[clang-tools-extra] [clangd][modules] Remove the options when driver detects that it was unsupported, and log them (PR #200001)

[Aleksandr Platonov via cfe-commits]

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@@ -273,6 +273,18 @@ void CommandMangler::operator()(tooling::CompileCommand &Command,
       SawInput(Cmd[I]);
     Cmd.resize(DashDashIndex);
   }
+
+  std::string UnsupportedArguments;
+  for (auto *UnknownArg : ArgList.filtered(options::OPT_UNKNOWN)) {
+    unsigned Index = UnknownArg->getIndex();
+    UnsupportedArguments += OriginalArgs[Index + 1];
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ArcsinX wrote:

Can we just use  UnknownArg->getValues() instead of `OriginalArgs[Index + 1]`?

https://github.com/llvm/llvm-project/pull/200001