Re: [PATCH 0/4] Add variant type

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2022-02-02 19:02, Andrew Burgess wrote:
> * Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> [2022-02-01 09:07:13 -0500]:
> 
>> I sometimes encounter situations where I think using std::variant would
>> be useful.  The benefits would be to be able to use non-POD types in the
>> alternatives, have them automatically constructed when making an
>> alternative active, and automatically destructing them when switching to
>> another alternative of destroying the variant.  Also, the validation of
>> access to the alternatives, to prevent accessing an alternative that is
>> not the current one.
>>
>> However, std::variant is only available in C++17.  I suggest that we
>> import a variant implementation to allow us to use it right now, a bit
>> like we did for optional and string_view.  We could maybe import the
>> implementation from libstdc++, like we did for these last two types, but
>> that sounds really tedious (we would also want to import any tests).
>> Instead, we can take advantage of a popular implementation distributed
>> as a single header file.  I chose this one:
>>
>>   https://github.com/martinmoene/variant-lite
>>
>> because it is close to the std implementation, and the license (Boost
>> Software License) is clear and compatible with the GPL v3.
> 
> Is this compatible with the copyright assignment requirement of
> contributing to GDB?
> 
> I'm assuming copyright of that file is not assigned to FSF.

Exactly, we're merely redistributing it (as its license allows).  Its
header does not say "Copyright FSF" like the other files.

> My concern would be, what if code was copied from that file into the
> rest of GDB?  Does that cause us problems?

Well, we should avoid that :).  I see it exactly like zlib, which is also bundled.

Simon