clang/lib/Basic/Diagnostic.cpp

//===--- Diagnostic.cpp - C Language Family Diagnostic Handling -----------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements the Diagnostic-related interfaces.
//
//===----------------------------------------------------------------------===//

#include "clang/AST/ASTDiagnostic.h"
#include "clang/Analysis/AnalysisDiagnostic.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/FileManager.h"
#include "clang/Basic/IdentifierTable.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Driver/DriverDiagnostic.h"
#include "clang/Frontend/FrontendDiagnostic.h"
#include "clang/Lex/LexDiagnostic.h"
#include "clang/Parse/ParseDiagnostic.h"
#include "clang/Sema/SemaDiagnostic.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.h"

#include <vector>
#include <map>
#include <cstring>
using namespace clang;

//===----------------------------------------------------------------------===//
// Builtin Diagnostic information
//===----------------------------------------------------------------------===//

// Diagnostic classes.
enum {
  CLASS_NOTE       = 0x01,
  CLASS_WARNING    = 0x02,
  CLASS_EXTENSION  = 0x03,
  CLASS_ERROR      = 0x04
};

struct StaticDiagInfoRec {
  unsigned short DiagID;
  unsigned Mapping : 3;
  unsigned Class : 3;
  bool SFINAE : 1;
  const char *Description;
  const char *OptionGroup;

  bool operator<(const StaticDiagInfoRec &RHS) const {
    return DiagID < RHS.DiagID;
  }
  bool operator>(const StaticDiagInfoRec &RHS) const {
    return DiagID > RHS.DiagID;
  }
};

static const StaticDiagInfoRec StaticDiagInfo[] = {
#define DIAG(ENUM,CLASS,DEFAULT_MAPPING,DESC,GROUP,SFINAE)    \
  { diag::ENUM, DEFAULT_MAPPING, CLASS, SFINAE, DESC, GROUP },
#include "clang/Basic/DiagnosticCommonKinds.inc"
#include "clang/Basic/DiagnosticDriverKinds.inc"
#include "clang/Basic/DiagnosticFrontendKinds.inc"
#include "clang/Basic/DiagnosticLexKinds.inc"
#include "clang/Basic/DiagnosticParseKinds.inc"
#include "clang/Basic/DiagnosticASTKinds.inc"
#include "clang/Basic/DiagnosticSemaKinds.inc"
#include "clang/Basic/DiagnosticAnalysisKinds.inc"
  { 0, 0, 0, 0, 0, 0}
};
#undef DIAG

/// GetDiagInfo - Return the StaticDiagInfoRec entry for the specified DiagID,
/// or null if the ID is invalid.
static const StaticDiagInfoRec *GetDiagInfo(unsigned DiagID) {
  unsigned NumDiagEntries = sizeof(StaticDiagInfo)/sizeof(StaticDiagInfo[0])-1;

  // If assertions are enabled, verify that the StaticDiagInfo array is sorted.
#ifndef NDEBUG
  static bool IsFirst = true;
  if (IsFirst) {
    for (unsigned i = 1; i != NumDiagEntries; ++i) {
      assert(StaticDiagInfo[i-1].DiagID != StaticDiagInfo[i].DiagID &&
             "Diag ID conflict, the enums at the start of clang::diag (in "
             "Diagnostic.h) probably need to be increased");

      assert(StaticDiagInfo[i-1] < StaticDiagInfo[i] &&
             "Improperly sorted diag info");
    }
    IsFirst = false;
  }
#endif

  // Search the diagnostic table with a binary search.
  StaticDiagInfoRec Find = { DiagID, 0, 0, 0, 0, 0 };

  const StaticDiagInfoRec *Found =
    std::lower_bound(StaticDiagInfo, StaticDiagInfo + NumDiagEntries, Find);
  if (Found == StaticDiagInfo + NumDiagEntries ||
      Found->DiagID != DiagID)
    return 0;

  return Found;
}

static unsigned GetDefaultDiagMapping(unsigned DiagID) {
  if (const StaticDiagInfoRec *Info = GetDiagInfo(DiagID))
    return Info->Mapping;
  return diag::MAP_FATAL;
}

/// getWarningOptionForDiag - Return the lowest-level warning option that
/// enables the specified diagnostic.  If there is no -Wfoo flag that controls
/// the diagnostic, this returns null.
const char *Diagnostic::getWarningOptionForDiag(unsigned DiagID) {
  if (const StaticDiagInfoRec *Info = GetDiagInfo(DiagID))
    return Info->OptionGroup;
  return 0;
}

Diagnostic::SFINAEResponse 
Diagnostic::getDiagnosticSFINAEResponse(unsigned DiagID) {
  if (const StaticDiagInfoRec *Info = GetDiagInfo(DiagID)) {
    if (!Info->SFINAE)
      return SFINAE_Report;

    if (Info->Class == CLASS_ERROR)
      return SFINAE_SubstitutionFailure;
    
