[llvm][unittests] Don't call raw_string_ostream::flush() (NFC)

raw_string_ostream::flush() is essentially a no-op (also specified in docs).
Don't call it in tests that aren't meant to test 'raw_string_ostream' itself.

p.s. remove a few redundant calls to raw_string_ostream::str()

32 files changed, 13 insertions, 101 deletions

diff --git a/llvm/unittests/ADT/RewriteBufferTest.cpp b/llvm/unittests/ADT/RewriteBufferTest.cpp
index 3b367da..5746ab1 100644
--- a/llvm/unittests/ADT/RewriteBufferTest.cpp
+++ b/llvm/unittests/ADT/RewriteBufferTest.cpp
@@ -19,7 +19,6 @@ static std::string writeOutput(const RewriteBuffer &Buf) {
   std::string Result;
   raw_string_ostream OS(Result);
   Buf.write(OS);
-  OS.flush();
   return Result;
 }
 
diff --git a/llvm/unittests/DebugInfo/DWARF/DWARFDebugFrameTest.cpp b/llvm/unittests/DebugInfo/DWARF/DWARFDebugFrameTest.cpp
index d9655317..17fb18fc 100644
--- a/llvm/unittests/DebugInfo/DWARF/DWARFDebugFrameTest.cpp
+++ b/llvm/unittests/DebugInfo/DWARF/DWARFDebugFrameTest.cpp
@@ -44,7 +44,6 @@ void expectDumpResult(const dwarf::CIE &TestCIE, bool IsEH,
   auto DumpOpts = DIDumpOptions();
   DumpOpts.IsEH = IsEH;
   TestCIE.dump(OS, DumpOpts);
-  OS.flush();
   StringRef FirstLine = StringRef(Output).split('\n').first;
   EXPECT_EQ(FirstLine, ExpectedFirstLine);
 }
@@ -56,7 +55,6 @@ void expectDumpResult(const dwarf::FDE &TestFDE, bool IsEH,
   auto DumpOpts = DIDumpOptions();
   DumpOpts.IsEH = IsEH;
   TestFDE.dump(OS, DumpOpts);
-  OS.flush();
   StringRef FirstLine = StringRef(Output).split('\n').first;
   EXPECT_EQ(FirstLine, ExpectedFirstLine);
 }
@@ -344,7 +342,6 @@ void expectDumpResult(const dwarf::UnwindLocation &Loc,
   std::string Output;
   raw_string_ostream OS(Output);
   OS << Loc;
-  OS.flush();
   StringRef FirstLine = StringRef(Output).split('\n').first;
   EXPECT_EQ(FirstLine, ExpectedFirstLine);
 }
@@ -387,7 +384,6 @@ void expectDumpResult(const dwarf::RegisterLocations &Locs,
   std::string Output;
   raw_string_ostream OS(Output);
   OS << Locs;
-  OS.flush();
   StringRef FirstLine = StringRef(Output).split('\n').first;
   EXPECT_EQ(FirstLine, ExpectedFirstLine);
 }
diff --git a/llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp b/llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp
index 980b627..e549128 100644
--- a/llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp
+++ b/llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp
@@ -1558,7 +1558,6 @@ TEST_F(DebugLineBasicFixture, VerboseOutput) {
   raw_string_ostream OS(Output);
   Parser.parseNext(RecordRecoverable, RecordUnrecoverable, &OS,
                    /*Verbose=*/true);
-  OS.flush();
   StringRef OutputRef(Output);
 
   size_t Pos = 0;
@@ -1805,7 +1804,6 @@ struct TruncatedOpcodeFixtureBase : public CommonFixture {
     raw_string_ostream OS(Output);
     Parser.parseNext(RecordRecoverable, RecordUnrecoverable, &OS,
                      /*Verbose=*/true);
-    OS.flush();
 
     std::string LinePrefix =
         ("0x0000002f: 0" + Twine::utohexstr(OpcodeValue) + " ").str();
diff --git a/llvm/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp b/llvm/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp
index 6934746..29d4db4 100644
--- a/llvm/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp
+++ b/llvm/unittests/DebugInfo/DWARF/DWARFFormValueTest.cpp
@@ -375,7 +375,6 @@ TEST_P(DumpValueFixture, Test) {
   Opts.ShowAddresses = true;
 
   Form.dump(OS, Opts);
-  OS.flush();
 
