//===--- SemaType.cpp - Semantic Analysis for Types -----------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements type-related semantic analysis.
//
//===----------------------------------------------------------------------===//

#include "Sema.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/Parse/DeclSpec.h"
#include "clang/Lex/IdentifierTable.h"
using namespace llvm;
using namespace clang;

/// ConvertDeclSpecToType - Convert the specified declspec to the appropriate
/// type object.  This returns null on error.
static TypeRef ConvertDeclSpecToType(const DeclSpec &DS, ASTContext &Ctx) {
  // FIXME: Should move the logic from DeclSpec::Finish to here for validity
  // checking.
  
  switch (DS.getTypeSpecType()) {
  default: return TypeRef(); // FIXME: Handle unimp cases!
  case DeclSpec::TST_void: return Ctx.VoidTy;
  case DeclSpec::TST_char:
    if (DS.getTypeSpecSign() == DeclSpec::TSS_unspecified)
      return Ctx.CharTy;
    else if (DS.getTypeSpecSign() == DeclSpec::TSS_signed)
      return Ctx.SignedCharTy;
    else {
      assert(DS.getTypeSpecSign() == DeclSpec::TSS_unsigned &&
             "Unknown TSS value");
      return Ctx.UnsignedCharTy;
    }
  case DeclSpec::TST_int:
    if (DS.getTypeSpecSign() != DeclSpec::TSS_unsigned) {
      switch (DS.getTypeSpecWidth()) {
      case DeclSpec::TSW_unspecified: return Ctx.IntTy;
      case DeclSpec::TSW_short:       return Ctx.ShortTy;
      case DeclSpec::TSW_long:        return Ctx.LongTy;
      case DeclSpec::TSW_longlong:    return Ctx.LongLongTy;
      }
    } else {
      switch (DS.getTypeSpecWidth()) {
      case DeclSpec::TSW_unspecified: return Ctx.UnsignedIntTy;
      case DeclSpec::TSW_short:       return Ctx.UnsignedShortTy;
      case DeclSpec::TSW_long:        return Ctx.UnsignedLongTy;
      case DeclSpec::TSW_longlong:    return Ctx.UnsignedLongLongTy;
      }
    }
  case DeclSpec::TST_float:
    if (DS.getTypeSpecComplex() == DeclSpec::TSC_unspecified)
      return Ctx.FloatTy;
    assert(DS.getTypeSpecComplex() == DeclSpec::TSC_complex &&
           "FIXME: imaginary types not supported yet!");
    return Ctx.FloatComplexTy;
    
  case DeclSpec::TST_double: {
    bool isLong = DS.getTypeSpecWidth() == DeclSpec::TSW_long;
    if (DS.getTypeSpecComplex() == DeclSpec::TSC_unspecified)
      return isLong ? Ctx.LongDoubleTy : Ctx.DoubleTy;
    assert(DS.getTypeSpecComplex() == DeclSpec::TSC_complex &&
           "FIXME: imaginary types not supported yet!");
    return isLong ? Ctx.LongDoubleComplexTy : Ctx.DoubleComplexTy;
  }
  case DeclSpec::TST_bool:         // _Bool or bool
    return Ctx.BoolTy;
  case DeclSpec::TST_decimal32:    // _Decimal32
  case DeclSpec::TST_decimal64:    // _Decimal64
  case DeclSpec::TST_decimal128:   // _Decimal128
    assert(0 && "FIXME: GNU decimal extensions not supported yet!"); 
  case DeclSpec::TST_enum:
  case DeclSpec::TST_union:
  case DeclSpec::TST_struct: {
    Decl *D = static_cast<Decl *>(DS.getTypeRep());
    assert(D && "Didn't get a decl for a enum/union/struct?");
    assert(DS.getTypeSpecWidth() == 0 && DS.getTypeSpecComplex() == 0 &&
           DS.getTypeSpecSign() == 0 &&
           "Can't handle qualifiers on typedef names yet!");
    // TypeQuals handled by caller.
    return Ctx.getTagDeclType(cast<TagDecl>(D));
  }    
  case DeclSpec::TST_typedef: {
    Decl *D = static_cast<Decl *>(DS.getTypeRep());
    assert(D && "Didn't get a decl for a typedef?");
    assert(DS.getTypeSpecWidth() == 0 && DS.getTypeSpecComplex() == 0 &&
           DS.getTypeSpecSign() == 0 &&
           "Can't handle qualifiers on typedef names yet!");
    // TypeQuals handled by caller.
    return Ctx.getTypedefType(cast<TypedefDecl>(D));
  }
  }
}

/// GetTypeForDeclarator - Convert the type for the specified declarator to Type
/// instances.
TypeRef Sema::GetTypeForDeclarator(Declarator &D, Scope *S) {
  TypeRef T = ConvertDeclSpecToType(D.getDeclSpec(), Context);

  // If there was an error parsing declspecs, return a null type pointer.
  if (T.isNull()) return T;
  
  // Apply const/volatile/restrict qualifiers to T.
  T = T.getQualifiedType(D.getDeclSpec().getTypeQualifiers());
  
  // Walk the DeclTypeInfo, building the recursive type as we go.  DeclTypeInfos
  // are ordered from the identifier out, which is opposite of what we want :).
  for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i) {
    const DeclaratorChunk &DeclType = D.getTypeObject(e-i-1);
    switch (DeclType.Kind) {
    default: assert(0 && "Unknown decltype!");
    case DeclaratorChunk::Pointer:
      T = Context.getPointerType(T);

