[clangd] Reuse compile commands during reparse

[krasimir]

Summary

Previously we always queried the compilation database and discarded the results
if the file was already opened.

[ilya-biryukov]

clangd/ClangdUnit.cpp

248 ↗

(On Diff #108023)

Also have to call it in codeComplete.

[krasimir]

• Address review comment

[ilya-biryukov]

LGTM

clang-tools-extra/trunk/clangd/ClangdUnit.cpp

 }
 
 void ClangdUnit::reparse(StringRef Contents,
                          IntrusiveRefCntPtr<vfs::FileSystem> VFS) {
   std::vector<const char *> ArgStrs;
   for (const auto &S : Command.CommandLine)
     ArgStrs.push_back(S.c_str());
 
+  VFS->setCurrentWorkingDirectory(Command.Directory);
+
   std::unique_ptr<CompilerInvocation> CI;
   {
     // FIXME(ibiryukov): store diagnostics from CommandLine when we start
     // reporting them.
     EmptyDiagsConsumer CommandLineDiagsConsumer;
     IntrusiveRefCntPtr<DiagnosticsEngine> CommandLineDiagsEngine =
         CompilerInstance::createDiagnostics(new DiagnosticOptions,
                                             &CommandLineDiagsConsumer, false);

 
 std::vector<CompletionItem>
 ClangdUnit::codeComplete(StringRef Contents, Position Pos,
                          IntrusiveRefCntPtr<vfs::FileSystem> VFS) {
   std::vector<const char *> ArgStrs;
   for (const auto &S : Command.CommandLine)
     ArgStrs.push_back(S.c_str());
 
+  VFS->setCurrentWorkingDirectory(Command.Directory);
+
   std::unique_ptr<CompilerInvocation> CI;
   EmptyDiagsConsumer DummyDiagsConsumer;
   {
     IntrusiveRefCntPtr<DiagnosticsEngine> CommandLineDiagsEngine =
         CompilerInstance::createDiagnostics(new DiagnosticOptions,
                                             &DummyDiagsConsumer, false);
     CI = createCompilerInvocation(ArgStrs, CommandLineDiagsEngine, VFS);
   }

clang-tools-extra/trunk/clangd/ClangdUnitStore.h

private:
   template <class Func>
   void runOnUnitImpl(PathRef File, StringRef FileContents,
                      StringRef ResourceDir, GlobalCompilationDatabase &CDB,
                      std::shared_ptr<PCHContainerOperations> PCHs,
                      bool ReparseBeforeAction,
                      IntrusiveRefCntPtr<vfs::FileSystem> VFS, Func Action) {
     std::lock_guard<std::mutex> Lock(Mutex);
 
+    auto It = OpenedFiles.find(File);
+    if (It == OpenedFiles.end()) {
       auto Commands = getCompileCommands(CDB, File);
       assert(!Commands.empty() &&
              "getCompileCommands should add default command");
-    VFS->setCurrentWorkingDirectory(Commands.front().Directory);
 
-    auto It = OpenedFiles.find(File);
-    if (It == OpenedFiles.end()) {
       It = OpenedFiles
                .insert(std::make_pair(File, ClangdUnit(File, FileContents,
                                                        ResourceDir, PCHs,
                                                        Commands, VFS)))
                .first;
     } else if (ReparseBeforeAction) {
       It->second.reparse(FileContents, VFS);
     }