In /usr/include/rhythmbox/rhythmdb/rhythmdb.h (the shipped external plugin headers that are provided after a `make install') we have the line

    #include <metadata/rb-ext-db-key.h>

This header is not shipped, because in metadata/Makefile.am we have

    metadatainclude_HEADERS = rb-metadata.h

The metadatainclude_HEADERS is a list of files in the metadata/ directory that are shipped in includedir. As you can see, rb-ext-db-key.h is not in the list.

Therefore, the following trivial C program will not compile:

#include <rhythmdb/rhythmdb.h>
int main() { return 0; }

with the command

gcc `pkg-config --cflags rhythmbox` -o test test.c


This prevents building third-party native plugins as add-ons in distros that ship recent Rhythmbox (the problem has existed in any build since git commit c5bef5be9e942a8bf8a54351ee4d0a92c10a51d8 from December 20, 2011).