   EXPECT_EQ(Output, ExpectedResult);
 }
diff --git a/llvm/unittests/DebugInfo/GSYM/GSYMTest.cpp b/llvm/unittests/DebugInfo/GSYM/GSYMTest.cpp
index 621b6fe..c6218e5 100644
--- a/llvm/unittests/DebugInfo/GSYM/GSYMTest.cpp
+++ b/llvm/unittests/DebugInfo/GSYM/GSYMTest.cpp
@@ -3802,7 +3802,6 @@ TEST(GSYMTest, TestRangeWarnings) {
   const uint32_t ThreadCount = 1;
   ASSERT_THAT_ERROR(DT.convert(ThreadCount, OSAgg), Succeeded());
   ASSERT_THAT_ERROR(GC.finalize(OSAgg), Succeeded());
-  OS.flush();
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   const auto ByteOrder = llvm::endianness::native;
@@ -4005,7 +4004,6 @@ TEST(GSYMTest, TestEmptyRangeWarnings) {
   const uint32_t ThreadCount = 1;
   ASSERT_THAT_ERROR(DT.convert(ThreadCount, OSAgg), Succeeded());
   ASSERT_THAT_ERROR(GC.finalize(OSAgg), Succeeded());
-  OS.flush();
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   const auto ByteOrder = llvm::endianness::native;
@@ -4158,7 +4156,6 @@ TEST(GSYMTest, TestEmptyLinkageName) {
   const uint32_t ThreadCount = 1;
   ASSERT_THAT_ERROR(DT.convert(ThreadCount, OSAgg), Succeeded());
   ASSERT_THAT_ERROR(GC.finalize(OSAgg), Succeeded());
-  OS.flush();
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   const auto ByteOrder = llvm::endianness::native;
@@ -4320,7 +4317,6 @@ TEST(GSYMTest, TestLineTablesWithEmptyRanges) {
   const uint32_t ThreadCount = 1;
   ASSERT_THAT_ERROR(DT.convert(ThreadCount, OSAgg), Succeeded());
   ASSERT_THAT_ERROR(GC.finalize(OSAgg), Succeeded());
-  OS.flush();
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   const auto ByteOrder = llvm::endianness::native;
@@ -4641,7 +4637,6 @@ TEST(GSYMTest, TestHandlingOfInvalidFileIndexes) {
   const uint32_t ThreadCount = 1;
   ASSERT_THAT_ERROR(DT.convert(ThreadCount, OSAgg), Succeeded());
   ASSERT_THAT_ERROR(GC.finalize(OSAgg), Succeeded());
-  OS.flush();
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   const auto ByteOrder = llvm::endianness::native;
@@ -4857,7 +4852,6 @@ TEST(GSYMTest, TestLookupsOfOverlappingAndUnequalRanges) {
   const uint32_t ThreadCount = 1;
   ASSERT_THAT_ERROR(DT.convert(ThreadCount, OSAgg), Succeeded());
   ASSERT_THAT_ERROR(GC.finalize(OSAgg), Succeeded());
-  OS.flush();
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   const auto ByteOrder = llvm::endianness::native;
diff --git a/llvm/unittests/IR/ConstantsTest.cpp b/llvm/unittests/IR/ConstantsTest.cpp
index 48d65be..ed608ba 100644
--- a/llvm/unittests/IR/ConstantsTest.cpp
+++ b/llvm/unittests/IR/ConstantsTest.cpp
@@ -172,7 +172,6 @@ TEST(ConstantsTest, PointerCast) {
     Instruction *__I = cast<ConstantExpr>(x)->getAsInstruction();              \
     __I->print(__o);                                                           \
     __I->deleteValue();                                                        \
-    __o.flush();                                                               \
     EXPECT_EQ(std::string("  <badref> = " y), __s);                            \
   }
 
diff --git a/llvm/unittests/IR/ManglerTest.cpp b/llvm/unittests/IR/ManglerTest.cpp
index f2b78a1..5ac784b 100644
--- a/llvm/unittests/IR/ManglerTest.cpp
+++ b/llvm/unittests/IR/ManglerTest.cpp
@@ -20,7 +20,6 @@ static std::string mangleStr(StringRef IRName, Mangler &Mang,
   std::string Mangled;
   raw_string_ostream SS(Mangled);
   Mang.getNameWithPrefix(SS, IRName, DL);
-  SS.flush();
   return Mangled;
 }
 
@@ -37,7 +36,6 @@ static std::string mangleFunc(StringRef IRName,
   std::string Mangled;
   raw_string_ostream SS(Mangled);
   Mang.getNameWithPrefix(SS, F, false);
-  SS.flush();
   F->eraseFromParent();
   return Mangled;
 }
diff --git a/llvm/unittests/IR/MetadataTest.cpp b/llvm/unittests/IR/MetadataTest.cpp
index e9bf367..e998934 100644
--- a/llvm/unittests/IR/MetadataTest.cpp
+++ b/llvm/unittests/IR/MetadataTest.cpp
@@ -299,7 +299,6 @@ TEST_F(MDNodeTest, Print) {
     std::string Actual_;                                                       \
     raw_string_ostream OS(Actual_);                                            \
     PRINT;                                                                     \
-    OS.flush();                                                                \
     std::string Expected_(EXPECTED);                                           \
     EXPECT_EQ(Expected_, Actual_);                                             \
   } while (false)
diff --git a/llvm/unittests/IR/ModuleSummaryIndexTest.cpp b/llvm/unittests/IR/ModuleSummaryIndexTest.cpp
index f716a04..aa136af 100644
--- a/llvm/unittests/IR/ModuleSummaryIndexTest.cpp
+++ b/llvm/unittests/IR/ModuleSummaryIndexTest.cpp
@@ -45,7 +45,6 @@ TEST(ModuleSummaryIndexTest, MemProfSummaryPrinting) {
   for (auto &AI : AllocSummary->allocs())
     OS << "\n" << AI;
 
-  OS.flush();
   EXPECT_EQ(Data, R"(
 Callee: 23 Clones: 0 StackIds: 2, 3
 Callee: 23 Clones: 0 StackIds: 2, 4
diff --git a/llvm/unittests/MC/MCInstPrinter.cpp b/llvm/unittests/MC/MCInstPrinter.cpp
index bff58c4..9002045 100644
--- a/llvm/unittests/MC/MCInstPrinter.cpp
+++ b/llvm/unittests/MC/MCInstPrinter.cpp
@@ -53,7 +53,6 @@ public:
     std::string Buffer;
     raw_string_ostream OS(Buffer);
     OS << Printer->formatHex(i);
-    OS.flush();
     return Buffer;
   }
 };
diff --git a/llvm/unittests/MIR/MachineMetadata.cpp b/llvm/unittests/MIR/MachineMetadata.cpp
index cd30768f..ac1397f 100644
--- a/llvm/unittests/MIR/MachineMetadata.cpp
+++ b/llvm/unittests/MIR/MachineMetadata.cpp
@@ -106,7 +106,6 @@ static std::string print(std::function<void(raw_ostream &OS)> PrintFn) {
   std::string Str;
   raw_string_ostream OS(Str);
   PrintFn(OS);
-  OS.flush();
   return Str;
 }
 
diff --git a/llvm/unittests/Object/SymbolicFileTest.cpp b/llvm/unittests/Object/SymbolicFileTest.cpp
index 8308a00..38875ce 100644
--- a/llvm/unittests/Object/SymbolicFileTest.cpp
+++ b/llvm/unittests/Object/SymbolicFileTest.cpp
@@ -35,7 +35,6 @@ TEST(Object, DataRefImplOstream) {
   }
 
