From df0353c0610f4838f6be32608b2eb325a9d60783 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Thu, 4 Jan 2018 01:02:18 +0000
Subject: [PATCH] PR35028: Retain duplicate alignas attributes in template
 instantiation.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@321777 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/Basic/Attr.td   |  1 +
 test/SemaTemplate/alignas.cpp | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/include/clang/Basic/Attr.td b/include/clang/Basic/Attr.td
index 7bb6c30807..a0dc1a2b9a 100644
--- a/include/clang/Basic/Attr.td
+++ b/include/clang/Basic/Attr.td
@@ -552,6 +552,7 @@ def Aligned : InheritableAttr {
                                           Keyword<"_Alignas">]>,
                    Accessor<"isDeclspec",[Declspec<"align">]>];
   let Documentation = [Undocumented];
+  let DuplicatesAllowedWhileMerging = 1;
 }
 
 def AlignValue : Attr {
diff --git a/test/SemaTemplate/alignas.cpp b/test/SemaTemplate/alignas.cpp
index 8a1f96e5bd..680f07b329 100644
--- a/test/SemaTemplate/alignas.cpp
+++ b/test/SemaTemplate/alignas.cpp
@@ -21,3 +21,14 @@ struct C { char a[16]; };
 
 static_assert(sizeof(my_union<A, B, C>) == 16, "");
 static_assert(alignof(my_union<A, B, C>) == 8, "");
+
+namespace PR35028 {
+  template<class X, int Alignment> struct alignas(X) alignas(long long) alignas(long double) alignas(Alignment) Aligned {
+    union {
+      long long align1;
+      long double align2;
+      char data[sizeof(X)];
+    };
+  };
+  Aligned<int, 1> a;
+}
-- 
2.40.0