    // Suppress notes, warnings, and extensions;
    return SFINAE_Suppress;
  }
  
  return SFINAE_Report;
}

/// getDiagClass - Return the class field of the diagnostic.
///
static unsigned getBuiltinDiagClass(unsigned DiagID) {
  if (const StaticDiagInfoRec *Info = GetDiagInfo(DiagID))
    return Info->Class;
  return ~0U;
}

//===----------------------------------------------------------------------===//
// Custom Diagnostic information
//===----------------------------------------------------------------------===//

namespace clang {
  namespace diag {
    class CustomDiagInfo {
      typedef std::pair<Diagnostic::Level, std::string> DiagDesc;
      std::vector<DiagDesc> DiagInfo;
      std::map<DiagDesc, unsigned> DiagIDs;
    public:

      /// getDescription - Return the description of the specified custom
      /// diagnostic.
      const char *getDescription(unsigned DiagID) const {
        assert(this && DiagID-DIAG_UPPER_LIMIT < DiagInfo.size() &&
               "Invalid diagnosic ID");
        return DiagInfo[DiagID-DIAG_UPPER_LIMIT].second.c_str();
      }

      /// getLevel - Return the level of the specified custom diagnostic.
      Diagnostic::Level getLevel(unsigned DiagID) const {
        assert(this && DiagID-DIAG_UPPER_LIMIT < DiagInfo.size() &&
               "Invalid diagnosic ID");
        return DiagInfo[DiagID-DIAG_UPPER_LIMIT].first;
      }

      unsigned getOrCreateDiagID(Diagnostic::Level L, llvm::StringRef Message,
                                 Diagnostic &Diags) {
        DiagDesc D(L, Message);
        // Check to see if it already exists.
        std::map<DiagDesc, unsigned>::iterator I = DiagIDs.lower_bound(D);
        if (I != DiagIDs.end() && I->first == D)
          return I->second;

        // If not, assign a new ID.
        unsigned ID = DiagInfo.size()+DIAG_UPPER_LIMIT;
        DiagIDs.insert(std::make_pair(D, ID));
        DiagInfo.push_back(D);
        return ID;
      }
    };

  } // end diag namespace
} // end clang namespace


//===----------------------------------------------------------------------===//
// Common Diagnostic implementation
//===----------------------------------------------------------------------===//

static void DummyArgToStringFn(Diagnostic::ArgumentKind AK, intptr_t QT,
                               const char *Modifier, unsigned ML,
                               const char *Argument, unsigned ArgLen,
                               const Diagnostic::ArgumentValue *PrevArgs,
                               unsigned NumPrevArgs,
                               llvm::SmallVectorImpl<char> &Output,
                               void *Cookie) {
  const char *Str = "<can't format argument>";
  Output.append(Str, Str+strlen(Str));
}


Diagnostic::Diagnostic(DiagnosticClient *client) : Client(client) {
  AllExtensionsSilenced = 0;
  IgnoreAllWarnings = false;
  WarningsAsErrors = false;
  ErrorsAsFatal = false;
  SuppressSystemWarnings = false;
  SuppressAllDiagnostics = false;
  ExtBehavior = Ext_Ignore;

  ErrorOccurred = false;
  FatalErrorOccurred = false;
  ErrorLimit = 0;
  
  NumWarnings = 0;
  NumErrors = 0;
  NumErrorsSuppressed = 0;
  CustomDiagInfo = 0;
  CurDiagID = ~0U;
  LastDiagLevel = Ignored;

  ArgToStringFn = DummyArgToStringFn;
  ArgToStringCookie = 0;

  DelayedDiagID = 0;

  // Set all mappings to 'unset'.
  DiagMappings BlankDiags(diag::DIAG_UPPER_LIMIT/2, 0);
  DiagMappingsStack.push_back(BlankDiags);
}

Diagnostic::~Diagnostic() {
  delete CustomDiagInfo;
}


void Diagnostic::pushMappings() {
  // Avoids undefined behavior when the stack has to resize.
  DiagMappingsStack.reserve(DiagMappingsStack.size() + 1);
  DiagMappingsStack.push_back(DiagMappingsStack.back());
}

bool Diagnostic::popMappings() {
  if (DiagMappingsStack.size() == 1)
    return false;

  DiagMappingsStack.pop_back();
  return true;
}

/// getCustomDiagID - Return an ID for a diagnostic with the specified message
/// and level.  If this is the first request for this diagnosic, it is
/// registered and created, otherwise the existing ID is returned.
unsigned Diagnostic::getCustomDiagID(Level L, llvm::StringRef Message) {
  if (CustomDiagInfo == 0)
    CustomDiagInfo = new diag::CustomDiagInfo();
  return CustomDiagInfo->getOrCreateDiagID(L, Message, *this);
}


/// isBuiltinWarningOrExtension - Return true if the unmapped diagnostic
/// level of the specified diagnostic ID is a Warning or Extension.
/// This only works on builtin diagnostics, not custom ones, and is not legal to
/// call on NOTEs.
bool Diagnostic::isBuiltinWarningOrExtension(unsigned DiagID) {
  return DiagID < diag::DIAG_UPPER_LIMIT &&
         getBuiltinDiagClass(DiagID) != CLASS_ERROR;
}

