//===- Diagnostic.cpp - C Language Family Diagnostic Handling -------------===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

//  This file implements the Diagnostic-related interfaces.

//

//===----------------------------------------------------------------------===//

#include "clang/Basic/Diagnostic.h"

#include "clang/Basic/CharInfo.h"

#include "clang/Basic/DiagnosticError.h"

#include "clang/Basic/DiagnosticIDs.h"

#include "clang/Basic/DiagnosticOptions.h"

#include "clang/Basic/IdentifierTable.h"

#include "clang/Basic/PartialDiagnostic.h"

#include "clang/Basic/SourceLocation.h"

#include "clang/Basic/SourceManager.h"

#include "clang/Basic/Specifiers.h"

#include "clang/Basic/TokenKinds.h"

#include "llvm/ADT/SmallString.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/ADT/StringExtras.h"

#include "llvm/ADT/StringRef.h"

#include "llvm/Support/ConvertUTF.h"

#include "llvm/Support/CrashRecoveryContext.h"

#include "llvm/Support/Unicode.h"

#include "llvm/Support/raw_ostream.h"

#include <algorithm>

#include <cassert>

#include <cstddef>

#include <cstdint>

#include <cstring>

#include <limits>

#include <string>

#include <utility>

#include <vector>

using namespace clang;

const StreamingDiagnostic &clang::operator<<(const StreamingDiagnostic &DB,

                                             DiagNullabilityKind nullability) {

  DB.AddString(

      ("'" +

       getNullabilitySpelling(nullability.first,

                              /*isContextSensitive=*/nullability.second) +

       "'")

          .str());

  return DB;

}

const StreamingDiagnostic &clang::operator<<(const StreamingDiagnostic &DB,

                                             llvm::Error &&E) {

  DB.AddString(toString(std::move(E)));

  return DB;

}

static void DummyArgToStringFn(DiagnosticsEngine::ArgumentKind AK, intptr_t QT,

                            StringRef Modifier, StringRef Argument,

                            ArrayRef<DiagnosticsEngine::ArgumentValue> PrevArgs,

                            SmallVectorImpl<char> &Output,

                            void *Cookie,

                            ArrayRef<intptr_t> QualTypeVals) {

  StringRef Str = "<can't format argument>";

  Output.append(Str.begin(), Str.end());

}

DiagnosticsEngine::DiagnosticsEngine(

    IntrusiveRefCntPtr<DiagnosticIDs> diags,

    IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts, DiagnosticConsumer *client,

    bool ShouldOwnClient)

    : Diags(std::move(diags)), DiagOpts(std::move(DiagOpts)) {

  setClient(client, ShouldOwnClient);

  ArgToStringFn = DummyArgToStringFn;

  Reset();

}

DiagnosticsEngine::~DiagnosticsEngine() {

  // If we own the diagnostic client, destroy it first so that it can access the

  // engine from its destructor.

  setClient(nullptr);

}

void DiagnosticsEngine::dump() const {

  DiagStatesByLoc.dump(*SourceMgr);

}

void DiagnosticsEngine::dump(StringRef DiagName) const {

  DiagStatesByLoc.dump(*SourceMgr, DiagName);

}

void DiagnosticsEngine::setClient(DiagnosticConsumer *client,

                                  bool ShouldOwnClient) {

  Owner.reset(ShouldOwnClient ? client : nullptr);

  Client = client;

}

void DiagnosticsEngine::pushMappings(SourceLocation Loc) {

  DiagStateOnPushStack.push_back(GetCurDiagState());

}

bool DiagnosticsEngine::popMappings(SourceLocation Loc) {

  if (DiagStateOnPushStack.empty())

    return false;

  if (DiagStateOnPushStack.back() != GetCurDiagState()) {

    // State changed at some point between push/pop.

    PushDiagStatePoint(DiagStateOnPushStack.back(), Loc);

  }

  DiagStateOnPushStack.pop_back();

  return true;

}

void DiagnosticsEngine::Reset(bool soft /*=false*/) {

  ErrorOccurred = false;

  UncompilableErrorOccurred = false;

  FatalErrorOccurred = false;

  UnrecoverableErrorOccurred = false;

  NumWarnings = 0;

  NumErrors = 0;

  TrapNumErrorsOccurred = 0;

  TrapNumUnrecoverableErrorsOccurred = 0;

  CurDiagID = std::numeric_limits<unsigned>::max();

  LastDiagLevel = DiagnosticIDs::Ignored;

  DelayedDiagID = 0;

  if (!soft) {

    // Clear state related to #pragma diagnostic.