   OS << Data;
-  OS.flush();
 
   EXPECT_EQ(Expected, s);
 }
diff --git a/llvm/unittests/ProfileData/InstrProfTest.cpp b/llvm/unittests/ProfileData/InstrProfTest.cpp
index 259d6ff..c252252 100644
--- a/llvm/unittests/ProfileData/InstrProfTest.cpp
+++ b/llvm/unittests/ProfileData/InstrProfTest.cpp
@@ -431,7 +431,6 @@ MATCHER_P(EqualsRecord, Want, "") {
     Want.print(OS);
     OS << "Got:\n";
     Got.print(OS);
-    OS.flush();
     *result_listener << "MemProf Record differs!\n" << Buffer;
     return false;
   };
diff --git a/llvm/unittests/ProfileData/MemProfTest.cpp b/llvm/unittests/ProfileData/MemProfTest.cpp
index 14623e18..b7a9170 100644
--- a/llvm/unittests/ProfileData/MemProfTest.cpp
+++ b/llvm/unittests/ProfileData/MemProfTest.cpp
@@ -255,7 +255,6 @@ TEST(MemProf, PortableWrapper) {
   std::string Buffer;
   llvm::raw_string_ostream OS(Buffer);
   WriteBlock.serialize(Schema, OS);
-  OS.flush();
 
   PortableMemInfoBlock ReadBlock(
       Schema, reinterpret_cast<const unsigned char *>(Buffer.data()));
@@ -296,7 +295,6 @@ TEST(MemProf, RecordSerializationRoundTripVersion0And1) {
   std::string Buffer;
   llvm::raw_string_ostream OS(Buffer);
   Record.serialize(Schema, OS, llvm::memprof::Version0);
-  OS.flush();
 
   const IndexedMemProfRecord GotRecord = IndexedMemProfRecord::deserialize(
       Schema, reinterpret_cast<const unsigned char *>(Buffer.data()),
@@ -326,7 +324,6 @@ TEST(MemProf, RecordSerializationRoundTripVerion2) {
   std::string Buffer;
   llvm::raw_string_ostream OS(Buffer);
   Record.serialize(Schema, OS, llvm::memprof::Version2);
-  OS.flush();
 
   const IndexedMemProfRecord GotRecord = IndexedMemProfRecord::deserialize(
       Schema, reinterpret_cast<const unsigned char *>(Buffer.data()),
@@ -378,7 +375,6 @@ TEST(MemProf, RecordSerializationRoundTripVersion2HotColdSchema) {
   std::string Buffer;
   llvm::raw_string_ostream OS(Buffer);
   Record.serialize(Schema, OS, llvm::memprof::Version2);
-  OS.flush();
 
   const IndexedMemProfRecord GotRecord = IndexedMemProfRecord::deserialize(
       Schema, reinterpret_cast<const unsigned char *>(Buffer.data()),
diff --git a/llvm/unittests/Support/CommandLineTest.cpp b/llvm/unittests/Support/CommandLineTest.cpp
index 23f6081..3df4107 100644
--- a/llvm/unittests/Support/CommandLineTest.cpp
+++ b/llvm/unittests/Support/CommandLineTest.cpp
@@ -520,7 +520,6 @@ TEST(CommandLineTest, LookupFailsInWrongSubCommand) {
 
   const char *args[] = {"prog", "sc1", "-sc2"};
   EXPECT_FALSE(cl::ParseCommandLineOptions(3, args, StringRef(), &OS));
-  OS.flush();
   EXPECT_FALSE(Errs.empty());
 }
 
@@ -616,7 +615,6 @@ TEST(CommandLineTest, AddToAllSubCommands) {
   EXPECT_TRUE(AllOpt);
 
   // Since all parsing succeeded, the error message should be empty.
-  OS.flush();
   EXPECT_TRUE(Errs.empty());
 }
 
@@ -657,14 +655,12 @@ TEST(CommandLineTest, RemoveFromRegularSubCommand) {
   EXPECT_FALSE(RemoveOption);
   EXPECT_TRUE(cl::ParseCommandLineOptions(3, args, StringRef(), &OS));
   EXPECT_TRUE(RemoveOption);
-  OS.flush();
   EXPECT_TRUE(Errs.empty());
 
   RemoveOption.removeArgument();
 
   cl::ResetAllOptionOccurrences();
   EXPECT_FALSE(cl::ParseCommandLineOptions(3, args, StringRef(), &OS));
-  OS.flush();
   EXPECT_FALSE(Errs.empty());
 }
 
@@ -1277,15 +1273,15 @@ TEST(CommandLineTest, PositionalEatArgsError) {
 
   std::string Errs;
   raw_string_ostream OS(Errs);
-  EXPECT_FALSE(cl::ParseCommandLineOptions(2, args, StringRef(), &OS)); OS.flush();
+  EXPECT_FALSE(cl::ParseCommandLineOptions(2, args, StringRef(), &OS));
   EXPECT_FALSE(Errs.empty()); Errs.clear();
-  EXPECT_FALSE(cl::ParseCommandLineOptions(3, args2, StringRef(), &OS)); OS.flush();
+  EXPECT_FALSE(cl::ParseCommandLineOptions(3, args2, StringRef(), &OS));
   EXPECT_FALSE(Errs.empty()); Errs.clear();
-  EXPECT_TRUE(cl::ParseCommandLineOptions(3, args3, StringRef(), &OS)); OS.flush();
+  EXPECT_TRUE(cl::ParseCommandLineOptions(3, args3, StringRef(), &OS));
   EXPECT_TRUE(Errs.empty()); Errs.clear();
 
   cl::ResetAllOptionOccurrences();
-  EXPECT_TRUE(cl::ParseCommandLineOptions(6, args4, StringRef(), &OS)); OS.flush();
+  EXPECT_TRUE(cl::ParseCommandLineOptions(6, args4, StringRef(), &OS));
   EXPECT_EQ(PosEatArgs.size(), 1u);
   EXPECT_EQ(PosEatArgs2.size(), 2u);
   EXPECT_TRUE(Errs.empty());
@@ -1875,7 +1871,7 @@ TEST(CommandLineTest, LongOptions) {
   //
 
