Move all of Sema's member-access-related checking out of SemaExpr.cpp

and into a new file, SemaExprMember.cpp, bringing SemaExpr.cpp just
under 10,000 lines of code (ugh). No functionality change, although I
intend to do some refactoring of this code to address PR8368 at some
point in the "near" future.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@133674 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 1582 insertions, 0 deletions

diff --git a/lib/Sema/SemaExprMember.cpp b/lib/Sema/SemaExprMember.cpp
new file mode 100644
index 0000000000..082691ffed
--- /dev/null
+++ b/lib/Sema/SemaExprMember.cpp
@@ -0,0 +1,1582 @@
+//===--- SemaExprMember.cpp - Semantic Analysis for Expressions -----------===//
+//
+//                     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 member access expressions.
+//
+//===----------------------------------------------------------------------===//
+#include "clang/Sema/SemaInternal.h"
+#include "clang/Sema/Lookup.h"
+#include "clang/Sema/Scope.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/DeclTemplate.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/ExprObjC.h"
+#include "clang/Lex/Preprocessor.h"
+
+using namespace clang;
+using namespace sema;
+
+/// Determines if the given class is provably not derived from all of
+/// the prospective base classes.
+static bool IsProvablyNotDerivedFrom(Sema &SemaRef,
+                                     CXXRecordDecl *Record,
+                            const llvm::SmallPtrSet<CXXRecordDecl*, 4> &Bases) {
+  if (Bases.count(Record->getCanonicalDecl()))
+    return false;
+
+  RecordDecl *RD = Record->getDefinition();
+  if (!RD) return false;
+  Record = cast<CXXRecordDecl>(RD);
+
+  for (CXXRecordDecl::base_class_iterator I = Record->bases_begin(),
+         E = Record->bases_end(); I != E; ++I) {
+    CanQualType BaseT = SemaRef.Context.getCanonicalType((*I).getType());
+    CanQual<RecordType> BaseRT = BaseT->getAs<RecordType>();
+    if (!BaseRT) return false;
+
+    CXXRecordDecl *BaseRecord = cast<CXXRecordDecl>(BaseRT->getDecl());
+    if (!IsProvablyNotDerivedFrom(SemaRef, BaseRecord, Bases))
+      return false;
+  }
+
+  return true;
+}
+
+enum IMAKind {
+  /// The reference is definitely not an instance member access.
+  IMA_Static,
+
+  /// The reference may be an implicit instance member access.
+  IMA_Mixed,
+
+  /// The reference may be to an instance member, but it is invalid if
+  /// so, because the context is not an instance method.
+  IMA_Mixed_StaticContext,
+
+  /// The reference may be to an instance member, but it is invalid if
+  /// so, because the context is from an unrelated class.
+  IMA_Mixed_Unrelated,
+
+  /// The reference is definitely an implicit instance member access.
+  IMA_Instance,
+
+  /// The reference may be to an unresolved using declaration.
+  IMA_Unresolved,
+
+  /// The reference may be to an unresolved using declaration and the
+  /// context is not an instance method.
+  IMA_Unresolved_StaticContext,
+
+  /// All possible referrents are instance members and the current
+  /// context is not an instance method.
+  IMA_Error_StaticContext,
+
+  /// All possible referrents are instance members of an unrelated
+  /// class.
+  IMA_Error_Unrelated
+};
+
+/// The given lookup names class member(s) and is not being used for
+/// an address-of-member expression.  Classify the type of access
+/// according to whether it's possible that this reference names an
+/// instance member.  This is best-effort; it is okay to
+/// conservatively answer "yes", in which case some errors will simply
+/// not be caught until template-instantiation.
+static IMAKind ClassifyImplicitMemberAccess(Sema &SemaRef,
+                                            Scope *CurScope,
+                                            const LookupResult &R) {
+  assert(!R.empty() && (*R.begin())->isCXXClassMember());
+
+  DeclContext *DC = SemaRef.getFunctionLevelDeclContext();
+
+  bool isStaticContext =
+    (!isa<CXXMethodDecl>(DC) ||
+     cast<CXXMethodDecl>(DC)->isStatic());
+
+  // C++0x [expr.prim]p4:
+  //   Otherwise, if a member-declarator declares a non-static data member
+  // of a class X, the expression this is a prvalue of type "pointer to X"
+  // within the optional brace-or-equal-initializer.
+  if (CurScope->getFlags() & Scope::ThisScope)
+    isStaticContext = false;
+
+  if (R.isUnresolvableResult())
+    return isStaticContext ? IMA_Unresolved_StaticContext : IMA_Unresolved;
+
+  // Collect all the declaring classes of instance members we find.