/// \brief Determine whether the given built-in diagnostic ID is a
/// Note.
bool Diagnostic::isBuiltinNote(unsigned DiagID) {
  return DiagID < diag::DIAG_UPPER_LIMIT &&
    getBuiltinDiagClass(DiagID) == CLASS_NOTE;
}

/// isBuiltinExtensionDiag - Determine whether the given built-in diagnostic
/// ID is for an extension of some sort.  This also returns EnabledByDefault,
/// which is set to indicate whether the diagnostic is ignored by default (in
/// which case -pedantic enables it) or treated as a warning/error by default.
///
bool Diagnostic::isBuiltinExtensionDiag(unsigned DiagID,
                                        bool &EnabledByDefault) {
  if (DiagID >= diag::DIAG_UPPER_LIMIT ||
      getBuiltinDiagClass(DiagID) != CLASS_EXTENSION)
    return false;
  
  EnabledByDefault = StaticDiagInfo[DiagID].Mapping != diag::MAP_IGNORE;
  return true;
}


/// getDescription - Given a diagnostic ID, return a description of the
/// issue.
const char *Diagnostic::getDescription(unsigned DiagID) const {
  if (const StaticDiagInfoRec *Info = GetDiagInfo(DiagID))
    return Info->Description;
  return CustomDiagInfo->getDescription(DiagID);
}

void Diagnostic::SetDelayedDiagnostic(unsigned DiagID, llvm::StringRef Arg1,
                                      llvm::StringRef Arg2) {
  if (DelayedDiagID)
    return;

  DelayedDiagID = DiagID;
  DelayedDiagArg1 = Arg1.str();
  DelayedDiagArg2 = Arg2.str();
}

void Diagnostic::ReportDelayed() {
  Report(DelayedDiagID) << DelayedDiagArg1 << DelayedDiagArg2;
  DelayedDiagID = 0;
  DelayedDiagArg1.clear();
  DelayedDiagArg2.clear();
}

/// getDiagnosticLevel - Based on the way the client configured the Diagnostic
/// object, classify the specified diagnostic ID into a Level, consumable by
/// the DiagnosticClient.
Diagnostic::Level Diagnostic::getDiagnosticLevel(unsigned DiagID) const {
  // Handle custom diagnostics, which cannot be mapped.
  if (DiagID >= diag::DIAG_UPPER_LIMIT)
    return CustomDiagInfo->getLevel(DiagID);

  unsigned DiagClass = getBuiltinDiagClass(DiagID);
  assert(DiagClass != CLASS_NOTE && "Cannot get diagnostic level of a note!");
  return getDiagnosticLevel(DiagID, DiagClass);
}

/// getDiagnosticLevel - Based on the way the client configured the Diagnostic
/// object, classify the specified diagnostic ID into a Level, consumable by
/// the DiagnosticClient.
Diagnostic::Level
Diagnostic::getDiagnosticLevel(unsigned DiagID, unsigned DiagClass) const {
  // Specific non-error diagnostics may be mapped to various levels from ignored
  // to error.  Errors can only be mapped to fatal.
  Diagnostic::Level Result = Diagnostic::Fatal;

  // Get the mapping information, if unset, compute it lazily.
  unsigned MappingInfo = getDiagnosticMappingInfo((diag::kind)DiagID);
  if (MappingInfo == 0) {
    MappingInfo = GetDefaultDiagMapping(DiagID);
    setDiagnosticMappingInternal(DiagID, MappingInfo, false);
  }

  switch (MappingInfo & 7) {
  default: assert(0 && "Unknown mapping!");
  case diag::MAP_IGNORE:
    // Ignore this, unless this is an extension diagnostic and we're mapping
    // them onto warnings or errors.
    if (!isBuiltinExtensionDiag(DiagID) ||  // Not an extension
        ExtBehavior == Ext_Ignore ||        // Extensions ignored anyway
        (MappingInfo & 8) != 0)             // User explicitly mapped it.
      return Diagnostic::Ignored;
    Result = Diagnostic::Warning;
    if (ExtBehavior == Ext_Error) Result = Diagnostic::Error;
    if (Result == Diagnostic::Error && ErrorsAsFatal)
      Result = Diagnostic::Fatal;
    break;
  case diag::MAP_ERROR:
    Result = Diagnostic::Error;
    if (ErrorsAsFatal)
      Result = Diagnostic::Fatal;
    break;
  case diag::MAP_FATAL:
    Result = Diagnostic::Fatal;
    break;
  case diag::MAP_WARNING:
    // If warnings are globally mapped to ignore or error, do it.
    if (IgnoreAllWarnings)
      return Diagnostic::Ignored;

    Result = Diagnostic::Warning;

