[clang] Avoid 'raw_string_ostream::str' (NFC)

Since `raw_string_ostream` doesn't own the string buffer, it is
desirable (in terms of memory safety) for users to directly reference
the string buffer rather than use `raw_string_ostream::str()`.

Work towards TODO item to remove `raw_string_ostream::str()`.

p.s. also remove some unneeded/dead code.

clang/lib/AST/JSONNodeDumper.cpp

@@ -237,7 +237,7 @@ void JSONNodeDumper::Visit(const APValue &Value, QualType Ty) {
   std::string Str;
   llvm::raw_string_ostream OS(Str);
   Value.printPretty(OS, Ctx, Ty);
-  JOS.attribute("value", OS.str());
+  JOS.attribute("value", Str);
 }
 
 void JSONNodeDumper::Visit(const ConceptReference *CR) {
@@ -802,7 +802,7 @@ void JSONNodeDumper::VisitTemplateSpecializationType(
   std::string Str;
   llvm::raw_string_ostream OS(Str);
   TST->getTemplateName().print(OS, PrintPolicy);
-  JOS.attribute("templateName", OS.str());
+  JOS.attribute("templateName", Str);
 }
 
 void JSONNodeDumper::VisitInjectedClassNameType(
@@ -824,7 +824,7 @@ void JSONNodeDumper::VisitElaboratedType(const ElaboratedType *ET) {
     std::string Str;
     llvm::raw_string_ostream OS(Str);
     NNS->print(OS, PrintPolicy, /*ResolveTemplateArgs*/ true);
-    JOS.attribute("qualifier", OS.str());
+    JOS.attribute("qualifier", Str);
   }
   if (const TagDecl *TD = ET->getOwnedTagDecl())
     JOS.attribute("ownedTagDecl", createBareDeclRef(TD));
@@ -1246,7 +1246,7 @@ void JSONNodeDumper::VisitObjCMessageExpr(const ObjCMessageExpr *OME) {
   llvm::raw_string_ostream OS(Str);
 
   OME->getSelector().print(OS);
-  JOS.attribute("selector", OS.str());
+  JOS.attribute("selector", Str);
 
   switch (OME->getReceiverKind()) {
   case ObjCMessageExpr::Instance:
@@ -1277,7 +1277,7 @@ void JSONNodeDumper::VisitObjCBoxedExpr(const ObjCBoxedExpr *OBE) {
     llvm::raw_string_ostream OS(Str);
 
     MD->getSelector().print(OS);
-    JOS.attribute("selector", OS.str());
+    JOS.attribute("selector", Str);
   }
 }
 
@@ -1286,7 +1286,7 @@ void JSONNodeDumper::VisitObjCSelectorExpr(const ObjCSelectorExpr *OSE) {
   llvm::raw_string_ostream OS(Str);
 
   OSE->getSelector().print(OS);
-  JOS.attribute("selector", OS.str());
+  JOS.attribute("selector", Str);
 }
 
 void JSONNodeDumper::VisitObjCProtocolExpr(const ObjCProtocolExpr *OPE) {
@@ -1634,7 +1634,7 @@ void JSONNodeDumper::VisitStringLiteral(const StringLiteral *SL) {
   std::string Buffer;
   llvm::raw_string_ostream SS(Buffer);
   SL->outputString(SS);
-  JOS.attribute("value", SS.str());
+  JOS.attribute("value", Buffer);
 }
 void JSONNodeDumper::VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *BLE) {
   JOS.attribute("value", BLE->getValue());

clang/lib/Driver/ToolChains/Darwin.cpp

@@ -3029,7 +3029,7 @@ void Darwin::addClangCC1ASTargetOptions(
       std::string Arg;
       llvm::raw_string_ostream OS(Arg);
       OS << "-target-sdk-version=" << V;
-      CC1ASArgs.push_back(Args.MakeArgString(OS.str()));
+      CC1ASArgs.push_back(Args.MakeArgString(Arg));
     };
 