+  bool hasNonInstance = false;
+  bool hasField = false;
+  llvm::SmallPtrSet<CXXRecordDecl*, 4> Classes;
+  for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I) {
+    NamedDecl *D = *I;
+
+    if (D->isCXXInstanceMember()) {
+      if (dyn_cast<FieldDecl>(D))
+        hasField = true;
+
+      CXXRecordDecl *R = cast<CXXRecordDecl>(D->getDeclContext());
+      Classes.insert(R->getCanonicalDecl());
+    }
+    else
+      hasNonInstance = true;
+  }
+
+  // If we didn't find any instance members, it can't be an implicit
+  // member reference.
+  if (Classes.empty())
+    return IMA_Static;
+
+  // If the current context is not an instance method, it can't be
+  // an implicit member reference.
+  if (isStaticContext) {
+    if (hasNonInstance)
+        return IMA_Mixed_StaticContext;
+        
+    if (SemaRef.getLangOptions().CPlusPlus0x && hasField) {
+      // C++0x [expr.prim.general]p10:
+      //   An id-expression that denotes a non-static data member or non-static
+      //   member function of a class can only be used:
+      //   (...)
+      //   - if that id-expression denotes a non-static data member and it
+      //     appears in an unevaluated operand.
+      const Sema::ExpressionEvaluationContextRecord& record
+        = SemaRef.ExprEvalContexts.back();
+      bool isUnevaluatedExpression = (record.Context == Sema::Unevaluated);
+      if (isUnevaluatedExpression)
+        return IMA_Mixed_StaticContext;
+    }
+    
+    return IMA_Error_StaticContext;
+  }
+
+  CXXRecordDecl *contextClass;
+  if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(DC))
+    contextClass = MD->getParent()->getCanonicalDecl();
+  else
+    contextClass = cast<CXXRecordDecl>(DC);
+
+  // [class.mfct.non-static]p3: 
+  // ...is used in the body of a non-static member function of class X,
+  // if name lookup (3.4.1) resolves the name in the id-expression to a
+  // non-static non-type member of some class C [...]
+  // ...if C is not X or a base class of X, the class member access expression
+  // is ill-formed.
+  if (R.getNamingClass() &&
+      contextClass != R.getNamingClass()->getCanonicalDecl() &&
+      contextClass->isProvablyNotDerivedFrom(R.getNamingClass()))
+    return (hasNonInstance ? IMA_Mixed_Unrelated : IMA_Error_Unrelated);
+
+  // If we can prove that the current context is unrelated to all the
+  // declaring classes, it can't be an implicit member reference (in
+  // which case it's an error if any of those members are selected).
+  if (IsProvablyNotDerivedFrom(SemaRef, contextClass, Classes))
+    return (hasNonInstance ? IMA_Mixed_Unrelated : IMA_Error_Unrelated);
+
+  return (hasNonInstance ? IMA_Mixed : IMA_Instance);
+}
+
+/// Diagnose a reference to a field with no object available.
+static void DiagnoseInstanceReference(Sema &SemaRef,
+                                      const CXXScopeSpec &SS,
+                                      NamedDecl *rep,
+                                      const DeclarationNameInfo &nameInfo) {
+  SourceLocation Loc = nameInfo.getLoc();
+  SourceRange Range(Loc);
+  if (SS.isSet()) Range.setBegin(SS.getRange().getBegin());
+  
+  if (isa<FieldDecl>(rep) || isa<IndirectFieldDecl>(rep)) {
+    if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(SemaRef.CurContext)) {
+      if (MD->isStatic()) {
+        // "invalid use of member 'x' in static member function"
+        SemaRef.Diag(Loc, diag::err_invalid_member_use_in_static_method)
+        << Range << nameInfo.getName();
+        return;
+      }
+    }
+    
+    SemaRef.Diag(Loc, diag::err_invalid_non_static_member_use)
+    << nameInfo.getName() << Range;
+    return;
+  }
+  
+  SemaRef.Diag(Loc, diag::err_member_call_without_object) << Range;
+}
+
+/// Builds an expression which might be an implicit member expression.
+ExprResult
+Sema::BuildPossibleImplicitMemberExpr(const CXXScopeSpec &SS,
+                                      LookupResult &R,
+                                const TemplateArgumentListInfo *TemplateArgs) {
+  switch (ClassifyImplicitMemberAccess(*this, CurScope, R)) {
+  case IMA_Instance:
+    return BuildImplicitMemberExpr(SS, R, TemplateArgs, true);
+
+  case IMA_Mixed:
+  case IMA_Mixed_Unrelated:
+  case IMA_Unresolved:
+    return BuildImplicitMemberExpr(SS, R, TemplateArgs, false);
+
+  case IMA_Static:
+  case IMA_Mixed_StaticContext:
+  case IMA_Unresolved_StaticContext:
+    if (TemplateArgs)
+      return BuildTemplateIdExpr(SS, R, false, *TemplateArgs);
+    return BuildDeclarationNameExpr(SS, R, false);
+
+  case IMA_Error_StaticContext:
+  case IMA_Error_Unrelated:
+    DiagnoseInstanceReference(*this, SS, R.getRepresentativeDecl(),
+                              R.getLookupNameInfo());
+    return ExprError();
+  }
+
+  llvm_unreachable("unexpected instance member access kind");
+  return ExprError();
+}
+
+/// Check an ext-vector component access expression.