    // If this is an extension diagnostic and we're in -pedantic-error mode, and
    // if the user didn't explicitly map it, upgrade to an error.
    if (ExtBehavior == Ext_Error &&
        (MappingInfo & 8) == 0 &&
        isBuiltinExtensionDiag(DiagID))
      Result = Diagnostic::Error;

    if (WarningsAsErrors)
      Result = Diagnostic::Error;
    if (Result == Diagnostic::Error && ErrorsAsFatal)
      Result = Diagnostic::Fatal;
    break;

  case diag::MAP_WARNING_NO_WERROR:
    // Diagnostics specified with -Wno-error=foo should be set to warnings, but
    // not be adjusted by -Werror or -pedantic-errors.
    Result = Diagnostic::Warning;

    // If warnings are globally mapped to ignore or error, do it.
    if (IgnoreAllWarnings)
      return Diagnostic::Ignored;

    break;

  case diag::MAP_ERROR_NO_WFATAL:
    // Diagnostics specified as -Wno-fatal-error=foo should be errors, but
    // unaffected by -Wfatal-errors.
    Result = Diagnostic::Error;
    break;
  }

  // Okay, we're about to return this as a "diagnostic to emit" one last check:
  // if this is any sort of extension warning, and if we're in an __extension__
  // block, silence it.
  if (AllExtensionsSilenced && isBuiltinExtensionDiag(DiagID))
    return Diagnostic::Ignored;

  return Result;
}

struct WarningOption {
  const char  *Name;
  const short *Members;
  const char  *SubGroups;
};

#define GET_DIAG_ARRAYS
#include "clang/Basic/DiagnosticGroups.inc"
#undef GET_DIAG_ARRAYS

// Second the table of options, sorted by name for fast binary lookup.
static const WarningOption OptionTable[] = {
#define GET_DIAG_TABLE
#include "clang/Basic/DiagnosticGroups.inc"
#undef GET_DIAG_TABLE
};
static const size_t OptionTableSize =
sizeof(OptionTable) / sizeof(OptionTable[0]);

static bool WarningOptionCompare(const WarningOption &LHS,
                                 const WarningOption &RHS) {
  return strcmp(LHS.Name, RHS.Name) < 0;
}

static void MapGroupMembers(const WarningOption *Group, diag::Mapping Mapping,
                            Diagnostic &Diags) {
  // Option exists, poke all the members of its diagnostic set.
  if (const short *Member = Group->Members) {
    for (; *Member != -1; ++Member)
      Diags.setDiagnosticMapping(*Member, Mapping);
  }

  // Enable/disable all subgroups along with this one.
  if (const char *SubGroups = Group->SubGroups) {
    for (; *SubGroups != (char)-1; ++SubGroups)
      MapGroupMembers(&OptionTable[(unsigned char)*SubGroups], Mapping, Diags);
  }
}

/// setDiagnosticGroupMapping - Change an entire diagnostic group (e.g.
/// "unknown-pragmas" to have the specified mapping.  This returns true and
/// ignores the request if "Group" was unknown, false otherwise.
bool Diagnostic::setDiagnosticGroupMapping(const char *Group,
                                           diag::Mapping Map) {

  WarningOption Key = { Group, 0, 0 };
  const WarningOption *Found =
  std::lower_bound(OptionTable, OptionTable + OptionTableSize, Key,
                   WarningOptionCompare);
  if (Found == OptionTable + OptionTableSize ||
      strcmp(Found->Name, Group) != 0)
    return true;  // Option not found.

  MapGroupMembers(Found, Map, *this);
  return false;
}


/// ProcessDiag - This is the method used to report a diagnostic that is
/// finally fully formed.
bool Diagnostic::ProcessDiag() {
  DiagnosticInfo Info(this);

  if (SuppressAllDiagnostics)
    return false;
  
  // Figure out the diagnostic level of this message.
  Diagnostic::Level DiagLevel;
  unsigned DiagID = Info.getID();

  // ShouldEmitInSystemHeader - True if this diagnostic should be produced even
  // in a system header.
  bool ShouldEmitInSystemHeader;

  if (DiagID >= diag::DIAG_UPPER_LIMIT) {
    // Handle custom diagnostics, which cannot be mapped.
    DiagLevel = CustomDiagInfo->getLevel(DiagID);

    // Custom diagnostics always are emitted in system headers.
    ShouldEmitInSystemHeader = true;
  } else {
    // Get the class of the diagnostic.  If this is a NOTE, map it onto whatever
    // the diagnostic level was for the previous diagnostic so that it is
    // filtered the same as the previous diagnostic.
    unsigned DiagClass = getBuiltinDiagClass(DiagID);
    if (DiagClass == CLASS_NOTE) {
      DiagLevel = Diagnostic::Note;
      ShouldEmitInSystemHeader = false;  // extra consideration is needed
    } else {
      // If this is not an error and we are in a system header, we ignore it.
      // Check the original Diag ID here, because we also want to ignore
      // extensions and warnings in -Werror and -pedantic-errors modes, which
      // *map* warnings/extensions to errors.
      ShouldEmitInSystemHeader = DiagClass == CLASS_ERROR;

