1.9.0 Deno.connect() types the connection to Conn<NetAddr> making code incompatible

[aricart]

Previous versions of deno had non-generic Conn. This breaks libraries that work perfectly with any version of deno.

[aricart]

Obviously, the backward and forwards solution is // @ts-ignore: Deno added generics to Conn but maybe there's something that can be done that is more elegant.

[bartlomieju]

@aricart could you provide example of code that got broken?

[aricart]

Sorry - Deno.startTls changed signature, so code as below, will fail to compile in 1.9.0

let conn: Deno.Conn;
const hostname = "connect.ngs.global";

conn = await Deno.connect({hostname: hostname, port: 4222});
// other stuff happening here after detecting the server supports TLS
....
conn = await Deno.startTls(
  conn,
  { hostname: hostname },
);

console.log("connected");

[aricart]

error: TS2345 [ERROR]: Argument of type 'Conn<Addr>' is not assignable to parameter of type 'Conn<NetAddr>'.
  Type 'Addr' is not assignable to type 'NetAddr'.
    Type 'UnixAddr' is missing the following properties from type 'NetAddr': hostname, port
  conn,

Pacifying it on 1.9.0 by specifying the Conn<NetAddr> will equally make the code incompatible on older versions.

[kitsonk]

Doing this:

const hostname = "connect.ngs.global";

let conn = await Deno.connect({ hostname: hostname, port: 4222 });
// other stuff happening here after detecting the server supports TLS

conn = await Deno.startTls(
  conn,
  { hostname: hostname },
);

console.log("connected");

Fixes it under Deno 1.9. Is that not acceptable?

[aricart]

When declared as a field in a class, as it is used by me, it doesn't. The type is declared and the generics breaks it for 1.9.0, and if I can get it it is broken for previous versions...

[kt3k]

I think #10012 wasn't breaking with the above example if we had set default of type parameter to NetAddr like:

interface Conn<Address extends Addr = NetAddr>