+///
+/// VK should be set in advance to the value kind of the base
+/// expression.
+static QualType
+CheckExtVectorComponent(Sema &S, QualType baseType, ExprValueKind &VK,
+                        SourceLocation OpLoc, const IdentifierInfo *CompName,
+                        SourceLocation CompLoc) {
+  // FIXME: Share logic with ExtVectorElementExpr::containsDuplicateElements,
+  // see FIXME there.
+  //
+  // FIXME: This logic can be greatly simplified by splitting it along
+  // halving/not halving and reworking the component checking.
+  const ExtVectorType *vecType = baseType->getAs<ExtVectorType>();
+
+  // The vector accessor can't exceed the number of elements.
+  const char *compStr = CompName->getNameStart();
+
+  // This flag determines whether or not the component is one of the four
+  // special names that indicate a subset of exactly half the elements are
+  // to be selected.
+  bool HalvingSwizzle = false;
+
+  // This flag determines whether or not CompName has an 's' char prefix,
+  // indicating that it is a string of hex values to be used as vector indices.
+  bool HexSwizzle = *compStr == 's' || *compStr == 'S';
+
+  bool HasRepeated = false;
+  bool HasIndex[16] = {};
+
+  int Idx;
+
+  // Check that we've found one of the special components, or that the component
+  // names must come from the same set.
+  if (!strcmp(compStr, "hi") || !strcmp(compStr, "lo") ||
+      !strcmp(compStr, "even") || !strcmp(compStr, "odd")) {
+    HalvingSwizzle = true;
+  } else if (!HexSwizzle &&
+             (Idx = vecType->getPointAccessorIdx(*compStr)) != -1) {
+    do {
+      if (HasIndex[Idx]) HasRepeated = true;
+      HasIndex[Idx] = true;
+      compStr++;
+    } while (*compStr && (Idx = vecType->getPointAccessorIdx(*compStr)) != -1);
+  } else {
+    if (HexSwizzle) compStr++;
+    while ((Idx = vecType->getNumericAccessorIdx(*compStr)) != -1) {
+      if (HasIndex[Idx]) HasRepeated = true;
+      HasIndex[Idx] = true;
+      compStr++;
+    }
+  }
+
+  if (!HalvingSwizzle && *compStr) {
+    // We didn't get to the end of the string. This means the component names
+    // didn't come from the same set *or* we encountered an illegal name.
+    S.Diag(OpLoc, diag::err_ext_vector_component_name_illegal)
+      << llvm::StringRef(compStr, 1) << SourceRange(CompLoc);
+    return QualType();
+  }
+
+  // Ensure no component accessor exceeds the width of the vector type it
+  // operates on.
+  if (!HalvingSwizzle) {
+    compStr = CompName->getNameStart();
+
+    if (HexSwizzle)
+      compStr++;
+
+    while (*compStr) {
+      if (!vecType->isAccessorWithinNumElements(*compStr++)) {
+        S.Diag(OpLoc, diag::err_ext_vector_component_exceeds_length)
+          << baseType << SourceRange(CompLoc);
+        return QualType();
+      }
+    }
+  }
+
+  // The component accessor looks fine - now we need to compute the actual type.
+  // The vector type is implied by the component accessor. For example,
+  // vec4.b is a float, vec4.xy is a vec2, vec4.rgb is a vec3, etc.
+  // vec4.s0 is a float, vec4.s23 is a vec3, etc.
+  // vec4.hi, vec4.lo, vec4.e, and vec4.o all return vec2.
+  unsigned CompSize = HalvingSwizzle ? (vecType->getNumElements() + 1) / 2
+                                     : CompName->getLength();
+  if (HexSwizzle)
+    CompSize--;
+
+  if (CompSize == 1)
+    return vecType->getElementType();
+
+  if (HasRepeated) VK = VK_RValue;
+
+  QualType VT = S.Context.getExtVectorType(vecType->getElementType(), CompSize);
+  // Now look up the TypeDefDecl from the vector type. Without this,
+  // diagostics look bad. We want extended vector types to appear built-in.
+  for (unsigned i = 0, E = S.ExtVectorDecls.size(); i != E; ++i) {
+    if (S.ExtVectorDecls[i]->getUnderlyingType() == VT)
+      return S.Context.getTypedefType(S.ExtVectorDecls[i]);
+  }
+  return VT; // should never get here (a typedef type should always be found).
