Eliminate QualifiedDeclRefExpr, which captured the notion of a

qualified reference to a declaration that is not a non-static data
member or non-static member function, e.g., 

  namespace N { int i; }
  int j = N::i;

Instead, extend DeclRefExpr to optionally store the qualifier. Most
clients won't see or care about the difference (since
QualifierDeclRefExpr inherited DeclRefExpr). However, this reduces the
number of top-level expression types that clients need to cope with,
brings the implementation of DeclRefExpr into line with MemberExpr,
and simplifies and unifies our handling of declaration references.

Extended DeclRefExpr to (optionally) store explicitly-specified
template arguments. This occurs when naming a declaration via a
template-id (which will be stored in a TemplateIdRefExpr) that,
following template argument deduction and (possibly) overload
resolution, is replaced with a DeclRefExpr that refers to a template
specialization but maintains the template arguments as written.





git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@84962 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 98 insertions, 115 deletions

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 589b0c6bd0..b7ccedec70 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -1420,8 +1420,7 @@ static DeclRefExpr* EvalVal(Expr *E) {
   // viewed AST node.  We then recursively traverse the AST by calling
   // EvalAddr and EvalVal appropriately.
   switch (E->getStmtClass()) {
-  case Stmt::DeclRefExprClass:
-  case Stmt::QualifiedDeclRefExprClass: {
+  case Stmt::DeclRefExprClass: {
     // DeclRefExpr: the base case.  When we hit a DeclRefExpr we are looking
     //  at code that refers to a variable's name.  We check if it has local
     //  storage within the function, and if so, return the expression.
diff --git a/lib/Sema/SemaCodeComplete.cpp b/lib/Sema/SemaCodeComplete.cpp
index 381151325a..b877b1cadb 100644
--- a/lib/Sema/SemaCodeComplete.cpp
+++ b/lib/Sema/SemaCodeComplete.cpp
@@ -1171,8 +1171,7 @@ void Sema::CodeCompleteCase(Scope *S) {
         // At the XXX, our completions are TagDecl::TK_union,
         // TagDecl::TK_struct, and TagDecl::TK_class, rather than TK_union,
         // TK_struct, and TK_class.
-        if (QualifiedDeclRefExpr *QDRE = dyn_cast<QualifiedDeclRefExpr>(DRE))
-          Qualifier = QDRE->getQualifier();
+        Qualifier = DRE->getQualifier();
       }
   }
   
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index ae45429952..accdc7e5c8 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -446,9 +446,7 @@ Sema::OwningExprResult Sema::ActOnIdentifierExpr(Scope *S, SourceLocation Loc,
                                   isAddressOfOperand);
 }
 
-/// BuildDeclRefExpr - Build either a DeclRefExpr or a
-/// QualifiedDeclRefExpr based on whether or not SS is a
-/// nested-name-specifier.
+/// BuildDeclRefExpr - Build a DeclRefExpr.
 Sema::OwningExprResult
 Sema::BuildDeclRefExpr(NamedDecl *D, QualType Ty, SourceLocation Loc,
                        bool TypeDependent, bool ValueDependent,
@@ -476,15 +474,11 @@ Sema::BuildDeclRefExpr(NamedDecl *D, QualType Ty, SourceLocation Loc,
 
   MarkDeclarationReferenced(Loc, D);
 
-  Expr *E;
-  if (SS && !SS->isEmpty()) {
-    E = new (Context) QualifiedDeclRefExpr(D, Ty, Loc, TypeDependent,
-                                          ValueDependent, SS->getRange(),
-                  static_cast<NestedNameSpecifier *>(SS->getScopeRep()));
-  } else
-    E = new (Context) DeclRefExpr(D, Ty, Loc, TypeDependent, ValueDependent);
-
-  return Owned(E);
+  return Owned(DeclRefExpr::Create(Context, 
+                              SS? (NestedNameSpecifier *)SS->getScopeRep() : 0, 
+                                   SS? SS->getRange() : SourceRange(), 
+                                   D, Loc, 
+                                   Ty, TypeDependent, ValueDependent));
 }
 
