[clangd] Make dexp command line options sticky

[yrouban]

Summary

Preparing for the cl::opt reset fix proposed on D115433 this patch fixes the dexp tool to preserve its three command line options (IndexLocation, ExecCommand, ProjectRoot) from reset that is done before parsing query options.

[lattner]

I'm not a competent reviewer for clangd

[jhenderson]

I don't know anything about clangd either. Not sure why I was added as a reviewer :)

[yrouban]

In D120713#3353481, @lattner wrote:

I'm not a competent reviewer for clangd

! In D120713#3353532, @jhenderson wrote:

I don't know anything about clangd either. Not sure why I was added as a reviewer :)

I took your names from https://reviews.llvm.org/D105959 which affected Dexp.cpp and was related to cl::opt.
Ok, I will shoot in the dark once more :)

[sammccall]

Thank you!

clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp

417

nit: comment echoes the code, say why instead?

Preserve global options when flag parser is reset, so commands can use them.

[kadircet]

clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp

418

also nit: /*initial=*/ true. same below

[yrouban]

Closed by commit https://reviews.llvm.org/rGc8a35727fe7c.

clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp

   using namespace clang::clangd;
 
   llvm::cl::ParseCommandLineOptions(argc, argv, Overview);
+
+  // Protect IndexLocation, ExecCommand and ProjectRoot from being reset.
+  IndexLocation.setValue(IndexLocation, true /* initial */);
+  ExecCommand.setValue(ExecCommand, true /* initial */);
+  ProjectRoot.setValue(ProjectRoot, true /* initial */);
+
   llvm::cl::ResetCommandLineParser(); // We reuse it for REPL commands.
   llvm::sys::PrintStackTraceOnErrorSignal(argv[0]);