Runtime Exception License and Other Projects - Clarification

[Ian Lance Taylor]

AJ Guillon <aj.guillon@utoronto.ca> writes:

> As you may or may not know, Threading Building Blocks is another
> project released under the same license as libstdc++.  It also has the
> runtime exception.
>
> See this link:
> http://www.threadingbuildingblocks.org/wiki/index.php?title=General_Questions_about_TBB#What_is_GPL_v2_with_the_runtime_exception.3F
>
> I have a project which has extended TBB in certain useful ways.  To
> comply with the license of TBB, I have adopted the same license for my
> work.  Because this is not as popular a license as the GPL or LGPL,
> I'd like to clarify my understanding of this license.
>
> My intention is to allow others to use my work without having to
> license their work under the GPL.  That is, my code may be used in
> closed-source applications (via linking or template instantiation).
> My understanding is that if others alter my code it falls under the
> GPL.  However others may link to my code, and instantiate templates
> provided without their work falling under the GPL.
>
> I actually tend to think of the libstdc++ license as the LGPL for C++
> with templates.
>
> I'd like to ask if I am right or wrong on this interpretation of the
> license.  I will see about meeting with a lawyer at my university,
> however it would help to know the intention behind the license.

That is not quite my understanding of the libstdc++ license.  My
understanding is that the exception remains even if the libstdc++ code
is modified.  Modifying the code does not cancel the exception, and thus
the code is not under the full GPL.

Note that in mainline development the libstdc++ license recently changed
to use the GCC Runtime Library Exception version 3.1.  However, I
believe that my comments are still accurate.

Ian