 /// getObjectForAnonymousRecordDecl - Retrieve the (unnamed) field or
@@ -2738,16 +2732,12 @@ void Sema::DeconstructCallFunction(Expr *FnExpr,
                cast<UnaryOperator>(FnExpr)->getOpcode()
                == UnaryOperator::AddrOf) {
       FnExpr = cast<UnaryOperator>(FnExpr)->getSubExpr();
-    } else if (QualifiedDeclRefExpr *QDRExpr 
-                 = dyn_cast<QualifiedDeclRefExpr>(FnExpr)) {
-      // Qualified names disable ADL (C++0x [basic.lookup.argdep]p1).
-      ArgumentDependentLookup = false;
-      Qualifier = QDRExpr->getQualifier();
-      QualifierRange = QDRExpr->getQualifierRange();
-      Function = dyn_cast<NamedDecl>(QDRExpr->getDecl());
-      break;
     } else if (DeclRefExpr *DRExpr = dyn_cast<DeclRefExpr>(FnExpr)) {
       Function = dyn_cast<NamedDecl>(DRExpr->getDecl());
+      if ((Qualifier = DRExpr->getQualifier())) {
+        ArgumentDependentLookup = false;
+        QualifierRange = DRExpr->getQualifierRange();
+      }      
       break;
     } else if (UnresolvedFunctionNameExpr *DepName
                = dyn_cast<UnresolvedFunctionNameExpr>(FnExpr)) {
@@ -2933,16 +2923,10 @@ Sema::ActOnCallExpr(Scope *S, ExprArg fn, SourceLocation LParenLoc,
         return ExprError();
 
       // Update Fn to refer to the actual function selected.
-      Expr *NewFn = 0;
-      if (Qualifier)
-        NewFn = new (Context) QualifiedDeclRefExpr(FDecl, FDecl->getType(),
-                                                   Fn->getLocStart(),
-                                                   false, false,
-                                                   QualifierRange,
-                                                   Qualifier);
-      else
-        NewFn = new (Context) DeclRefExpr(FDecl, FDecl->getType(),
-                                          Fn->getLocStart());
+      // FIXME: Use FixOverloadedFunctionReference?
+      Expr *NewFn = DeclRefExpr::Create(Context, Qualifier, QualifierRange, FDecl, 
+                                        Fn->getLocStart(), FDecl->getType(), false, 
+                                        false);
       Fn->Destroy(Context);
       Fn = NewFn;
     }
@@ -5083,7 +5067,6 @@ QualType Sema::CheckIncrementDecrementOperand(Expr *Op, SourceLocation OpLoc,
 static NamedDecl *getPrimaryDecl(Expr *E) {
   switch (E->getStmtClass()) {
   case Stmt::DeclRefExprClass:
-  case Stmt::QualifiedDeclRefExprClass:
     return cast<DeclRefExpr>(E)->getDecl();
   case Stmt::MemberExprClass:
     // If this is an arrow operator, the address is an offset from
@@ -5199,7 +5182,7 @@ QualType Sema::CheckAddressOfOperand(Expr *op, SourceLocation OpLoc) {
       // Okay: we can take the address of a field.
       // Could be a pointer to member, though, if there is an explicit
       // scope qualifier for the class.
-      if (isa<QualifiedDeclRefExpr>(op)) {
+      if (isa<DeclRefExpr>(op) && cast<DeclRefExpr>(op)->getQualifier()) {
         DeclContext *Ctx = dcl->getDeclContext();
         if (Ctx && Ctx->isRecord()) {
           if (FD->getType()->isReferenceType()) {
@@ -5216,7 +5199,8 @@ QualType Sema::CheckAddressOfOperand(Expr *op, SourceLocation OpLoc) {
     } else if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(dcl)) {
       // Okay: we can take the address of a function.
       // As above.
-      if (isa<QualifiedDeclRefExpr>(op) && MD->isInstance())
+      if (isa<DeclRefExpr>(op) && cast<DeclRefExpr>(op)->getQualifier() &&
+          MD->isInstance())
         return Context.getMemberPointerType(op->getType(),
               Context.getTypeDeclType(MD->getParent()).getTypePtr());
     } else if (!isa<FunctionDecl>(dcl))
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index ebcf3ad8e2..9e79b999e7 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -5370,18 +5370,19 @@ Expr *Sema::FixOverloadedFunctionReference(Expr *E, FunctionDecl *Fn) {
       if (Method->isStatic()) {
         // Do nothing: static member functions aren't any different
         // from non-member functions.
-      } else if (QualifiedDeclRefExpr *DRE
-                 = dyn_cast<QualifiedDeclRefExpr>(UnOp->getSubExpr())) {
-        // We have taken the address of a pointer to member
-        // function. Perform the computation here so that we get the
-        // appropriate pointer to member type.
-        DRE->setDecl(Fn);
-        DRE->setType(Fn->getType());
-        QualType ClassType
-          = Context.getTypeDeclType(cast<RecordDecl>(Method->getDeclContext()));
-        E->setType(Context.getMemberPointerType(Fn->getType(),
-                                                ClassType.getTypePtr()));
-        return E;
+      } else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(UnOp->getSubExpr())) {
+        if (DRE->getQualifier()) {
+          // We have taken the address of a pointer to member
+          // function. Perform the computation here so that we get the
+          // appropriate pointer to member type.
+          DRE->setDecl(Fn);
+          DRE->setType(Fn->getType());
+          QualType ClassType
+            = Context.getTypeDeclType(cast<RecordDecl>(Method->getDeclContext()));
+          E->setType(Context.getMemberPointerType(Fn->getType(),
+                                                  ClassType.getTypePtr()));
+          return E;
+        }
       }
       // FIXME: TemplateIdRefExpr referring to a member function template
       // specialization!
@@ -5401,18 +5402,20 @@ Expr *Sema::FixOverloadedFunctionReference(Expr *E, FunctionDecl *Fn) {
     MemExpr->setMemberDecl(Fn);
     E->setType(Fn->getType());
   } else if (TemplateIdRefExpr *TID = dyn_cast<TemplateIdRefExpr>(E)) {
-    // FIXME: We should capture the template arguments here.
-    if (NestedNameSpecifier *Qualifier = TID->getQualifier())
-      E = new (Context) QualifiedDeclRefExpr(Fn, Fn->getType(),
-                                             TID->getTemplateNameLoc(),
-                                             /*FIXME?*/false, /*FIXME?*/false,
-                                             TID->getQualifierRange(),
-                                             Qualifier);
-    else
-      E = new (Context) DeclRefExpr(Fn, Fn->getType(), 
-                                    TID->getTemplateNameLoc());
+    E = DeclRefExpr::Create(Context, 
+                            TID->getQualifier(), TID->getQualifierRange(),
+                            Fn, TID->getTemplateNameLoc(), 
+                            true,
+                            TID->getLAngleLoc(),
+                            TID->getTemplateArgs(),
+                            TID->getNumTemplateArgs(),
+                            TID->getRAngleLoc(),
+                            Fn->getType(), 
+                            /*FIXME?*/false, /*FIXME?*/false);
     