      DiagLevel = getDiagnosticLevel(DiagID, DiagClass);
    }
  }

  if (DiagLevel != Diagnostic::Note) {
    // Record that a fatal error occurred only when we see a second
    // non-note diagnostic. This allows notes to be attached to the
    // fatal error, but suppresses any diagnostics that follow those
    // notes.
    if (LastDiagLevel == Diagnostic::Fatal)
      FatalErrorOccurred = true;

    LastDiagLevel = DiagLevel;
  }

  // If a fatal error has already been emitted, silence all subsequent
  // diagnostics.
  if (FatalErrorOccurred) {
    if (DiagLevel >= Diagnostic::Error) {
      ++NumErrors;
      ++NumErrorsSuppressed;
    }
    
    return false;
  }

  // If the client doesn't care about this message, don't issue it.  If this is
  // a note and the last real diagnostic was ignored, ignore it too.
  if (DiagLevel == Diagnostic::Ignored ||
      (DiagLevel == Diagnostic::Note && LastDiagLevel == Diagnostic::Ignored))
    return false;

  // If this diagnostic is in a system header and is not a clang error, suppress
  // it.
  if (SuppressSystemWarnings && !ShouldEmitInSystemHeader &&
      Info.getLocation().isValid() &&
      Info.getLocation().getInstantiationLoc().isInSystemHeader() &&
      (DiagLevel != Diagnostic::Note || LastDiagLevel == Diagnostic::Ignored)) {
    LastDiagLevel = Diagnostic::Ignored;
    return false;
  }

  if (DiagLevel >= Diagnostic::Error) {
    ErrorOccurred = true;
    ++NumErrors;
    
    // If we've emitted a lot of errors, emit a fatal error after it to stop a
    // flood of bogus errors.
    if (ErrorLimit && NumErrors >= ErrorLimit &&
        DiagLevel == Diagnostic::Error)
      SetDelayedDiagnostic(diag::fatal_too_many_errors);
  }

  // Finally, report it.
  Client->HandleDiagnostic(DiagLevel, Info);
  if (Client->IncludeInDiagnosticCounts()) {
    if (DiagLevel == Diagnostic::Warning)
      ++NumWarnings;
  }

  CurDiagID = ~0U;

  return true;
}

bool DiagnosticBuilder::Emit() {
  // If DiagObj is null, then its soul was stolen by the copy ctor
  // or the user called Emit().
  if (DiagObj == 0) return false;

  // When emitting diagnostics, we set the final argument count into
  // the Diagnostic object.
  DiagObj->NumDiagArgs = NumArgs;
  DiagObj->NumDiagRanges = NumRanges;
  DiagObj->NumFixItHints = NumFixItHints;

  // Process the diagnostic, sending the accumulated information to the
  // DiagnosticClient.
  bool Emitted = DiagObj->ProcessDiag();

  // Clear out the current diagnostic object.
  unsigned DiagID = DiagObj->CurDiagID;
  DiagObj->Clear();

  // If there was a delayed diagnostic, emit it now.
  if (DiagObj->DelayedDiagID && DiagObj->DelayedDiagID != DiagID)
    DiagObj->ReportDelayed();

  // This diagnostic is dead.
  DiagObj = 0;

  return Emitted;
}


DiagnosticClient::~DiagnosticClient() {}


/// 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);
}

/// 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) && !ispunct(*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 DiagnosticInfo &DInfo, unsigned ValNo,
                                 const char *Argument, unsigned ArgumentLen,
                                 llvm::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,
                                   llvm::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,
                                  llvm::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;

  // It is critically important that we do this perfectly for
  // user-written sequences with over 100 elements.
  switch (ValNo % 100) {
  case 11:
  case 12:
  case 13:
    Out << "th"; return;
  default:
    switch (ValNo % 10) {
    case 1: Out << "st"; return;
    case 2: Out << "nd"; return;
    case 3: Out << "rd"; return;
    default: Out << "th"; return;
    }
  }
}


/// 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 (1) {
    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(unsigned ValNo,
                                 const char *Argument, unsigned ArgumentLen,
                                 llvm::SmallVectorImpl<char> &OutStr) {
  const char *ArgumentEnd = Argument + ArgumentLen;
  while (1) {
    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, '|');
      OutStr.append(Argument, ExprEnd);
      return;
    }
    Argument = ScanFormat(Argument, ArgumentEnd - 1, '|') + 1;
  }
}


/// FormatDiagnostic - Format this diagnostic into a string, substituting the
/// formal arguments into the %0 slots.  The result is appended onto the Str
/// array.
void DiagnosticInfo::
FormatDiagnostic(llvm::SmallVectorImpl<char> &OutStr) const {
  const char *DiagStr = getDiags()->getDescription(getID());
  const char *DiagEnd = DiagStr+strlen(DiagStr);

