Fix format conflict with std::format

[mtfishman]

Trying to address #418.

The unfortunate part is that this relies on not introducing format from tinyformat into the namespace, so it would break user code that depends on just being able to directly use format.

I couldn't reproduce the original issue locally, @Wentzell could you see if this fixes the issue you saw? If it does then we can try to think of a safer fix.

[Wentzell]

With these changes I can successfully compile ITensor using gcc-13.
Thank you for looking into this so quickly @mtfishman

[mtfishman]

@emstoudenmire any opinion on how to deal with the namespace clash of tinyformat::format, now that there is a std::format?

[mtfishman]

@Wentzell glad that helped, I guess at least you and others can use this branch with the newer compilers while we decide on a more permanent solution.

[emstoudenmire]

Thanks Matt, I think this is a good fix to just to not introduce format into the namespace. I think it's now better to leave it up to users whether they want to do something like using std::format; or using tfm::format; or just use the qualified names. Even though technically this is a breaking change, I think it's a very minor one in the sense of I wonder how many users were using format as introduced by ITensor?

[mtfishman]

format is being used in some examples so I imagine some people copied it from there. I'm ok making this change, as you say it's easy enough to tell people to add using tfm::format; at the top of their code.

I guess with the new website we've lost our "News" section where we used to announce new versions and breaking changes for C++ ITensor, would be nice to find a place to announce this on the website so we don't catch people off guard. We can also announce things like that on the Discourse forum. For Julia we just do it in the Julia docs and Github README.

[emstoudenmire]

I was thinking of starting a blog on the new itensor.org site at some point in the near future, where we could discuss new features in ITensor among other things. It could also serve as a guide to the community about changes like e.g. in the future when we migrate from "legacy" MPS to ITensorNetworks for things like MPS and MPO algorithms. For now I think the Discourse forum is a good venue. I can make a post there –

…

On Fri, 23 Jun 2023 at 13:10, Matt Fishman ***@***.***> wrote: format is being used in some examples so I imagine some people copied it from there. I'm ok making this change, as you say it's easy enough to tell people to add using tfm::format; at the top of their code. I guess with the new website we've lost our "News" section where we used to announce new versions and breaking changes for C++ ITensor, would be nice to find a place to announce this on the website so we don't catch people off guard. We can also announce things like that on the Discourse forum. For Julia we just do it in the Julia docs and Github README. — Reply to this email directly, view it on GitHub <#419 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAHJ3RIQ5HVYNREWR3SN22TXMXEZVANCNFSM6AAAAAAZQZURMM> . You are receiving this because you were mentioned.Message ID: ***@***.***>

-- -=Miles Stoudenmire=- ***@***.*** ***@***.*** http://itensor.org/miles/

[mtfishman]

@emstoudenmire would you be ready to make a post about this if I merge it soon? @Wentzell wants this merged so they can use the official ITensor version in their CI tests.

[mtfishman]

@emstoudenmire should I merge this?

[emstoudenmire]

I've added a News entry publicly about this now on https://itensor.org

Please have a look to let me know if it's accurate.

[mtfishman]

Thanks, looks great and that will be very helpful to have going forward! To be on the conservative side, I'm going to avoid introducing the tfm shorthand into the namespace by default, so users will have to use tinyformat::format. Could you change that "News" item appropriately? We could mention that the tfm shorthand can be used by defining:

namespace tfm = tinyformat;

[mtfishman]

@emstoudenmire I updated the News item already.

[emstoudenmire]

Thanks for updating it!