Out of curiosity I have checked all files that get bundled in a tarball of an autoconfiscated project. I haven't found anything interesting among them, but noticed gettext.h (copied from the gettext package, as suggested in the manual), which is under LGPL.
The project is licensed under OSL 2.0, so I got curious
about the combination. LGPL paragraph 6 requires that with each binary of my project the distributor must "give prominent
notice that the Library is used in it" ..., "supply a copy
of this License", "include the copyright notice of the Library" and "a reference directing the user to the copy of this License".
So, apparently I can ship gettext.h in the tarball
as long as I also ship COPYING.LIB. But anyone distributing a binary must make sure there is a "prominent notice" and modify the program to add the
copyright notice for gettext and a pointer to COPYING.LIB.
I ended up rewriting gettext.h from scratch; I don't want to "accidentaly" put such requirements on users of my software.
It gets worse, though. Reading /usr/include/string.h from glibc you see that
if you compile with gcc -O (and don't define __NO_STRING_INLINES), #include <string.h> pulls also /usr/include/bits/string2.h, which contains
very large inline functions that can not be considered trivial (due to the C aliasing model they can not even be written in strictly conforming C99). So any executable that uses the functions from glibc is clearly a derived work of glibc and falls under LGPL paragraph 6.
(Even though LGPL paragraph 6 seems to indicate that they consider executables using shared linking to still be derived works of the library, I can imagine the judge would disagree; but the string inlines are not a case of shared linking.)
What does it mean? Since gcc is the canonical compiler on Linux, almost everybody is using optimization and almost every program calls memset (), strcpy (), strncpy () or strcmp () (this list is not exhaustive), almost any program for Linux distributed in binary form must be shipped acompanied with COPYING.LIB, must give a prominent notice it uses glibc and must contain the glibc copyright notice along with other copyright notices.
I find it quite surprising. In fact I don't know about any program that does that.