I want to use GprBuild to create a product not licensed under the GPL. Is this possible, and what variant of it and GNAT would I need to use for this to be legal?
I read that in order to make an application not licensed under the GPL with GNAT, I would need to use the FSF distributed version, because that version is released with a linking exception (supposedly; the FSF library directory doesn't actually state that it is licensed under such an exception, but Wikipedia does).
That said, I am struggling to find any similar information for GprBuild. Is it possible that GprBuild doesn't need this exception in order to be used as such? I get the impression that if the latter is true, then it is for a technical reason that I don't fully understand.
The reason why the GCC runtimes need the exception is that the runtimes are included in a delivered product, either as object code or as source (in the case of e.g. the Bison parser generator).
The GCC compiler itself is licensed under pure GPL, because no part of the compiler ends up in the delivered product; and the same applies to tools like gprbuild.
So, FSF compiler/runtime and gprbuild => OK to deliver under proprietary licence.