+}
+
+static Decl *FindGetterSetterNameDeclFromProtocolList(const ObjCProtocolDecl*PDecl,
+                                                IdentifierInfo *Member,
+                                                const Selector &Sel,
+                                                ASTContext &Context) {
+  if (Member)
+    if (ObjCPropertyDecl *PD = PDecl->FindPropertyDeclaration(Member))
+      return PD;
+  if (ObjCMethodDecl *OMD = PDecl->getInstanceMethod(Sel))
+    return OMD;
+
+  for (ObjCProtocolDecl::protocol_iterator I = PDecl->protocol_begin(),
+       E = PDecl->protocol_end(); I != E; ++I) {
+    if (Decl *D = FindGetterSetterNameDeclFromProtocolList(*I, Member, Sel,
+                                                           Context))
+      return D;
+  }
+  return 0;
+}
+
+static Decl *FindGetterSetterNameDecl(const ObjCObjectPointerType *QIdTy,
+                                      IdentifierInfo *Member,
+                                      const Selector &Sel,
+                                      ASTContext &Context) {
+  // Check protocols on qualified interfaces.
+  Decl *GDecl = 0;
+  for (ObjCObjectPointerType::qual_iterator I = QIdTy->qual_begin(),
+       E = QIdTy->qual_end(); I != E; ++I) {
+    if (Member)
+      if (ObjCPropertyDecl *PD = (*I)->FindPropertyDeclaration(Member)) {
+        GDecl = PD;
+        break;
+      }
+    // Also must look for a getter or setter name which uses property syntax.
+    if (ObjCMethodDecl *OMD = (*I)->getInstanceMethod(Sel)) {
+      GDecl = OMD;
+      break;
+    }
+  }
+  if (!GDecl) {
+    for (ObjCObjectPointerType::qual_iterator I = QIdTy->qual_begin(),
+         E = QIdTy->qual_end(); I != E; ++I) {
+      // Search in the protocol-qualifier list of current protocol.
+      GDecl = FindGetterSetterNameDeclFromProtocolList(*I, Member, Sel, 
+                                                       Context);
+      if (GDecl)
+        return GDecl;
+    }
+  }
+  return GDecl;
+}
+
+ExprResult
+Sema::ActOnDependentMemberExpr(Expr *BaseExpr, QualType BaseType,
+                               bool IsArrow, SourceLocation OpLoc,
+                               const CXXScopeSpec &SS,
+                               NamedDecl *FirstQualifierInScope,
+                               const DeclarationNameInfo &NameInfo,
+                               const TemplateArgumentListInfo *TemplateArgs) {
+  // Even in dependent contexts, try to diagnose base expressions with
+  // obviously wrong types, e.g.:
+  //
+  // T* t;
+  // t.f;
+  //
+  // In Obj-C++, however, the above expression is valid, since it could be
+  // accessing the 'f' property if T is an Obj-C interface. The extra check
+  // allows this, while still reporting an error if T is a struct pointer.
+  if (!IsArrow) {
+    const PointerType *PT = BaseType->getAs<PointerType>();
+    if (PT && (!getLangOptions().ObjC1 ||
+               PT->getPointeeType()->isRecordType())) {
+      assert(BaseExpr && "cannot happen with implicit member accesses");
+      Diag(NameInfo.getLoc(), diag::err_typecheck_member_reference_struct_union)
+        << BaseType << BaseExpr->getSourceRange();
+      return ExprError();
+    }
+  }
+
+  assert(BaseType->isDependentType() ||
+         NameInfo.getName().isDependentName() ||
+         isDependentScopeSpecifier(SS));
+
+  // Get the type being accessed in BaseType.  If this is an arrow, the BaseExpr
+  // must have pointer type, and the accessed type is the pointee.
+  return Owned(CXXDependentScopeMemberExpr::Create(Context, BaseExpr, BaseType,
+                                                   IsArrow, OpLoc,
+                                               SS.getWithLocInContext(Context),
+                                                   FirstQualifierInScope,
+                                                   NameInfo, TemplateArgs));
+}
+
+/// We know that the given qualified member reference points only to
+/// declarations which do not belong to the static type of the base
+/// expression.  Diagnose the problem.
+static void DiagnoseQualifiedMemberReference(Sema &SemaRef,
+                                             Expr *BaseExpr,
+                                             QualType BaseType,
+                                             const CXXScopeSpec &SS,
+                                             NamedDecl *rep,
+                                       const DeclarationNameInfo &nameInfo) {
+  // If this is an implicit member access, use a different set of
+  // diagnostics.
+  if (!BaseExpr)
+    return DiagnoseInstanceReference(SemaRef, SS, rep, nameInfo);
+
+  SemaRef.Diag(nameInfo.getLoc(), diag::err_qualified_member_of_unrelated)
+    << SS.getRange() << rep << BaseType;
+}
+
+// Check whether the declarations we found through a nested-name
+// specifier in a member expression are actually members of the base
+// type.  The restriction here is:
+//
+//   C++ [expr.ref]p2:
+//     ... In these cases, the id-expression shall name a
+//     member of the class or of one of its base classes.
+//
+// So it's perfectly legitimate for the nested-name specifier to name
+// an unrelated class, and for us to find an overload set including
+// decls from classes which are not superclasses, as long as the decl
+// we actually pick through overload resolution is from a superclass.