    DiagStates.clear();

    DiagStatesByLoc.clear();

    DiagStateOnPushStack.clear();

    // Create a DiagState and DiagStatePoint representing diagnostic changes

    // through command-line.

    DiagStates.emplace_back();

    DiagStatesByLoc.appendFirst(&DiagStates.back());

  }

}

void DiagnosticsEngine::SetDelayedDiagnostic(unsigned DiagID, StringRef Arg1,

                                             StringRef Arg2, StringRef Arg3) {

  if (DelayedDiagID)

    return;

  DelayedDiagID = DiagID;

  DelayedDiagArg1 = Arg1.str();

  DelayedDiagArg2 = Arg2.str();

  DelayedDiagArg3 = Arg3.str();

}

void DiagnosticsEngine::ReportDelayed() {

  unsigned ID = DelayedDiagID;

  DelayedDiagID = 0;

  Report(ID) << DelayedDiagArg1 << DelayedDiagArg2 << DelayedDiagArg3;

}

DiagnosticMapping &

DiagnosticsEngine::DiagState::getOrAddMapping(diag::kind Diag) {

  std::pair<iterator, bool> Result =

      DiagMap.insert(std::make_pair(Diag, DiagnosticMapping()));

  // Initialize the entry if we added it.

  if (Result.second)

    Result.first->second = DiagnosticIDs::getDefaultMapping(Diag);

  return Result.first->second;

}

void DiagnosticsEngine::DiagStateMap::appendFirst(DiagState *State) {

  assert(Files.empty() && "not first");

  FirstDiagState = CurDiagState = State;

  CurDiagStateLoc = SourceLocation();

}

void DiagnosticsEngine::DiagStateMap::append(SourceManager &SrcMgr,

                                             SourceLocation Loc,

                                             DiagState *State) {

  CurDiagState = State;

  CurDiagStateLoc = Loc;

  std::pair<FileID, unsigned> Decomp = SrcMgr.getDecomposedLoc(Loc);

  unsigned Offset = Decomp.second;

  for (File *F = getFile(SrcMgr, Decomp.first); F;

       Offset = F->ParentOffset, F = F->Parent) {

    F->HasLocalTransitions = true;

    auto &Last = F->StateTransitions.back();

    assert(Last.Offset <= Offset && "state transitions added out of order");

    if (Last.Offset == Offset) {

      if (Last.State == State)

        break;

      Last.State = State;

      continue;

    }

    F->StateTransitions.push_back({State, Offset});

  }

}

DiagnosticsEngine::DiagState *

DiagnosticsEngine::DiagStateMap::lookup(SourceManager &SrcMgr,

                                        SourceLocation Loc) const {

  // Common case: we have not seen any diagnostic pragmas.

  if (Files.empty())

    return FirstDiagState;

  std::pair<FileID, unsigned> Decomp = SrcMgr.getDecomposedLoc(Loc);

  const File *F = getFile(SrcMgr, Decomp.first);

  return F->lookup(Decomp.second);

}

DiagnosticsEngine::DiagState *

DiagnosticsEngine::DiagStateMap::File::lookup(unsigned Offset) const {

  auto OnePastIt =

      llvm::partition_point(StateTransitions, [=](const DiagStatePoint &P) {

        return P.Offset <= Offset;

      });

  assert(OnePastIt != StateTransitions.begin() && "missing initial state");

  return OnePastIt[-1].State;

}

DiagnosticsEngine::DiagStateMap::File *

DiagnosticsEngine::DiagStateMap::getFile(SourceManager &SrcMgr,

                                         FileID ID) const {

  // Get or insert the File for this ID.

  auto Range = Files.equal_range(ID);

  if (Range.first != Range.second)

    return &Range.first->second;

  auto &F = Files.insert(Range.first, std::make_pair(ID, File()))->second;

  // We created a new File; look up the diagnostic state at the start of it and

  // initialize it.

  if (ID.isValid()) {

    std::pair<FileID, unsigned> Decomp = SrcMgr.getDecomposedIncludedLoc(ID);

    F.Parent = getFile(SrcMgr, Decomp.first);

    F.ParentOffset = Decomp.second;

    F.StateTransitions.push_back({F.Parent->lookup(Decomp.second), 0});

  } else {

    // This is the (imaginary) root file into which we pretend all top-level

    // files are included; it descends from the initial state.

    //

    // FIXME: This doesn't guarantee that we use the same ordering as

    // isBeforeInTranslationUnit in the cases where someone invented another

    // top-level file and added diagnostic pragmas to it. See the code at the

    // end of isBeforeInTranslationUnit for the quirks it deals with.