  FormatDiagnostic(DiagStr, DiagEnd, OutStr);
}

void DiagnosticInfo::
FormatDiagnostic(const char *DiagStr, const char *DiagEnd,
                 llvm::SmallVectorImpl<char> &OutStr) const {

  /// 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.
  llvm::SmallVector<Diagnostic::ArgumentValue, 8> FormattedArgs;
  
  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 (ispunct(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 = 0, *Argument = 0;
    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';

    Diagnostic::ArgumentKind Kind = getArgKind(ArgNo);
    
    switch (Kind) {
    // ---- STRINGS ----
    case Diagnostic::ak_std_string: {
      const std::string &S = getArgStdStr(ArgNo);
      assert(ModifierLen == 0 && "No modifiers for strings yet");
      OutStr.append(S.begin(), S.end());
      break;
    }
    case Diagnostic::ak_c_string: {
      const char *S = getArgCStr(ArgNo);
      assert(ModifierLen == 0 && "No modifiers for strings yet");

      // Don't crash if get passed a null pointer by accident.
      if (!S)
        S = "(null)";

      OutStr.append(S, S + strlen(S));
      break;
    }
    // ---- INTEGERS ----
    case Diagnostic::ak_sint: {
      int Val = getArgSInt(ArgNo);

      if (ModifierIs(Modifier, ModifierLen, "select")) {
        HandleSelectModifier(*this, (unsigned)Val, Argument, ArgumentLen, OutStr);
      } else if (ModifierIs(Modifier, ModifierLen, "s")) {
        HandleIntegerSModifier(Val, OutStr);
      } else if (ModifierIs(Modifier, ModifierLen, "plural")) {
        HandlePluralModifier((unsigned)Val, Argument, ArgumentLen, OutStr);
      } else if (ModifierIs(Modifier, ModifierLen, "ordinal")) {
        HandleOrdinalModifier((unsigned)Val, OutStr);
      } else {
        assert(ModifierLen == 0 && "Unknown integer modifier");
        llvm::raw_svector_ostream(OutStr) << Val;
      }
      break;
    }
    case Diagnostic::ak_uint: {
      unsigned Val = getArgUInt(ArgNo);

      if (ModifierIs(Modifier, ModifierLen, "select")) {
        HandleSelectModifier(*this, Val, Argument, ArgumentLen, OutStr);
      } else if (ModifierIs(Modifier, ModifierLen, "s")) {
        HandleIntegerSModifier(Val, OutStr);
      } else if (ModifierIs(Modifier, ModifierLen, "plural")) {
        HandlePluralModifier((unsigned)Val, Argument, ArgumentLen, OutStr);
      } else if (ModifierIs(Modifier, ModifierLen, "ordinal")) {
        HandleOrdinalModifier(Val, OutStr);
      } else {
        assert(ModifierLen == 0 && "Unknown integer modifier");
        llvm::raw_svector_ostream(OutStr) << Val;
      }
      break;
    }
    // ---- NAMES and TYPES ----
    case Diagnostic::ak_identifierinfo: {
      const IdentifierInfo *II = getArgIdentifier(ArgNo);
      assert(ModifierLen == 0 && "No modifiers for strings yet");

      // Don't crash if get passed a null pointer by accident.
      if (!II) {
        const char *S = "(null)";
        OutStr.append(S, S + strlen(S));
        continue;
      }

      llvm::raw_svector_ostream(OutStr) << '\'' << II->getName() << '\'';
      break;
    }
    case Diagnostic::ak_qualtype:
    case Diagnostic::ak_declarationname:
    case Diagnostic::ak_nameddecl:
    case Diagnostic::ak_nestednamespec:
    case Diagnostic::ak_declcontext:
      getDiags()->ConvertArgToString(Kind, getRawArg(ArgNo),
                                     Modifier, ModifierLen,
                                     Argument, ArgumentLen,
                                     FormattedArgs.data(), FormattedArgs.size(),
                                     OutStr);
      break;
    }
    
    // Remember this argument info for subsequent formatting operations.  Turn
    // std::strings into a null terminated string to make it be the same case as
    // all the other ones.
    if (Kind != Diagnostic::ak_std_string)
      FormattedArgs.push_back(std::make_pair(Kind, getRawArg(ArgNo)));
    else
      FormattedArgs.push_back(std::make_pair(Diagnostic::ak_c_string,
                                        (intptr_t)getArgStdStr(ArgNo).c_str()));
    
  }
}

StoredDiagnostic::StoredDiagnostic() { }

StoredDiagnostic::StoredDiagnostic(Diagnostic::Level Level, 
                                   llvm::StringRef Message)
  : Level(Level), Loc(), Message(Message) { }

StoredDiagnostic::StoredDiagnostic(Diagnostic::Level Level, 
                                   const DiagnosticInfo &Info)
  : Level(Level), Loc(Info.getLocation()) 
{
  llvm::SmallString<64> Message;
  Info.FormatDiagnostic(Message);
  this->Message.assign(Message.begin(), Message.end());

