So do I.

> Adacore holds at least the copyright of their own contributions and therefore can decide whether they want to release their version of GNAT with or without the runtime library exception.

Indeed.

> the FSF version eventually inherits also the contributions of Adacore, but the Adacore version is more current.

AdaCore contributes to GCC, with some contributions copyright FSF, some copyright AdaCore.

AdaCore retains full rights on the later, limited by whatever private agreement they have with the FSF.

Whether it is more current or not is not relevant to the discussion, and given that GNAT CE has release cycles of 1 year it stands to reason that FSF GNAT gets bugfixes that GNAT CE will only get in 2022.

> This doesn't have anything to do with source or binary version.

I'm now pretty convinced you're reading things that I didn't write.

You seem to be under the impression that dual licensing only works because AdaCore GNAT contains newer files.

However, AdaCore can download stock upstream gcc, remove the linking exception from files they hold copyright over, and distribute this result in source and binary form on their website.

This is due to their unique status with the FSF, something that other companies and private contributors can not do.

Finally, I have never suggested recompiling AdaCore GNAT CE sources will result in a GNAT compiler with runtime exception.

Instead I've pointed out the mechanism of how they achieve this dual licensing: A) unique status as copyright holders alongside the FSF B) strategic inclusion or removal of the runtime exception in each and every file they hold copyright over.