Implement access control for overloaded functions. Suppress access control

diagnostics in "early" lookups, such as during typename checks and when building
unresolved lookup expressions.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@94647 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 182 insertions, 95 deletions

diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index d041f54a02..86d867858b 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -60,6 +60,7 @@ namespace clang {
   class CallExpr;
   class DeclRefExpr;
   class UnresolvedLookupExpr;
+  class UnresolvedMemberExpr;
   class VarDecl;
   class ParmVarDecl;
   class TypedefDecl;
@@ -2376,8 +2377,14 @@ public:
                                                CXXBasePaths &Paths,
                                                bool NoPrivileges = false);
 
-  void CheckAccess(const LookupResult &R);
+  bool CheckUnresolvedMemberAccess(UnresolvedMemberExpr *E,
+                                   NamedDecl *D,
+                                   AccessSpecifier Access);
+  bool CheckUnresolvedLookupAccess(UnresolvedLookupExpr *E,
+                                   NamedDecl *D,
+                                   AccessSpecifier Access);
   bool CheckAccess(const LookupResult &R, NamedDecl *D, AccessSpecifier Access);
+  void CheckAccess(const LookupResult &R);
 
   bool CheckBaseClassAccess(QualType Derived, QualType Base,
                             unsigned InaccessibleBaseID,
@@ -2882,14 +2889,13 @@ public:
   FunctionTemplateDecl *getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
                                                    FunctionTemplateDecl *FT2,
                                            TemplatePartialOrderingContext TPOC);
-  FunctionDecl *getMostSpecialized(FunctionDecl **Specializations,
-                                   unsigned NumSpecializations,
-                                   TemplatePartialOrderingContext TPOC,
-                                   SourceLocation Loc,
-                                   const PartialDiagnostic &NoneDiag,
-                                   const PartialDiagnostic &AmbigDiag,
-                                   const PartialDiagnostic &CandidateDiag,
-                                   unsigned *Index = 0);
+  UnresolvedSetIterator getMostSpecialized(UnresolvedSetIterator SBegin,
+                                           UnresolvedSetIterator SEnd,
+                                           TemplatePartialOrderingContext TPOC,
+                                           SourceLocation Loc,
+                                           const PartialDiagnostic &NoneDiag,
+                                           const PartialDiagnostic &AmbigDiag,
+                                        const PartialDiagnostic &CandidateDiag);
                                    
   ClassTemplatePartialSpecializationDecl *
   getMoreSpecializedPartialSpecialization(
diff --git a/lib/Sema/SemaAccess.cpp b/lib/Sema/SemaAccess.cpp
index 51f9e300ef..26bafa525d 100644
--- a/lib/Sema/SemaAccess.cpp
+++ b/lib/Sema/SemaAccess.cpp
@@ -16,6 +16,8 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/CXXInheritance.h"
 #include "clang/AST/DeclCXX.h"
+#include "clang/AST/ExprCXX.h"
+
 using namespace clang;
 
 /// SetMemberAccessSpecifier - Set the access specifier of a member.
@@ -231,6 +233,46 @@ bool Sema::CheckAccess(const LookupResult &R, NamedDecl *D,
   return true;
 }
 
