swift-foundation recently landed a change (in
swiftlang/swift-foundation#764) which requires `any Sendable` values in
`JSONEncoder.userInfo`. This causes a build failure:
```
JSONRPCConnection.swift:370:50: error: type '(RequestID) -> Optional<any ResponseType.Type>' does not conform to the 'Sendable' protocol
368 |
369 | // Setup callback for response type.
370 | decoder.userInfo[.responseTypeCallbackKey] = { (id: RequestID) -> ResponseType.Type? in
| |- error: type '(RequestID) -> Optional<any ResponseType.Type>' does not conform to the 'Sendable' protocol
| `- note: a function type must be marked '@Sendable' to conform to 'Sendable'
371 | guard let outstanding = self.outstandingRequests[id] else {
372 | logger.error("Unknown request for \(id, privacy: .public)")
```
Make the closure sendable, which is safe as we're only reading from
`outstandingRequests` (where all our writes are guarded by the same
queue that the decoding is on).
The URI standard RFC 3986 is ambiguous about whether percent encoding and their represented characters are considered equivalent. VS Code considers them equivalent and treats them the same:
```js
vscode.Uri.parse("x://a?b=xxxx%3Dyyyy").toString() -> 'x://a?b%3Dxxxx%3Dyyyy'
vscode.Uri.parse("x://a?b=xxxx%3Dyyyy").toString(/*skipEncoding=*/true) -> 'x://a?b=xxxx=yyyy'
```
This causes issues because SourceKit-LSP's macro expansion URLs encoded by URLComponents use `=` do denote the separation of a key and a value in the outer query. The value of the `parent` key may itself contain query items, which use the escaped form '%3D'. Simplified, such a URL may look like `scheme://host?parent=scheme://host?line%3D2`.
But after running this through VS Code's URI type `=` and `%3D` get canonicalized and are indistinguishable.
To avoid this ambiguity, always percent escape the characters we use to distinguish URL query parameters, producing the following URL: `scheme://host?parent%3Dscheme://host%3Fline%253D2`.
We will be able to split the LSP modules off later. These LSP modules
will provide the ability to write custom LSP servers and clients in
Swift. The sourcekit-lsp repository will build on top of this new
package to provide an LSP implementation that creates a language server
for Swift and C-based-languages.