  Ranges.reserve(Info.getNumRanges());
  for (unsigned I = 0, N = Info.getNumRanges(); I != N; ++I)
    Ranges.push_back(Info.getRange(I));

  FixIts.reserve(Info.getNumFixItHints());
  for (unsigned I = 0, N = Info.getNumFixItHints(); I != N; ++I)
    FixIts.push_back(Info.getFixItHint(I));
}

StoredDiagnostic::~StoredDiagnostic() { }

static void WriteUnsigned(llvm::raw_ostream &OS, unsigned Value) {
  OS.write((const char *)&Value, sizeof(unsigned));
}

static void WriteString(llvm::raw_ostream &OS, llvm::StringRef String) {
  WriteUnsigned(OS, String.size());
  OS.write(String.data(), String.size());
}

static void WriteSourceLocation(llvm::raw_ostream &OS, 
                                SourceManager *SM,
                                SourceLocation Location) {
  if (!SM || Location.isInvalid()) {
    // If we don't have a source manager or this location is invalid,
    // just write an invalid location.
    WriteUnsigned(OS, 0);
    WriteUnsigned(OS, 0);
    WriteUnsigned(OS, 0);
    return;
  }

  Location = SM->getInstantiationLoc(Location);
  std::pair<FileID, unsigned> Decomposed = SM->getDecomposedLoc(Location);

  const FileEntry *FE = SM->getFileEntryForID(Decomposed.first);
  if (FE)
    WriteString(OS, FE->getName());
  else {
    // Fallback to using the buffer name when there is no entry.
    WriteString(OS, SM->getBuffer(Decomposed.first)->getBufferIdentifier());
  }

  WriteUnsigned(OS, SM->getLineNumber(Decomposed.first, Decomposed.second));
  WriteUnsigned(OS, SM->getColumnNumber(Decomposed.first, Decomposed.second));
}

void StoredDiagnostic::Serialize(llvm::raw_ostream &OS) const {
  SourceManager *SM = 0;
  if (getLocation().isValid())
    SM = &const_cast<SourceManager &>(getLocation().getManager());

  // Write a short header to help identify diagnostics.
  OS << (char)0x06 << (char)0x07;
  
  // Write the diagnostic level and location.
  WriteUnsigned(OS, (unsigned)Level);
  WriteSourceLocation(OS, SM, getLocation());

  // Write the diagnostic message.
  llvm::SmallString<64> Message;
  WriteString(OS, getMessage());
  
  // Count the number of ranges that don't point into macros, since
  // only simple file ranges serialize well.
  unsigned NumNonMacroRanges = 0;
  for (range_iterator R = range_begin(), REnd = range_end(); R != REnd; ++R) {
    if (R->getBegin().isMacroID() || R->getEnd().isMacroID())
      continue;

    ++NumNonMacroRanges;
  }

  // Write the ranges.
  WriteUnsigned(OS, NumNonMacroRanges);
  if (NumNonMacroRanges) {
    for (range_iterator R = range_begin(), REnd = range_end(); R != REnd; ++R) {
      if (R->getBegin().isMacroID() || R->getEnd().isMacroID())
        continue;
      
      WriteSourceLocation(OS, SM, R->getBegin());
      WriteSourceLocation(OS, SM, R->getEnd());
    }
  }

  // Determine if all of the fix-its involve rewrites with simple file
  // locations (not in macro instantiations). If so, we can write
  // fix-it information.
  unsigned NumFixIts = 0;
  for (fixit_iterator F = fixit_begin(), FEnd = fixit_end(); F != FEnd; ++F) {
    if (F->RemoveRange.isValid() &&
        (F->RemoveRange.getBegin().isMacroID() ||
         F->RemoveRange.getEnd().isMacroID())) {
      NumFixIts = 0;
      break;
    }

    if (F->InsertionLoc.isValid() && F->InsertionLoc.isMacroID()) {
      NumFixIts = 0;
      break;
    }

    ++NumFixIts;
  }

  // Write the fix-its.
  WriteUnsigned(OS, NumFixIts);
  for (fixit_iterator F = fixit_begin(), FEnd = fixit_end(); F != FEnd; ++F) {
    WriteSourceLocation(OS, SM, F->RemoveRange.getBegin());
    WriteSourceLocation(OS, SM, F->RemoveRange.getEnd());
    WriteSourceLocation(OS, SM, F->InsertionLoc);
    WriteString(OS, F->CodeToInsert);
  }
}

static bool ReadUnsigned(const char *&Memory, const char *MemoryEnd,
                         unsigned &Value) {
  if (Memory + sizeof(unsigned) > MemoryEnd)
    return true;

  memmove(&Value, Memory, sizeof(unsigned));
  Memory += sizeof(unsigned);
  return false;
}

static bool ReadSourceLocation(FileManager &FM, SourceManager &SM,
                               const char *&Memory, const char *MemoryEnd,
                               SourceLocation &Location) {
  // Read the filename.
  unsigned FileNameLen = 0;
  if (ReadUnsigned(Memory, MemoryEnd, FileNameLen) || 
      Memory + FileNameLen > MemoryEnd)
    return true;

  llvm::StringRef FileName(Memory, FileNameLen);
  Memory += FileNameLen;

