[clang] Tidy uses of raw_string_ostream (NFC)

As specified in the docs,
1) raw_string_ostream is always unbuffered and
2) the underlying buffer may be used directly

( 65b1361 for further reference )

* Don't call raw_string_ostream::flush(), which is essentially a no-op.
* Avoid unneeded calls to raw_string_ostream::str(), to avoid excess indirection.

Author: JOE1994

clang/lib/ExtractAPI/DeclarationFragments.cpp

@@ -1110,7 +1110,6 @@ DeclarationFragmentsBuilder::getFragmentsForTemplateArguments(
           Spelling.clear();
           raw_string_ostream OutStream(Spelling);
           CTA.print(Context.getPrintingPolicy(), OutStream, false);
-          OutStream.flush();
         }
       }
 

clang/lib/Frontend/ChainedIncludesSource.cpp

@@ -159,7 +159,7 @@ IntrusiveRefCntPtr<ExternalSemaSource> clang::createChainedIncludesSource(
       std::string pchName = includes[i-1];
       llvm::raw_string_ostream os(pchName);
       os << ".pch" << i-1;
-      serialBufNames.push_back(os.str());
+      serialBufNames.push_back(pchName);
 
       IntrusiveRefCntPtr<ASTReader> Reader;
       Reader = createASTReader(

clang/lib/Frontend/CompilerInstance.cpp

@@ -1383,7 +1383,6 @@ static bool compileModule(CompilerInstance &ImportingInstance,
     std::string InferredModuleMapContent;
     llvm::raw_string_ostream OS(InferredModuleMapContent);
     Module->print(OS);
-    OS.flush();
 
     Result = compileModuleImpl(
         ImportingInstance, ImportLoc, Module->getTopLevelModuleName(),

clang/lib/Frontend/CompilerInvocation.cpp

@@ -817,7 +817,6 @@ static bool RoundTrip(ParseFn Parse, GenerateFn Generate,
       llvm::sys::printArg(OS, Arg, /*Quote=*/true);
       OS << ' ';
     }
-    OS.flush();
     return Buffer;
   };
 
@@ -1186,7 +1185,6 @@ static bool ParseAnalyzerArgs(AnalyzerOptions &Opts, ArgList &Args,
       os << " ";
     os << Args.getArgString(i);
   }
-  os.flush();
 
   return Diags.getNumErrors() == NumErrorsBefore;
 }
@@ -3735,7 +3733,7 @@ void CompilerInvocationBase::GenerateLangArgs(const LangOptions &Opts,
     llvm::interleave(
         Opts.OMPTargetTriples, OS,
         [&OS](const llvm::Triple &T) { OS << T.str(); }, ",");
-    GenerateArg(Consumer, OPT_fopenmp_targets_EQ, OS.str());
+    GenerateArg(Consumer, OPT_fopenmp_targets_EQ, Targets);
   }
 
   if (!Opts.OMPHostIRFile.empty())

clang/lib/Frontend/Rewrite/RewriteObjC.cpp

@@ -221,10 +221,9 @@ namespace {
         return;
       }
       // Get the new text.
-      std::string SStr;
-      llvm::raw_string_ostream S(SStr);
+      std::string Str;
+      llvm::raw_string_ostream S(Str);
       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)) {
@@ -1702,7 +1701,7 @@ Stmt *RewriteObjC::RewriteObjCSynchronizedStmt(ObjCAtSynchronizedStmt *S) {
   llvm::raw_string_ostream syncExprBuf(syncExprBufS);
   assert(syncExpr != nullptr && "Expected non-null Expr");
   syncExpr->printPretty(syncExprBuf, nullptr, PrintingPolicy(LangOpts));
-  syncBuf += syncExprBuf.str();
+  syncBuf += syncExprBufS;
   syncBuf += ");";
 
   buf += syncBuf;
@@ -2508,7 +2507,7 @@ Stmt *RewriteObjC::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";
 

clang/lib/StaticAnalyzer/Checkers/OSObjectCStyleCast.cpp

@@ -68,7 +68,7 @@ static void emitDiagnostics(const BoundNodes &Nodes,
     Checker,
     /*Name=*/"OSObject C-Style Cast",
     categories::SecurityError,
-    OS.str(),
+    Diagnostics,
     PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), ADC),
     CE->getSourceRange());
 }