    F.StateTransitions.push_back({FirstDiagState, 0});

  }

  return &F;

}

void DiagnosticsEngine::DiagStateMap::dump(SourceManager &SrcMgr,

                                           StringRef DiagName) const {

  llvm::errs() << "diagnostic state at ";

  CurDiagStateLoc.print(llvm::errs(), SrcMgr);

  llvm::errs() << ": " << CurDiagState << "\n";

  for (auto &F : Files) {

    FileID ID = F.first;

    File &File = F.second;

    bool PrintedOuterHeading = false;

    auto PrintOuterHeading = [&] {

      if (PrintedOuterHeading) return;

      PrintedOuterHeading = true;

      llvm::errs() << "File " << &File << " <FileID " << ID.getHashValue()

                   << ">: " << SrcMgr.getBufferOrFake(ID).getBufferIdentifier();

      if (F.second.Parent) {

        std::pair<FileID, unsigned> Decomp =

            SrcMgr.getDecomposedIncludedLoc(ID);

        assert(File.ParentOffset == Decomp.second);

        llvm::errs() << " parent " << File.Parent << " <FileID "

                     << Decomp.first.getHashValue() << "> ";

        SrcMgr.getLocForStartOfFile(Decomp.first)

              .getLocWithOffset(Decomp.second)

              .print(llvm::errs(), SrcMgr);

      }

      if (File.HasLocalTransitions)

        llvm::errs() << " has_local_transitions";

      llvm::errs() << "\n";

    };

    if (DiagName.empty())

      PrintOuterHeading();

    for (DiagStatePoint &Transition : File.StateTransitions) {

      bool PrintedInnerHeading = false;

      auto PrintInnerHeading = [&] {

        if (PrintedInnerHeading) return;

        PrintedInnerHeading = true;

        PrintOuterHeading();

        llvm::errs() << "  ";

        SrcMgr.getLocForStartOfFile(ID)

              .getLocWithOffset(Transition.Offset)

              .print(llvm::errs(), SrcMgr);

        llvm::errs() << ": state " << Transition.State << ":\n";

      };

      if (DiagName.empty())

        PrintInnerHeading();

      for (auto &Mapping : *Transition.State) {

        StringRef Option =

            DiagnosticIDs::getWarningOptionForDiag(Mapping.first);

        if (!DiagName.empty() && DiagName != Option)

          continue;

        PrintInnerHeading();

        llvm::errs() << "    ";

        if (Option.empty())

          llvm::errs() << "<unknown " << Mapping.first << ">";

        else

          llvm::errs() << Option;

        llvm::errs() << ": ";

        switch (Mapping.second.getSeverity()) {

        case diag::Severity::Ignored: llvm::errs() << "ignored"; break;

        case diag::Severity::Remark: llvm::errs() << "remark"; break;

        case diag::Severity::Warning: llvm::errs() << "warning"; break;

        case diag::Severity::Error: llvm::errs() << "error"; break;

        case diag::Severity::Fatal: llvm::errs() << "fatal"; break;

        }

        if (!Mapping.second.isUser())

          llvm::errs() << " default";

        if (Mapping.second.isPragma())

          llvm::errs() << " pragma";

        if (Mapping.second.hasNoWarningAsError())

          llvm::errs() << " no-error";

        if (Mapping.second.hasNoErrorAsFatal())

          llvm::errs() << " no-fatal";

        if (Mapping.second.wasUpgradedFromWarning())

          llvm::errs() << " overruled";

        llvm::errs() << "\n";

      }

    }

  }

}

void DiagnosticsEngine::PushDiagStatePoint(DiagState *State,

                                           SourceLocation Loc) {

  assert(Loc.isValid() && "Adding invalid loc point");

  DiagStatesByLoc.append(*SourceMgr, Loc, State);

}

void DiagnosticsEngine::setSeverity(diag::kind Diag, diag::Severity Map,

                                    SourceLocation L) {

  assert(Diag < diag::DIAG_UPPER_LIMIT &&

         "Can only map builtin diagnostics");

  assert((Diags->isBuiltinWarningOrExtension(Diag) ||

          (Map == diag::Severity::Fatal || Map == diag::Severity::Error)) &&

         "Cannot map errors into warnings!");

  assert((L.isInvalid() || SourceMgr) && "No SourceMgr for valid location");

  // Don't allow a mapping to a warning override an error/fatal mapping.

  bool WasUpgradedFromWarning = false;

  if (Map == diag::Severity::Warning) {

    DiagnosticMapping &Info = GetCurDiagState()->getOrAddMapping(Diag);

    if (Info.getSeverity() == diag::Severity::Error ||

        Info.getSeverity() == diag::Severity::Fatal) {

      Map = Info.getSeverity();

      WasUpgradedFromWarning = true;

    }

  }

  DiagnosticMapping Mapping = makeUserMapping(Map, L);

  Mapping.setUpgradedFromWarning(WasUpgradedFromWarning);

  // Make sure we propagate the NoWarningAsError flag from an existing

  // mapping (which may be the default mapping).