   EXPECT_TRUE(
-      cl::ParseCommandLineOptions(4, args1, StringRef(), &OS)); OS.flush();
+      cl::ParseCommandLineOptions(4, args1, StringRef(), &OS));
   EXPECT_TRUE(OptA);
   EXPECT_FALSE(OptBLong);
   EXPECT_STREQ("val1", OptAB.c_str());
@@ -1883,7 +1879,7 @@ TEST(CommandLineTest, LongOptions) {
   cl::ResetAllOptionOccurrences();
 
   EXPECT_TRUE(
-      cl::ParseCommandLineOptions(4, args2, StringRef(), &OS)); OS.flush();
+      cl::ParseCommandLineOptions(4, args2, StringRef(), &OS));
   EXPECT_TRUE(OptA);
   EXPECT_FALSE(OptBLong);
   EXPECT_STREQ("val1", OptAB.c_str());
@@ -1893,7 +1889,7 @@ TEST(CommandLineTest, LongOptions) {
   // Fails because `-ab` and `--ab` are treated the same and appear more than
   // once.  Also, `val1` is unexpected.
   EXPECT_FALSE(
-      cl::ParseCommandLineOptions(4, args3, StringRef(), &OS)); OS.flush();
+      cl::ParseCommandLineOptions(4, args3, StringRef(), &OS));
   outs()<< Errs << "\n";
   EXPECT_FALSE(Errs.empty()); Errs.clear();
   cl::ResetAllOptionOccurrences();
@@ -1906,13 +1902,13 @@ TEST(CommandLineTest, LongOptions) {
   // Fails because `-ab` is treated as `-a -b`, so `-a` is seen twice, and
   // `val1` is unexpected.
   EXPECT_FALSE(cl::ParseCommandLineOptions(4, args1, StringRef(),
-                                           &OS, nullptr, true)); OS.flush();
+                                           &OS, nullptr, true));
   EXPECT_FALSE(Errs.empty()); Errs.clear();
   cl::ResetAllOptionOccurrences();
 
   // Works because `-a` is treated differently than `--ab`.
   EXPECT_TRUE(cl::ParseCommandLineOptions(4, args2, StringRef(),
-                                           &OS, nullptr, true)); OS.flush();
+                                           &OS, nullptr, true));
   EXPECT_TRUE(Errs.empty()); Errs.clear();
   cl::ResetAllOptionOccurrences();
 
@@ -1922,7 +1918,6 @@ TEST(CommandLineTest, LongOptions) {
   EXPECT_TRUE(OptA);
   EXPECT_TRUE(OptBLong);
   EXPECT_STREQ("val1", OptAB.c_str());
-  OS.flush();
   EXPECT_TRUE(Errs.empty()); Errs.clear();
   cl::ResetAllOptionOccurrences();
 }
@@ -1941,12 +1936,10 @@ TEST(CommandLineTest, OptionErrorMessage) {
   raw_string_ostream OS(Errs);
 
   OptA.error("custom error", OS);
-  OS.flush();
   EXPECT_NE(Errs.find("for the -a option:"), std::string::npos);
   Errs.clear();
 
   OptLong.error("custom error", OS);
-  OS.flush();
   EXPECT_NE(Errs.find("for the --long option:"), std::string::npos);
   Errs.clear();
 
@@ -1969,7 +1962,6 @@ TEST(CommandLineTest, OptionErrorMessageSuggest) {
   raw_string_ostream OS(Errs);
 
   EXPECT_FALSE(cl::ParseCommandLineOptions(2, args, StringRef(), &OS));
-  OS.flush();
   EXPECT_NE(Errs.find("prog: Did you mean '--aluminium'?\n"),
             std::string::npos);
   Errs.clear();
@@ -1992,7 +1984,6 @@ TEST(CommandLineTest, OptionErrorMessageSuggestNoHidden) {
   raw_string_ostream OS(Errs);
 
   EXPECT_FALSE(cl::ParseCommandLineOptions(2, args, StringRef(), &OS));
-  OS.flush();
   EXPECT_NE(Errs.find("prog: Did you mean '--aluminium'?\n"),
             std::string::npos);
   Errs.clear();
@@ -2082,7 +2073,6 @@ TEST(CommandLineTest, ConsumeAfterOnePositional) {
   std::string Errs;
   raw_string_ostream OS(Errs);
   EXPECT_TRUE(cl::ParseCommandLineOptions(4, Args, StringRef(), &OS));
-  OS.flush();
   EXPECT_EQ("input", Input);
   EXPECT_EQ(ExtraArgs.size(), 2u);
   EXPECT_EQ(ExtraArgs[0], "arg1");
@@ -2105,7 +2095,6 @@ TEST(CommandLineTest, ConsumeAfterTwoPositionals) {
   std::string Errs;
   raw_string_ostream OS(Errs);
   EXPECT_TRUE(cl::ParseCommandLineOptions(5, Args, StringRef(), &OS));
-  OS.flush();
   EXPECT_EQ("input1", Input1);
   EXPECT_EQ("input2", Input2);
   EXPECT_EQ(ExtraArgs.size(), 2u);
diff --git a/llvm/unittests/Support/CrashRecoveryTest.cpp b/llvm/unittests/Support/CrashRecoveryTest.cpp
index 4026300..a22e532 100644
--- a/llvm/unittests/Support/CrashRecoveryTest.cpp
+++ b/llvm/unittests/Support/CrashRecoveryTest.cpp
@@ -111,8 +111,7 @@ TEST(CrashRecoveryTest, LimitedStackTrace) {
   std::string Res;
   llvm::raw_string_ostream RawStream(Res);
   PrintStackTrace(RawStream, 1);
-  std::string Str = RawStream.str();
-  EXPECT_EQ(std::string::npos, Str.find("#1"));
+  EXPECT_EQ(std::string::npos, Res.find("#1"));
 }
 