-    TID->Destroy(Context);
+    // FIXME: Don't destroy TID here, since we need its template arguments
+    // to survive.
+    // TID->Destroy(Context);
   } else {
     assert(false && "Invalid reference to overloaded function");
   }
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 0f223208a9..2bb790dda4 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -1845,7 +1845,7 @@ Sema::CheckTemplateArgumentPointerToMember(Expr *Arg, NamedDecl *&Member) {
   //   template-parameter shall be one of: [...]
   //
   //     -- a pointer to member expressed as described in 5.3.1.
-  QualifiedDeclRefExpr *DRE = 0;
+  DeclRefExpr *DRE = 0;
 
   // Ignore (and complain about) any excess parentheses.
   while (ParenExpr *Parens = dyn_cast<ParenExpr>(Arg)) {
@@ -1860,8 +1860,11 @@ Sema::CheckTemplateArgumentPointerToMember(Expr *Arg, NamedDecl *&Member) {
   }
 
   if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg))
-    if (UnOp->getOpcode() == UnaryOperator::AddrOf)
-      DRE = dyn_cast<QualifiedDeclRefExpr>(UnOp->getSubExpr());
+    if (UnOp->getOpcode() == UnaryOperator::AddrOf) {
+      DRE = dyn_cast<DeclRefExpr>(UnOp->getSubExpr());
+      if (DRE && !DRE->getQualifier())
+        DRE = 0;
+    }
 
   if (!DRE)
     return Diag(Arg->getSourceRange().getBegin(),
diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 53d158088c..1790d27eeb 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -618,10 +618,21 @@ TemplateInstantiator::TransformDeclRefExpr(DeclRefExpr *E) {
   // FIXME: Is this correct? Maybe FindInstantiatedDecl should do this?
   InstD = InstD->getUnderlyingDecl();
 
-  // FIXME: nested-name-specifier for QualifiedDeclRefExpr
+  CXXScopeSpec SS;
+  NestedNameSpecifier *Qualifier = 0;
+  if (E->getQualifier()) {
+    Qualifier = TransformNestedNameSpecifier(E->getQualifier(),
+                                             E->getQualifierRange());
+    if (!Qualifier)
+      return SemaRef.ExprError();
+    
+    SS.setScopeRep(Qualifier);
+    SS.setRange(E->getQualifierRange());
+  }
+  
   return SemaRef.BuildDeclarationNameExpr(E->getLocation(), InstD,
                                           /*FIXME:*/false,
-                                          /*FIXME:*/0,
+                                          &SS,
                                           /*FIXME:*/false);
 }
 
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index dec94994a8..94a0e11ec8 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -781,10 +781,15 @@ public:
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
-  OwningExprResult RebuildDeclRefExpr(NamedDecl *ND, SourceLocation Loc) {
+  OwningExprResult RebuildDeclRefExpr(NestedNameSpecifier *Qualifier,
+                                      SourceRange QualifierRange,
+                                      NamedDecl *ND, SourceLocation Loc) {
+    CXXScopeSpec SS;
+    SS.setScopeRep(Qualifier);
+    SS.setRange(QualifierRange);
     return getSema().BuildDeclarationNameExpr(Loc, ND,
                                               /*FIXME:*/false,
-                                              /*SS=*/0,
+                                              &SS,
                                               /*FIXME:*/false);
   }
 
