Make llvm::StringRef to std::string conversions explicit.

This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.

This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.

This doesn't actually modify StringRef yet, I'll do that in a follow-up.

Author: d0k

clang-tools-extra/clang-change-namespace/ChangeNamespace.cpp

@@ -23,7 +23,7 @@ inline std::string
 joinNamespaces(const llvm::SmallVectorImpl<StringRef> &Namespaces) {
   if (Namespaces.empty())
     return "";
-  std::string Result = Namespaces.front();
+  std::string Result(Namespaces.front());
   for (auto I = Namespaces.begin() + 1, E = Namespaces.end(); I != E; ++I)
     Result += ("::" + *I).str();
   return Result;
@@ -184,7 +184,7 @@ void addReplacementOrDie(
     const SourceManager &SM,
     std::map<std::string, tooling::Replacements> *FileToReplacements) {
   const auto R = createReplacement(Start, End, ReplacementText, SM);
-  auto Err = (*FileToReplacements)[R.getFilePath()].add(R);
+  auto Err = (*FileToReplacements)[std::string(R.getFilePath())].add(R);
   if (Err)
     llvm_unreachable(llvm::toString(std::move(Err)).c_str());
 }
@@ -213,18 +213,18 @@ std::string getShortestQualifiedNameInNamespace(llvm::StringRef DeclName,
   DeclName = DeclName.ltrim(':');
   NsName = NsName.ltrim(':');
   if (DeclName.find(':') == llvm::StringRef::npos)
-    return DeclName;
+    return std::string(DeclName);
 
   auto NsNameSplitted = splitSymbolName(NsName);
   auto DeclNsSplitted = splitSymbolName(DeclName);
   llvm::StringRef UnqualifiedDeclName = DeclNsSplitted.pop_back_val();
   // If the Decl is in global namespace, there is no need to shorten it.
   if (DeclNsSplitted.empty())
-    return UnqualifiedDeclName;
+    return std::string(UnqualifiedDeclName);
   // If NsName is the global namespace, we can simply use the DeclName sans
   // leading "::".
   if (NsNameSplitted.empty())
-    return DeclName;
+    return std::string(DeclName);
 
   if (NsNameSplitted.front() != DeclNsSplitted.front()) {
     // The DeclName must be fully-qualified, but we still need to decide if a
@@ -233,7 +233,7 @@ std::string getShortestQualifiedNameInNamespace(llvm::StringRef DeclName,
     // to avoid conflict.
     if (llvm::is_contained(NsNameSplitted, DeclNsSplitted.front()))
       return ("::" + DeclName).str();
-    return DeclName;
+    return std::string(DeclName);
   }
   // Since there is already an overlap namespace, we know that `DeclName` can be
   // shortened, so we reduce the longest common prefix.
@@ -711,7 +711,7 @@ void ChangeNamespaceTool::moveOldNamespace(
   MoveNs.InsertionOffset = SM.getFileOffset(SM.getSpellingLoc(InsertionLoc));
   MoveNs.FID = SM.getFileID(Start);
   MoveNs.SourceMgr = Result.SourceManager;
-  MoveNamespaces[SM.getFilename(Start)].push_back(MoveNs);
+  MoveNamespaces[std::string(SM.getFilename(Start))].push_back(MoveNs);
 }
 
 // Removes a class forward declaration from the code in the moved namespace and
@@ -762,7 +762,7 @@ void ChangeNamespaceTool::moveClassForwardDeclaration(
   InsertForwardDeclaration InsertFwd;
   InsertFwd.InsertionOffset = Insertion.getOffset();
   InsertFwd.ForwardDeclText = Insertion.getReplacementText().str();
-  InsertFwdDecls[Insertion.getFilePath()].push_back(InsertFwd);
+  InsertFwdDecls[std::string(Insertion.getFilePath())].push_back(InsertFwd);
 }
 
 // Replaces a qualified symbol (in \p DeclCtx) that refers to a declaration \p
@@ -816,7 +816,7 @@ void ChangeNamespaceTool::replaceQualifiedSymbolInDeclContext(
                                           ->getQualifiedNameAsString())) {
       FromDeclNameRef = FromDeclNameRef.drop_front(2);
       if (FromDeclNameRef.size() < ReplaceName.size())
-        ReplaceName = FromDeclNameRef;
+        ReplaceName = std::string(FromDeclNameRef);
     }
   }
   // Checks if there is any namespace alias declarations that can shorten the

clang-tools-extra/clang-change-namespace/tool/ClangChangeNamespace.cpp

@@ -91,7 +91,7 @@ llvm::ErrorOr<std::vector<std::string>> GetWhiteListedSymbolPatterns() {
   llvm::StringRef Content = File.get()->getBuffer();
   Content.split(Lines, '\n', /*MaxSplit=*/-1, /*KeepEmpty=*/false);
   for (auto Line : Lines)
-    Patterns.push_back(Line.trim());
+    Patterns.push_back(std::string(Line.trim()));
   return Patterns;
 }
 

clang-tools-extra/clang-doc/Representation.cpp

@@ -286,9 +286,9 @@ ClangDocContext::ClangDocContext(tooling::ExecutionContext *ECtx,
   if (SourceRoot.empty())
     // If no SourceRoot was provided the current path is used as the default
     llvm::sys::fs::current_path(SourceRootDir);
-  this->SourceRoot = SourceRootDir.str();
+  this->SourceRoot = std::string(SourceRootDir.str());
   if (!RepositoryUrl.empty()) {
-    this->RepositoryUrl = RepositoryUrl;
+    this->RepositoryUrl = std::string(RepositoryUrl);
     if (!RepositoryUrl.empty() && RepositoryUrl.find("http://") != 0 &&
         RepositoryUrl.find("https://") != 0)
       this->RepositoryUrl->insert(0, "https://");

