Question

I have a project that produces a shared library which is linked against another, also shared, library.

When I compile and link it with gcc 4.4, everything works:

1. no compile-time warning or error,
2. no linking time warning or error and
3. ldd libmyproject.so correctly reports the dependency with the other shared library.

When I compile and link it with gcc 4.5, on the other hand (with the exact same flags), I have the following symptoms:

1. no compile-time warning or error,
2. no linking time warning or error but
3. the library is not correctly linked against the other shared lib: this manifest itself when I run ldd and don’t see the connection, and also when I try to use it: while it works with gcc 4.4, it crashes at run-time with gcc 4.5 with a “symbol not found” error (of course from the other lib).

I looked at the release notes and my intuition is that it has something to do with the new link-time optimization, but I could not understand them in enough details.

Did anyone encounter a similar situation and/or has any advice to offer?

(Note that results with 4.6 are in appearance identical to 4.5).

Answer 1

To summarize Mat’s answer from GCC 4.5 vs 4.4 linking with dependencies and the discussion in the comments, you need to link with:

--copy-dt-needed-entries and --no-as-needed