+bool Sema::CheckQualifiedMemberReference(Expr *BaseExpr,
+                                         QualType BaseType,
+                                         const CXXScopeSpec &SS,
+                                         const LookupResult &R) {
+  const RecordType *BaseRT = BaseType->getAs<RecordType>();
+  if (!BaseRT) {
+    // We can't check this yet because the base type is still
+    // dependent.
+    assert(BaseType->isDependentType());
+    return false;
+  }
+  CXXRecordDecl *BaseRecord = cast<CXXRecordDecl>(BaseRT->getDecl());
+
+  for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I) {
+    // If this is an implicit member reference and we find a
+    // non-instance member, it's not an error.
+    if (!BaseExpr && !(*I)->isCXXInstanceMember())
+      return false;
+
+    // Note that we use the DC of the decl, not the underlying decl.
+    DeclContext *DC = (*I)->getDeclContext();
+    while (DC->isTransparentContext())
+      DC = DC->getParent();
+
+    if (!DC->isRecord())
+      continue;
+    
+    llvm::SmallPtrSet<CXXRecordDecl*,4> MemberRecord;
+    MemberRecord.insert(cast<CXXRecordDecl>(DC)->getCanonicalDecl());
+
+    if (!IsProvablyNotDerivedFrom(*this, BaseRecord, MemberRecord))
+      return false;
+  }
+
+  DiagnoseQualifiedMemberReference(*this, BaseExpr, BaseType, SS,
+                                   R.getRepresentativeDecl(),
+                                   R.getLookupNameInfo());
+  return true;
+}
+
+static bool
+LookupMemberExprInRecord(Sema &SemaRef, LookupResult &R,
+                         SourceRange BaseRange, const RecordType *RTy,
+                         SourceLocation OpLoc, CXXScopeSpec &SS,
+                         bool HasTemplateArgs) {
+  RecordDecl *RDecl = RTy->getDecl();
+  if (SemaRef.RequireCompleteType(OpLoc, QualType(RTy, 0),
+                              SemaRef.PDiag(diag::err_typecheck_incomplete_tag)
+                                    << BaseRange))
+    return true;
+
+  if (HasTemplateArgs) {
+    // LookupTemplateName doesn't expect these both to exist simultaneously.
+    QualType ObjectType = SS.isSet() ? QualType() : QualType(RTy, 0);
+
+    bool MOUS;
+    SemaRef.LookupTemplateName(R, 0, SS, ObjectType, false, MOUS);
+    return false;
+  }
+
+  DeclContext *DC = RDecl;
+  if (SS.isSet()) {
+    // If the member name was a qualified-id, look into the
+    // nested-name-specifier.
+    DC = SemaRef.computeDeclContext(SS, false);
+
+    if (SemaRef.RequireCompleteDeclContext(SS, DC)) {
+      SemaRef.Diag(SS.getRange().getEnd(), diag::err_typecheck_incomplete_tag)
+        << SS.getRange() << DC;
+      return true;
+    }
+
+    assert(DC && "Cannot handle non-computable dependent contexts in lookup");
+
+    if (!isa<TypeDecl>(DC)) {
+      SemaRef.Diag(R.getNameLoc(), diag::err_qualified_member_nonclass)
+        << DC << SS.getRange();
+      return true;
+    }
+  }
+
+  // The record definition is complete, now look up the member.
+  SemaRef.LookupQualifiedName(R, DC);
+
+  if (!R.empty())
+    return false;
+
+  // We didn't find anything with the given name, so try to correct
+  // for typos.
+  DeclarationName Name = R.getLookupName();
+  if (SemaRef.CorrectTypo(R, 0, &SS, DC, false, Sema::CTC_MemberLookup) &&
+      !R.empty() &&
+      (isa<ValueDecl>(*R.begin()) || isa<FunctionTemplateDecl>(*R.begin()))) {
+    SemaRef.Diag(R.getNameLoc(), diag::err_no_member_suggest)
+      << Name << DC << R.getLookupName() << SS.getRange()
+      << FixItHint::CreateReplacement(R.getNameLoc(),
+                                      R.getLookupName().getAsString());
+    if (NamedDecl *ND = R.getAsSingle<NamedDecl>())
+      SemaRef.Diag(ND->getLocation(), diag::note_previous_decl)
+        << ND->getDeclName();
+    return false;
+  } else {
+    R.clear();
+    R.setLookupName(Name);
+  }
+
+  return false;
+}
+
+ExprResult
+Sema::BuildMemberReferenceExpr(Expr *Base, QualType BaseType,
+                               SourceLocation OpLoc, bool IsArrow,
+                               CXXScopeSpec &SS,
+                               NamedDecl *FirstQualifierInScope,
+                               const DeclarationNameInfo &NameInfo,
+                               const TemplateArgumentListInfo *TemplateArgs) {
+  if (BaseType->isDependentType() ||
+      (SS.isSet() && isDependentScopeSpecifier(SS)))
+    return ActOnDependentMemberExpr(Base, BaseType,
+                                    IsArrow, OpLoc,
+                                    SS, FirstQualifierInScope,
+                                    NameInfo, TemplateArgs);
+
+  LookupResult R(*this, NameInfo, LookupMemberName);
+
+  // Implicit member accesses.
