The ability to link freely isn't automatic in GPL libraries, it is something that GNU explicitly adds as an exception to the license of GCC; otherwise, GCC is p

The ability to link freely isn't automatic in GPL libraries, it is something that GNU explicitly adds as an exception to the license of GCC; otherwise, GCC is pure GPL [1]. The GNU C library is a related runtime that also explicitly allows linking to proprietary software because it is under the LGPL and not the GPL [2]. What it boils down to is that GPL by itself does not allow reuse without similar disclosures of code, etc. and only a different license (like LGPL) or a documented exception to the license (like in GCC) will change that. [1] http://gcc.gnu.org/onlinedocs/libstdc++/manual/license.html http://gcc.gnu.org/onlinedocs/libstdc++/manual/license.html [2] http://www.gnu.org/s/libc/manual/html_mono/libc.html#Copying http://www.gnu.org/s/libc/manual/html_mono/libc.html#Copying