lib/AST/ASTDiagnostic.cpp

//===--- ASTDiagnostic.cpp - Diagnostic Printing Hooks for AST Nodes ------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a diagnostic formatting hook for AST elements.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/ASTDiagnostic.h"

#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/Type.h"
#include "llvm/Support/raw_ostream.h"

using namespace clang;

/// Determines whether we should have an a.k.a. clause when
/// pretty-printing a type.  There are three main criteria:
///
/// 1) Some types provide very minimal sugar that doesn't impede the
///    user's understanding --- for example, elaborated type
///    specifiers.  If this is all the sugar we see, we don't want an
///    a.k.a. clause.
/// 2) Some types are technically sugared but are much more familiar
///    when seen in their sugared form --- for example, va_list,
///    vector types, and the magic Objective C types.  We don't
///    want to desugar these, even if we do produce an a.k.a. clause.
/// 3) Some types may have already been desugared previously in this diagnostic.
///    if this is the case, doing another "aka" would just be clutter.
///
static bool ShouldAKA(ASTContext &Context, QualType QT,
                      const Diagnostic::ArgumentValue *PrevArgs,
                      unsigned NumPrevArgs,
                      QualType &DesugaredQT) {
  QualType InputTy = QT;
  
  bool AKA = false;
  QualifierCollector Qc;
  
  while (true) {
    const Type *Ty = Qc.strip(QT);
    
    // Don't aka just because we saw an elaborated type...
    if (isa<ElaboratedType>(Ty)) {
      QT = cast<ElaboratedType>(Ty)->desugar();
      continue;
    }
    
    // ...or a qualified name type...
    if (isa<QualifiedNameType>(Ty)) {
      QT = cast<QualifiedNameType>(Ty)->desugar();
      continue;
    }
    
    // ...or a substituted template type parameter.
    if (isa<SubstTemplateTypeParmType>(Ty)) {
      QT = cast<SubstTemplateTypeParmType>(Ty)->desugar();
      continue;
    }
    
    // Don't desugar template specializations. 
    if (isa<TemplateSpecializationType>(Ty))
      break;
    
    // Don't desugar magic Objective-C types.
    if (QualType(Ty,0) == Context.getObjCIdType() ||
        QualType(Ty,0) == Context.getObjCClassType() ||
        QualType(Ty,0) == Context.getObjCSelType() ||
        QualType(Ty,0) == Context.getObjCProtoType())
      break;
    
    // Don't desugar va_list.
    if (QualType(Ty,0) == Context.getBuiltinVaListType())
      break;
    
    // Otherwise, do a single-step desugar.
    QualType Underlying;
    bool IsSugar = false;
    switch (Ty->getTypeClass()) {
#define ABSTRACT_TYPE(Class, Base)
#define TYPE(Class, Base) \
case Type::Class: { \
const Class##Type *CTy = cast<Class##Type>(Ty); \
if (CTy->isSugared()) { \
IsSugar = true; \
Underlying = CTy->desugar(); \
} \
break; \
}
#include "clang/AST/TypeNodes.def"
    }
    
    // If it wasn't sugared, we're done.
    if (!IsSugar)
      break;
    
    // If the desugared type is a vector type, we don't want to expand
    // it, it will turn into an attribute mess. People want their "vec4".
    if (isa<VectorType>(Underlying))
      break;
    
    // Don't desugar through the primary typedef of an anonymous type.
    if (isa<TagType>(Underlying) && isa<TypedefType>(QT))
      if (cast<TagType>(Underlying)->getDecl()->getTypedefForAnonDecl() ==
          cast<TypedefType>(QT)->getDecl())
        break;
    
    // Otherwise, we're tearing through something opaque; note that
    // we'll eventually need an a.k.a. clause and keep going.
    AKA = true;
    QT = Underlying;
    continue;
  }
  
  // If we never tore through opaque sugar, don't print aka.
  if (!AKA) return false;
  
  // If we did, check to see if we already desugared this type in this
  // diagnostic.  If so, don't do it again.
  for (unsigned i = 0; i != NumPrevArgs; ++i) {
    // TODO: Handle ak_declcontext case.
    if (PrevArgs[i].first == Diagnostic::ak_qualtype) {
      void *Ptr = (void*)PrevArgs[i].second;
      QualType PrevTy(QualType::getFromOpaquePtr(Ptr));
      if (PrevTy == InputTy)
        return false;
    }
  }
  
  DesugaredQT = Qc.apply(QT);
  return true;
}

/// \brief Convert the given type to a string suitable for printing as part of 
/// a diagnostic. 
///
/// \param Context the context in which the type was allocated
/// \param Ty the type to print
static std::string
ConvertTypeToDiagnosticString(ASTContext &Context, QualType Ty,
                              const Diagnostic::ArgumentValue *PrevArgs,
                              unsigned NumPrevArgs) {
  // FIXME: Playing with std::string is really slow.
  std::string S = Ty.getAsString(Context.PrintingPolicy);
  
  // Consider producing an a.k.a. clause if removing all the direct
  // sugar gives us something "significantly different".
  