+bool Sema::CheckUnresolvedLookupAccess(UnresolvedLookupExpr *E,
+                                       NamedDecl *D, AccessSpecifier Access) {
+  if (!getLangOptions().AccessControl || !E->getNamingClass())
+    return false;
+
+  // Fake up a lookup result.
+  LookupResult R(*this, E->getName(), E->getNameLoc(), LookupOrdinaryName);
+  R.suppressDiagnostics();
+
+  R.setNamingClass(E->getNamingClass());
+  R.addDecl(D, Access);
+
+  // FIXME: protected check (triggers for member-address expressions)
+
+  return CheckAccess(R, D, Access);
+}
+
+/// Perform access-control checking on a previously-unresolved member
+/// access which has now been resolved to a member.
+bool Sema::CheckUnresolvedMemberAccess(UnresolvedMemberExpr *E,
+                                       NamedDecl *D, AccessSpecifier Access) {
+  if (!getLangOptions().AccessControl)
+    return false;
+
+  // Fake up a lookup result.
+  LookupResult R(*this, E->getMemberName(), E->getMemberLoc(),
+                 LookupOrdinaryName);
+  R.suppressDiagnostics();
+
+  R.setNamingClass(E->getNamingClass());
+  R.addDecl(D, Access);
+
+  if (CheckAccess(R, D, Access))
+    return true;
+
+  // FIXME: protected check
+
+  return false;
+}
+
 /// Checks access to all the declarations in the given result set.
 void Sema::CheckAccess(const LookupResult &R) {
   for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I)
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 876fcb32ba..398c156f9b 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -135,6 +135,7 @@ Sema::TypeTy *Sema::getTypeName(IdentifierInfo &II, SourceLocation NameLoc,
   case LookupResult::NotFoundInCurrentInstantiation:
   case LookupResult::FoundOverloaded:
   case LookupResult::FoundUnresolvedValue:
+    Result.suppressDiagnostics();
     return 0;
 
   case LookupResult::Ambiguous:
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 1d0374dcbb..5be017a754 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1497,16 +1497,20 @@ Sema::BuildDeclarationNameExpr(const CXXScopeSpec &SS,
       CheckDeclInExpr(*this, R.getNameLoc(), R.getFoundDecl()))
     return ExprError();
 
+  // Otherwise, just build an unresolved lookup expression.  Suppress
+  // any lookup-related diagnostics; we'll hash these out later, when
+  // we've picked a target.
+  R.suppressDiagnostics();
+
   bool Dependent
     = UnresolvedLookupExpr::ComputeDependence(R.begin(), R.end(), 0);
   UnresolvedLookupExpr *ULE
-    = UnresolvedLookupExpr::Create(Context, Dependent,
+    = UnresolvedLookupExpr::Create(Context, Dependent, R.getNamingClass(),
                                    (NestedNameSpecifier*) SS.getScopeRep(),
                                    SS.getRange(),
                                    R.getLookupName(), R.getNameLoc(),
                                    NeedsADL, R.isOverloadedResult());
-  for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I)
-    ULE->addDecl(*I);
+  ULE->addDecls(R.begin(), R.end());
 
   return Owned(ULE);
 }
@@ -2544,6 +2548,10 @@ Sema::BuildMemberReferenceExpr(ExprArg Base, QualType BaseExprType,
       R.isUnresolvableResult() ||
       UnresolvedLookupExpr::ComputeDependence(R.begin(), R.end(), TemplateArgs);
 
+    // Suppress any lookup-related diagnostics; we'll do these when we
+    // pick a member.
+    R.suppressDiagnostics();
+
     UnresolvedMemberExpr *MemExpr
       = UnresolvedMemberExpr::Create(Context, Dependent,
                                      R.isUnresolvableResult(),
@@ -2552,8 +2560,7 @@ Sema::BuildMemberReferenceExpr(ExprArg Base, QualType BaseExprType,
                                      Qualifier, SS.getRange(),
                                      MemberName, MemberLoc,
                                      TemplateArgs);
-    for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I)
-      MemExpr->addDecl(*I);
+    MemExpr->addDecls(R.begin(), R.end());
 
     return Owned(MemExpr);
   }
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 47a7d17519..f2f24ea59a 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -4851,6 +4851,14 @@ Sema::PrintOverloadCandidates(OverloadCandidateSet& CandidateSet,
   }
 }
 
+static bool CheckUnresolvedAccess(Sema &S, Expr *E, NamedDecl *D,
+                                  AccessSpecifier AS) {
+  if (isa<UnresolvedLookupExpr>(E))
+    return S.CheckUnresolvedLookupAccess(cast<UnresolvedLookupExpr>(E), D, AS);
+
+  return S.CheckUnresolvedMemberAccess(cast<UnresolvedMemberExpr>(E), D, AS);
+}
+
 /// ResolveAddressOfOverloadedFunction - Try to resolve the address of
 /// an overloaded function (C++ [over.over]), where @p From is an
 /// expression with overloaded function type and @p ToType is the type
@@ -4928,7 +4936,7 @@ Sema::ResolveAddressOfOverloadedFunction(Expr *From, QualType ToType,
 