  DiagnosticMapping &Info = GetCurDiagState()->getOrAddMapping(Diag);

  Mapping.setNoWarningAsError(Info.hasNoWarningAsError() ||

                              Mapping.hasNoWarningAsError());

  // Common case; setting all the diagnostics of a group in one place.

  if ((L.isInvalid() || L == DiagStatesByLoc.getCurDiagStateLoc()) &&

      DiagStatesByLoc.getCurDiagState()) {

    // FIXME: This is theoretically wrong: if the current state is shared with

    // some other location (via push/pop) we will change the state for that

    // other location as well. This cannot currently happen, as we can't update

    // the diagnostic state at the same location at which we pop.

    DiagStatesByLoc.getCurDiagState()->setMapping(Diag, Mapping);

    return;

  }

  // A diagnostic pragma occurred, create a new DiagState initialized with

  // the current one and a new DiagStatePoint to record at which location

  // the new state became active.

  DiagStates.push_back(*GetCurDiagState());

  DiagStates.back().setMapping(Diag, Mapping);

  PushDiagStatePoint(&DiagStates.back(), L);

}

bool DiagnosticsEngine::setSeverityForGroup(diag::Flavor Flavor,

                                            StringRef Group, diag::Severity Map,

                                            SourceLocation Loc) {

  // Get the diagnostics in this group.

  SmallVector<diag::kind, 256> GroupDiags;

  if (Diags->getDiagnosticsInGroup(Flavor, Group, GroupDiags))

    return true;

  // Set the mapping.

  for (diag::kind Diag : GroupDiags)

    setSeverity(Diag, Map, Loc);

  return false;

}

bool DiagnosticsEngine::setSeverityForGroup(diag::Flavor Flavor,

                                            diag::Group Group,

                                            diag::Severity Map,

                                            SourceLocation Loc) {

  return setSeverityForGroup(Flavor, Diags->getWarningOptionForGroup(Group),

                             Map, Loc);

}

bool DiagnosticsEngine::setDiagnosticGroupWarningAsError(StringRef Group,

                                                         bool Enabled) {

  // If we are enabling this feature, just set the diagnostic mappings to map to

  // errors.

  if (Enabled)

    return setSeverityForGroup(diag::Flavor::WarningOrError, Group,

                               diag::Severity::Error);

  // Otherwise, we want to set the diagnostic mapping's "no Werror" bit, and

  // potentially downgrade anything already mapped to be a warning.

  // Get the diagnostics in this group.

  SmallVector<diag::kind, 8> GroupDiags;

  if (Diags->getDiagnosticsInGroup(diag::Flavor::WarningOrError, Group,

                                   GroupDiags))

    return true;

  // Perform the mapping change.

  for (diag::kind Diag : GroupDiags) {

    DiagnosticMapping &Info = GetCurDiagState()->getOrAddMapping(Diag);

    if (Info.getSeverity() == diag::Severity::Error ||

        Info.getSeverity() == diag::Severity::Fatal)

      Info.setSeverity(diag::Severity::Warning);

    Info.setNoWarningAsError(true);

  }

  return false;

}

bool DiagnosticsEngine::setDiagnosticGroupErrorAsFatal(StringRef Group,

                                                       bool Enabled) {

  // If we are enabling this feature, just set the diagnostic mappings to map to

  // fatal errors.

  if (Enabled)

    return setSeverityForGroup(diag::Flavor::WarningOrError, Group,

                               diag::Severity::Fatal);

  // Otherwise, we want to set the diagnostic mapping's "no Wfatal-errors" bit,

  // and potentially downgrade anything already mapped to be a fatal error.

  // Get the diagnostics in this group.

