libidn update broke the action workflow on Windows

[smorimoto]

curl relies on libidn and is temporarily broken by the update, namely it complains about curl missing.

[dra27]

This was a packaging mistake which has been fixed upstream. It's propagating to mirrors: setup.ini with a timestamp on or after 20210803 16:21:27+0000 is working.

[dra27]

One thing we could do is to adopt a trick used in opam and ocaml's AppVeyor scripts (see appveyor_build.cmd in ocaml/ocaml). There, you have CYGWIN_PACKAGES containing the name of a package (e.g. mingw64-x86_64-gcc-core) which is required along with a command which should be run to check it in CYGWIN_COMMANDS (e.g. x86_64-w64-mingw32-gcc). The assumption is that x86_64-w64-mingw32-gcc --version should return an exit code of 0 but it will fail if there's a DLL which can't load - just like has happened here. So we could use that second part to test the Cygwin installation to display a better error message should this happen again.

[dra27]

(it could be tested with the glorious-website-named Cygwin Time Machine)

[smorimoto]

Notice to users: It's completely resolved as it was updated on the mirror server that setup-ocaml currently uses.