 #ifdef _WIN32
diff --git a/llvm/unittests/Support/ErrorTest.cpp b/llvm/unittests/Support/ErrorTest.cpp
index 16e4865..98d19e8 100644
--- a/llvm/unittests/Support/ErrorTest.cpp
+++ b/llvm/unittests/Support/ErrorTest.cpp
@@ -460,13 +460,11 @@ TEST(Error, createStringError) {
   EXPECT_EQ(Msg, "foobar10xff\n")
       << "Unexpected createStringError() log result";
 
-  S.flush();
   Msg.clear();
   logAllUnhandledErrors(createStringError(EC, Bar), S);
   EXPECT_EQ(Msg, "bar\n")
       << "Unexpected createStringError() (overloaded) log result";
 
-  S.flush();
   Msg.clear();
   auto Res = errorToErrorCode(createStringError(EC, "foo%s", Bar));
   EXPECT_EQ(Res, EC)
diff --git a/llvm/unittests/Support/FormatVariadicTest.cpp b/llvm/unittests/Support/FormatVariadicTest.cpp
index 6893848..8e326e1 100644
--- a/llvm/unittests/Support/FormatVariadicTest.cpp
+++ b/llvm/unittests/Support/FormatVariadicTest.cpp
@@ -585,7 +585,6 @@ TEST(FormatVariadicTest, BigTest) {
   for (auto &Item : Ts) {
     Stream << std::apply(format_tuple(Line), Item) << "\n";
   }
-  Stream.flush();
   const char *Expected =
       R"foo(There are {14} items in the tuple, and {2} tuple(s) in the array.
   Char|  HexInt|   Str    |   Ref    |  std::str   | double|  float|   pointer|comma  |       exp|          bigint|          bigint2| limit|byte
diff --git a/llvm/unittests/Support/LEB128Test.cpp b/llvm/unittests/Support/LEB128Test.cpp
index 5aa7139..0c54a28 100644
--- a/llvm/unittests/Support/LEB128Test.cpp
+++ b/llvm/unittests/Support/LEB128Test.cpp
@@ -24,7 +24,6 @@ TEST(LEB128Test, EncodeSLEB128) {
     std::string Actual1; \
     raw_string_ostream Stream(Actual1); \
     encodeSLEB128(VALUE, Stream, PAD); \
-    Stream.flush(); \
     EXPECT_EQ(Expected, Actual1); \
     \
     /* encodeSLEB128(uint64_t, uint8_t *, unsigned) */ \
@@ -69,7 +68,6 @@ TEST(LEB128Test, EncodeULEB128) {
     std::string Actual1; \
     raw_string_ostream Stream(Actual1); \
     encodeULEB128(VALUE, Stream, PAD); \
-    Stream.flush(); \
     EXPECT_EQ(Expected, Actual1); \
     \
     /* encodeULEB128(uint64_t, uint8_t *, unsigned) */ \
diff --git a/llvm/unittests/Support/ModRefTest.cpp b/llvm/unittests/Support/ModRefTest.cpp
index 5ebb5f6..35107e5 100644
--- a/llvm/unittests/Support/ModRefTest.cpp
+++ b/llvm/unittests/Support/ModRefTest.cpp
@@ -21,7 +21,6 @@ TEST(ModRefTest, PrintMemoryEffects) {
   std::string S;

   raw_string_ostream OS(S);

   OS << MemoryEffects::none();

-  OS.flush();

   EXPECT_EQ(S, "ArgMem: NoModRef, InaccessibleMem: NoModRef, Other: NoModRef");

 }

 

diff --git a/llvm/unittests/Support/NativeFormatTests.cpp b/llvm/unittests/Support/NativeFormatTests.cpp
index 1175306..ac04c5a 100644
--- a/llvm/unittests/Support/NativeFormatTests.cpp
+++ b/llvm/unittests/Support/NativeFormatTests.cpp
@@ -20,7 +20,6 @@ template <typename T> std::string format_number(T N, IntegerStyle Style) {
   std::string S;
   llvm::raw_string_ostream Str(S);
   write_integer(Str, N, 0, Style);
-  Str.flush();
   return S;
 }
 
@@ -29,7 +28,6 @@ std::string format_number(uint64_t N, HexPrintStyle Style,
   std::string S;
   llvm::raw_string_ostream Str(S);
   write_hex(Str, N, Style, Width);
-  Str.flush();
   return S;
 }
 
@@ -38,7 +36,6 @@ std::string format_number(double D, FloatStyle Style,
   std::string S;
   llvm::raw_string_ostream Str(S);
   write_double(Str, D, Style, Precision);
-  Str.flush();
   return S;
 }
 
diff --git a/llvm/unittests/Support/RISCVAttributeParserTest.cpp b/llvm/unittests/Support/RISCVAttributeParserTest.cpp
index 498f58e..aa73bb9 100644
--- a/llvm/unittests/Support/RISCVAttributeParserTest.cpp
+++ b/llvm/unittests/Support/RISCVAttributeParserTest.cpp
@@ -38,8 +38,8 @@ static bool testAttribute(unsigned Tag, unsigned Value, unsigned ExpectedTag,
   raw_string_ostream OS(buffer);
   RISCVAttributeSection Section(Tag, Value);
   Section.write(OS);
-  ArrayRef<uint8_t> Bytes(reinterpret_cast<const uint8_t *>(OS.str().c_str()),
-                          OS.str().size());
+  ArrayRef<uint8_t> Bytes(reinterpret_cast<const uint8_t *>(buffer.c_str()),
+                          buffer.size());
 