  // Read the line, column.
  unsigned Line = 0, Column = 0;
  if (ReadUnsigned(Memory, MemoryEnd, Line) ||
      ReadUnsigned(Memory, MemoryEnd, Column))
    return true;

  if (FileName.empty()) {
    Location = SourceLocation();
    return false;
  }

  const FileEntry *File = FM.getFile(FileName);
  if (!File)
    return true;

  // Make sure that this file has an entry in the source manager.
  if (!SM.hasFileInfo(File))
    SM.createFileID(File, SourceLocation(), SrcMgr::C_User);

  Location = SM.getLocation(File, Line, Column);
  return false;
}

StoredDiagnostic 
StoredDiagnostic::Deserialize(FileManager &FM, SourceManager &SM, 
                              const char *&Memory, const char *MemoryEnd) {
  while (true) {
    if (Memory == MemoryEnd)
      return StoredDiagnostic();
    
    if (*Memory != 0x06) {
      ++Memory;
      continue;
    }
    
    ++Memory;
    if (Memory == MemoryEnd)
      return StoredDiagnostic();
  
    if (*Memory != 0x07) {
      ++Memory;
      continue;
    }
    
    // We found the header. We're done.
    ++Memory;
    break;
  }
  
  // Read the severity level.
  unsigned Level = 0;
  if (ReadUnsigned(Memory, MemoryEnd, Level) || Level > Diagnostic::Fatal)
    return StoredDiagnostic();

  // Read the source location.
  SourceLocation Location;
  if (ReadSourceLocation(FM, SM, Memory, MemoryEnd, Location))
    return StoredDiagnostic();

  // Read the diagnostic text.
  if (Memory == MemoryEnd)
    return StoredDiagnostic();

  unsigned MessageLen = 0;
  if (ReadUnsigned(Memory, MemoryEnd, MessageLen) ||
      Memory + MessageLen > MemoryEnd)
    return StoredDiagnostic();
  
  llvm::StringRef Message(Memory, MessageLen);
  Memory += MessageLen;


  // At this point, we have enough information to form a diagnostic. Do so.
  StoredDiagnostic Diag;
  Diag.Level = (Diagnostic::Level)Level;
  Diag.Loc = FullSourceLoc(Location, SM);
  Diag.Message = Message;
  if (Memory == MemoryEnd)
    return Diag;

  // Read the source ranges.
  unsigned NumSourceRanges = 0;
  if (ReadUnsigned(Memory, MemoryEnd, NumSourceRanges))
    return Diag;
  for (unsigned I = 0; I != NumSourceRanges; ++I) {
    SourceLocation Begin, End;
    if (ReadSourceLocation(FM, SM, Memory, MemoryEnd, Begin) ||
        ReadSourceLocation(FM, SM, Memory, MemoryEnd, End))
      return Diag;

    Diag.Ranges.push_back(SourceRange(Begin, End));
  }

  // Read the fix-it hints.
  unsigned NumFixIts = 0;
  if (ReadUnsigned(Memory, MemoryEnd, NumFixIts))
    return Diag;
  for (unsigned I = 0; I != NumFixIts; ++I) {
    SourceLocation RemoveBegin, RemoveEnd, InsertionLoc;
    unsigned InsertLen = 0;
    if (ReadSourceLocation(FM, SM, Memory, MemoryEnd, RemoveBegin) ||
        ReadSourceLocation(FM, SM, Memory, MemoryEnd, RemoveEnd) ||
        ReadSourceLocation(FM, SM, Memory, MemoryEnd, InsertionLoc) ||
        ReadUnsigned(Memory, MemoryEnd, InsertLen) ||
        Memory + InsertLen > MemoryEnd) {
      Diag.FixIts.clear();
      return Diag;
    }

    FixItHint Hint;
    Hint.RemoveRange = SourceRange(RemoveBegin, RemoveEnd);
    Hint.InsertionLoc = InsertionLoc;
    Hint.CodeToInsert.assign(Memory, Memory + InsertLen);
    Memory += InsertLen;
    Diag.FixIts.push_back(Hint);
  }

  return Diag;
}

/// IncludeInDiagnosticCounts - This method (whose default implementation
///  returns true) indicates whether the diagnostics handled by this
///  DiagnosticClient should be included in the number of diagnostics
///  reported by Diagnostic.
bool DiagnosticClient::IncludeInDiagnosticCounts() const { return true; }

PartialDiagnostic::StorageAllocator::StorageAllocator() {
  for (unsigned I = 0; I != NumCached; ++I)
    FreeList[I] = Cached + I;
  NumFreeListEntries = NumCached;
}

PartialDiagnostic::StorageAllocator::~StorageAllocator() {
  assert(NumFreeListEntries == NumCached && "A partial is on the lamb");
}