From 98a75581e155a7dac853a69b0151960f8e2aacbd Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Thu, 13 Jun 2013 00:45:47 +0000
Subject: [PATCH] Include the unexpanded packs in the initializer expression
 when checking a pack expanded constructor initializer list. Fixes PR16303!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@183878 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaTemplateInstantiateDecl.cpp      |  3 ++-
 test/CXX/temp/temp.decls/temp.variadic/p5.cpp | 11 +++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 030b9c72c1..c947bcc9f2 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -3165,8 +3165,9 @@ Sema::InstantiateMemInitializers(CXXConstructorDecl *New,
     if (Init->isPackExpansion()) {
       // This is a pack expansion. We should expand it now.
       TypeLoc BaseTL = Init->getTypeSourceInfo()->getTypeLoc();
-      SmallVector<UnexpandedParameterPack, 2> Unexpanded;
+      SmallVector<UnexpandedParameterPack, 4> Unexpanded;
       collectUnexpandedParameterPacks(BaseTL, Unexpanded);
+      collectUnexpandedParameterPacks(Init->getInit(), Unexpanded);
       bool ShouldExpand = false;
       bool RetainExpansion = false;
       Optional<unsigned> NumExpansions;
diff --git a/test/CXX/temp/temp.decls/temp.variadic/p5.cpp b/test/CXX/temp/temp.decls/temp.variadic/p5.cpp
index 945379872f..218990e9bb 100644
--- a/test/CXX/temp/temp.decls/temp.variadic/p5.cpp
+++ b/test/CXX/temp/temp.decls/temp.variadic/p5.cpp
@@ -410,3 +410,14 @@ namespace WorkingPaperExample {
     f(h(args ...) + args ...);
   }
 }
+
+namespace PR16303 {
+  template<int> struct A { A(int); };
+  template<int...N> struct B {
+    template<int...M> struct C : A<N>... {
+      C() : A<N>(M)... {} // expected-error{{pack expansion contains parameter packs 'N' and 'M' that have different lengths (2 vs. 3)}} expected-error{{pack expansion contains parameter packs 'N' and 'M' that have different lengths (4 vs. 3)}}
+    };
+  };
+  B<1,2>::C<4,5,6> c1; // expected-note{{in instantiation of}}
+  B<1,2,3,4>::C<4,5,6> c2; // expected-note{{in instantiation of}}
+}
-- 
2.40.0