path: root/lib/Sema/SemaNamedCast.cpp

//===--- SemaNamedCast.cpp - Semantic Analysis for Named Casts ------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements semantic analysis for C++ named casts.
//
//===----------------------------------------------------------------------===//

#include "Sema.h"
#include "SemaInherit.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ASTContext.h"
#include "llvm/ADT/SmallVector.h"
#include <set>
using namespace clang;

enum TryStaticCastResult {
  TSC_NotApplicable, ///< The cast method is not applicable.
  TSC_Success,       ///< The cast method is appropriate and successful.
  TSC_Failed         ///< The cast method is appropriate, but failed. A
                     ///< diagnostic has been emitted.
};

static void CheckConstCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
                           const SourceRange &OpRange,
                           const SourceRange &DestRange);
static void CheckReinterpretCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
                                 const SourceRange &OpRange,
                                 const SourceRange &DestRange);
static void CheckStaticCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
                            const SourceRange &OpRange);
static void CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
                             const SourceRange &OpRange,
                             const SourceRange &DestRange);

static bool CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType);
static TryStaticCastResult TryLValueToRValueCast(
  Sema &Self, Expr *SrcExpr, QualType DestType, const SourceRange &OpRange);
static TryStaticCastResult TryStaticReferenceDowncast(
  Sema &Self, Expr *SrcExpr, QualType DestType, const SourceRange &OpRange);
static TryStaticCastResult TryStaticPointerDowncast(
  Sema &Self, QualType SrcType, QualType DestType, const SourceRange &OpRange);
static TryStaticCastResult TryStaticMemberPointerUpcast(
  Sema &Self, QualType SrcType, QualType DestType, const SourceRange &OpRange);
static TryStaticCastResult TryStaticDowncast(Sema &Self, QualType SrcType,
                                             QualType DestType,
                                             const SourceRange &OpRange,
                                             QualType OrigSrcType,
                                             QualType OrigDestType);
static TryStaticCastResult TryStaticImplicitCast(Sema &Self, Expr *SrcExpr,
                                                 QualType DestType,
                                                 const SourceRange &OpRange);

/// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's.
Action::OwningExprResult
Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
                        SourceLocation LAngleBracketLoc, TypeTy *Ty,
                        SourceLocation RAngleBracketLoc,
                        SourceLocation LParenLoc, ExprArg E,
                        SourceLocation RParenLoc) {
  Expr *Ex = E.takeAs<Expr>();
  QualType DestType = QualType::getFromOpaquePtr(Ty);
  SourceRange OpRange(OpLoc, RParenLoc);
  SourceRange DestRange(LAngleBracketLoc, RAngleBracketLoc);

  // If the type is dependent, we won't do the semantic analysis now.
  // FIXME: should we check this in a more fine-grained manner?
  bool TypeDependent = DestType->isDependentType() || Ex->isTypeDependent();

  switch (Kind) {
  default: assert(0 && "Unknown C++ cast!");

  case tok::kw_const_cast:
    if (!TypeDependent)
      CheckConstCast(*this, Ex, DestType, OpRange, DestRange);
    return Owned(new (Context) CXXConstCastExpr(DestType.getNonReferenceType(),
                                                Ex, DestType, OpLoc));

  case tok::kw_dynamic_cast:
    if (!TypeDependent)
      CheckDynamicCast(*this, Ex, DestType, OpRange, DestRange);
    return Owned(new (Context)CXXDynamicCastExpr(DestType.getNonReferenceType(),
                                                 Ex, DestType, OpLoc));

  case tok::kw_reinterpret_cast:
    if (!TypeDependent)
      CheckReinterpretCast(*this, Ex, DestType, OpRange, DestRange);
    return Owned(new (Context) CXXReinterpretCastExpr(
                                  DestType.getNonReferenceType(),
                                  Ex, DestType, OpLoc));

  case tok::kw_static_cast:
    if (!TypeDependent)
      CheckStaticCast(*this, Ex, DestType, OpRange);
    return Owned(new (Context) CXXStaticCastExpr(DestType.getNonReferenceType(),
                                                 Ex, DestType, OpLoc));
  }

  return ExprError();
}

/// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid.
/// Refer to C++ 5.2.11 for details. const_cast is typically used in code
/// like this:
/// const char *str = "literal";
/// legacy_function(const_cast\<char*\>(str));
void
CheckConstCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
               const SourceRange &OpRange, const SourceRange &DestRange)
{
  QualType OrigDestType = DestType, OrigSrcType = SrcExpr->getType();

  DestType = Self.Context.getCanonicalType