[clangd] Remove 'using namespace llvm' from .cpp files. NFC

The new guideline is to qualify with 'llvm::' explicitly both in
'.h' and '.cpp' files. This simplifies moving the code between
header and source files and is easier to keep consistent.

llvm-svn: 350531
diff --git a/clang-tools-extra/clangd/Headers.cpp b/clang-tools-extra/clangd/Headers.cpp
index c43d72c..06f822b 100644
--- a/clang-tools-extra/clangd/Headers.cpp
+++ b/clang-tools-extra/clangd/Headers.cpp
@@ -17,7 +17,6 @@
 #include "clang/Lex/HeaderSearch.h"
 #include "llvm/Support/Path.h"
 
-using namespace llvm;
 namespace clang {
 namespace clangd {
 namespace {
@@ -30,9 +29,10 @@
   // Record existing #includes - both written and resolved paths. Only #includes
   // in the main file are collected.
   void InclusionDirective(SourceLocation HashLoc, const Token & /*IncludeTok*/,
-                          StringRef FileName, bool IsAngled,
+                          llvm::StringRef FileName, bool IsAngled,
                           CharSourceRange FilenameRange, const FileEntry *File,
-                          StringRef /*SearchPath*/, StringRef /*RelativePath*/,
+                          llvm::StringRef /*SearchPath*/,
+                          llvm::StringRef /*RelativePath*/,
                           const Module * /*Imported*/,
                           SrcMgr::CharacteristicKind FileKind) override {
     if (SM.isWrittenInMainFile(HashLoc)) {
@@ -65,13 +65,13 @@
 
 } // namespace
 
-bool isLiteralInclude(StringRef Include) {
+bool isLiteralInclude(llvm::StringRef Include) {
   return Include.startswith("<") || Include.startswith("\"");
 }
 
 bool HeaderFile::valid() const {
   return (Verbatim && isLiteralInclude(File)) ||
-         (!Verbatim && sys::path::is_absolute(File));
+         (!Verbatim && llvm::sys::path::is_absolute(File));
 }
 
 std::unique_ptr<PPCallbacks>
@@ -80,9 +80,9 @@
   return llvm::make_unique<RecordHeaders>(SM, Out);
 }
 
-void IncludeStructure::recordInclude(StringRef IncludingName,
-                                     StringRef IncludedName,
-                                     StringRef IncludedRealName) {
+void IncludeStructure::recordInclude(llvm::StringRef IncludingName,
+                                     llvm::StringRef IncludedName,
+                                     llvm::StringRef IncludedRealName) {
   auto Child = fileIndex(IncludedName);
   if (!IncludedRealName.empty() && RealPathNames[Child].empty())
     RealPathNames[Child] = IncludedRealName;
@@ -90,19 +90,20 @@
   IncludeChildren[Parent].push_back(Child);
 }
 
-unsigned IncludeStructure::fileIndex(StringRef Name) {
+unsigned IncludeStructure::fileIndex(llvm::StringRef Name) {
   auto R = NameToIndex.try_emplace(Name, RealPathNames.size());
   if (R.second)
     RealPathNames.emplace_back();
   return R.first->getValue();
 }
 
-StringMap<unsigned> IncludeStructure::includeDepth(StringRef Root) const {
+llvm::StringMap<unsigned>
+IncludeStructure::includeDepth(llvm::StringRef Root) const {
   // Include depth 0 is the main file only.
-  StringMap<unsigned> Result;
+  llvm::StringMap<unsigned> Result;
   Result[Root] = 0;
   std::vector<unsigned> CurrentLevel;
-  DenseSet<unsigned> Seen;
+  llvm::DenseSet<unsigned> Seen;
   auto It = NameToIndex.find(Root);
   if (It != NameToIndex.end()) {
     CurrentLevel.push_back(It->second);
@@ -142,7 +143,7 @@
   assert(DeclaringHeader.valid() && InsertedHeader.valid());
   if (FileName == DeclaringHeader.File || FileName == InsertedHeader.File)
     return false;
-  auto Included = [&](StringRef Header) {
+  auto Included = [&](llvm::StringRef Header) {
     return IncludedHeaders.find(Header) != IncludedHeaders.end();
   };
   return !Included(DeclaringHeader.File) && !Included(InsertedHeader.File);
@@ -164,8 +165,9 @@
   return Suggested;
 }
 
-Optional<TextEdit> IncludeInserter::insert(StringRef VerbatimHeader) const {
-  Optional<TextEdit> Edit = None;
+llvm::Optional<TextEdit>
+IncludeInserter::insert(llvm::StringRef VerbatimHeader) const {
+  llvm::Optional<TextEdit> Edit = None;
   if (auto Insertion = Inserter.insert(VerbatimHeader.trim("\"<>"),
                                        VerbatimHeader.startswith("<")))
     Edit = replacementToEdit(Code, *Insertion);