  SmallVector<diag::kind, 8> GroupDiags;

  if (Diags->getDiagnosticsInGroup(diag::Flavor::WarningOrError, Group,

                                   GroupDiags))

    return true;

  // Perform the mapping change.

  for (diag::kind Diag : GroupDiags) {

    DiagnosticMapping &Info = GetCurDiagState()->getOrAddMapping(Diag);

    if (Info.getSeverity() == diag::Severity::Fatal)

      Info.setSeverity(diag::Severity::Error);

    Info.setNoErrorAsFatal(true);

  }

  return false;

}

void DiagnosticsEngine::setSeverityForAll(diag::Flavor Flavor,

                                          diag::Severity Map,

                                          SourceLocation Loc) {

  // Get all the diagnostics.

  std::vector<diag::kind> AllDiags;

  DiagnosticIDs::getAllDiagnostics(Flavor, AllDiags);

  // Set the mapping.

  for (diag::kind Diag : AllDiags)

    if (Diags->isBuiltinWarningOrExtension(Diag))

      setSeverity(Diag, Map, Loc);

}

void DiagnosticsEngine::Report(const StoredDiagnostic &storedDiag) {

  assert(CurDiagID == std::numeric_limits<unsigned>::max() &&

         "Multiple diagnostics in flight at once!");

  CurDiagLoc = storedDiag.getLocation();

  CurDiagID = storedDiag.getID();

  DiagStorage.NumDiagArgs = 0;

  DiagStorage.DiagRanges.clear();

  DiagStorage.DiagRanges.append(storedDiag.range_begin(),

                                storedDiag.range_end());

  DiagStorage.FixItHints.clear();

  DiagStorage.FixItHints.append(storedDiag.fixit_begin(),

                                storedDiag.fixit_end());

  assert(Client && "DiagnosticConsumer not set!");

  Level DiagLevel = storedDiag.getLevel();

  Diagnostic Info(this, storedDiag.getMessage());

  Client->HandleDiagnostic(DiagLevel, Info);

  if (Client->IncludeInDiagnosticCounts()) {

    if (DiagLevel == DiagnosticsEngine::Warning)

      ++NumWarnings;

  }

  CurDiagID = std::numeric_limits<unsigned>::max();

}

bool DiagnosticsEngine::EmitCurrentDiagnostic(bool Force) {

  assert(getClient() && "DiagnosticClient not set!");

  bool Emitted;

  if (Force) {

    Diagnostic Info(this);

    // Figure out the diagnostic level of this message.

    DiagnosticIDs::Level DiagLevel

      = Diags->getDiagnosticLevel(Info.getID(), Info.getLocation(), *this);

    Emitted = (DiagLevel != DiagnosticIDs::Ignored);

    if (Emitted) {

      // Emit the diagnostic regardless of suppression level.

      Diags->EmitDiag(*this, DiagLevel);

    }

  } else {

    // Process the diagnostic, sending the accumulated information to the

    // DiagnosticConsumer.

    Emitted = ProcessDiag();

  }

  // Clear out the current diagnostic object.

  Clear();

  // If there was a delayed diagnostic, emit it now.

  if (!Force && DelayedDiagID)

    ReportDelayed();

  return Emitted;

}

DiagnosticConsumer::~DiagnosticConsumer() = default;

void DiagnosticConsumer::HandleDiagnostic(DiagnosticsEngine::Level DiagLevel,

                                        const Diagnostic &Info) {

  if (!IncludeInDiagnosticCounts())

    return;

  if (DiagLevel == DiagnosticsEngine::Warning)

    ++NumWarnings;

  else if (DiagLevel >= DiagnosticsEngine::Error)

    ++NumErrors;

}

/// ModifierIs - Return true if the specified modifier matches specified string.

template <std::size_t StrLen>

static bool ModifierIs(const char *Modifier, unsigned ModifierLen,

                       const char (&Str)[StrLen]) {

  return StrLen-1 == ModifierLen && memcmp(Modifier, Str, StrLen-1) == 0;

}

Unexecuted instantiation: Diagnostic.cpp:bool ModifierIs<5ul>(char const*, unsigned int, char const (&) [5ul])

Unexecuted instantiation: Diagnostic.cpp:bool ModifierIs<7ul>(char const*, unsigned int, char const (&) [7ul])

Unexecuted instantiation: Diagnostic.cpp:bool ModifierIs<2ul>(char const*, unsigned int, char const (&) [2ul])

Unexecuted instantiation: Diagnostic.cpp:bool ModifierIs<8ul>(char const*, unsigned int, char const (&) [8ul])

/// ScanForward - Scans forward, looking for the given character, skipping

/// nested clauses and escaped characters.

static const char *ScanFormat(const char *I, const char *E, char Target) {

  unsigned Depth = 0;

  for ( ; I != E; ++I) {

    if (Depth == 0 && *I == Target) return I;

    if (Depth != 0 && *I == '}') Depth--;

    if (*I == '%') {

      I++;

      if (I == E) break;

      // Escaped characters get implicitly skipped here.