clang/lib/StaticAnalyzer/Checkers/ObjCSuperDeallocChecker.cpp

@@ -164,7 +164,7 @@ void ObjCSuperDeallocChecker::checkLocation(SVal L, bool IsLoad, const Stmt *S,
   if (IvarRegion) {
     OS << "Use of instance variable '" << *IvarRegion->getDecl() <<
           "' after 'self' has been deallocated";
-    Desc = OS.str();
+    Desc = Buf;
   }
 
   reportUseAfterDealloc(BaseSym, Desc, S, C);

clang/lib/StaticAnalyzer/Checkers/PointerIterationChecker.cpp

@@ -51,7 +51,7 @@ static void emitDiagnostics(const BoundNodes &Match, const Decl *D,
 
   BR.EmitBasicReport(ADC->getDecl(), Checker,
                      "Iteration of pointer-like elements", "Non-determinism",
-                     OS.str(), Location, Range);
+                     Diagnostics, Location, Range);
 }
 
 // Assumption: Iteration of ordered containers of pointers is deterministic.

clang/lib/StaticAnalyzer/Core/BugReporter.cpp

@@ -804,8 +804,7 @@ PathDiagnosticPieceRef PathDiagnosticBuilder::generateDiagForSwitchOP(
     os << "'Default' branch taken. ";
     End = ExecutionContinues(os, C);
   }
-  return std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                       os.str());
+  return std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, sbuf);
 }
 
 PathDiagnosticPieceRef PathDiagnosticBuilder::generateDiagForGotoOP(
@@ -816,7 +815,7 @@ PathDiagnosticPieceRef PathDiagnosticBuilder::generateDiagForGotoOP(
   const PathDiagnosticLocation &End =
       getEnclosingStmtLocation(S, C.getCurrLocationContext());
   os << "Control jumps to line " << End.asLocation().getExpansionLineNumber();
-  return std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, os.str());
+  return std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, sbuf);
 }
 
 PathDiagnosticPieceRef PathDiagnosticBuilder::generateDiagForBinaryOP(
@@ -863,8 +862,7 @@ PathDiagnosticPieceRef PathDiagnosticBuilder::generateDiagForBinaryOP(
         PathDiagnosticLocation::createOperatorLoc(B, SM);
     }
   }
-  return std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                         os.str());
+  return std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, sbuf);
 }
 
 void PathDiagnosticBuilder::generateMinimalDiagForBlockEdge(
@@ -900,7 +898,7 @@ void PathDiagnosticBuilder::generateMinimalDiagForBlockEdge(
     llvm::raw_string_ostream os(sbuf);
     PathDiagnosticLocation End = ExecutionContinues(os, C);
     C.getActivePath().push_front(
-        std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, os.str()));
+        std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, sbuf));
     break;
   }
 
@@ -922,7 +920,7 @@ void PathDiagnosticBuilder::generateMinimalDiagForBlockEdge(
       End = getEnclosingStmtLocation(S, C.getCurrLocationContext());
 
     C.getActivePath().push_front(
-        std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, os.str()));
+        std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, sbuf));
     break;
   }
 
@@ -947,8 +945,7 @@ void PathDiagnosticBuilder::generateMinimalDiagForBlockEdge(
         End = getEnclosingStmtLocation(S, C.getCurrLocationContext());
 
       C.getActivePath().push_front(
-          std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                           os.str()));
+          std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, sbuf));
     } else {
       PathDiagnosticLocation End = ExecutionContinues(C);
 
@@ -973,8 +970,7 @@ void PathDiagnosticBuilder::generateMinimalDiagForBlockEdge(
         End = getEnclosingStmtLocation(S, C.getCurrLocationContext());
 
       C.getActivePath().push_front(
-          std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                           os.str()));
+          std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, sbuf));
     } else {
       PathDiagnosticLocation End = ExecutionContinues(C);
       if (const Stmt *S = End.asStmt())

clang/lib/StaticAnalyzer/Core/PlistDiagnostics.cpp

@@ -812,7 +812,6 @@ void PlistDiagnostics::FlushDiagnosticsImpl(
     std::string stats;
     llvm::raw_string_ostream os(stats);
     llvm::PrintStatisticsJSON(os);
-    os.flush();
     EmitString(o, html::EscapeText(stats)) << '\n';
   }