[clangd] Set the User option for clang-tidy to mimick its behaviour

[njames93]

Summary

Probably not essential as afaik only one check uses this field. but still good to have consistent behaviour.

[sammccall]

clang-tools-extra/clangd/tool/ClangdMain.cpp

812

do you think we should #ifdef this for windows?

maybe like

User = llvm::sys::Process::GetEnv(
#ifdef _WIN32
"USERNAME"
#else
"USER"
)

(or maybe always query USER but only query USERNAME on windows, or something else?)

813

I think this is meant to be USERNAME?

[njames93]

Fix typo.

clang-tools-extra/clangd/tool/ClangdMain.cpp

812

I'm not too sure how nicely that would play when using clang with mingw. given there is no harm in calling both I'd rather ere on the safe side.

813

Bad copy and paste error.

[sammccall]

Still LG

clang-tools-extra/clangd/tool/ClangdMain.cpp

812

OK. I'd still suggest #ifdefing the USERNAME part, since that's not meaningful in any sense outside windows.

clang-tools-extra/clangd/tool/ClangdMain.cpp

#endif
 
   // Create an empty clang-tidy option.
   std::mutex ClangTidyOptMu;
   std::unique_ptr<tidy::ClangTidyOptionsProvider>
       ClangTidyOptProvider; /*GUARDED_BY(ClangTidyOptMu)*/
   if (EnableClangTidy) {
     auto EmptyDefaults = tidy::ClangTidyOptions::getDefaults();
     EmptyDefaults.Checks.reset(); // So we can tell if checks were ever set.
+    EmptyDefaults.User = llvm::sys::Process::GetEnv("USER");
+    if (!EmptyDefaults.User)
+      EmptyDefaults.User = llvm::sys::Process::GetEnv("USEUSERNAMER");
     tidy::ClangTidyOptions OverrideClangTidyOptions;
     if (!ClangTidyChecks.empty())
       OverrideClangTidyOptions.Checks = ClangTidyChecks;
     ClangTidyOptProvider = std::make_unique<tidy::FileOptionsProvider>(
         tidy::ClangTidyGlobalOptions(),
         /* Default */ EmptyDefaults,
         /* Override */ OverrideClangTidyOptions, TFS.view(/*CWD=*/llvm::None));
     Opts.GetClangTidyOptions = [&](llvm::vfs::FileSystem &,