GNAT project and search directories

["Hibou57 (Yannick Duchêne)" <yannick_duchene@yahoo.fr>]

Hi all, hope you have a merry Christmas in peace

Compiling AdaDep, I've noticed different behaviors when compiling with
and without the provided GPR file.

When the compilation is done without the GPR file, I have to give
gnatmake, the path for the ASIS source directory with an -I option.

When the compilation is done with the GPR file, this option is not
needed while there is no directory specification at all for the ASIS
library path in the GPR file.

So, it seems search paths are not the same with and without a GPR
file.

I've searched the web about it, and did not find a clear explanation.

http://gcc.gnu.org/onlinedocs/gcc-3.4.6/gnat_ugn_unw/Search-Paths-for-gnatbind.html
and http://gcc.gnu.org/onlinedocs/gcc-3.4.6/gnat_ugn_unw/Search-Paths-and-the-Run_002dTime-Library-_0028RTL_0029.html
are just talking about ADA_PRJ_OBJECTS_FILE and ADA_PRJ_INCLUDE_FILE,
but lack explanation about how these are assigned.

Why are the paths not the same with and without a GPR file and what
are formally the difference when a a GPR file is or is not used ?

By the way, just because I feel inquisitive with it : did someone know
what is the license of the GPRBuild language ?