no member named 'on_error' in 'fmt::basic_format_parse_context<char>'

[mjerabek]

The example for custom formatter specifies that in case of format parse error, one should call ctx.on_error("invalid format"). But this method got removed in d174508 and the impl uses detail::throw_format_error, which should not be used from outsude.

What is the recommended way to report parse errors now?

Works in 9.1.0. Broken in 10.0.0. Still fails on master.

godbolt link: https://godbolt.org/z/dEWEKEsTc

[mjerabek]

I worked this around by defining my own throw_format_error function and using that, but I think the lib should expose such a function. One can just throw format_error(...) directly, but then including <fmt/core.h> is not enough (and including <fmt/format.h> in a header is too heavy).

[vitaut]

Duplicate of #3458.

[mjerabek]

Ah, right, didn't find that.

The example is still wrong, though, as now including <fmt/core.h> is not enough. We could change the include in just the one example (as the rest doesn't need <fmt/format.h>).

But IMO having the throwing function available directly from the library (and having the includes consistent) would be less confusing.

I can create a PR with whatever variant you want to use if you want.

[vitaut]

Good catch, thanks. Fixed the include in 8e87d3a.

A PR to expose throw_format_error via the public API is welcome but note that for ABI compatibility reasons it should be done via an alias rather than moving the function to another namespace.