Implement support for pack expansions whose pattern is a non-type

template argument (described by an expression, of course). For
example:

  template<int...> struct int_tuple { };

  template<int ...Values>
  struct square {
    typedef int_tuple<(Values*Values)...> type;
  };

It also lays the foundation for pack expansions in an initializer-list.
  

llvm-svn: 122751

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index 4a667cdf57c..99b6daceed9 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -2926,6 +2926,10 @@ MarkUsedTemplateParameters(Sema &SemaRef,
                            bool OnlyDeduced,
                            unsigned Depth,
                            llvm::SmallVectorImpl<bool> &Used) {
+  // We can deduce from a pack expansion.
+  if (const PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(E))
+    E = Expansion->getPattern();
+      
   // FIXME: if !OnlyDeduced, we have to walk the whole subexpression to 
   // find other occurrences of template parameters.
   const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E);