@@ -1392,26 +1397,6 @@ public:
                                          T.getAsOpaquePtr(), RParenLoc);
   }
 
-  /// \brief Build a new qualified declaration reference expression.
-  ///
-  /// By default, performs semantic analysis to build the new expression.
-  /// Subclasses may override this routine to provide different behavior.
-  OwningExprResult RebuildQualifiedDeclRefExpr(NestedNameSpecifier *NNS,
-                                               SourceRange QualifierRange,
-                                               NamedDecl *ND,
-                                               SourceLocation Location,
-                                               bool IsAddressOfOperand) {
-    CXXScopeSpec SS;
-    SS.setRange(QualifierRange);
-    SS.setScopeRep(NNS);
-    return getSema().ActOnDeclarationNameExpr(/*Scope=*/0,
-                                              Location,
-                                              ND->getDeclName(),
-                                              /*Trailing lparen=*/false,
-                                              &SS,
-                                              IsAddressOfOperand);
-  }
-
   /// \brief Build a new (previously unresolved) declaration reference
   /// expression.
   ///
@@ -3276,15 +3261,40 @@ TreeTransform<Derived>::TransformPredefinedExpr(PredefinedExpr *E) {
 template<typename Derived>
 Sema::OwningExprResult
 TreeTransform<Derived>::TransformDeclRefExpr(DeclRefExpr *E) {
+  NestedNameSpecifier *Qualifier = 0;
+  if (E->getQualifier()) {
+    Qualifier = getDerived().TransformNestedNameSpecifier(E->getQualifier(),
+                                                       E->getQualifierRange());
+    if (!Qualifier)
+      return SemaRef.ExprError();
+  }
+  
   NamedDecl *ND
     = dyn_cast_or_null<NamedDecl>(getDerived().TransformDecl(E->getDecl()));
   if (!ND)
     return SemaRef.ExprError();
 
-  if (!getDerived().AlwaysRebuild() && ND == E->getDecl())
+  if (!getDerived().AlwaysRebuild() && 
+      Qualifier == E->getQualifier() &&
+      ND == E->getDecl() &&
+      !E->hasExplicitTemplateArgumentList())
     return SemaRef.Owned(E->Retain());
 
-  return getDerived().RebuildDeclRefExpr(ND, E->getLocation());
+  // FIXME: We're losing the explicit template arguments in this transformation.
+
+  llvm::SmallVector<TemplateArgument, 4> TransArgs;
+  for (unsigned I = 0, N = E->getNumTemplateArgs(); I != N; ++I) {
+    TemplateArgument TransArg
+      = getDerived().TransformTemplateArgument(E->getTemplateArgs()[I]);
+    if (TransArg.isNull())
+      return SemaRef.ExprError();
+    
+    TransArgs.push_back(TransArg);
+  }
+  
+  // FIXME: Pass the qualifier/qualifier range along.
+  return getDerived().RebuildDeclRefExpr(Qualifier, E->getQualifierRange(),
+                                         ND, E->getLocation());
 }
 
 template<typename Derived>
@@ -4301,32 +4311,6 @@ TreeTransform<Derived>::TransformUnaryTypeTraitExpr(UnaryTypeTraitExpr *E) {
 
 template<typename Derived>
 Sema::OwningExprResult
-TreeTransform<Derived>::TransformQualifiedDeclRefExpr(QualifiedDeclRefExpr *E) {
-  NestedNameSpecifier *NNS
-    = getDerived().TransformNestedNameSpecifier(E->getQualifier(),
-                                                E->getQualifierRange());
-  if (!NNS)
-    return SemaRef.ExprError();
-
-  NamedDecl *ND
-    = dyn_cast_or_null<NamedDecl>(getDerived().TransformDecl(E->getDecl()));
-  if (!ND)
-    return SemaRef.ExprError();
-
-  if (!getDerived().AlwaysRebuild() &&
-      NNS == E->getQualifier() &&
-      ND == E->getDecl())
-    return SemaRef.Owned(E->Retain());
-
-  return getDerived().RebuildQualifiedDeclRefExpr(NNS,
-                                                  E->getQualifierRange(),
-                                                  ND,
-                                                  E->getLocation(),
-                                                  /*FIXME:*/false);
-}
-
-template<typename Derived>
-Sema::OwningExprResult
 TreeTransform<Derived>::TransformUnresolvedDeclRefExpr(
                                                     UnresolvedDeclRefExpr *E) {
   NestedNameSpecifier *NNS