      // Apply the pointer typequals to the pointer object.
      T = T.getQualifiedType(DeclType.Ptr.TypeQuals);
      break;
    case DeclaratorChunk::Array: {
      const DeclaratorChunk::ArrayTypeInfo &ATI = DeclType.Arr;
      ArrayType::ArraySizeModifier ASM;
      if (ATI.isStar)
        ASM = ArrayType::Star;
      else if (ATI.hasStatic)
        ASM = ArrayType::Static;
      else
        ASM = ArrayType::Normal;
      
      Type *CanonicalT = T->getCanonicalType();
      
      // C99 6.7.5.2p1: If the element type is an incomplete or function type, 
      // reject it (e.g. void ary[7], struct foo ary[7], void ary[7]())
      if (T->isIncompleteType()) { 
        std::string Name;
        T->getAsString(Name);
        Diag(D.getIdentifierLoc(), diag::err_illegal_decl_array_incomplete_type,
             Name);
        return TypeRef();
      } else if (isa<FunctionType>(CanonicalT)) {
        Diag(D.getIdentifierLoc(), diag::err_illegal_decl_array_of_functions,
             D.getIdentifier()->getName());
        return TypeRef();
      } else if (RecordType *EltTy = dyn_cast<RecordType>(CanonicalT)) {
        // If the element type is a struct or union that contains a variadic
        // array, reject it: C99 6.7.2.1p2.
        if (EltTy->getDecl()->hasFlexibleArrayMember()) {
          std::string Name;
          T->getAsString(Name);
          Diag(DeclType.Loc, diag::err_flexible_array_in_array, Name);
          return TypeRef();
        }
      }
      T = Context.getArrayType(T, ASM, ATI.TypeQuals, 
                               static_cast<Expr *>(ATI.NumElts));
      break;
    }
    case DeclaratorChunk::Function:
      // If the function declarator has a prototype (i.e. it is not () and
      // does not have a K&R-style identifier list), then the arguments are part
      // of the type, otherwise the argument list is ().
      const DeclaratorChunk::FunctionTypeInfo &FTI = DeclType.Fun;
      if (!FTI.hasPrototype) {
        // Simple void foo(), where the incoming T is the result type.
        T = Context.getFunctionTypeNoProto(T);

        // C99 6.7.5.3p3: Reject int(x,y,z) when it's not a function definition.
        if (FTI.NumArgs != 0)
          Diag(FTI.ArgInfo[0].IdentLoc, diag::err_ident_list_in_fn_declaration);
        
      } else {
        // Otherwise, we have a function with an argument list that is
        // potentially variadic.
        SmallVector<TypeRef, 16> ArgTys;
        
        for (unsigned i = 0, e = FTI.NumArgs; i != e; ++i) {
          TypeRef ArgTy = TypeRef::getFromOpaquePtr(FTI.ArgInfo[i].TypeInfo);
          if (ArgTy.isNull())
            return TypeRef();  // Error occurred parsing argument type.
          
          // Look for 'void'.  void is allowed only as a single argument to a
          // function with no other parameters (C99 6.7.5.3p10).  We record
          // int(void) as a FunctionTypeProto with an empty argument list.
          if (ArgTy->isVoidType()) {
            // If this is something like 'float(int, void)', reject it.  'void'
            // is an incomplete type (C99 6.2.5p19) and function decls cannot
            // have arguments of incomplete type.
            if (FTI.NumArgs != 1 || FTI.isVariadic) {
              Diag(DeclType.Loc, diag::err_void_only_param);
              return TypeRef();
            }
            // Reject, but continue to parse 'int(void abc)'.
            if (FTI.ArgInfo[i].Ident)
              Diag(FTI.ArgInfo[i].IdentLoc,
                   diag::err_void_param_with_identifier);
            
            // Reject, but continue to parse 'float(const void)'.
            if (ArgTy.getQualifiers())
              Diag(DeclType.Loc, diag::err_void_param_qualified);
            
            // Do not add 'void' to the ArgTys list.
            break;
          }
          
          ArgTys.push_back(ArgTy);
        }
        T = Context.getFunctionType(T, &ArgTys[0], ArgTys.size(),
                                    FTI.isVariadic);
      }
      break;
    }
  }
  
  return T;
}

Sema::TypeResult Sema::ParseTypeName(Scope *S, Declarator &D) {
  // C99 6.7.6: Type names have no identifier.  This is already validated by
  // the parser.
  assert(D.getIdentifier() == 0 && "Type name should have no identifier!");
  
  TypeRef T = GetTypeForDeclarator(D, S);
  
  // If the type of the declarator was invalid, this is an invalid typename.
  if (T.isNull())
    return true;
  
  return T.getAsOpaquePtr();
}

Sema::TypeResult Sema::ParseParamDeclaratorType(Scope *S, Declarator &D) {
  // Note: parameters have identifiers, but we don't care about them here, we
  // just want the type converted.
  TypeRef T = GetTypeForDeclarator(D, S);
  
  // If the type of the declarator was invalid, this is an invalid typename.
  if (T.isNull())
    return true;
  
  return T.getAsOpaquePtr();
}