+  if (!Base) {
+    QualType RecordTy = BaseType;
+    if (IsArrow) RecordTy = RecordTy->getAs<PointerType>()->getPointeeType();
+    if (LookupMemberExprInRecord(*this, R, SourceRange(),
+                                 RecordTy->getAs<RecordType>(),
+                                 OpLoc, SS, TemplateArgs != 0))
+      return ExprError();
+
+  // Explicit member accesses.
+  } else {
+    ExprResult BaseResult = Owned(Base);
+    ExprResult Result =
+      LookupMemberExpr(R, BaseResult, IsArrow, OpLoc,
+                       SS, /*ObjCImpDecl*/ 0, TemplateArgs != 0);
+
+    if (BaseResult.isInvalid())
+      return ExprError();
+    Base = BaseResult.take();
+
+    if (Result.isInvalid()) {
+      Owned(Base);
+      return ExprError();
+    }
+
+    if (Result.get())
+      return move(Result);
+
+    // LookupMemberExpr can modify Base, and thus change BaseType
+    BaseType = Base->getType();
+  }
+
+  return BuildMemberReferenceExpr(Base, BaseType,
+                                  OpLoc, IsArrow, SS, FirstQualifierInScope,
+                                  R, TemplateArgs);
+}
+
+static ExprResult
+BuildFieldReferenceExpr(Sema &S, Expr *BaseExpr, bool IsArrow,
+                        const CXXScopeSpec &SS, FieldDecl *Field,
+                        DeclAccessPair FoundDecl,
+                        const DeclarationNameInfo &MemberNameInfo);
+
+ExprResult
+Sema::BuildAnonymousStructUnionMemberReference(const CXXScopeSpec &SS,
+                                               SourceLocation loc,
+                                               IndirectFieldDecl *indirectField,
+                                               Expr *baseObjectExpr,
+                                               SourceLocation opLoc) {
+  // First, build the expression that refers to the base object.
+  
+  bool baseObjectIsPointer = false;
+  Qualifiers baseQuals;
+  
+  // Case 1:  the base of the indirect field is not a field.
+  VarDecl *baseVariable = indirectField->getVarDecl();
+  CXXScopeSpec EmptySS;
+  if (baseVariable) {
+    assert(baseVariable->getType()->isRecordType());
+    
+    // In principle we could have a member access expression that
+    // accesses an anonymous struct/union that's a static member of
+    // the base object's class.  However, under the current standard,
+    // static data members cannot be anonymous structs or unions.
+    // Supporting this is as easy as building a MemberExpr here.
+    assert(!baseObjectExpr && "anonymous struct/union is static data member?");
+    
+    DeclarationNameInfo baseNameInfo(DeclarationName(), loc);
+    
+    ExprResult result 
+      = BuildDeclarationNameExpr(EmptySS, baseNameInfo, baseVariable);
+    if (result.isInvalid()) return ExprError();
+    
+    baseObjectExpr = result.take();    
+    baseObjectIsPointer = false;
+    baseQuals = baseObjectExpr->getType().getQualifiers();
+    
+    // Case 2: the base of the indirect field is a field and the user
+    // wrote a member expression.
+  } else if (baseObjectExpr) {
+    // The caller provided the base object expression. Determine
+    // whether its a pointer and whether it adds any qualifiers to the
+    // anonymous struct/union fields we're looking into.
+    QualType objectType = baseObjectExpr->getType();
+    
+    if (const PointerType *ptr = objectType->getAs<PointerType>()) {
+      baseObjectIsPointer = true;
+      objectType = ptr->getPointeeType();
+    } else {
+      baseObjectIsPointer = false;
+    }
+    baseQuals = objectType.getQualifiers();
+    
+    // Case 3: the base of the indirect field is a field and we should
+    // build an implicit member access.
+  } else {
+    // We've found a member of an anonymous struct/union that is
+    // inside a non-anonymous struct/union, so in a well-formed
+    // program our base object expression is "this".
+    QualType ThisTy = getAndCaptureCurrentThisType();
+    if (ThisTy.isNull()) {
+      Diag(loc, diag::err_invalid_member_use_in_static_method)
+        << indirectField->getDeclName();
+      return ExprError();
+    }
+    
+    // Our base object expression is "this".
+    baseObjectExpr 
+      = new (Context) CXXThisExpr(loc, ThisTy, /*isImplicit=*/ true);
+    baseObjectIsPointer = true;
+    baseQuals = ThisTy->castAs<PointerType>()->getPointeeType().getQualifiers();
+  }
+  
+  // Build the implicit member references to the field of the
+  // anonymous struct/union.
