[PATCH] D44226: [clangd] Add -log-lsp-to-stderr option

[Ilya Biryukov via Phabricator via cfe-commits]

ilya-biryukov added a comment.

In https://reviews.llvm.org/D44226#1030639, @simark wrote:

> In https://reviews.llvm.org/D44226#1030625, @ilya-biryukov wrote:
>
> > I would vouch for adding a log level instead. It's a very well understood concept that certainly covers this use-case and can be useful in other places.
> >  WDYT?
>
>
> I agree.  How would you prefer the flags to look like?
>
> - Use -v multiple times to be more verbose: "-v" to show info, "-v -v" to show debug.  Without -v, we show warnings and errors.


Let's go with two levels (info and verbose) and a single `-v ` flag to enable the verbose level.
Keeping consistent the way people use many logging levels across the whole project is hard (i.e. different people might have different ideas about to distinguishing `warning` from `info`). A distinction between verbose and non-verbose messages should be easier to agree on.

As for the changes in the code, let's make the current `log` function emit info messages and add a `vlog` function that emits "verbose" messages. Verbose message are only output when `-v` is passed.



================
Comment at: clangd/JSONRPCDispatcher.cpp:312
+          // Log the formatted message.
+          log(llvm::formatv(Out.Pretty ? "<-- {0:2}\n" : "<-- {0}\n", *Doc));
+        }
----------------
Since we're replacing `log` with `vlog` here, could we add a normal info `log` that captures the name of the LSP method?  
And `log` with LSP method name should probably go before `vlog` with message contents, that's easy to achieve by moving the logging code into the body of `Dispatcher.call`


Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D44226