Fix lookup through injected-class-names in implicit deduction guides in the

case where the class template has a parameter pack.

Checking of the template arguments expects an "as-written" template argument
list, which in particular does not have any parameter packs. So flatten the
packs into separate arguments before passing them in.

llvm-svn: 295710

1 files changed, 10 insertions, 4 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index b285d4f3814..7ccbb8571c5 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -4957,11 +4957,17 @@ NamedDecl *Sema::FindInstantiatedDecl(SourceLocation Loc, NamedDecl *D,
         auto *Guide = dyn_cast<CXXDeductionGuideDecl>(FD);
         if (Guide && Guide->isImplicit()) {
           TemplateDecl *TD = Guide->getDeducedTemplate();
+          // Convert the arguments to an "as-written" list.
           TemplateArgumentListInfo Args(Loc, Loc);
-          for (auto Arg : TemplateArgs.getInnermost().take_front(
-                                      TD->getTemplateParameters()->size()))
-            Args.addArgument(
-                getTrivialTemplateArgumentLoc(Arg, QualType(), Loc));
+          for (TemplateArgument Arg : TemplateArgs.getInnermost().take_front(
+                                        TD->getTemplateParameters()->size())) {
+            ArrayRef<TemplateArgument> Unpacked(Arg);
+            if (Arg.getKind() == TemplateArgument::Pack)
+              Unpacked = Arg.pack_elements();
+            for (TemplateArgument UnpackedArg : Unpacked)
+              Args.addArgument(
+                  getTrivialTemplateArgumentLoc(UnpackedArg, QualType(), Loc));
+          }
           QualType T = CheckTemplateIdType(TemplateName(TD), Loc, Args);
           if (T.isNull())
             return nullptr;