      // Format specifier.

      if (!isDigit(*I) && !isPunctuation(*I)) {

        for (I++; I != E && !isDigit(*I) && *I != '{'; I++) ;

        if (I == E) break;

        if (*I == '{')

          Depth++;

      }

    }

  }

  return E;

}

/// HandleSelectModifier - Handle the integer 'select' modifier.  This is used

/// like this:  %select{foo|bar|baz}2.  This means that the integer argument

/// "%2" has a value from 0-2.  If the value is 0, the diagnostic prints 'foo'.

/// If the value is 1, it prints 'bar'.  If it has the value 2, it prints 'baz'.

/// This is very useful for certain classes of variant diagnostics.

static void HandleSelectModifier(const Diagnostic &DInfo, unsigned ValNo,

                                 const char *Argument, unsigned ArgumentLen,

                                 SmallVectorImpl<char> &OutStr) {

  const char *ArgumentEnd = Argument+ArgumentLen;

  // Skip over 'ValNo' |'s.

  while (ValNo) {

    const char *NextVal = ScanFormat(Argument, ArgumentEnd, '|');

    assert(NextVal != ArgumentEnd && "Value for integer select modifier was"

           " larger than the number of options in the diagnostic string!");

    Argument = NextVal+1;  // Skip this string.

    --ValNo;

  }

  // Get the end of the value.  This is either the } or the |.

  const char *EndPtr = ScanFormat(Argument, ArgumentEnd, '|');

  // Recursively format the result of the select clause into the output string.

  DInfo.FormatDiagnostic(Argument, EndPtr, OutStr);

}

/// HandleIntegerSModifier - Handle the integer 's' modifier.  This adds the

/// letter 's' to the string if the value is not 1.  This is used in cases like

/// this:  "you idiot, you have %4 parameter%s4!".

static void HandleIntegerSModifier(unsigned ValNo,

                                   SmallVectorImpl<char> &OutStr) {

  if (ValNo != 1)

    OutStr.push_back('s');

}

/// HandleOrdinalModifier - Handle the integer 'ord' modifier.  This

/// prints the ordinal form of the given integer, with 1 corresponding

/// to the first ordinal.  Currently this is hard-coded to use the

/// English form.

static void HandleOrdinalModifier(unsigned ValNo,

                                  SmallVectorImpl<char> &OutStr) {

  assert(ValNo != 0 && "ValNo must be strictly positive!");

  llvm::raw_svector_ostream Out(OutStr);

  // We could use text forms for the first N ordinals, but the numeric

  // forms are actually nicer in diagnostics because they stand out.

  Out << ValNo << llvm::getOrdinalSuffix(ValNo);

}

/// PluralNumber - Parse an unsigned integer and advance Start.

static unsigned PluralNumber(const char *&Start, const char *End) {

  // Programming 101: Parse a decimal number :-)

  unsigned Val = 0;

  while (Start != End && *Start >= '0' && *Start <= '9') {

    Val *= 10;

    Val += *Start - '0';

    ++Start;

  }

  return Val;

}

/// TestPluralRange - Test if Val is in the parsed range. Modifies Start.

static bool TestPluralRange(unsigned Val, const char *&Start, const char *End) {

  if (*Start != '[') {

    unsigned Ref = PluralNumber(Start, End);

    return Ref == Val;

  }

  ++Start;

  unsigned Low = PluralNumber(Start, End);

  assert(*Start == ',' && "Bad plural expression syntax: expected ,");

  ++Start;

  unsigned High = PluralNumber(Start, End);

  assert(*Start == ']' && "Bad plural expression syntax: expected )");

  ++Start;

  return Low <= Val && Val <= High;

}

/// EvalPluralExpr - Actual expression evaluator for HandlePluralModifier.

static bool EvalPluralExpr(unsigned ValNo, const char *Start, const char *End) {

  // Empty condition?

  if (*Start == ':')

    return true;

  while (true) {

    char C = *Start;

    if (C == '%') {

      // Modulo expression

      ++Start;

      unsigned Arg = PluralNumber(Start, End);

      assert(*Start == '=' && "Bad plural expression syntax: expected =");

      ++Start;

      unsigned ValMod = ValNo % Arg;

      if (TestPluralRange(ValMod, Start, End))

        return true;

    } else {

      assert((C == '[' || (C >= '0' && C <= '9')) &&

             "Bad plural expression syntax: unexpected character");

      // Range expression

      if (TestPluralRange(ValNo, Start, End))

        return true;

    }

    // Scan for next or-expr part.

