Fix usage with std::generator

[Arghnews]

Fixes #4053

Tested on (docker image) Ubuntu 24.04 with gcc 14

[vitaut]

Thanks for the PR but could you add a test case that exercises this path to ranges-test?

[Arghnews]

Thanks for the PR but could you add a test case that exercises this path to ranges-test?

Sure thing, will do.

I'll put the test behind an ifdef for __cpp_lib_generator
Note though, that currently only gcc14 supports the <generator> header, see https://en.cppreference.com/w/cpp/compiler_support#cpp23
So if you would like the fmtlib CI test matrix to actually test this code, it would need an Ubuntu 24.04 instance with gcc 14 added to the github workflows

[vitaut]

I think we don't need to use generator, just some range with move-only iterators.

[Arghnews]

I think we don't need to use generator, just some range with move-only iterators.

Good point, have added a test

[vitaut]

Merged, thanks!