   RISCVAttributeParser Parser;
   cantFail(Parser.parse(Bytes, llvm::endianness::little));
diff --git a/llvm/unittests/Support/SourceMgrTest.cpp b/llvm/unittests/Support/SourceMgrTest.cpp
index 75a0cfe..f5366a7 100644
--- a/llvm/unittests/Support/SourceMgrTest.cpp
+++ b/llvm/unittests/Support/SourceMgrTest.cpp
@@ -537,7 +537,6 @@ TEST_F(SourceMgrTest, PrintWithoutLoc) {
   auto Diag =
       llvm::SMDiagnostic("file.in", llvm::SourceMgr::DK_Error, "message");
   Diag.print(nullptr, OS);
-  OS.flush();
   EXPECT_EQ("file.in: error: message\n", Output);
   Output.clear();
   Diag.print(nullptr, OS, false, false, false);
diff --git a/llvm/unittests/Support/VirtualFileSystemTest.cpp b/llvm/unittests/Support/VirtualFileSystemTest.cpp
index 8d1eb69..eb590e4 100644
--- a/llvm/unittests/Support/VirtualFileSystemTest.cpp
+++ b/llvm/unittests/Support/VirtualFileSystemTest.cpp
@@ -2927,7 +2927,6 @@ TEST_F(VFSFromYAMLTest, YAMLVFSWriterTest) {
   std::string Buffer;
   raw_string_ostream OS(Buffer);
   VFSWriter.write(OS);
-  OS.flush();
 
   IntrusiveRefCntPtr<ErrorDummyFileSystem> Lower(new ErrorDummyFileSystem());
   Lower->addDirectory("//root/");
@@ -2978,7 +2977,6 @@ TEST_F(VFSFromYAMLTest, YAMLVFSWriterTest2) {
   std::string Buffer;
   raw_string_ostream OS(Buffer);
   VFSWriter.write(OS);
-  OS.flush();
 
   IntrusiveRefCntPtr<ErrorDummyFileSystem> Lower(new ErrorDummyFileSystem());
   IntrusiveRefCntPtr<vfs::FileSystem> FS = getFromYAMLRawString(Buffer, Lower);
@@ -3011,7 +3009,6 @@ TEST_F(VFSFromYAMLTest, YAMLVFSWriterTest3) {
   std::string Buffer;
   raw_string_ostream OS(Buffer);
   VFSWriter.write(OS);
-  OS.flush();
 
   IntrusiveRefCntPtr<ErrorDummyFileSystem> Lower(new ErrorDummyFileSystem());
   IntrusiveRefCntPtr<vfs::FileSystem> FS = getFromYAMLRawString(Buffer, Lower);
@@ -3032,7 +3029,6 @@ TEST_F(VFSFromYAMLTest, YAMLVFSWriterTestHandleDirs) {
   std::string Buffer;
   raw_string_ostream OS(Buffer);
   VFSWriter.write(OS);
-  OS.flush();
 
   // We didn't add a single file - only directories.
   EXPECT_EQ(Buffer.find("'type': 'file'"), std::string::npos);
diff --git a/llvm/unittests/Support/YAMLIOTest.cpp b/llvm/unittests/Support/YAMLIOTest.cpp
index 69537fc..e10fe09 100644
--- a/llvm/unittests/Support/YAMLIOTest.cpp
+++ b/llvm/unittests/Support/YAMLIOTest.cpp
@@ -1378,7 +1378,6 @@ TEST(YAMLIO, TestReadWriteMyFlowSequence) {
     yout << map;
 
     // Verify sequences were written in flow style
-    ostr.flush();
     llvm::StringRef flowOut(intermediate);
     EXPECT_NE(llvm::StringRef::npos, flowOut.find("one, two"));
     EXPECT_NE(llvm::StringRef::npos, flowOut.find("10, -30, 1024"));
@@ -1424,7 +1423,6 @@ TEST(YAMLIO, TestReadWriteSequenceOfMyFlowSequence) {
 
     // Verify sequences were written in flow style
     // and that the parent sequence used '-'.
-    ostr.flush();
     llvm::StringRef flowOut(intermediate);
     EXPECT_NE(llvm::StringRef::npos, flowOut.find("- [ 0 ]"));
     EXPECT_NE(llvm::StringRef::npos, flowOut.find("- [ 12, 1, -512 ]"));
@@ -1935,7 +1933,6 @@ TEST(YAMLIO, TestReadWriteMyFlowMapping) {
     yout << doc;
 
     // Verify that mappings were written in flow style
-    ostr.flush();
     llvm::StringRef flowOut(intermediate);
     EXPECT_NE(llvm::StringRef::npos, flowOut.find("{ foo: 42, bar: 907 }"));
     EXPECT_NE(llvm::StringRef::npos, flowOut.find("- { foo: 1, bar: 2 }"));
@@ -2538,7 +2535,6 @@ TEST(YAMLIO, TestWrapFlow) {
     Output yout(ostr, nullptr, 15);
 
     yout << Map;
-    ostr.flush();
     EXPECT_EQ(out,
               "---\n"
               "{ str1: This is str1, \n"
@@ -2548,7 +2544,6 @@ TEST(YAMLIO, TestWrapFlow) {
     out.clear();
 
     yout << Seq;
-    ostr.flush();
     EXPECT_EQ(out,
               "---\n"
               "[ This is str1, \n"
@@ -2562,7 +2557,6 @@ TEST(YAMLIO, TestWrapFlow) {
     Output yout(ostr, nullptr, 25);
 
     yout << Map;
-    ostr.flush();
     EXPECT_EQ(out,
               "---\n"
               "{ str1: This is str1, str2: This is str2, \n"
@@ -2571,7 +2565,6 @@ TEST(YAMLIO, TestWrapFlow) {
     out.clear();
 
     yout << Seq;
-    ostr.flush();
     EXPECT_EQ(out,
               "---\n"
               "[ This is str1, This is str2, \n"
@@ -2584,7 +2577,6 @@ TEST(YAMLIO, TestWrapFlow) {
     Output yout(ostr, nullptr, 0);
 
     yout << Map;
-    ostr.flush();
     EXPECT_EQ(out,
               "---\n"
               "{ str1: This is str1, str2: This is str2, str3: This is str3 }\n"
@@ -2592,7 +2584,6 @@ TEST(YAMLIO, TestWrapFlow) {
     out.clear();
 
