Improve the textDocument/callHierarchy extension

[MaskRay]

Requested to create a new issue. I haven't looked closely to the latest updates.

Pasted from #420 (comment)

I think the proposal has several deficiency that require further improvement. Comments inlined below:

export interface CallHierarchyCall {
  // If there are multiple `CallHierarchyCall` elements with the same `from`, will the `from: CallHierarchySymbol` be duplicated multiple times?
  range: Range;
  from: CallHierarchySymbol;
  to: CallHierarchySymbol;
}
result: CallHierarchyCall[] | null

export interface CallHierarchySymbol {
  // There is no id field. `name` or `detail` may not identify a specific target that can be suitable for further requests (e.g. node expansion).
  name: string;
  detail?: string;
  kind: SymbolKind;
  uri: string;
  range: Range;
  selectionRange: Range;
}

In ccls (https://github.com/MaskRay/ccls/blob/master/src/messages/ccls_call.cc), we use:

struct Out_cclsCall {
  Usr usr;  // language server specific
  std::string id;
  std::string_view name;
  Location location;
  CallType callType = CallType::Direct;
  int numChildren;
  // Empty if the |levels| limit is reached.
  std::vector<Out_cclsCall> children;
};

The method $ccls/call was designed so that the result can either be a hierarchy or a flattened list (like textDocument/references).

[dbaeumer]

@jrieken @aeschli FYI.

[jrieken]

We have discussed to model the call hierarchy as object graph and decided against it because it raises questions about loops, recursion, and depth. Instead we went with retrieving nodes only (and repeatedly). The latest proposal (which addresses some of your feedback) is here: microsoft/vscode#70231 (comment)

[KamasamaK]

The VS Code API has been finalized.

[kjeremy]

Since the VS Code API has been finalized can the LSP side be finalized?

[dbaeumer]

Yes. A PR would currently speed this up :-).

[kjeremy]

@dbaeumer I don't see any steps for moving something out of the proposed state. Is that mechanically just moving everything out of proposed and updating the md file?

@dbaeumer see #614

[dbaeumer]

I merge the PR and did some cleanup work and added it to the spec.

[dbaeumer]

Closing the issue since the PR is merged.