Compilation fails to link static libcurl on macOS <= 10.13

[sagebind]

See alexcrichton/curl-rust#279.

Statically linking to libcurl is currently broken on macOS <= 10.13 due to a missing symbol.

Generally static linking is preferred unless there's a good reason not to do it, because it means you are running against a consistent, immutable version of the library and have less system dependencies; both of which are great for portability and testability.

We could either wait for this to get fixed upstream and recommend that people disable the static-curl feature, or disable it by default, or find another workaround.

There does appear to already be an upstream PR to fix this, so it might be worth waiting it out to see if it is merged and published soon: alexcrichton/curl-rust#283

[sagebind]

Good news, this was fixed upstream by alexcrichton/curl-rust#314 and alexcrichton/curl-rust#283! Now we just have to force curl-sys to version 0.4.25 to get this applied to Isahc.

Actually looks like 0.4.25 only contains one of the fixes. We'll have to prod upstream to make a new patch release that we can add as a minimum requirement (probably 0.4.26...).

[sagebind]

curl-sys version 0.4.26 has now been published, so in theory all we have to do is bump our dependency to 0.4.26 to fix this issue now.

[sagebind]

This is now fixed in the 0.9.0 release!

[ta3pks]

curl requires openssl which makes is impossible to be able to be built out of box for musl targets. Do you think there is anything to do about this ?

[sagebind]

I think for musl targets the appropriate solution would be to either disable the static-curl feature, or to configure TLS differently, either by using MesaLink with the curl/mesalink feature or by attempting to statically compile OpenSSL as well with the curl/static-ssl feature. I'm not sure what the best approach would be there.