   // Look through all of the overloaded functions, searching for one
   // whose type matches exactly.
-  llvm::SmallPtrSet<FunctionDecl *, 4> Matches;
+  UnresolvedSet<4> Matches;  // contains only FunctionDecls
   bool FoundNonTemplateFunction = false;
   for (UnresolvedSetIterator I = Fns->begin(), E = Fns->end(); I != E; ++I) {
     // Look through any using declarations to find the underlying function.
@@ -4972,8 +4980,8 @@ Sema::ResolveAddressOfOverloadedFunction(Expr *From, QualType ToType,
         // a candidate? Find a testcase before changing the code.
         assert(FunctionType
                  == Context.getCanonicalType(Specialization->getType()));
-        Matches.insert(
-                cast<FunctionDecl>(Specialization->getCanonicalDecl()));
+        Matches.addDecl(cast<FunctionDecl>(Specialization->getCanonicalDecl()),
+                        I.getAccess());
       }
 
       continue;
@@ -4996,7 +5004,8 @@ Sema::ResolveAddressOfOverloadedFunction(Expr *From, QualType ToType,
       if (Context.hasSameUnqualifiedType(FunctionType, FunDecl->getType()) ||
           IsNoReturnConversion(Context, FunDecl->getType(), FunctionType, 
                                ResultTy)) {
-        Matches.insert(cast<FunctionDecl>(FunDecl->getCanonicalDecl()));
+        Matches.addDecl(cast<FunctionDecl>(FunDecl->getCanonicalDecl()),
+                        I.getAccess());
         FoundNonTemplateFunction = true;
       }
     }
@@ -5006,14 +5015,15 @@ Sema::ResolveAddressOfOverloadedFunction(Expr *From, QualType ToType,
   if (Matches.empty())
     return 0;
   else if (Matches.size() == 1) {
-    FunctionDecl *Result = *Matches.begin();
+    FunctionDecl *Result = cast<FunctionDecl>(*Matches.begin());
     MarkDeclarationReferenced(From->getLocStart(), Result);
+    if (Complain)
+      CheckUnresolvedAccess(*this, OvlExpr, Result, Matches.begin().getAccess());
     return Result;
   }
 
   // C++ [over.over]p4:
   //   If more than one function is selected, [...]
-  typedef llvm::SmallPtrSet<FunctionDecl *, 4>::iterator MatchIter;
   if (!FoundNonTemplateFunction) {
     //   [...] and any given function template specialization F1 is
     //   eliminated if the set contains a second function template
@@ -5025,41 +5035,50 @@ Sema::ResolveAddressOfOverloadedFunction(Expr *From, QualType ToType,
     // two-pass algorithm (similar to the one used to identify the
     // best viable function in an overload set) that identifies the
     // best function template (if it exists).
-    llvm::SmallVector<FunctionDecl *, 8> TemplateMatches(Matches.begin(),
-                                                         Matches.end());
-    FunctionDecl *Result =
-        getMostSpecialized(TemplateMatches.data(), TemplateMatches.size(),
+    
+    UnresolvedSetIterator Result =
+        getMostSpecialized(Matches.begin(), Matches.end(),
                            TPOC_Other, From->getLocStart(),
                            PDiag(),
                            PDiag(diag::err_addr_ovl_ambiguous)
-                               << TemplateMatches[0]->getDeclName(),
+                               << Matches[0]->getDeclName(),
                            PDiag(diag::note_ovl_candidate)
                                << (unsigned) oc_function_template);
-    MarkDeclarationReferenced(From->getLocStart(), Result);
-    return Result;
+    assert(Result != Matches.end() && "no most-specialized template");
+    MarkDeclarationReferenced(From->getLocStart(), *Result);
+    if (Complain)
+      CheckUnresolvedAccess(*this, OvlExpr, *Result, Result.getAccess());
+    return cast<FunctionDecl>(*Result);
   }
 
