -lA -u symbol_A . Here -u is from GCC manual:

http://gcc.gnu.org/onlinedocs/gcc/Link-Options.html

It suggests use -u to force linking unused library, and symbol_A is some symbol in libA.a

But it doesn't work. After linking, I can not find any LibA.a's stuff in Bo

May anyone give me some hint?

ps I am using GCC 3.4.4, eclipse+CDT under windows, and Bo will be deployed under linux.

Answer 1

The explanation of the -u flag from GCC means the following:

If you have a symbol aka variable or function that is defined in your source tell GCC to pretend that it is undefined so it takes the definition of such variable or function from the library you are linking.

So if your Bc has nothing that may be defined in libA.a the -u flag won't help you since the symbol_A is not needed by Bc and by the same token Bo , so will be simply ignored.