    Start = std::find(Start, End, ',');

    if (Start == End)

      break;

    ++Start;

  }

  return false;

}

/// HandlePluralModifier - Handle the integer 'plural' modifier. This is used

/// for complex plural forms, or in languages where all plurals are complex.

/// The syntax is: %plural{cond1:form1|cond2:form2|:form3}, where condn are

/// conditions that are tested in order, the form corresponding to the first

/// that applies being emitted. The empty condition is always true, making the

/// last form a default case.

/// Conditions are simple boolean expressions, where n is the number argument.

/// Here are the rules.

/// condition  := expression | empty

/// empty      :=                             -> always true

/// expression := numeric [',' expression]    -> logical or

/// numeric    := range                       -> true if n in range

///             | '%' number '=' range        -> true if n % number in range

/// range      := number

///             | '[' number ',' number ']'   -> ranges are inclusive both ends

///

/// Here are some examples from the GNU gettext manual written in this form:

/// English:

/// {1:form0|:form1}

/// Latvian:

/// {0:form2|%100=11,%10=0,%10=[2,9]:form1|:form0}

/// Gaeilge:

/// {1:form0|2:form1|:form2}

/// Romanian:

/// {1:form0|0,%100=[1,19]:form1|:form2}

/// Lithuanian:

/// {%10=0,%100=[10,19]:form2|%10=1:form0|:form1}

/// Russian (requires repeated form):

/// {%100=[11,14]:form2|%10=1:form0|%10=[2,4]:form1|:form2}

/// Slovak

/// {1:form0|[2,4]:form1|:form2}

/// Polish (requires repeated form):

/// {1:form0|%100=[10,20]:form2|%10=[2,4]:form1|:form2}

static void HandlePluralModifier(const Diagnostic &DInfo, unsigned ValNo,

                                 const char *Argument, unsigned ArgumentLen,

                                 SmallVectorImpl<char> &OutStr) {

  const char *ArgumentEnd = Argument + ArgumentLen;

  while (true) {

    assert(Argument < ArgumentEnd && "Plural expression didn't match.");

    const char *ExprEnd = Argument;

    while (*ExprEnd != ':') {

      assert(ExprEnd != ArgumentEnd && "Plural missing expression end");

      ++ExprEnd;

    }

    if (EvalPluralExpr(ValNo, Argument, ExprEnd)) {

      Argument = ExprEnd + 1;

      ExprEnd = ScanFormat(Argument, ArgumentEnd, '|');

      // Recursively format the result of the plural clause into the

      // output string.

      DInfo.FormatDiagnostic(Argument, ExprEnd, OutStr);

      return;

    }

    Argument = ScanFormat(Argument, ArgumentEnd - 1, '|') + 1;

  }

}

/// Returns the friendly description for a token kind that will appear

/// without quotes in diagnostic messages. These strings may be translatable in

/// future.

static const char *getTokenDescForDiagnostic(tok::TokenKind Kind) {

  switch (Kind) {

  case tok::identifier:

    return "identifier";

  default:

    return nullptr;

  }

}

/// FormatDiagnostic - Format this diagnostic into a string, substituting the

/// formal arguments into the %0 slots.  The result is appended onto the Str

/// array.

void Diagnostic::

FormatDiagnostic(SmallVectorImpl<char> &OutStr) const {

  if (StoredDiagMessage.has_value()) {

    OutStr.append(StoredDiagMessage->begin(), StoredDiagMessage->end());

    return;

  }

  StringRef Diag =

    getDiags()->getDiagnosticIDs()->getDescription(getID());

  FormatDiagnostic(Diag.begin(), Diag.end(), OutStr);

}

/// EscapeStringForDiagnostic - Append Str to the diagnostic buffer,

/// escaping non-printable characters and ill-formed code unit sequences.

void clang::EscapeStringForDiagnostic(StringRef Str,

                                      SmallVectorImpl<char> &OutStr) {

  OutStr.reserve(OutStr.size() + Str.size());

  auto *Begin = reinterpret_cast<const unsigned char *>(Str.data());

  llvm::raw_svector_ostream OutStream(OutStr);

  const unsigned char *End = Begin + Str.size();

  while (Begin != End) {

    // ASCII case

    if (isPrintable(*Begin) || isWhitespace(*Begin)) {

      OutStream << *Begin;

      ++Begin;

      continue;