   //   [...] any function template specializations in the set are
   //   eliminated if the set also contains a non-template function, [...]
-  llvm::SmallVector<FunctionDecl *, 4> RemainingMatches;
-  for (MatchIter M = Matches.begin(), MEnd = Matches.end(); M != MEnd; ++M)
-    if ((*M)->getPrimaryTemplate() == 0)
-      RemainingMatches.push_back(*M);
+  for (unsigned I = 0, N = Matches.size(); I != N; ) {
+    if (cast<FunctionDecl>(Matches[I].getDecl())->getPrimaryTemplate() == 0)
+      ++I;
+    else {
+      Matches.erase(I);
+      --N;
+    }
+  }
   
   // [...] After such eliminations, if any, there shall remain exactly one
   // selected function.
-  if (RemainingMatches.size() == 1) {
-    FunctionDecl *Result = RemainingMatches.front();
-    MarkDeclarationReferenced(From->getLocStart(), Result);
-    return Result;
+  if (Matches.size() == 1) {
+    UnresolvedSetIterator Match = Matches.begin();
+    MarkDeclarationReferenced(From->getLocStart(), *Match);
+    if (Complain)
+      CheckUnresolvedAccess(*this, OvlExpr, *Match, Match.getAccess());
+    return cast<FunctionDecl>(*Match);
   }
 
   // FIXME: We should probably return the same thing that BestViableFunction
   // returns (even if we issue the diagnostics here).
   Diag(From->getLocStart(), diag::err_addr_ovl_ambiguous)
-    << RemainingMatches[0]->getDeclName();
-  for (unsigned I = 0, N = RemainingMatches.size(); I != N; ++I)
-    NoteOverloadCandidate(RemainingMatches[I]);
+    << Matches[0]->getDeclName();
+  for (UnresolvedSetIterator I = Matches.begin(),
+         E = Matches.end(); I != E; ++I)
+    NoteOverloadCandidate(cast<FunctionDecl>(*I));
   return 0;
 }
 
@@ -5345,6 +5364,7 @@ Sema::BuildOverloadedCallExpr(Expr *Fn, UnresolvedLookupExpr *ULE,
   switch (BestViableFunction(CandidateSet, Fn->getLocStart(), Best)) {
   case OR_Success: {
     FunctionDecl *FDecl = Best->Function;
+    CheckUnresolvedLookupAccess(ULE, FDecl, Best->getAccess());
     Fn = FixOverloadedFunctionReference(Fn, FDecl);
     return BuildResolvedCallExpr(Fn, FDecl, LParenLoc, Args, NumArgs, RParenLoc);
   }
@@ -5425,8 +5445,9 @@ Sema::CreateOverloadedUnaryOp(SourceLocation OpLoc, unsigned OpcIn,
   }
 
   if (Input->isTypeDependent()) {
+    CXXRecordDecl *NamingClass = 0; // because lookup ignores member operators
     UnresolvedLookupExpr *Fn
-      = UnresolvedLookupExpr::Create(Context, /*Dependent*/ true,
+      = UnresolvedLookupExpr::Create(Context, /*Dependent*/ true, NamingClass,
                                      0, SourceRange(), OpName, OpLoc,
                                      /*ADL*/ true, IsOverloaded(Fns));
     Fn->addDecls(Fns.begin(), Fns.end());
@@ -5467,6 +5488,8 @@ Sema::CreateOverloadedUnaryOp(SourceLocation OpLoc, unsigned OpcIn,
       // We matched an overloaded operator. Build a call to that
       // operator.
 
+      // FIXME: access control
+
       // Convert the arguments.
       if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(FnDecl)) {
         if (PerformObjectArgumentInitialization(Input, Method))
@@ -5592,8 +5615,9 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
     }
 
     // FIXME: save results of ADL from here?
+    CXXRecordDecl *NamingClass = 0; // because lookup ignores member operators
     UnresolvedLookupExpr *Fn
-      = UnresolvedLookupExpr::Create(Context, /*Dependent*/ true,
+      = UnresolvedLookupExpr::Create(Context, /*Dependent*/ true, NamingClass,
                                      0, SourceRange(), OpName, OpLoc,
                                      /*ADL*/ true, IsOverloaded(Fns));
 
@@ -5647,6 +5671,8 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
         // We matched an overloaded operator. Build a call to that
         // operator.
 
