[PATCH] D43227: [clangd] Make functions of ClangdServer callback-based

[Ilya Biryukov via Phabricator via cfe-commits]

ilya-biryukov added inline comments.


================
Comment at: clangd/ClangdLSPServer.cpp:194
+        if (!Replacements)
+          return replyError(ErrorCode::InternalError,
+                            llvm::toString(Replacements.takeError()));
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ioeric wrote:
> nit: since we are not spelling out the return type here, it might be clearer if we do:
> ```
> replyError(...);
> return;
> ```
> 
> `return replyError(...)` makes me wonder what the return type is.
This trick was used in the code before (there are usages below), so I figured it's ok to do this.
If it's confusing I'll change it everywhere.


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Comment at: clangd/ClangdServer.cpp:209
+  auto Action = [Contents, Pos, TaggedFS,
+                 PCHs](Path File, decltype(Callback) Callback,
+                       llvm::Expected<InputsAndPreamble> IP) {
----------------
ioeric wrote:
> nit: I'd probably use a different name than `Callback` for this parameter for clarity.
I actually think we should keep it this way. It's a bit tricky to grasp, but it has two important advantages:
  - Makes referencing `Callback` from outer scope impossible
  - saves us from coming up with names for that superficial variable, i.e. should it be called `InnerCallback`, `Callback2`, `C` or something else?

Is it that too confusing or do you feel we can keep it?


================
Comment at: clangd/ClangdServer.cpp:441
 
-  using RetType = llvm::Expected<Tagged<std::vector<DocumentHighlight>>>;
-  auto Action = [=](llvm::Expected<InputsAndAST> InpAST) -> RetType {
+  auto Action = [=](decltype(Callback) Callback,
+                    llvm::Expected<InputsAndAST> InpAST) {
----------------
ioeric wrote:
> Consider spelling out the captured values, just in case new variables which are not expected to be captured are added in the future.
Thanks for spotting this!


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Comment at: unittests/clangd/SyncAPI.cpp:69
+  llvm::Expected<Tagged<SignatureHelp>> Result = Tagged<SignatureHelp>();
+  (void)(bool)Result; // Expected has to be checked.
+  Server.signatureHelp(File, Pos, capture(Result), OverridenContents);
----------------
ioeric wrote:
> I'd expect this to be checked by callers. Would `return std::move(Result);` work?
The reason why we need it is because `capture(Result)` writes return value of the callback to the `Result` variable. But we have to first check the default-constructed value that was there **before** calling `Server.signatureHelp`


Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D43227