     yout << Seq;
-    ostr.flush();
     EXPECT_EQ(out,
               "---\n"
               "[ This is str1, This is str2, This is str3 ]\n"
@@ -2646,7 +2637,6 @@ TEST(YAMLIO, TestMapWithContext) {
   Output yout(ostr, nullptr, 15);
 
   yout << Nested;
-  ostr.flush();
   EXPECT_EQ(1, Context.A);
   EXPECT_EQ("---\n"
             "Simple:\n"
@@ -2661,7 +2651,6 @@ TEST(YAMLIO, TestMapWithContext) {
   Nested.Simple.B = 2;
   Nested.Simple.C = 3;
   yout << Nested;
-  ostr.flush();
   EXPECT_EQ(2, Context.A);
   EXPECT_EQ("---\n"
             "Simple:\n"
@@ -2683,7 +2672,6 @@ TEST(YAMLIO, TestCustomMapping) {
   Output xout(ostr, nullptr, 0);
 
   xout << x;
-  ostr.flush();
   EXPECT_EQ("---\n"
             "{}\n"
             "...\n",
@@ -2694,7 +2682,6 @@ TEST(YAMLIO, TestCustomMapping) {
 
   out.clear();
   xout << x;
-  ostr.flush();
   EXPECT_EQ("---\n"
             "bar:             2\n"
             "foo:             1\n"
@@ -2723,7 +2710,6 @@ TEST(YAMLIO, TestCustomMappingStruct) {
   Output xout(ostr, nullptr, 0);
 
   xout << x;
-  ostr.flush();
   EXPECT_EQ("---\n"
             "bar:\n"
             "  foo:             3\n"
@@ -2795,8 +2781,6 @@ static void TestEscaped(llvm::StringRef Input, llvm::StringRef Expected) {
   llvm::yaml::EmptyContext Ctx;
   yamlize(xout, Input, true, Ctx);
 
-  ostr.flush();
-
   // Make a separate StringRef so we get nice byte-by-byte output.
   llvm::StringRef Got(out);
   EXPECT_EQ(Expected, Got);
diff --git a/llvm/unittests/Target/RISCV/RISCVInstrInfoTest.cpp b/llvm/unittests/Target/RISCV/RISCVInstrInfoTest.cpp
index cc0aca1..820918f 100644
--- a/llvm/unittests/Target/RISCV/RISCVInstrInfoTest.cpp
+++ b/llvm/unittests/Target/RISCV/RISCVInstrInfoTest.cpp
@@ -243,8 +243,7 @@ static void expectDIEPrintResult(const DIExpression *Expr, StringRef Expected) {
   std::string Output;
   raw_string_ostream OS(Output);
   Expr->print(OS);
-  OS.flush();
-  EXPECT_EQ(OS.str(), Expected);
+  EXPECT_EQ(Output, Expected);
 }
 
 TEST_P(RISCVInstrInfoTest, DescribeLoadedValue) {
diff --git a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
index 9cf9060..a7ff510 100644
--- a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
+++ b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
@@ -705,7 +705,6 @@ TEST(VPBasicBlockTest, print) {
     raw_string_ostream OS(I3Dump);
     VPSlotTracker SlotTracker;
     I3->print(OS, "", SlotTracker);
-    OS.flush();
     EXPECT_EQ("EMIT br <badref>, <badref>", I3Dump);
   }
 
@@ -769,7 +768,6 @@ No successors
     raw_string_ostream OS(I3Dump);
     VPSlotTracker SlotTracker(&Plan);
     I3->print(OS, "", SlotTracker);
-    OS.flush();
     EXPECT_EQ("EMIT br vp<%2>, vp<%3>", I3Dump);
   }
 
@@ -777,7 +775,6 @@ No successors
     std::string I4Dump;
     raw_string_ostream OS(I4Dump);
     OS << *I4;
-    OS.flush();
     EXPECT_EQ("EMIT vp<%5> = mul vp<%3>, vp<%2>", I4Dump);
   }
 }
diff --git a/llvm/unittests/XRay/FDRProducerConsumerTest.cpp b/llvm/unittests/XRay/FDRProducerConsumerTest.cpp
index ab55e22..24acb89 100644
--- a/llvm/unittests/XRay/FDRProducerConsumerTest.cpp
+++ b/llvm/unittests/XRay/FDRProducerConsumerTest.cpp
@@ -127,7 +127,6 @@ TYPED_TEST_P(RoundTripTest, RoundTripsSingleValue) {
   ASSERT_FALSE(errorToBool(BE.apply(*this->Writer)));
   auto &R = this->Rec;
   ASSERT_FALSE(errorToBool(R->apply(*this->Writer)));
-  this->OS.flush();
 
   DataExtractor DE(this->Data, sys::IsLittleEndianHost, 8);
   uint64_t OffsetPtr = 0;
@@ -151,7 +150,6 @@ TYPED_TEST_P(RoundTripTest, RoundTripsSingleValue) {
   FDRTraceWriter Writer2(OS2, this->H);
   for (auto &P : Records)
     ASSERT_FALSE(errorToBool(P->apply(Writer2)));
-  OS2.flush();
 
   EXPECT_EQ(Data2.substr(sizeof(XRayFileHeader)),
             this->Data.substr(sizeof(XRayFileHeader)));
@@ -168,7 +166,6 @@ TYPED_TEST_P(RoundTripTestV5, RoundTripsSingleValue) {
   ASSERT_FALSE(errorToBool(BE.apply(*this->Writer)));
   auto &R = this->Rec;
   ASSERT_FALSE(errorToBool(R->apply(*this->Writer)));
-  this->OS.flush();
 
   DataExtractor DE(this->Data, sys::IsLittleEndianHost, 8);
   uint64_t OffsetPtr = 0;
@@ -192,7 +189,6 @@ TYPED_TEST_P(RoundTripTestV5, RoundTripsSingleValue) {
   FDRTraceWriter Writer2(OS2, this->H);
   for (auto &P : Records)
     ASSERT_FALSE(errorToBool(P->apply(Writer2)));
-  OS2.flush();
 