+        // FIXME: access control
+
         // Convert the arguments.
         if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(FnDecl)) {
           OwningExprResult Arg1
@@ -5783,8 +5809,9 @@ Sema::CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
   // expression.
   if (Args[0]->isTypeDependent() || Args[1]->isTypeDependent()) {
 
+    CXXRecordDecl *NamingClass = 0; // because lookup ignores member operators
     UnresolvedLookupExpr *Fn
-      = UnresolvedLookupExpr::Create(Context, /*Dependent*/ true,
+      = UnresolvedLookupExpr::Create(Context, /*Dependent*/ true, NamingClass,
                                      0, SourceRange(), OpName, LLoc,
                                      /*ADL*/ true, /*Overloaded*/ false);
     // Can't add any actual overloads yet
@@ -5819,6 +5846,8 @@ Sema::CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
         // We matched an overloaded operator. Build a call to that
         // operator.
 
+        // FIXME: access control
+
         // Convert the arguments.
         CXXMethodDecl *Method = cast<CXXMethodDecl>(FnDecl);
         if (PerformObjectArgumentInitialization(Args[0], Method) ||
@@ -5968,6 +5997,7 @@ Sema::BuildCallToMemberFunction(Scope *S, Expr *MemExprE,
     switch (BestViableFunction(CandidateSet, UnresExpr->getLocStart(), Best)) {
     case OR_Success:
       Method = cast<CXXMethodDecl>(Best->Function);
+      CheckUnresolvedMemberAccess(UnresExpr, Method, Best->getAccess());
       break;
 
     case OR_No_Viable_Function:
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 00401560c6..f660b3c2ee 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -1525,17 +1525,19 @@ Sema::OwningExprResult Sema::BuildTemplateIdExpr(const CXXScopeSpec &SS,
     Qualifier = static_cast<NestedNameSpecifier*>(SS.getScopeRep());
     QualifierRange = SS.getRange();
   }
+
+  // We don't want lookup warnings at this point.
+  R.suppressDiagnostics();
   
   bool Dependent
     = UnresolvedLookupExpr::ComputeDependence(R.begin(), R.end(),
                                               &TemplateArgs);
   UnresolvedLookupExpr *ULE
-    = UnresolvedLookupExpr::Create(Context, Dependent,
+    = UnresolvedLookupExpr::Create(Context, Dependent, R.getNamingClass(),
                                    Qualifier, QualifierRange,
                                    R.getLookupName(), R.getNameLoc(),
                                    RequiresADL, TemplateArgs);
-  for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I)
-    ULE->addDecl(*I);
+  ULE->addDecls(R.begin(), R.end());
 
   return Owned(ULE);
 }
@@ -3817,8 +3819,7 @@ Sema::CheckFunctionTemplateSpecialization(FunctionDecl *FD,
                                           LookupResult &Previous) {
   // The set of function template specializations that could match this
   // explicit function template specialization.
-  typedef llvm::SmallVector<FunctionDecl *, 8> CandidateSet;
-  CandidateSet Candidates;
+  UnresolvedSet<8> Candidates;
   
   DeclContext *FDLookupContext = FD->getDeclContext()->getLookupContext();
   for (LookupResult::iterator I = Previous.begin(), E = Previous.end();
@@ -3851,22 +3852,24 @@ Sema::CheckFunctionTemplateSpecialization(FunctionDecl *FD,
       }
       
       // Record this candidate.
-      Candidates.push_back(Specialization);
+      Candidates.addDecl(Specialization, I.getAccess());
     }
   }
   
