Skip compile-time symbol resolution when building Linux shared libraries with dependencies

Question

Is there a gcc flag to skip resolution of symbols by the compile-time linker when building a shared library (that depends on other shared libraries)? For some reason my toolchain is giving undefined reference errors when I try to build shared library C that depends on B.so and A.so, even though the dependencies are specified and exist. I heard there existed a gcc flag to delay the dependency resolution to runtime.

Answer 1

I think you're looking for --allow-shlib-undefined. From the ld man page:

--allow-shlib-undefined
--no-allow-shlib-undefined
    Allows (the default) or disallows undefined symbols in shared libraries. 
    This switch is similar to --no-undefined except that it determines the 
    behaviour when the undefined symbols are in a shared library rather than 
    a regular object file. It does not affect how undefined symbols in regular
    object files are handled.

    The reason that --allow-shlib-undefined is the default is that the shared
    library being specified at link time may not be the same as the one that 
    is available at load time, so the symbols might actually be resolvable at 
    load time. Plus there are some systems, (eg BeOS) where undefined symbols 
    in shared libraries is normal. (The kernel patches them at load time to 
    select which function is most appropriate for the current architecture. 
    This is used for example to dynamically select an appropriate memset 
    function). Apparently it is also normal for HPPA shared libraries to have
    undefined symbols.

Allowing undefined symbols is the default, though, so I'm guessing your problem is actually something different.