   EXPECT_EQ(Data2.substr(sizeof(XRayFileHeader)),
             this->Data.substr(sizeof(XRayFileHeader)));
diff --git a/llvm/unittests/XRay/FDRRecordPrinterTest.cpp b/llvm/unittests/XRay/FDRRecordPrinterTest.cpp
index a29112f..19ce21c 100644
--- a/llvm/unittests/XRay/FDRRecordPrinterTest.cpp
+++ b/llvm/unittests/XRay/FDRRecordPrinterTest.cpp
@@ -112,7 +112,6 @@ TYPED_TEST_SUITE_P(PrinterTest);
 TYPED_TEST_P(PrinterTest, PrintsRecord) {
   ASSERT_NE(nullptr, this->R);
   ASSERT_FALSE(errorToBool(this->R->apply(this->P)));
-  this->OS.flush();
   EXPECT_THAT(this->Data, Eq(Helper<TypeParam>::expected()));
 }
 
@@ -130,7 +129,6 @@ TEST(FDRRecordPrinterTest, WriteFunctionRecordEnter) {
   RecordPrinter P(OS);
   FunctionRecord R(RecordTypes::ENTER, 1, 2);
   ASSERT_FALSE(errorToBool(R.apply(P)));
-  OS.flush();
   EXPECT_THAT(Data, Eq("<Function Enter: #1 delta = +2>"));
 }
 
@@ -140,7 +138,6 @@ TEST(FDRRecordPrinterTest, WriteFunctionRecordExit) {
   RecordPrinter P(OS);
   FunctionRecord R(RecordTypes::EXIT, 1, 2);
   ASSERT_FALSE(errorToBool(R.apply(P)));
-  OS.flush();
   EXPECT_THAT(Data, Eq("<Function Exit: #1 delta = +2>"));
 }
 
@@ -150,7 +147,6 @@ TEST(FDRRecordPrinterTest, WriteFunctionRecordTailExit) {
   RecordPrinter P(OS);
   FunctionRecord R(RecordTypes::TAIL_EXIT, 1, 2);
   ASSERT_FALSE(errorToBool(R.apply(P)));
-  OS.flush();
   EXPECT_THAT(Data, Eq("<Function Tail Exit: #1 delta = +2>"));
 }
 
@@ -160,7 +156,6 @@ TEST(FDRRecordPrinterTest, WriteFunctionRecordEnterArg) {
   RecordPrinter P(OS);
   FunctionRecord R(RecordTypes::ENTER_ARG, 1, 2);
   ASSERT_FALSE(errorToBool(R.apply(P)));
-  OS.flush();
   EXPECT_THAT(Data, Eq("<Function Enter With Arg: #1 delta = +2>"));
 }
 
diff --git a/llvm/unittests/XRay/FDRRecordsTest.cpp b/llvm/unittests/XRay/FDRRecordsTest.cpp
index aac3c86..e231bf5 100644
--- a/llvm/unittests/XRay/FDRRecordsTest.cpp
+++ b/llvm/unittests/XRay/FDRRecordsTest.cpp
@@ -158,7 +158,6 @@ TEST(XRayFDRTest, IndexAndVerifyBlocks) {
     }
   }
 
-  OS.flush();
   EXPECT_THAT(Output, Not(Eq("")));
 }
 
diff --git a/llvm/unittests/XRay/FDRTraceWriterTest.cpp b/llvm/unittests/XRay/FDRTraceWriterTest.cpp
index 4f2f06e4..32c75e4 100644
--- a/llvm/unittests/XRay/FDRTraceWriterTest.cpp
+++ b/llvm/unittests/XRay/FDRTraceWriterTest.cpp
@@ -52,7 +52,6 @@ TEST(FDRTraceWriterTest, WriteToStringBufferVersion3) {
                .consume();
   for (auto &P : L)
     ASSERT_FALSE(errorToBool(P->apply(Writer)));
-  OS.flush();
 
   // Then from here we load the Trace file.
   DataExtractor DE(Data, sys::IsLittleEndianHost, 8);
@@ -97,7 +96,6 @@ TEST(FDRTraceWriterTest, WriteToStringBufferVersion2) {
                .consume();
   for (auto &P : L)
     ASSERT_FALSE(errorToBool(P->apply(Writer)));
-  OS.flush();
 
   // Then from here we load the Trace file.
   DataExtractor DE(Data, sys::IsLittleEndianHost, 8);
@@ -134,7 +132,6 @@ TEST(FDRTraceWriterTest, WriteToStringBufferVersion1) {
   std::memcpy(H.FreeFormData, reinterpret_cast<const char *>(&BufferSize),
               sizeof(BufferSize));
   FDRTraceWriter Writer(OS, H);
-  OS.flush();
 
   // Ensure that at this point the Data buffer has the file header serialized
   // size.
@@ -152,7 +149,6 @@ TEST(FDRTraceWriterTest, WriteToStringBufferVersion1) {
 
   // We need to pad the buffer with 4016 (4096 - 80) bytes of zeros.
   OS.write_zeros(4016);
-  OS.flush();
 
   // For version 1 of the log, we need the whole buffer to be the size of the
   // file header plus 32.
diff --git a/llvm/unittests/tools/llvm-exegesis/ProgressMeterTest.cpp b/llvm/unittests/tools/llvm-exegesis/ProgressMeterTest.cpp
index 0b06499..58cc5304 100644
--- a/llvm/unittests/tools/llvm-exegesis/ProgressMeterTest.cpp
+++ b/llvm/unittests/tools/llvm-exegesis/ProgressMeterTest.cpp
@@ -47,7 +47,6 @@ TEST(ProgressMeterTest, Integration) {
   ProgressMeter<PreprogrammedClock> m(5, SS);
   for (int i = 0; i != 5; ++i)
     decltype(m)::ProgressMeterStep s(&m);
-  SS.flush();
   ASSERT_EQ("Processing...  20%, ETA 00:20\n"
             "Processing...  40%, ETA 00:29\n"
             "Processing...  60%, ETA 00:23\n"