   // Find the most specialized function template.
-  FunctionDecl *Specialization = getMostSpecialized(Candidates.data(),
-                                                    Candidates.size(),
-                                                    TPOC_Other,
-                                                    FD->getLocation(),
+  UnresolvedSetIterator Result
+    = getMostSpecialized(Candidates.begin(), Candidates.end(),
+                         TPOC_Other, FD->getLocation(),
                   PartialDiagnostic(diag::err_function_template_spec_no_match) 
                     << FD->getDeclName(),
                   PartialDiagnostic(diag::err_function_template_spec_ambiguous)
                     << FD->getDeclName() << (ExplicitTemplateArgs != 0),
                   PartialDiagnostic(diag::note_function_template_spec_matched));
-  if (!Specialization)
+  if (Result == Candidates.end())
     return true;
+
+  // Ignore access information;  it doesn't figure into redeclaration checking.
+  FunctionDecl *Specialization = cast<FunctionDecl>(*Result);
   
   // FIXME: Check if the prior specialization has a point of instantiation.
   // If so, we have run afoul of .
@@ -4568,7 +4571,7 @@ Sema::DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
   //   A member function [...] of a class template can be explicitly 
   //  instantiated from the member definition associated with its class 
   //  template.
-  llvm::SmallVector<FunctionDecl *, 8> Matches;
+  UnresolvedSet<8> Matches;
   for (LookupResult::iterator P = Previous.begin(), PEnd = Previous.end();
        P != PEnd; ++P) {
     NamedDecl *Prev = *P;
@@ -4577,7 +4580,7 @@ Sema::DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
         if (Context.hasSameUnqualifiedType(Method->getType(), R)) {
           Matches.clear();
 
-          Matches.push_back(Method);
+          Matches.addDecl(Method, P.getAccess());
           if (Method->getTemplateSpecializationKind() == TSK_Undeclared)
             break;
         }
@@ -4599,19 +4602,22 @@ Sema::DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
       continue;
     }
     
-    Matches.push_back(Specialization);
+    Matches.addDecl(Specialization, P.getAccess());
   }
   
   // Find the most specialized function template specialization.
-  FunctionDecl *Specialization
-    = getMostSpecialized(Matches.data(), Matches.size(), TPOC_Other, 
+  UnresolvedSetIterator Result
+    = getMostSpecialized(Matches.begin(), Matches.end(), TPOC_Other, 
                          D.getIdentifierLoc(), 
           PartialDiagnostic(diag::err_explicit_instantiation_not_known) << Name,
           PartialDiagnostic(diag::err_explicit_instantiation_ambiguous) << Name,
                 PartialDiagnostic(diag::note_explicit_instantiation_candidate));
 
-  if (!Specialization)
+  if (Result == Matches.end())
     return true;
+
+  // Ignore access control bits, we don't need them for redeclaration checking.
+  FunctionDecl *Specialization = cast<FunctionDecl>(*Result);
   
   if (Specialization->getTemplateSpecializationKind() == TSK_Undeclared) {
     Diag(D.getIdentifierLoc(), 
diff --git a/lib/Sema/SemaTemplateDeduction.cpp b/lib/Sema/SemaTemplateDeduction.cpp
index 7b433e901e..b9160930cb 100644
--- a/lib/Sema/SemaTemplateDeduction.cpp
+++ b/lib/Sema/SemaTemplateDeduction.cpp
@@ -1987,11 +1987,11 @@ static bool isSameTemplate(TemplateDecl *T1, TemplateDecl *T2) {
 /// \brief Retrieve the most specialized of the given function template
 /// specializations.
 ///
-/// \param Specializations the set of function template specializations that
-/// we will be comparing.
+/// \param SpecBegin the start iterator of the function template
+/// specializations that we will be comparing.
 ///
-/// \param NumSpecializations the number of function template specializations in
-/// \p Specializations
+/// \param SpecEnd the end iterator of the function template
+/// specializations, paired with \p SpecBegin.
 ///
 /// \param TPOC the partial ordering context to use to compare the function
 /// template specializations.
@@ -2015,41 +2015,37 @@ static bool isSameTemplate(TemplateDecl *T1, TemplateDecl *T2) {
 /// specialization.
 ///
 /// \returns the most specialized function template specialization, if 
-/// found. Otherwise, returns NULL.
+/// found. Otherwise, returns SpecEnd.
 ///
 /// \todo FIXME: Consider passing in the "also-ran" candidates that failed 
 /// template argument deduction.
-FunctionDecl *Sema::getMostSpecialized(FunctionDecl **Specializations,
-                                       unsigned NumSpecializations,
-                                       TemplatePartialOrderingContext TPOC,
-                                       SourceLocation Loc,
-                                       const PartialDiagnostic &NoneDiag,
-                                       const PartialDiagnostic &AmbigDiag,
-                                       const PartialDiagnostic &CandidateDiag,
-                                       unsigned *Index) {
-  if (NumSpecializations == 0) {
+UnresolvedSetIterator
+Sema::getMostSpecialized(UnresolvedSetIterator SpecBegin,
+                         UnresolvedSetIterator SpecEnd,
+                         TemplatePartialOrderingContext TPOC,
+                         SourceLocation Loc,
+                         const PartialDiagnostic &NoneDiag,
+                         const PartialDiagnostic &AmbigDiag,
+                         const PartialDiagnostic &CandidateDiag) {
+  if (SpecBegin == SpecEnd) {
     Diag(Loc, NoneDiag);
-    return 0;
+    return SpecEnd;
   }
   
