Commit d25db7ed authored by John McCall's avatar John McCall
Browse files

Grab-bag of bit-field fixes: 

  - References to ObjC bit-field ivars are bit-field lvalues;
    fixes rdar://13794269, which got me started down this.
  - Introduce Expr::refersToBitField, switch a couple users to
    it where semantically important, and comment the difference
    between this and the existing API.
  - Discourage Expr::getBitField by making it a bit longer and
    less general-sounding.
  - Lock down on const_casts of bit-field gl-values until we
    hear back from the committee as to whether they're allowed.

llvm-svn: 181252
parent 252a0acc

clang/include/clang/AST/Expr.h

+16 −4
Original line number Diff line number Diff line
@@ -427,12 +427,24 @@ private: 


public:



  /// \brief Returns true if this expression is a gl-value that

  /// potentially refers to a bit-field.

  ///

  /// In C++, whether a gl-value refers to a bitfield is essentially

  /// an aspect of the value-kind type system.

  bool refersToBitField() const { return getObjectKind() == OK_BitField; }



  /// \brief If this expression refers to a bit-field, retrieve the

  /// declaration of that bit-field.

  FieldDecl *getBitField();



  const FieldDecl *getBitField() const {

    return const_cast<Expr*>(this)->getBitField();

  ///

  /// Note that this returns a non-null pointer in subtly different

  /// places than refersToBitField returns true.  In particular, this can

  /// return a non-null pointer even for r-values loaded from

  /// bit-fields, but it will return null for a conditional bit-field.

  FieldDecl *getSourceBitField();



  const FieldDecl *getSourceBitField() const {

    return const_cast<Expr*>(this)->getSourceBitField();

  }



  /// \brief If this expression is an l-value for an Objective C

clang/include/clang/AST/ExprObjC.h

+2 −1
Original line number Diff line number Diff line
@@ -476,7 +476,8 @@ public: 
                  SourceLocation l, SourceLocation oploc,

                  Expr *base,

                  bool arrow = false, bool freeIvar = false) :

    Expr(ObjCIvarRefExprClass, t, VK_LValue, OK_Ordinary,

    Expr(ObjCIvarRefExprClass, t, VK_LValue,

         d->isBitField() ? OK_BitField : OK_Ordinary,

         /*TypeDependent=*/false, base->isValueDependent(), 

         base->isInstantiationDependent(),

         base->containsUnexpandedParameterPack()),

clang/include/clang/Basic/DiagnosticSemaKinds.td

+5 −1
Original line number Diff line number Diff line
@@ -1307,7 +1307,8 @@ def err_member_function_call_bad_cvr : Error<"member function %0 not viable: " 
    "volatile or restrict|const, volatile, or restrict}2">;



def err_reference_bind_to_bitfield : Error<

  "%select{non-const|volatile}0 reference cannot bind to bit-field %1">;

  "%select{non-const|volatile}0 reference cannot bind to "

  "bit-field%select{| %1}2">;

def err_reference_bind_to_vector_element : Error<

  "%select{non-const|volatile}0 reference cannot bind to vector element">;

def err_reference_var_requires_init : Error<
@@ -4629,6 +4630,9 @@ def err_bad_cxx_cast_generic : Error< 
def err_bad_cxx_cast_rvalue : Error<

  "%select{const_cast|static_cast|reinterpret_cast|dynamic_cast|C-style cast|"

  "functional-style cast}0 from rvalue to reference type %2">;

def err_bad_cxx_cast_bitfield : Error<

  "%select{const_cast|static_cast|reinterpret_cast|dynamic_cast|C-style cast|"

  "functional-style cast}0 from bit-field lvalue to reference type %2">;

def err_bad_cxx_cast_qualifiers_away : Error<

  "%select{const_cast|static_cast|reinterpret_cast|dynamic_cast|C-style cast|"

  "functional-style cast}0 from %1 to %2 casts away qualifiers">;

clang/lib/AST/ASTContext.cpp

+1 −1
Original line number Diff line number Diff line
@@ -4277,7 +4277,7 @@ QualType ASTContext::isPromotableBitField(Expr *E) const { 
  if (E->isTypeDependent() || E->isValueDependent())

    return QualType();

  

  FieldDecl *Field = E->getBitField();

  FieldDecl *Field = E->getSourceBitField(); // FIXME: conditional bit-fields?

  if (!Field)

    return QualType();

clang/lib/AST/Expr.cpp

+8 −3
Original line number Diff line number Diff line
@@ -3149,7 +3149,7 @@ bool Expr::isObjCSelfExpr() const { 
  return M->getSelfDecl() == Param;

}



FieldDecl *Expr::getBitField() {

FieldDecl *Expr::getSourceBitField() {

  Expr *E = this->IgnoreParens();



  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
@@ -3165,6 +3165,11 @@ FieldDecl *Expr::getBitField() { 
      if (Field->isBitField())

        return Field;



  if (ObjCIvarRefExpr *IvarRef = dyn_cast<ObjCIvarRefExpr>(E))

    if (FieldDecl *Ivar = dyn_cast<FieldDecl>(IvarRef->getDecl()))

      if (Ivar->isBitField())

        return Ivar;



  if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(E))

    if (FieldDecl *Field = dyn_cast<FieldDecl>(DeclRef->getDecl()))

      if (Field->isBitField())
@@ -3172,10 +3177,10 @@ FieldDecl *Expr::getBitField() { 


  if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(E)) {

    if (BinOp->isAssignmentOp() && BinOp->getLHS())

      return BinOp->getLHS()->getBitField();

      return BinOp->getLHS()->getSourceBitField();



    if (BinOp->getOpcode() == BO_Comma && BinOp->getRHS())

      return BinOp->getRHS()->getBitField();

      return BinOp->getRHS()->getSourceBitField();

  }



  return 0;