+  Expr *result = baseObjectExpr;
+  IndirectFieldDecl::chain_iterator
+  FI = indirectField->chain_begin(), FEnd = indirectField->chain_end();
+  
+  // Build the first member access in the chain with full information.
+  if (!baseVariable) {
+    FieldDecl *field = cast<FieldDecl>(*FI);
+    
+    // FIXME: use the real found-decl info!
+    DeclAccessPair foundDecl = DeclAccessPair::make(field, field->getAccess());
+    
+    // Make a nameInfo that properly uses the anonymous name.
+    DeclarationNameInfo memberNameInfo(field->getDeclName(), loc);
+    
+    result = BuildFieldReferenceExpr(*this, result, baseObjectIsPointer,
+                                     EmptySS, field, foundDecl,
+                                     memberNameInfo).take();
+    baseObjectIsPointer = false;
+    
+    // FIXME: check qualified member access
+  }
+  
+  // In all cases, we should now skip the first declaration in the chain.
+  ++FI;
+  
+  while (FI != FEnd) {
+    FieldDecl *field = cast<FieldDecl>(*FI++);
+    
+    // FIXME: these are somewhat meaningless
+    DeclarationNameInfo memberNameInfo(field->getDeclName(), loc);
+    DeclAccessPair foundDecl = DeclAccessPair::make(field, field->getAccess());
+    
+    result = BuildFieldReferenceExpr(*this, result, /*isarrow*/ false,
+                                     (FI == FEnd? SS : EmptySS), field, 
+                                     foundDecl, memberNameInfo).take();
+  }
+  
+  return Owned(result);
+}
+
+/// \brief Build a MemberExpr AST node.
+static MemberExpr *BuildMemberExpr(ASTContext &C, Expr *Base, bool isArrow,
+                                   const CXXScopeSpec &SS, ValueDecl *Member,
+                                   DeclAccessPair FoundDecl,
+                                   const DeclarationNameInfo &MemberNameInfo,
+                                   QualType Ty,
+                                   ExprValueKind VK, ExprObjectKind OK,
+                                   const TemplateArgumentListInfo *TemplateArgs = 0) {
+  return MemberExpr::Create(C, Base, isArrow, SS.getWithLocInContext(C),
+                            Member, FoundDecl, MemberNameInfo,
+                            TemplateArgs, Ty, VK, OK);
+}
+
+ExprResult
+Sema::BuildMemberReferenceExpr(Expr *BaseExpr, QualType BaseExprType,
+                               SourceLocation OpLoc, bool IsArrow,
+                               const CXXScopeSpec &SS,
+                               NamedDecl *FirstQualifierInScope,
+                               LookupResult &R,
+                         const TemplateArgumentListInfo *TemplateArgs,
+                               bool SuppressQualifierCheck) {
+  QualType BaseType = BaseExprType;
+  if (IsArrow) {
+    assert(BaseType->isPointerType());
+    BaseType = BaseType->getAs<PointerType>()->getPointeeType();
+  }
+  R.setBaseObjectType(BaseType);
+
+  const DeclarationNameInfo &MemberNameInfo = R.getLookupNameInfo();
+  DeclarationName MemberName = MemberNameInfo.getName();
+  SourceLocation MemberLoc = MemberNameInfo.getLoc();
+
+  if (R.isAmbiguous())
+    return ExprError();
+
+  if (R.empty()) {
+    // Rederive where we looked up.
+    DeclContext *DC = (SS.isSet()
+                       ? computeDeclContext(SS, false)
+                       : BaseType->getAs<RecordType>()->getDecl());
+
+    Diag(R.getNameLoc(), diag::err_no_member)
+      << MemberName << DC
+      << (BaseExpr ? BaseExpr->getSourceRange() : SourceRange());
+    return ExprError();
+  }
+
+  // Diagnose lookups that find only declarations from a non-base
+  // type.  This is possible for either qualified lookups (which may
+  // have been qualified with an unrelated type) or implicit member
+  // expressions (which were found with unqualified lookup and thus
+  // may have come from an enclosing scope).  Note that it's okay for
+  // lookup to find declarations from a non-base type as long as those
+  // aren't the ones picked by overload resolution.
+  if ((SS.isSet() || !BaseExpr ||
+       (isa<CXXThisExpr>(BaseExpr) &&
+        cast<CXXThisExpr>(BaseExpr)->isImplicit())) &&
+      !SuppressQualifierCheck &&
+      CheckQualifiedMemberReference(BaseExpr, BaseType, SS, R))
+    return ExprError();
+
+  // Construct an unresolved result if we in fact got an unresolved
+  // result.
+  if (R.isOverloadedResult() || R.isUnresolvableResult()) {
+    // Suppress any lookup-related diagnostics; we'll do these when we
+    // pick a member.