     if (isTargetMacCatalyst()) {
@@ -3052,7 +3052,7 @@ void Darwin::addClangCC1ASTargetOptions(
         std::string Arg;
         llvm::raw_string_ostream OS(Arg);
         OS << "-darwin-target-variant-sdk-version=" << SDKInfo->getVersion();
-        CC1ASArgs.push_back(Args.MakeArgString(OS.str()));
+        CC1ASArgs.push_back(Args.MakeArgString(Arg));
       } else if (const auto *MacOStoMacCatalystMapping =
                      SDKInfo->getVersionMapping(
                          DarwinSDKInfo::OSEnvPair::macOStoMacCatalystPair())) {
@@ -3063,7 +3063,7 @@ void Darwin::addClangCC1ASTargetOptions(
           std::string Arg;
           llvm::raw_string_ostream OS(Arg);
           OS << "-darwin-target-variant-sdk-version=" << *SDKVersion;
-          CC1ASArgs.push_back(Args.MakeArgString(OS.str()));
+          CC1ASArgs.push_back(Args.MakeArgString(Arg));
         }
       }
     }

clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp

@@ -273,10 +273,9 @@ namespace {
       std::string SStr;
       llvm::raw_string_ostream S(SStr);
       New->printPretty(S, nullptr, PrintingPolicy(LangOpts));
-      const std::string &Str = S.str();
 
       // If replacement succeeded or warning disabled return with no warning.
-      if (!Rewrite.ReplaceText(SrcRange.getBegin(), Size, Str)) {
+      if (!Rewrite.ReplaceText(SrcRange.getBegin(), Size, SStr)) {
         ReplacedNodes[Old] = New;
         return;
       }
@@ -2581,7 +2580,7 @@ Stmt *RewriteModernObjC::RewriteObjCStringLiteral(ObjCStringLiteral *Exp) {
   std::string prettyBufS;
   llvm::raw_string_ostream prettyBuf(prettyBufS);
   Exp->getString()->printPretty(prettyBuf, nullptr, PrintingPolicy(LangOpts));
-  Preamble += prettyBuf.str();
+  Preamble += prettyBufS;
   Preamble += ",";
   Preamble += utostr(Exp->getString()->getByteLength()) + "};\n";
 
@@ -4414,7 +4413,7 @@ void RewriteModernObjC::SynthesizeBlockLiterals(SourceLocation FunLocStart,
     llvm::raw_string_ostream constructorExprBuf(SStr);
     GlobalConstructionExp->printPretty(constructorExprBuf, nullptr,
                                        PrintingPolicy(LangOpts));
-    globalBuf += constructorExprBuf.str();
+    globalBuf += SStr;
     globalBuf += ";\n";
     InsertText(FunLocStart, globalBuf);
     GlobalConstructionExp = nullptr;

clang/lib/Sema/SemaCodeComplete.cpp

@@ -2117,8 +2117,6 @@ static void AddOverrideResults(ResultBuilder &Results,
         // Generates a new CodeCompletionResult by taking this function and
         // converting it into an override declaration with only one chunk in the
         // final CodeCompletionString as a TypedTextChunk.
-        std::string OverrideSignature;
-        llvm::raw_string_ostream OS(OverrideSignature);
         CodeCompletionResult CCR(Method, 0);
         PrintingPolicy Policy =
             getCompletionPrintingPolicy(S.getASTContext(), S.getPreprocessor());
@@ -3186,7 +3184,6 @@ static void AddTemplateParameterChunks(
       else if (const auto *TC = TTP->getTypeConstraint()) {
         llvm::raw_string_ostream OS(PlaceholderStr);
         TC->print(OS, Policy);
-        OS.flush();
       } else
         PlaceholderStr = "class";
 
@@ -4025,7 +4022,7 @@ CodeCompleteConsumer::OverloadCandidate::CreateSignatureString(
     std::string Name;
     llvm::raw_string_ostream OS(Name);
     FDecl->getDeclName().print(OS, Policy);
-    Result.AddTextChunk(Result.getAllocator().CopyString(OS.str()));
+    Result.AddTextChunk(Result.getAllocator().CopyString(Name));
   } else {
     // Function without a declaration. Just give the return type.
     Result.AddResultTypeChunk(Result.getAllocator().CopyString(
@@ -4343,7 +4340,7 @@ static void MaybeAddOverrideCalls(Sema &S, DeclContext *InContext,
         std::string Str;
         llvm::raw_string_ostream OS(Str);
         NNS->print(OS, Policy);
-        Builder.AddTextChunk(Results.getAllocator().CopyString(OS.str()));
+        Builder.AddTextChunk(Results.getAllocator().CopyString(Str));
       }
     } else if (!InContext->Equals(Overridden->getDeclContext()))
       continue;