    }

    if (llvm::isLegalUTF8Sequence(Begin, End)) {

      llvm::UTF32 CodepointValue;

      llvm::UTF32 *CpPtr = &CodepointValue;

      const unsigned char *CodepointBegin = Begin;

      const unsigned char *CodepointEnd =

          Begin + llvm::getNumBytesForUTF8(*Begin);

      llvm::ConversionResult Res = llvm::ConvertUTF8toUTF32(

          &Begin, CodepointEnd, &CpPtr, CpPtr + 1, llvm::strictConversion);

      (void)Res;

      assert(

          llvm::conversionOK == Res &&

          "the sequence is legal UTF-8 but we couldn't convert it to UTF-32");

      assert(Begin == CodepointEnd &&

             "we must be further along in the string now");

      if (llvm::sys::unicode::isPrintable(CodepointValue) ||

          llvm::sys::unicode::isFormatting(CodepointValue)) {

        OutStr.append(CodepointBegin, CodepointEnd);

        continue;

      }

      // Unprintable code point.

      OutStream << "<U+" << llvm::format_hex_no_prefix(CodepointValue, 4, true)

                << ">";

      continue;

    }

    // Invalid code unit.

    OutStream << "<" << llvm::format_hex_no_prefix(*Begin, 2, true) << ">";

    ++Begin;

  }

}

void Diagnostic::

FormatDiagnostic(const char *DiagStr, const char *DiagEnd,

                 SmallVectorImpl<char> &OutStr) const {

  // When the diagnostic string is only "%0", the entire string is being given

  // by an outside source.  Remove unprintable characters from this string

  // and skip all the other string processing.

  if (DiagEnd - DiagStr == 2 &&

      StringRef(DiagStr, DiagEnd - DiagStr).equals("%0") &&

      getArgKind(0) == DiagnosticsEngine::ak_std_string) {

    const std::string &S = getArgStdStr(0);

    EscapeStringForDiagnostic(S, OutStr);

    return;

  }

  /// FormattedArgs - Keep track of all of the arguments formatted by

  /// ConvertArgToString and pass them into subsequent calls to

  /// ConvertArgToString, allowing the implementation to avoid redundancies in

  /// obvious cases.

  SmallVector<DiagnosticsEngine::ArgumentValue, 8> FormattedArgs;

  /// QualTypeVals - Pass a vector of arrays so that QualType names can be

  /// compared to see if more information is needed to be printed.

  SmallVector<intptr_t, 2> QualTypeVals;

  SmallString<64> Tree;

  for (unsigned i = 0, e = getNumArgs(); i < e; ++i)

    if (getArgKind(i) == DiagnosticsEngine::ak_qualtype)

      QualTypeVals.push_back(getRawArg(i));

  while (DiagStr != DiagEnd) {

    if (DiagStr[0] != '%') {

      // Append non-%0 substrings to Str if we have one.

      const char *StrEnd = std::find(DiagStr, DiagEnd, '%');

      OutStr.append(DiagStr, StrEnd);

      DiagStr = StrEnd;

      continue;

    } else if (isPunctuation(DiagStr[1])) {

      OutStr.push_back(DiagStr[1]);  // %% -> %.

      DiagStr += 2;

      continue;

    }

    // Skip the %.

    ++DiagStr;

    // This must be a placeholder for a diagnostic argument.  The format for a

    // placeholder is one of "%0", "%modifier0", or "%modifier{arguments}0".

    // The digit is a number from 0-9 indicating which argument this comes from.

    // The modifier is a string of digits from the set [-a-z]+, arguments is a

    // brace enclosed string.

    const char *Modifier = nullptr, *Argument = nullptr;

    unsigned ModifierLen = 0, ArgumentLen = 0;

    // Check to see if we have a modifier.  If so eat it.

    if (!isDigit(DiagStr[0])) {

      Modifier = DiagStr;

      while (DiagStr[0] == '-' ||

             (DiagStr[0] >= 'a' && DiagStr[0] <= 'z'))

        ++DiagStr;

      ModifierLen = DiagStr-Modifier;

      // If we have an argument, get it next.

      if (DiagStr[0] == '{') {

        ++DiagStr; // Skip {.

        Argument = DiagStr;

        DiagStr = ScanFormat(DiagStr, DiagEnd, '}');

        assert(DiagStr != DiagEnd && "Mismatched {}'s in diagnostic string!");

        ArgumentLen = DiagStr-Argument;

        ++DiagStr;  // Skip }.

      }

    }

    assert(isDigit(*DiagStr) && "Invalid format for argument in diagnostic");

    unsigned ArgNo = *DiagStr++ - '0';

    // Only used for type diffing.

    unsigned ArgNo2 = ArgNo;

    DiagnosticsEngine::ArgumentKind Kind = getArgKind(ArgNo);