These pragmas are used by the IWYU (Include-What-You-Use) program to find out
which header files need to be included in your C/C++ program. The pragmas
added tell IWYU that osmpbf.h acts as a "facade" for the other header files.
You can't initialize strings in header files, because they might be included from several source files and the linker will see several copies of the same string.
Jochen Topf