How do you reach that conclusion? Where is this "textual copying" in the case of C language header files? The literal text of readline.h, if it is copyrightable at all, appears nowhere in the compiled binary. As already mentioned in earlier comments, there is ample [USA] precedent that using the published API of a library does not make the caller a derived work. So if it is OK for a program to use the library API, and no library text is copied, what is your basis for stating that the binary is a derived work of an external library? I am aware that some people make a strong distinction between linking to a shared library (OK) and including the library itself into a static executable (arguably not OK). That may or may not be a tenable distinction, but it doesn't hinge on use of the header files.