clang-tools-extra/clang-doc/tool/ClangDocMain.cpp

@@ -232,7 +232,7 @@ int main(int argc, const char **argv) {
     llvm::sys::path::native(AssetsPath, IndexJS);
     llvm::sys::path::append(IndexJS, "index.js");
     CDCtx.UserStylesheets.insert(CDCtx.UserStylesheets.begin(),
-                                 DefaultStylesheet.str());
+                                 std::string(DefaultStylesheet.str()));
     CDCtx.FilesToCopy.emplace_back(IndexJS.str());
   }
 

clang-tools-extra/clang-include-fixer/InMemorySymbolIndex.cpp

@@ -16,12 +16,12 @@ namespace include_fixer {
 InMemorySymbolIndex::InMemorySymbolIndex(
     const std::vector<SymbolAndSignals> &Symbols) {
   for (const auto &Symbol : Symbols)
-    LookupTable[Symbol.Symbol.getName()].push_back(Symbol);
+    LookupTable[std::string(Symbol.Symbol.getName())].push_back(Symbol);
 }
 
 std::vector<SymbolAndSignals>
 InMemorySymbolIndex::search(llvm::StringRef Identifier) {
-  auto I = LookupTable.find(Identifier);
+  auto I = LookupTable.find(std::string(Identifier));
   if (I != LookupTable.end())
     return I->second;
   return {};

clang-tools-extra/clang-include-fixer/IncludeFixer.cpp

@@ -302,7 +302,7 @@ std::string IncludeFixerSemaSource::minimizeInclude(
     StringRef Include, const clang::SourceManager &SourceManager,
     clang::HeaderSearch &HeaderSearch) const {
   if (!MinimizeIncludePaths)
-    return Include;
+    return std::string(Include);
 
   // Get the FileEntry for the include.
   StringRef StrippedInclude = Include.trim("\"<>");
@@ -311,7 +311,7 @@ std::string IncludeFixerSemaSource::minimizeInclude(
   // If the file doesn't exist return the path from the database.
   // FIXME: This should never happen.
   if (!Entry)
-    return Include;
+    return std::string(Include);
 
   bool IsSystem = false;
   std::string Suggestion =
@@ -352,7 +352,8 @@ IncludeFixerSemaSource::query(StringRef Query, StringRef ScopedQualifiers,
   if (!GenerateDiagnostics && !QuerySymbolInfos.empty()) {
     if (ScopedQualifiers == QuerySymbolInfos.front().ScopedQualifiers &&
         Query == QuerySymbolInfos.front().RawIdentifier) {
-      QuerySymbolInfos.push_back({Query.str(), ScopedQualifiers, Range});
+      QuerySymbolInfos.push_back(
+          {Query.str(), std::string(ScopedQualifiers), Range});
     }
     return {};
   }
@@ -367,7 +368,8 @@ IncludeFixerSemaSource::query(StringRef Query, StringRef ScopedQualifiers,
       CI->getSourceManager().getLocForStartOfFile(
           CI->getSourceManager().getMainFileID()));
 
-  QuerySymbolInfos.push_back({Query.str(), ScopedQualifiers, Range});
+  QuerySymbolInfos.push_back(
+      {Query.str(), std::string(ScopedQualifiers), Range});
 
   // Query the symbol based on C++ name Lookup rules.
   // Firstly, lookup the identifier with scoped namespace contexts;

clang-tools-extra/clang-include-fixer/IncludeFixer.h

@@ -92,7 +92,9 @@ class IncludeFixerSemaSource : public clang::ExternalSemaSource {
         GenerateDiagnostics(GenerateDiagnostics) {}
 
   void setCompilerInstance(CompilerInstance *CI) { this->CI = CI; }
-  void setFilePath(StringRef FilePath) { this->FilePath = FilePath; }
+  void setFilePath(StringRef FilePath) {
+    this->FilePath = std::string(FilePath);
+  }
 
   /// Callback for incomplete types. If we encounter a forward declaration we
   /// have the fully qualified name ready. Just query that.

clang-tools-extra/clang-include-fixer/IncludeFixerContext.cpp

@@ -29,7 +29,7 @@ std::string createQualifiedNameForReplacement(
   // No need to add missing qualifiers if SymbolIdentifier has a global scope
   // operator "::".
   if (RawSymbolName.startswith("::"))
-    return RawSymbolName;
+    return std::string(RawSymbolName);
 
   std::string QualifiedName = MatchedSymbol.getQualifiedName();
 

clang-tools-extra/clang-include-fixer/find-all-symbols/FindAllSymbols.cpp

@@ -251,7 +251,8 @@ void FindAllSymbols::run(const MatchFinder::MatchResult &Result) {
 
   const SourceManager *SM = Result.SourceManager;
   if (auto Symbol = CreateSymbolInfo(ND, *SM, Collector)) {
-    Filename = SM->getFileEntryForID(SM->getMainFileID())->getName();
+    Filename =
+        std::string(SM->getFileEntryForID(SM->getMainFileID())->getName());
     FileSymbols[*Symbol] += Signals;
   }
 }

clang-tools-extra/clang-include-fixer/find-all-symbols/HeaderMapCollector.h

@@ -29,7 +29,7 @@ class HeaderMapCollector {
 
   void addHeaderMapping(llvm::StringRef OrignalHeaderPath,
                         llvm::StringRef MappingHeaderPath) {
-    HeaderMappingTable[OrignalHeaderPath] = MappingHeaderPath;
+    HeaderMappingTable[OrignalHeaderPath] = std::string(MappingHeaderPath);
   };
 
   /// Check if there is a mapping from \p Header or a regex pattern that matches