+    R.suppressDiagnostics();
+
+    UnresolvedMemberExpr *MemExpr
+      = UnresolvedMemberExpr::Create(Context, R.isUnresolvableResult(),
+                                     BaseExpr, BaseExprType,
+                                     IsArrow, OpLoc,
+                                     SS.getWithLocInContext(Context),
+                                     MemberNameInfo,
+                                     TemplateArgs, R.begin(), R.end());
+
+    return Owned(MemExpr);
+  }
+
+  assert(R.isSingleResult());
+  DeclAccessPair FoundDecl = R.begin().getPair();
+  NamedDecl *MemberDecl = R.getFoundDecl();
+
+  // FIXME: diagnose the presence of template arguments now.
+
+  // If the decl being referenced had an error, return an error for this
+  // sub-expr without emitting another error, in order to avoid cascading
+  // error cases.
+  if (MemberDecl->isInvalidDecl())
+    return ExprError();
+
+  // Handle the implicit-member-access case.
+  if (!BaseExpr) {
+    // If this is not an instance member, convert to a non-member access.
+    if (!MemberDecl->isCXXInstanceMember())
+      return BuildDeclarationNameExpr(SS, R.getLookupNameInfo(), MemberDecl);
+
+    SourceLocation Loc = R.getNameLoc();
+    if (SS.getRange().isValid())
+      Loc = SS.getRange().getBegin();
+    BaseExpr = new (Context) CXXThisExpr(Loc, BaseExprType,/*isImplicit=*/true);
+  }
+
+  bool ShouldCheckUse = true;
+  if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MemberDecl)) {
+    // Don't diagnose the use of a virtual member function unless it's
+    // explicitly qualified.
+    if (MD->isVirtual() && !SS.isSet())
+      ShouldCheckUse = false;
+  }
+
+  // Check the use of this member.
+  if (ShouldCheckUse && DiagnoseUseOfDecl(MemberDecl, MemberLoc)) {
+    Owned(BaseExpr);
+    return ExprError();
+  }
+
+  // Perform a property load on the base regardless of whether we
+  // actually need it for the declaration.
+  if (BaseExpr->getObjectKind() == OK_ObjCProperty) {
+    ExprResult Result = ConvertPropertyForRValue(BaseExpr);
+    if (Result.isInvalid())
+      return ExprError();
+    BaseExpr = Result.take();
+  }
+
+  if (FieldDecl *FD = dyn_cast<FieldDecl>(MemberDecl))
+    return BuildFieldReferenceExpr(*this, BaseExpr, IsArrow,
+                                   SS, FD, FoundDecl, MemberNameInfo);
+
+  if (IndirectFieldDecl *FD = dyn_cast<IndirectFieldDecl>(MemberDecl))
+    // We may have found a field within an anonymous union or struct
+    // (C++ [class.union]).
+    return BuildAnonymousStructUnionMemberReference(SS, MemberLoc, FD,
+                                                    BaseExpr, OpLoc);
+
+  if (VarDecl *Var = dyn_cast<VarDecl>(MemberDecl)) {
+    MarkDeclarationReferenced(MemberLoc, Var);
+    return Owned(BuildMemberExpr(Context, BaseExpr, IsArrow, SS,
+                                 Var, FoundDecl, MemberNameInfo,
+                                 Var->getType().getNonReferenceType(),
+                                 VK_LValue, OK_Ordinary));
+  }
+
+  if (CXXMethodDecl *MemberFn = dyn_cast<CXXMethodDecl>(MemberDecl)) {
+    ExprValueKind valueKind;
+    QualType type;
+    if (MemberFn->isInstance()) {
+      valueKind = VK_RValue;
+      type = Context.BoundMemberTy;
+    } else {
+      valueKind = VK_LValue;
+      type = MemberFn->getType();
+    }
+
+    MarkDeclarationReferenced(MemberLoc, MemberDecl);
+    return Owned(BuildMemberExpr(Context, BaseExpr, IsArrow, SS,
+                                 MemberFn, FoundDecl, MemberNameInfo,
+                                 type, valueKind, OK_Ordinary));
+  }
+  assert(!isa<FunctionDecl>(MemberDecl) && "member function not C++ method?");
+
+  if (EnumConstantDecl *Enum = dyn_cast<EnumConstantDecl>(MemberDecl)) {
+    MarkDeclarationReferenced(MemberLoc, MemberDecl);
+    return Owned(BuildMemberExpr(Context, BaseExpr, IsArrow, SS,
+                                 Enum, FoundDecl, MemberNameInfo,
+                                 Enum->getType(), VK_RValue, OK_Ordinary));
+  }
+
+  Owned(BaseExpr);
+
+  // We found something that we didn't expect. Complain.
+  if (isa<TypeDecl>(MemberDecl))
+    Diag(MemberLoc, diag::err_typecheck_member_reference_type)
+      << MemberName << BaseType << int(IsArrow);
+  else
+    Diag(MemberLoc, diag::err_typecheck_member_reference_unknown)
+      << MemberName << BaseType << int(IsArrow);
+
+  Diag(MemberDecl->getLocation(), diag::note_member_declared_here)
+    << MemberName;
+  R.suppressDiagnostics();
+  return ExprError();