Make join() handle non-const-only begin/end ranges

[tonyelewis]

See #1784.

Add tests that demonstrate the problem and check obvious variations.

I agree that my contributions are licensed under the {fmt} license, and agree to future changes to the licensing.

[vitaut]

Thanks for the PR. Looks good but please apply clang-format.

[tonyelewis]

Roger - I've applied clang-format.

[mattgodbolt]

Will there be a release including this fix any time? I just hit it and saw that it's been fixed for a while, but doesn't seem to be any 7.0.x release (although the fix is a few months old by 7.0.x.) Thanks!

[vitaut]

I plan to make a new minor release in the next two months or so. This is more than a fix which is why it's not included in patch releases. BTW master is stable so you don't need to wait for release, just pin to a specific commit.

[mattgodbolt]

Thanks @vitaut - understood completely :) I'm using conan and the public conan repo in the project that hit this issue: it's not deadly enough to try and get a new packaging system in; I can wait for 7.1.x :) Thanks for all your hard work!

[tonyelewis]

I'm using conan and the public conan repo in the project that hit this issue

Yep – FWIW, I'm in this same situation as @mattgodbolt. I wish conan provided some way of accessing a dependency's master. But I too can wait for 7.1.x.

Thanks for all your hard work!

👍