
vec_c() falls back to c() for foreign classes
=============================================

> vec_c(foobar(1), foobar(2))
Error: Can't find vctrs or base methods for concatenation.
vctrs methods must be implemented for class `vctrs_foobar`.
See <https://vctrs.r-lib.org/articles/s3-vector.html>.


vec_c() fallback doesn't support `name_spec` or `ptype`
=======================================================

> vec_c(foobar(1), foobar(2), .name_spec = "{outer}_{inner}")
Error: Can't use a name specification with non-vctrs types.
vctrs methods must be implemented for class `vctrs_foobar`.
See <https://vctrs.r-lib.org/articles/s3-vector.html>.

> vec_c(foobar(1), foobar(2), .ptype = "")
Error: Can't specify a prototype with non-vctrs types.
vctrs methods must be implemented for class `vctrs_foobar`.
See <https://vctrs.r-lib.org/articles/s3-vector.html>.

