GCC plugin architecture and GPL [closed]

Question

I am trying to do build a plugin to gcc (possible with version 4.5) onwards. I wish to deliver this plugin to a customer along with some software in source code form. This source code can be compiled by any GCC, when the aforementioned plugin is provided.

It says that the plugin has to be under GPL. I am not selling GCC, but the software. Do I have to send the source code of plugin to the customer? Is it enforced in GPL?

Answer 1

The exact answer to your question should probably be given by a lawyer after reading carefully the Gcc runtime exception

I am not a lawyer (but a contributor to GCC), but my understanding of it is that a GCC plugin has to be GPLv3 compatible (and actually, there is code inside GCC that checks for a *plugin_is_GPL_compatible* symbol in the plugin), or -if the plugin is proprietary- that only GPL software is compiled with it.

Otherwise, you are probably not allowed to redistribute the executable produced by the GCC enhanced by your proprietary plugin, unless you also distribute the source code of the compiled executable under a GPL license.

In short, to compile proprietary program, a GCC plugin -or some other GCC extension, like a GCC branch or a MELT extension- should be free software, GPLv3 compatible.

The GCC runtime exception license is related to the tiny bits of code (like libgcc) linked into every program compiled by GCC. It is tricky, and it has been changed to permit GCC plugins.

Regards.

-- Basile Starynkevitch, the main creator of GCC MELT, a plugin and domain specific language to ease the extension of GCC.