6 files changed, 36 insertions, 26 deletions

diff --git a/clang/lib/Sema/SemaAccess.cpp b/clang/lib/Sema/SemaAccess.cpp
index ea6481bd8ab..c3a1e752105 100644
--- a/clang/lib/Sema/SemaAccess.cpp
+++ b/clang/lib/Sema/SemaAccess.cpp
@@ -516,8 +516,9 @@ static AccessResult MatchesFriend(Sema &S,
 static AccessResult MatchesFriend(Sema &S,
                                   const EffectiveContext &EC,
                                   FriendDecl *FriendD) {
-  // Whitelist accesses if there's an invalid friend declaration.
-  if (FriendD->isInvalidDecl())
+  // Whitelist accesses if there's an invalid or unsupported friend
+  // declaration.
+  if (FriendD->isInvalidDecl() || FriendD->isUnsupportedFriend())
     return AR_accessible;
 
   if (TypeSourceInfo *T = FriendD->getFriendType())
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index e7714521c84..d11819461ec 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -3410,11 +3410,11 @@ Sema::ActOnFunctionDeclarator(Scope* S, Declarator& D, DeclContext* DC,
         = MatchTemplateParametersToScopeSpecifier(
                                   D.getDeclSpec().getSourceRange().getBegin(),
                                   D.getCXXScopeSpec(),
-                           (TemplateParameterList**)TemplateParamLists.get(),
-                                                  TemplateParamLists.size(),
-                                                  isFriend,
-                                                  isExplicitSpecialization,
-                                                  Invalid)) {
+                                  TemplateParamLists.get(),
+                                  TemplateParamLists.size(),
+                                  isFriend,
+                                  isExplicitSpecialization,
+                                  Invalid)) {
     // All but one template parameter lists have been matching.
     --NumMatchedTemplateParamLists;
 
@@ -3462,7 +3462,7 @@ Sema::ActOnFunctionDeclarator(Scope* S, Declarator& D, DeclContext* DC,
   if (NumMatchedTemplateParamLists > 0 && D.getCXXScopeSpec().isSet()) {
     NewFD->setTemplateParameterListsInfo(Context,
                                          NumMatchedTemplateParamLists,
-                        (TemplateParameterList**)TemplateParamLists.release());
+                                         TemplateParamLists.release());
   }
 
   if (Invalid) {
@@ -3732,14 +3732,20 @@ Sema::ActOnFunctionDeclarator(Scope* S, Declarator& D, DeclContext* DC,
 
     // Qualified decls generally require a previous declaration.
     if (D.getCXXScopeSpec().isSet()) {
-      // ...with the major exception of dependent friend declarations.
-      // In theory, this condition could be whether the qualifier
-      // is dependent;  in practice, the way we nest template parameters
-      // prevents this sort of matching from working, so we have to base it
-      // on the general dependence of the context.
-      if (isFriend && CurContext->isDependentContext()) {
+      // ...with the major exception of templated-scope or
+      // dependent-scope friend declarations.
+
+      // TODO: we currently also suppress this check in dependent
+      // contexts because (1) the parameter depth will be off when
+      // matching friend templates and (2) we might actually be
+      // selecting a friend based on a dependent factor.  But there
+      // are situations where these conditions don't apply and we
+      // can actually do this check immediately.
+      if (isFriend &&
+          (NumMatchedTemplateParamLists ||
+           D.getCXXScopeSpec().getScopeRep()->isDependent() ||
+           CurContext->isDependentContext())) {
         // ignore these
-
       } else {
         // The user tried to provide an out-of-line definition for a
         // function that is a member of a class or namespace, but there
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index be1ee358e2a..583f7c59b41 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -6532,6 +6532,17 @@ Decl *Sema::ActOnFriendFunctionDecl(Scope *S, Declarator &D, bool IsDefinition,
 
   if (ND->isInvalidDecl())
     FrD->setInvalidDecl();
+  else {
+    FunctionDecl *FD;
+    if (FunctionTemplateDecl *FTD = dyn_cast<FunctionTemplateDecl>(ND))
+      FD = FTD->getTemplatedDecl();
+    else
+      FD = cast<FunctionDecl>(ND);
+
+    // Mark templated-scope function declarations as unsupported.
+    if (FD->getNumTemplateParameterLists())
+      FrD->setUnsupportedFriend(true);
+  }
 
   return ND;
 }
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index f85c3f00709..66ded48c240 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -1375,13 +1375,8 @@ Sema::MatchTemplateParametersToScopeSpecifier(SourceLocation DeclStartLoc,
   // If there were at least as many template-ids as there were template
   // parameter lists, then there are no template parameter lists remaining for
   // the declaration itself.
-  if (Idx >= NumParamLists) {
-    // Silently drop template member friend declarations.
-    // TODO: implement these
-    if (IsFriend && NumParamLists) Invalid = true;
-
+  if (Idx >= NumParamLists)
     return 0;
-  }
 
   // If there were too many template parameter lists, complain about that now.
   if (Idx != NumParamLists - 1) {
@@ -1410,11 +1405,6 @@ Sema::MatchTemplateParametersToScopeSpecifier(SourceLocation DeclStartLoc,
     }
   }
 
-  // Silently drop template member template friend declarations.
-  // TODO: implement these
-  if (IsFriend && NumParamLists > 1)
-    Invalid = true;
-
   // Return the last template parameter list, which corresponds to the
   // entity being declared.
   return ParamLists[NumParamLists - 1];
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index c89273567e5..05ade637195 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -908,6 +908,7 @@ void ASTDeclReader::VisitFriendDecl(FriendDecl *D) {
   else
     D->Friend = cast<NamedDecl>(Reader.GetDecl(Record[Idx++]));
   D->NextFriend = cast_or_null<FriendDecl>(Reader.GetDecl(Record[Idx++]));
+  D->UnsupportedFriend = (Record[Idx++] != 0);
   D->FriendLoc = ReadSourceLocation(Record, Idx);
 }
 
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index 0dcc822fbc9..bf7c259635f 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -835,6 +835,7 @@ void ASTDeclWriter::VisitFriendDecl(FriendDecl *D) {
   else
     Writer.AddDeclRef(D->Friend.get<NamedDecl*>(), Record);
   Writer.AddDeclRef(D->NextFriend, Record);
+  Record.push_back(D->UnsupportedFriend);
   Writer.AddSourceLocation(D->FriendLoc, Record);
   Code = serialization::DECL_FRIEND;
 }