  QualType DesugaredTy;
  if (ShouldAKA(Context, Ty, PrevArgs, NumPrevArgs, DesugaredTy)) {
    S = "'"+S+"' (aka '";
    S += DesugaredTy.getAsString(Context.PrintingPolicy);
    S += "')";
    return S;
  }
  
  S = "'" + S + "'";
  return S;
}

void clang::FormatASTNodeDiagnosticArgument(Diagnostic::ArgumentKind Kind, 
                                            intptr_t Val,
                                            const char *Modifier, 
                                            unsigned ModLen,
                                            const char *Argument, 
                                            unsigned ArgLen,
                                    const Diagnostic::ArgumentValue *PrevArgs,
                                            unsigned NumPrevArgs,
                                            llvm::SmallVectorImpl<char> &Output,
                                            void *Cookie) {
  ASTContext &Context = *static_cast<ASTContext*>(Cookie);
  
  std::string S;
  bool NeedQuotes = true;
  
  switch (Kind) {
    default: assert(0 && "unknown ArgumentKind");
    case Diagnostic::ak_qualtype: {
      assert(ModLen == 0 && ArgLen == 0 &&
             "Invalid modifier for QualType argument");
      
      QualType Ty(QualType::getFromOpaquePtr(reinterpret_cast<void*>(Val)));
      S = ConvertTypeToDiagnosticString(Context, Ty, PrevArgs, NumPrevArgs);
      NeedQuotes = false;
      break;
    }
    case Diagnostic::ak_declarationname: {
      DeclarationName N = DeclarationName::getFromOpaqueInteger(Val);
      S = N.getAsString();
      
      if (ModLen == 9 && !memcmp(Modifier, "objcclass", 9) && ArgLen == 0)
        S = '+' + S;
      else if (ModLen == 12 && !memcmp(Modifier, "objcinstance", 12)
                && ArgLen==0)
        S = '-' + S;
      else
        assert(ModLen == 0 && ArgLen == 0 &&
               "Invalid modifier for DeclarationName argument");
      break;
    }
    case Diagnostic::ak_nameddecl: {
      bool Qualified;
      if (ModLen == 1 && Modifier[0] == 'q' && ArgLen == 0)
        Qualified = true;
      else {
        assert(ModLen == 0 && ArgLen == 0 &&
               "Invalid modifier for NamedDecl* argument");
        Qualified = false;
      }
      reinterpret_cast<NamedDecl*>(Val)->
      getNameForDiagnostic(S, Context.PrintingPolicy, Qualified);
      break;
    }
    case Diagnostic::ak_nestednamespec: {
      llvm::raw_string_ostream OS(S);
      reinterpret_cast<NestedNameSpecifier*>(Val)->print(OS,
                                                        Context.PrintingPolicy);
      NeedQuotes = false;
      break;
    }
    case Diagnostic::ak_declcontext: {
      DeclContext *DC = reinterpret_cast<DeclContext *> (Val);
      assert(DC && "Should never have a null declaration context");
      
      if (DC->isTranslationUnit()) {
        // FIXME: Get these strings from some localized place
        if (Context.getLangOptions().CPlusPlus)
          S = "the global namespace";
        else
          S = "the global scope";
      } else if (TypeDecl *Type = dyn_cast<TypeDecl>(DC)) {
        S = ConvertTypeToDiagnosticString(Context, 
                                          Context.getTypeDeclType(Type),
                                          PrevArgs, NumPrevArgs);
      } else {
        // FIXME: Get these strings from some localized place
        NamedDecl *ND = cast<NamedDecl>(DC);
        if (isa<NamespaceDecl>(ND))
          S += "namespace ";
        else if (isa<ObjCMethodDecl>(ND))
          S += "method ";
        else if (isa<FunctionDecl>(ND))
          S += "function ";
        
        S += "'";
        ND->getNameForDiagnostic(S, Context.PrintingPolicy, true);
        S += "'";
      }
      NeedQuotes = false;
      break;
    }
  }
  
  if (NeedQuotes)
    Output.push_back('\'');
  
  Output.append(S.begin(), S.end());
  
  if (NeedQuotes)
    Output.push_back('\'');
}