Dear Richard M. Stallman,
As illustrated in a recent thread on the emacs mailing list, you are opposed to GCC dumping the AST, as you are afraid proprietary programs will be created to modify GCC's AST output, which would not be open source.
Let me put your fears to rest: nobody cares about using GCC's AST for this purpose.
If anyone wanted to do so, they would already use the non-copylefted clang and LLVM. By being stubborn about this issue, you are actually harming the copyleft cause.
You see, if someone cares about the issue enough, GCC will be forked, a fork that does exactly what you're afraid of. Remember EGCS? Remember libc5? These alone demonstrate a fork of FSF software is not only possible, but easy to promote with sufficient clout. This is not a good state of affairs for the FSF's definition of FOSS, and is not good for GCC.
To put it simply: nothing stops someone from making a GCC fork with the needed modifications to dump the AST (though I believe GCC can already do so with a plugin). It is quite irrelevant if it's copylefted — vendors have enough clout to push it as the blessed fork if they truly cared.
The reason that this hasn't materialised is not because copyleft is magically protecting GCC. It is because clang already does what people want, and there is no need to modify the AST or IR to do specific optimisations. You can just modify the compiler directly.
All this is accomplishing is reducing the effectiveness of GCC as a weapon against non-FOSS software to the point of having the injury potential to non-free software equal to a mosquito. Given enough time, GCC will be doomed to obscurity, at the hands of people with far more clout than the FSF. Clang itself was created under such conditions, and has become dominant in academia and business. This is truly unfortunate, as clang and GCC ought to coexist, for the good of them both — competition breeds innovation.
I may not necessarily agree with the ideals of copyleft (I do not feel it is more free than a copycenter license with my definition of free), but I do not want to see GCC doomed to obscurity. I ask you to consider your position carefully, lest your walled copyleft city is simply abandoned.