rust-analyzer reports its own analysis (a missing field, a wrong type) only
to clients that pull diagnostics; it pushes just `cargo check`'s, so in the
editor a Rust type error showed up only after saving. The client now
advertises `textDocument/diagnostic` and pulls an open file's diagnostics
from servers with a `diagnosticProvider`: when it opens or its server
starts, after edits (once typing pauses), on save (and other open files
for servers with inter-file dependencies) and on
`workspace/diagnostic/refresh`. Pulled and pushed diagnostics are kept
apart and shown, and given to code actions, together; a newer pull
supersedes an older reply, a server-cancelled pull is retried, and closing
a file drops what was pulled.
l0ng-ai
20c439baaa