-  if (NumSpecializations == 1) {
-    if (Index)
-      *Index = 0;
-    
-    return Specializations[0];
-  }
-    
+  if (SpecBegin + 1 == SpecEnd)    
+    return SpecBegin;
   
   // Find the function template that is better than all of the templates it
   // has been compared to.
-  unsigned Best = 0;
+  UnresolvedSetIterator Best = SpecBegin;
   FunctionTemplateDecl *BestTemplate 
-    = Specializations[Best]->getPrimaryTemplate();
+    = cast<FunctionDecl>(*Best)->getPrimaryTemplate();
   assert(BestTemplate && "Not a function template specialization?");
-  for (unsigned I = 1; I != NumSpecializations; ++I) {
-    FunctionTemplateDecl *Challenger = Specializations[I]->getPrimaryTemplate();
+  for (UnresolvedSetIterator I = SpecBegin + 1; I != SpecEnd; ++I) {
+    FunctionTemplateDecl *Challenger
+      = cast<FunctionDecl>(*I)->getPrimaryTemplate();
     assert(Challenger && "Not a function template specialization?");
-    if (isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger, 
+    if (isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger,
                                                   TPOC),
                        Challenger)) {
       Best = I;
@@ -2060,8 +2056,9 @@ FunctionDecl *Sema::getMostSpecialized(FunctionDecl **Specializations,
   // Make sure that the "best" function template is more specialized than all
   // of the others.
   bool Ambiguous = false;
-  for (unsigned I = 0; I != NumSpecializations; ++I) {
-    FunctionTemplateDecl *Challenger = Specializations[I]->getPrimaryTemplate();
+  for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
+    FunctionTemplateDecl *Challenger
+      = cast<FunctionDecl>(*I)->getPrimaryTemplate();
     if (I != Best &&
         !isSameTemplate(getMoreSpecializedTemplate(BestTemplate, Challenger, 
                                                   TPOC),
@@ -2073,22 +2070,20 @@ FunctionDecl *Sema::getMostSpecialized(FunctionDecl **Specializations,
   
   if (!Ambiguous) {
     // We found an answer. Return it.
-    if (Index)
-      *Index = Best;
-    return Specializations[Best];
+    return Best;
   }
   
   // Diagnose the ambiguity.
   Diag(Loc, AmbigDiag);
   
   // FIXME: Can we order the candidates in some sane way?
-  for (unsigned I = 0; I != NumSpecializations; ++I)
-    Diag(Specializations[I]->getLocation(), CandidateDiag)
+  for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I)
+    Diag((*I)->getLocation(), CandidateDiag)
       << getTemplateArgumentBindingsText(
-            Specializations[I]->getPrimaryTemplate()->getTemplateParameters(),
-                         *Specializations[I]->getTemplateSpecializationArgs());
+        cast<FunctionDecl>(*I)->getPrimaryTemplate()->getTemplateParameters(),
+                    *cast<FunctionDecl>(*I)->getTemplateSpecializationArgs());
   
-  return 0;
+  return SpecEnd;
 }
 
 /// \brief Returns the more specialized class template partial specialization